Social work

The work undertaken by professional social workers is shaped by the cultural and social norms of the society in which they operate. However, the relationship between social workers and people who use social services within capitalist societies has always been difficult to determine. The attitudes of social workers can range from solidarity with oppressed service users to outright contempt for the "undeserving poor" and everything in between.

Professional social workers have a strong tradition of working for social justice, and of refusing to recreate unequal social structures. This means going beyond state sponsored practices which merely cater for individual needs, in order to transform society as a whole. Social work maintains this radical kernel and today many social workers internationally have strong connections with social and political movements for the emancipation of the oppressed.

The main tasks of professional social workers are case management (linking clients with agencies and programs that will meet their psychosocial needs), medical social work, counseling (psychotherapy), human services management, social welfare policy analysis, community organizing, advocacy, teaching (in schools of social work), and social science research.

Professional social workers work in a variety of settings, including: non-profit or public social service agencies, grassroots advocacy organizations, hospitals, hospices, community health agencies, schools, faith-based organizations, and even the military. Other social workers work as psychotherapists, counselors, or mental health practitioners, normally working in coordination with psychiatrists, psychologists, or other medical professionals. Additionally, some social workers have chosen to focus their efforts on social policy or academic research into the practice or ethics of social work. The emphasis has varied among these task areas by historical era and country, and some of these areas have been the subject of controversy as to whether they are properly part of social work's mission.

[edit] Role of social work in the USA

In the United States of America, leaders and scholars in the field of social work have debated the purpose and nature of the profession since its beginning in the late 1800s. Workers, beginning with the settlement house movement, have argued for a focus on social reform, political activism, and systemic causes of poverty. Social workers of the Settlement House Movement were primarily young women from middle-income families and chose to live in lower-income neighbourhoods to engage in community organizing. These workers sometimes received stipends from charitable organizations and sometimes worked for free. Formal training programs for these workers became available later in the movement.

In contrast to the settlement house movement, the friendly visitors were women from middle-income families who visited (but did not reside among) families in lower-income neighbourhoods. Friendly visitors emphasized conventional morality (such as thrift and abstinence from alcohol) rather than social activism.

Others have advocated an emphasis on direct practice, aid to individual clients and families with targeted material assistance or interventions using the diagnostic and statistical manual of mental diseases DSM-IV. While social work has been defined as direct, individual practice in last quarter of the twentieth century, there is a growing resurgence of community practice in social work. Of broad and growing significance are the relationship counseling and Relationship Education movements which seek to assist in interpersonal social skill building which can be of great societal value in promoting marriage and family stability. Relationship education and counseling primarily aid that majority of individuals who are free of pathology or who have found that DSM-IV based services are ineffectual. This majority can benefit from education and exposure to relationship skills that have not otherwise been discussed and distributed by social services in this time of weakened family, church, and societal conventions.

Community practice is the new term of art for what used to be known as "macro practice" social work. Community practice includes working for change at the systems level, including human services management (administration, planning, marketing, and program development); community organizing (community development, Grassroots Organizing, policy advocacy); social policy and politics; and international social development.

The National Association of Social Workers (NASW) is the largest and most recognized membership organization of professional social workers in the world. Representing 150,000 members from 56 chapters in the United States and abroad, the association promotes, develops and protects the practice of social work and social workers. NASW also seeks to enhance the well-being of individuals, families, and communities through its work and advocacy.

Although membership is generally not required for licensure, NASW survey data give a rough idea of how social workers are employed in the US. According to NASW:

Nearly 40% of NASW members say that mental health is their primary practice area. The health sector employs 8% of NASW’s members, and 8% practice in child welfare or family organizations. Six percent of NASW members say school social work is their primary practice area, and another 3% work primarily with adolescents. (NASW, 2005) These figures are significantly confounded by the fact that NASW members are primarily licensed practitioners working in the clinical arena, and the fact that many social workers in the field do not actually hold a degree in social work. NASW is usually concerned with issues like licensing, reimbursement, etc., that are not relevant to child welfare practice, for instance.

Within the mental health field, social workers may work in private practice, much like clinical psychologists or members of other counselling professions often do. Social workers are often in the position of recommending the use of psychopharmaceutical agents, though not prescribing them. The increasingly widespread usage of these agents in the U.S. has received little scrutiny by the NASW, despite that fact that these drugs are prescribed far more heavily in the U.S. than anywhere else in the world. Social workers in private practice may take direct payments from clients and may also receive third-party reimbursement from insurance companies or government programs such as Medicaid. Insurance reimbursement for mental health services involves the designation of the recipient of services as mentally ill, or more specifically a label is assigned from the DSM-IV, the diagnostic and statistical manual of mental illness. This assignment, when recorded to an individual's medical history can prove to be a significant impediment to future pursuits. It can raise the cost to the individual for health or nursing home insurance; it can be the basis of denial for life insurance; and it can limit an individual's professional choices, such as in health care, motor vehicle operation, or airplane piloting.

Private practice was not part of the social work profession when it began in the late 1800s, and private practice has been controversial among social workers, some of whom feel that the more lucrative opportunities of private practice have led many social workers to abandon the field's historic mission of assisting disadvantaged populations. The private practice model can be at odds with the community development and political activism strains of social work.

Social workers in mental health may also work for an agency, whether publicly funded, supported by private charity, or some combination of the two. These agencies provide a range of mental health services to disadvantaged populations in the US.

Some social workers are child welfare workers, a role that looms large in the public's perception of social work. This role contributes to a negative view of social work in the U.S., since child welfare authorities can remove abused or neglected children from the custody of their parents, a practice that is fraught with controversy and sometimes with scandalous incompetence. Many child welfare workers in the US do not in fact have social work degrees (though all caseworkers in most states have at least a Bachelor's degree in a related field).

Some states restrict the use of the title social worker to licensed practitioners, who must hold a degree in the field. Such restrictions are a high legislative priority of NASW.

[edit] Role of social work in the United Kingdom

In the United Kingdom and elsewhere, a social worker is a trained professional with a recognised social work qualification, employed most commonly in the public sector by local authorities.

Spending on social services departments is a major component of British local government expenditure.

In the UK, the title "social worker" is protected by law (since 1 April 2005) and can be used only by people who have a recognised qualification and are registered with the General Social Care Council (in England), the Scottish Social Services Council, the Care Council for Wales (Welsh: Cyngor Gofal Cymru), or the Northern Ireland Social Care Council.

The strategic direction of statutory social work in Britain is broadly divided into children's and adults' services. Social work activity within England and Wales for children and young people is under the remit of the Department for Education and Skills while the same for adults remains the responsibility for the Department of Health. Within local authorities, this division is usually reflected in the organisation of social services departments. The structure of service delivery in Scotland is different.

Within children services some social workers are child protection workers, a role that looms large in the public's perception of social work. This role contributes to a negative view of social work in the U.K., since child protection workers for local authorities can remove suspected abused or neglected children from the custody of their parents, a practice that is fraught with controversy and media critisism.

In 2007, the General Social Care Council launched a wide-ranging consultation, in concert with a number of other social care organisations, to agree a clear professional understanding of social work in the UK [1]

[edit] Social Work Knowledge Building

The history of social work is a history plagued by a fundamental question – is social work a profession? This debate can be traced back to the early 20th century debate between Mary Richmond's Charity Organization Society (COS) and Jane Adam's Settlement House Movement. The essence of this debate was whether the problem should be approached from COS’ traditional, scientific method focused on efficiency and prevention or the Settlement House Movement’s immersion into the problem, blurring the lines of practitioner and client.

The impetus for both movements was the glaring reality of social problems and the question over how to best attack them. This debate is arguably the earliest example of a larger debate within social work – how is knowledge acquired? This debate pits positivism against post-positivism in the pursuit of achieving respect as a profession. The positivistic argument asserts knowledge has to be observable and testable (quantitative), free from bias, and ultimately replicable if it is to have any merit. Post-positivists argue there is no way to completely eliminate bias, and knowledge can be obtained via qualitative research methods.

The debate reached its greatest intensity in the 1980s, reflecting the debate within the larger world of the social sciences. Subsequently, most of those interested in social work knowledge building have joined in a consensus that both perspectives are necessary to fully understand the the complex realities encountered by social work practitioners. Today, most text books intended for social work research courses, while they may devote more pages to quantitative approaches, also include one or more chapters on qualitative approaches, and make an effort not to favor one over the other.

Meanwhile, practitioners, and often educators in social work practice, have felt left out of the debate. A frequent complaint was that social work programs were favoring research over practice skills in faculty hiring, thus weakening their ability to teach practice skills to new practitioners. The reliance among practitioners on shared practice wisdom, and the development of skills and techniques through clinical supervision and mentorship was not considered as valid as knowledge building by either camp. There have been attempts to bridge the gap between practice-based knowledge and knowledge obtained through more formal research approaches. One such strategy is single-subject research--also known s Single Subject Design (SSD), in which the clinician, working together with the client, carefully specifies a target of intervention, then measures its frequency, duration, intensity, or any relevant characteristics during a baseline period when no intervention is tried. Following this, an intervention is introduced, and measurement of the target problem is continued. Two claims made for SSD were that it would improve clinical work, since effectiveness of interventions could be determined, and that single cases could be aggregated into research reports, which, published, would constite an empirically verified set of interventions for clinical use. Although SSD has been championed by social work graduate programs for more than two decades, there is little evidence that it has been widely adopted by social work practitioners.

The current state of social work knowledge building is characterized by two realities. There is a great deal of traditional research, both qualitative and quantitative being carried out, primarily by university-based researchers, but also in different fields, by researchers based in institutes, foundations, or social service agencies. Meanwhile, the majority of social work practitioners continue to look elsewhere for knowledge. This is a state of affairs that has persisted since the outset of the profession in the first decade of the twentieth century. One reason for the practice-research gap is that practitioners deal with situations that are unique and idiosyncratic, while research deals with regularities and aggregates. The translation between the two is often imperfect. A hopeful development for bridging this gap is the compilation in many practice fields of collections of "best practices," largely taken from research findings, but also distilled from the experience of respected practitioners.

[edit] Levels of professional social work intervention

Three Levels on intervention: Micro (individual) Mezzo (group) and Macro (organizations & Communities)

[edit] Clinical or Direct Practice

* Assessment and diagnosis
* Adult Therapy
* Brief therapies
* Case management
* Child/Adolescent Therapy
* Clinical supervision
* Counselling
* Crisis intervention
* Family therapy/Family interventions
* Gerontology
* Group work/group therapy
* Employee assistance programs
* Medical social work
* Psychosocial and psychoeducational interventions
* Psychotherapy
* Relationship counseling
* Relationship/interpersonal counselling
* Relationship Education

[edit] Community practice

* Community organizing
* Community development
* Community economic development
* Community education
* International development
* Management
* Mediation
* Neighborhood development
* Policy advocacy
* Policy analysis
* Political social work
* Program development
* Program evaluation
* Research
* Social planning

[edit] Fields of professional social work practice (both direct and community levels)

* Aging or gerontology
o Nursing home
o Hospice
* Anti-poverty
o Income assistance
o Job training/placement
* Anti-racism
* Child welfare
o Adoption
o Child abuse
o Foster care
* Disability services
* Family planning
* Food bank programs
* Forensic Social Work programs
* Health and wellness
o Hospital social work
* Housing and homelessness
* Immigrant and refugee services and supports
* Juvenile and criminal justice
* Lesbian, gay, bisexual and transgendered supports
* Medical Social Work
* Mental Health
* Praxis intervention
* Religious and spiritual settings
* Substance abuse
* School social worker
* Violence prevention

[edit] Qualifications for professional social work

In a number of countries and jurisdictions where registration of people working as social workers is required there are mandated qualifications, those required in the UK and USA are detailed below, in other places the professional association sets academic and experiential requirements for admission to membership. Illustrating the success of these professional bodies in many places these requirements are recognised by many employers as necessary for employment by those agencies.

[edit] Qualifications for social work in the USA

Main articles: Council on Social Work Education and Master of Social Work

A social worker practicing in the United States usually requires a master's degree (MSW) or a bachelor's degree (BSW) in social work from a Council on Social Work Education accredited program to receive a license in most states. In some areas, however, a social worker may be able to receive a license with a bachelor's degree in any discipline. The National Association of Social Workers (NASW) is the largest organization of professional social workers in the United States.

A person with a BSW is considered a "generalist" and the MSW is considered "a specialist or advanced generalist"; a Ph.D. or D.S.W. (Doctor of Social Work) generally conducts research, teaches, or analyzes policy, often in higher education settings.

Various states in the United States "protect" the use of the title social worker by statute. Use of the title requires licensure or certification in most states. A number of states have different levels of licensure, Maryland being one example.

[edit] Qualifications for social work in the UK

The main qualification for social work is the undergraduate Bachelor's degree (BA, BSc or BSW) in social work, offered at British universities from September 2003 onwards. There is also available a master's degree (MA, MSc or MSW). These have replaced the previous qualifying award, the postgraduate Diploma in Social Work (DipSW), which was first awarded in 1991 and will be phased out across the UK by 2009. Prior to this, the recognised qualification was the Certificate of Qualification in Social Work (CQSW), awarded between 1975 and 1991.

Purporting to be either a social worker or a student social worker without registering with the Social Work Register and holding or undergoing training for the recognised qualifications is now a criminal offence. Social workers must renew their registration every three years. These regulations offer protection to vulnerable people by guaranteeing the professional regulation of people working as social workers. They also promote workforce development, as all social workers must participate in at least fifteen days of professional training over a three year period in order to be eligible for renewal of their registration.

After qualifying, social workers can undertake further training under the social work 'Post-Qualifying Framework'. Until 2007, there are four awards available under this framework:

* Post-Qualifying Award - for advanced social work practice and management
* Mental Health Social Work award (in England, Approved Social Worker award; in Scotland, Mental Health Officer award) - qualification to work with people with mental health needs under the Mental Health Act
* Child Care Award - qualification to work with children and young people
* Practice Teaching Award - qualification to work as a tutor, supervisor and assessor for social work students on their work placement

From 2007, the General Social Care Council and UK partners are implementing a new framework which unifies these awards in a simpler structure allowing broader study to count towards three levels of social work award: specialist, higher specialist, and advanced.

[edit] Qualifications for social work in Australia

A four-year Bachelor of Social Work (BSW) is required for entry into the occupation of Social Worker in Australia, although some universities also offer a two-year, accelerated, graduate-entry BSW. Whilst there are no legal registration requirements, most employers stipulate that applicants must be eligible for membership of the Australian Association of Social Workers (Australia) (AASW). Only graduates of courses recognised by the AASW are eligible for membership. Continuing Professional Education (CPE) is an ongoing requirement of accredited membership of the AASW and must incorporate accountability, gaining new knowledge and information & skill development (CPE Policy 2006, AASW). A person with overseas qualifications can apply for consideration of recognition of their qualifications via a formal application for assessment by the AASW.

[edit] Qualifications for social work in Canada

A four-year Bachelor of Social Work (BSW) is required for entry into the field. A Masters Degree in Social Work (MSW) is usually required to provide psychotherapy treatment. In Canada social workers may provide treatment but cannot diagnose.

Wind power

Global Wind Energy Council (GWEC) figures show that 2006 recorded an increase of installed capacity of 15,197 megawatts (MW), taking the total installed wind energy capacity to 74,223 MW, up from 59,091 MW in 2005. Despite constraints facing supply chains for wind turbines, the annual market for wind continued to increase at an estimated rate of 32% following the 2005 record year, in which the market grew by 41%. In terms of economic value, the wind energy sector has become one of the important players in the energy markets, with the total value of new generating equipment installed in 2006 reaching €18 billion, or US$23 billion. [3]

The countries with the highest total installed capacity are Germany (20,621 MW), Spain (11,615 MW), the USA (11,603 MW), India (6,270 MW) and Denmark (3,136). Thirteen countries around the world can now be counted among those with over 1000 MW of wind capacity. In terms of new installed capacity in 2006, the US lead with 2,454 MW, followed by Germany (2,233 MW), India (1,840 MW), Spain (1,587 MW), China (1,347 MW) and France (810 MW).[3]

In 2004, wind energy cost one-fifth of what it did in the 1980s, and some expected that downward trend to continue as larger multi-megawatt turbines are mass-produced.[4] However, installation costs have increased significantly in 2005 and 2006, and according to the major U.S. wind industry trade group, now average over 1600 U.S. dollars per kilowatt,[5] compared to $1200/kW just a few years before. A British Wind Energy Association report gives an average generation cost of onshore wind power of around 3.2 pence per kilowatt hour (2005).[6] Cost per unit of energy produced was estimated in 2006 to be comparable to the cost of new generating capacity in the United States for coal and natural gas: wind cost was estimated at $55.80 per MWh, coal at $53.10/MWh and natural gas at $52.50.[7] Other sources in various studies have estimated wind to be more expensive than other sources (see Economics of new nuclear power plants, Clean coal, and Carbon capture and storage).

Most major forms of electricity generation are capital intensive, meaning that they require substantial investments at project inception, and low ongoing costs (generally for fuel and maintenance). This is particularly true for wind and hydro power, which have fuel costs close to zero and relatively low maintenance costs; in economic terms, wind power has an extremely low marginal cost and a high proportion of up-front capital costs. The estimated "cost" of wind energy per unit of production is generally based on average cost per unit, which incorporates the cost of construction, borrowed funds, return to investors (including cost of risk), estimated annual production, and other components. Since these costs are averaged over the projected useful life of the equipment, which may be in excess of twenty years, cost estimates per unit of generation are highly dependent on these assumptions. Figures for cost of wind energy per unit of production cited in various studies can therefore differ substantially. The cost of wind power also depends on several other factors, such as installation of power lines from the wind farm to the national grid and the frequency of wind at the site in question.

Estimates for cost of production use similar methodologies for other sources of electricity generation. Existing generation capacity represents sunk costs, and the decision to continue production will depend on marginal costs going forward, not estimated average costs at project inception. For example, the estimated cost of new wind power capacity may be lower than that for "new coal" (estimated average costs for new generation capacity) but higher than for "old coal" (marginal cost of production for existing capacity). Therefore, the choice to increase wind capacity by building new facilities will depend on more complex factors than cost estimates, including the profile of existing generation capacity.

Research from a wide variety of sources in various countries shows that support for wind power is consistently between 70 and 80 per cent amongst the general public.[8]

[edit] Wind energy

Main article: Wind

An estimated 1% to 3% of energy from the Sun that hits the earth is converted into wind energy. This is about 50 to 100 times more energy than is converted into biomass by all the plants on Earth through photosynthesis.[citation needed] Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) occur. Eventually, the wind energy is converted through friction into diffuse heat throughout the Earth's surface and the atmosphere.

The origin of wind is complex. The Earth is unevenly heated by the sun resulting in the poles receiving less energy from the sun than the equator does. Also the dry land heats up (and cools down) more quickly than the seas do. The differential heating powers a global atmospheric convection system reaching from the Earth's surface to the stratosphere which acts as a virtual ceiling.

[edit] Wind variability and turbine power
A Darrieus wind turbine.
A Darrieus wind turbine.

The power in the wind can be extracted by allowing it to blow past moving wings that exert torque on a rotor. The amount of power transferred is directly proportional to the density of the air, the area swept out by the rotor, and the cube of the wind speed.

The power P available in the wind is given by:

P = \begin{matrix}\frac{1}{2}\end{matrix}\rho\pi R^2 v^3

The mass flow of air that travels through the swept area of a wind turbine varies with the wind speed and air density. As an example, on a cool 15°C (59°F) day at sea level, air density is 1.225 kilograms per cubic metre. An 8 m/s breeze blowing through a 100 meter diameter rotor would move almost 77,000 kilograms of air per second through the swept area.

The kinetic energy of a given mass varies with the square of its velocity. Because the mass flow increases linearly with the wind speed, the wind energy available to a wind turbine increases as the cube of the wind speed. The power of the example breeze above through the example rotor would be about 2.5 megawatts.

As the wind turbine extracts energy from the air flow, the air is slowed down, which causes it to spread out and diverts it around the wind turbine to some extent. Albert Betz, a German physicist, determined in 1919 (see Betz' law) that a wind turbine can extract at most 59% of the energy that would otherwise flow through the turbine's cross section. The Betz limit applies regardless of the design of the turbine.
Distribution of wind speed (red) and energy (blue) for all of 2002 at the Lee Ranch facility in Colorado. The histogram shows measured data, while the curve is the Rayleigh model distribution for the same average wind speed. Energy is the Betz limit through a 100 meter diameter circle facing directly into the wind. Total energy for the year through that circle was 15.4 gigawatt-hours.
Distribution of wind speed (red) and energy (blue) for all of 2002 at the Lee Ranch facility in Colorado. The histogram shows measured data, while the curve is the Rayleigh model distribution for the same average wind speed. Energy is the Betz limit through a 100 meter diameter circle facing directly into the wind. Total energy for the year through that circle was 15.4 gigawatt-hours.

The Big Spring Wind Power Project in Texas has 46 wind turbines that generate enough electricity to power 7,300 homes.

Windiness varies, and an average value for a given location does not alone indicate the amount of energy a wind turbine could produce there. To assess the climatology of wind speeds at a particular location, a probability distribution function is often fit to the observed data. Different locations will have different wind speed distributions. The distribution model most frequently used to model wind speed climatology is a two-parameter Weibull distribution because it is able to conform to a wide variety of distribution shapes, from Gaussian to exponential. The Rayleigh model, an example of which is shown plotted against an actual measured dataset, is a specific form of the Weibull function in which the shape parameter equals 2, and very closely mirrors the actual distribution of hourly wind speeds at many locations.

Because so much power is generated by higher windspeed, much of the average power available to a windmill comes in short bursts. The 2002 Lee Ranch sample is telling; half of the energy available arrived in just 15% of the operating time. The consequence of which, is that wind energy does not have as consistent an output as fuel-fired power plants; additional output can only be made to compensate for load increase by utilizing advanced wind storing technologies (e.g. giant compressed air storage-tank facilities). — Since wind speed is not constant, a wind generator's annual energy production is never as much as its nameplate rating multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. A well-sited wind generator will have a capacity factor of about 35%. This compares to typical capacity factors of 90% for nuclear plants, 70% for coal plants, and 30% for oil plants.[9] When comparing the size of wind turbine plants to fueled power plants, it is important to note that 1000 kW of wind-turbine potential power would be expected to produce as much energy in a year as approximately 500 kW of coal-fired generation. Though the short-term (hours or days) output of a wind-plant is not completely predictable, the annual output of energy tends to vary only a few percent points between years. — When storage, such as with pumped hydroelectric storage, or other forms of generation are used to "shape" wind power (by assuring constant delivery reliability), commercial delivery represents a cost increase of about 25%, yielding viable commercial performance.[10] Electricity consumption can be adapted to production variability to some extent with Energy Demand Management and smart meters that offer variable market pricing over the course of the day. For example, municipal water pumps that feed a water tower do not need to operate continuously and can be restricted to times when electricity is plentiful and cheap. Consumers could choose when to run the dishwasher or charge an electric vehicle, making it very convenient.

[edit] Turbine siting
Map of available wind power over the United States. Color codes indicate wind power density class.
Map of available wind power over the United States. Color codes indicate wind power density class.

As a general rule, wind generators are practical where the average wind speed is 10 mph (16 km/h or 4.5 m/s) or greater. Usually sites are pre-selected on basis of a wind atlas, and validated with wind measurements. Obviously, meteorology plays an important part in determining possible locations for wind parks, though it has great accuracy limitations. Meteorological wind data is not usually sufficient for accurate siting of a large wind power project. An 'ideal' location would have a near constant flow of non-turbulent wind throughout the year and would not suffer too many sudden powerful bursts of wind. An important turbine siting factor is access to local demand or transmission capacity.

The wind blows faster at higher altitudes because of the reduced influence of drag of the surface (sea or land) and the reduced viscosity of the air. The increase in velocity with altitude is most dramatic near the surface and is affected by topography, surface roughness, and upwind obstacles such as trees or buildings. Typically, the increase of wind speeds with increasing height follows a logarithmic profile that can be reasonably approximated by the wind profile power law, using an exponent of 1/7th, which predicts that wind speed rises proportionally to the seventh root of altitude. Doubling the altitude of a turbine, then, increases the expected wind speeds by 10% and the expected power by 34% (calculation: increase in power = (2.0) ^(3/7) – 1 = 34%).

Wind farms or wind parks often have many turbines installed. Since each turbine extracts some of the energy of the wind, it is important to provide adequate spacing between turbines to avoid excess energy loss. Where land area is sufficient, turbines are spaced three to five rotor diameters apart perpendicular to the prevailing wind, and five to ten rotor diameters apart in the direction of the prevailing wind, to minimize efficiency loss. The "wind park effect" loss can be as low as 2% of the combined nameplate rating of the turbines.

Utility-scale wind turbine generators have minimum temperature operating limits which restrict the application in areas that routinely experience temperatures less than −20°C. Wind turbines must be protected from ice accumulation, which can make anemometer readings inaccurate and which can cause high structure loads and damage. Some turbine manufacturers offer low-temperature packages at a few percent extra cost, which include internal heaters, different lubricants, and different alloys for structural elements, to make it possible to operate the turbines at lower temperatures. If the low-temperature interval is combined with a low-wind condition, the wind turbine will require station service power, equivalent to a few percent of its output rating, to maintain internal temperatures during the cold snap. For example, the St. Leon, Manitoba project has a total rating of 99 MW and is estimated to need up to 3 MW (around 3% of capacity) of station service power a few days a year for temperatures down to −30°C. This factor affects the economics of wind turbine operation in cold climates.[citation needed]

[edit] Onshore

Onshore turbine installations in hilly or mountainous regions tend to be on ridgelines generally three kilometers or more inland from the nearest shoreline. This is done to exploit the so-called topographic acceleration. The hill or ridge causes the wind to accelerate as it is forced over it. The additional wind speeds gained in this way make large differences to the amount of energy that is produced. Great attention must be paid to the exact positions of the turbines (a process known as micro-siting) because a difference of 30 m can sometimes mean a doubling in output. Local winds are often monitored for a year or more with anemometers and detailed wind maps constructed before wind generators are installed.

For smaller installations where such data collection is too expensive or time consuming, the normal way of prospecting for wind-power sites is to directly look for trees or vegetation that are permanently "cast" or deformed by the prevailing winds. Another way is to use a wind-speed survey map, or historical data from a nearby meteorological station, although these methods are less reliable.

Wind farm siting can sometimes be highly controversial, particularly as the hilltop, often coastal sites preferred are often picturesque and environmentally sensitive (for instance, having substantial bird life). Local residents in a number of potential sites have strongly opposed the installation of wind farms, and political support has resulted in the blocking of construction of some installations.[11]

[edit] Near-Shore

Near-Shore turbine installations are generally considered to be inside a zone that is on land within three kilometers of a shoreline and on water within ten kilometers of land. Wind speeds in these zones share wind speed characteristics of both onshore wind and offshore wind depending on the prevailing wind direction. Common issues that are shared within Near-shore wind development zones are aviary (including bird migration and nesting), aquatic habitat, transportation (including shipping and boating) and visual aesthetics amongst several others.

Sea shores also tend to be windy areas and good sites for turbine installation, because a primary source of wind is convection from the differential heating and cooling of land and sea over the course of day and night. Winds at sea level carry somewhat more energy than winds of the same speed in mountainous areas because the air at sea level is more dense.

Near-shore wind farm siting can sometimes be highly controversial as coastal sites are often picturesque and environmentally sensitive (for instance, having substantial bird life). Local residents in a number of potential sites have strongly opposed the installation of wind farms due to visual aesthetic concerns.

[edit] Offshore
Offshore wind turbines near Copenhagen
Offshore wind turbines near Copenhagen

Offshore wind development zones are generally considered to be ten kilometers or more from land. Offshore wind turbines are less obtrusive than turbines on land, as their apparent size and noise can be mitigated by distance. Because water has less surface roughness than land (especially deeper water), the average wind speed is usually considerably higher over open water. Capacity factors (utilisation rates) are considerably higher than for onshore and near-shore locations which allows offshore turbines to use shorter towers, making them less visible.

In stormy areas with extended shallow continental shelves (such as Denmark), turbines are practical to install — Denmark's wind generation provides about 18% of total electricity demand in the country, with many offshore windfarms. Denmark plans to increase wind energy's contribution to as much as half of its electrical supply.

Locations have begun to be developed in the Great Lakes - with one project by Trillium Power approximately 20 km from shore and over 700 MW in size. Ontario, Canada is aggressively pursuing wind power development and has many onshore wind farms and several proposed near-shore locations but presently only one offshore development.

In most cases offshore environment is more expensive than onshore. Offshore towers are generally taller than onshore towers once the submerged height is included, and offshore foundations are more difficult to build and more expensive. Power transmission from offshore turbines is generally through undersea cable, which is more expensive to install than cables on land, and may use high voltage direct current operation if significant distance is to be covered — which then requires yet more equipment. Offshore saltwater environments can also raise maintenance costs by corroding the towers, but fresh-water locations such as the Great Lakes do not. Repairs and maintenance are usually much more difficult, and generally more costly, than on onshore turbines. Offshore saltwater wind turbines are outfitted with extensive corrosion protection measures like coatings and cathodic protection, which may not be required in fresh water locations.

While there is a significant market for small land-based windmills, offshore wind turbines have recently been and will probably continue to be the largest wind turbines in operation, because larger turbines allow for the spread of the high fixed costs involved in offshore operation over a greater quantity of generation, reducing the average cost. For similar reasons, offshore wind farms tend to be quite large—often involving over 100 turbines—as opposed to onshore wind farms which can operate competitively even with much smaller installations.

[edit] Airborne

Main article: Airborne wind turbine

Wind turbines might also be flown in high speed winds at altitude,[12] although no such systems currently exist in the marketplace. An Ontario (Canada) company, Magenn Power, Inc., is attempting to commercialize tethered aerial turbines suspended with helium[13]

The Italian project called "Kitegen" uses a prototype vertical-axis wind turbine. It is an innovative plan (still in the construction phase) that consists of one wind farm with a vertical spin axis, and employs kites to exploit high-altitude winds. The Kite Wind Generator (KWG) or KiteGen is claimed to eliminate all the static and dynamic problems that prevent the increase of the power (in terms of dimensions) obtainable from the traditional horizontal-axis wind turbine generators. A number of other designs for vertical-axis turbines have been developed or proposed, including small scale commercial or pilot installations. However, vertical-axis turbines remain a commercially unproven technology.

[edit] Utilization

[edit] Large scale
Total installed windpower capacity
(end of year data)[3][14]
Rank Nation 2005 (MW) 2006 (MW) Latest(MW)
1 Germany 18,415 20,622
2 Spain 10,028 11,615
3 United States 9,149 11,603 11,699
4 India 4,430 6,270 7,086
5 Denmark (incl. Faroe) 3,136 3,140
6 China 1,260 2,604
7 Italy 1,718 2,123
8 United Kingdom 1,332 1,963 2,144
9 Portugal 1,022 1,716
10 France 757 1,567
11 Netherlands 1,219 1,560
12 Canada 683 1,459 1,492
13 Japan 1,061 1,394
14 Austria 819 965
15 Australia 708 817
16 Greece 573 746
17 Ireland 496 745
18 Sweden 510 572
19 Norway 267 314
20 Brazil 29 237
21 Egypt 145 230
22 Belgium 167 193
23 Taiwan 104 188
24 South Korea 98 173
25 New Zealand 169 171
26 Poland 83 153 216.5
27 Morocco 64 124
28 Mexico 3 88
29 Finland 82 86
30 Ukraine 77 86
31 Costa Rica 71 74
32 Hungary 18 61
33 Lithuania 6 55
34 Turkey 20 51
35 Czech Republic 28 50
36 Iran 23 48
Rest of Europe 129 163
Rest of Americas 109 109
Rest of Asia 38 38
Rest of Africa & Middle East 31 31
Rest of Oceania 12 12
World total 59,091 MW 74,223 MW

There are many thousands of wind turbines operating, with a total capacity of 58,982 MW of which Europe accounts for 69% (2005). The average output of one megawatt of wind power is equivalent to the average consumption of about 160 American households. Wind power was the most rapidly-growing means of alternative electricity generation at the turn of the century and world wind generation capacity more than quadrupled between 1999 and 2005. 90% of wind power installations are in the US and Europe, but the share of the top five countries in terms of new installations fell from 71% in 2004 to 55% in 2005. By 2010, the World Wind Energy Association expects 160,000 MW to be installed worldwide,[15] implying an anticipated growth rate of more than 15% per year.

Germany, Spain, the United States, India, and Denmark have made the largest investments in wind generated electricity. Denmark is prominent in the manufacturing and use of wind turbines, with a commitment made in the 1970s to eventually produce half of the country's power by wind. Denmark generates over 20% of its electricity with wind turbines, the highest percentage of any country and is fifth in the world in total power generation (which can be compared with the fact that Denmark is 56th on the general electricity consumption list). Denmark and Germany are leading exporters of large (0.66 to 5 MW) turbines.

Wind accounts for 1% of the total electricity production on a global scale (2005). Germany is the leading producer of wind power with 32% of the total world capacity in 2005 (6% of German electricity); the official target is that by 2010, renewable energy will meet 12.5% of German electricity needs — it can be expected that this target will be reached even earlier. Germany has 16,000 wind turbines, mostly in the north of the country — including three of the biggest in the world, constructed by the companies Enercon (6 MW), Multibrid (5 MW) and Repower (5 MW). Germany's Schleswig-Holstein province generates 35% of its power with wind turbines.

Spain and the United States are next in terms of installed capacity. In 2005, the government of Spain approved a new national goal for installed wind power capacity of 20,000 MW by 2012. According to trade journal Windpower Monthly; however, in 2006 they abruptly halted subsidies and price supports for wind power. According to the American Wind Energy Association, wind generated enough electricity to power 0.4% (1.6 million households) of total electricity in US, up from less than 0.1% in 1999. In 2005, both Germany and Spain have produced more electricity from wind power than from hydropower plants. US Department of Energy studies have concluded wind harvested in just three of the fifty U.S. states could provide enough electricity to power the entire nation, and that offshore wind farms could do the same job.[10] Wind power growth was estimated at up to 50% in the U.S. in 2006,[16] and has reached 11,603 MW of installed capacity for growth of 27% in one year.[17]

India ranks 4th in the world with a total wind power capacity of 6,270 MW. Wind power generates 3% of all electricity produced in India. The World Wind Energy Conference in New Delhi in November 2006 has given additional impetus to the Indian wind industry.[15] The windfarm near Muppandal, India, provides an impoverished village with energy for work.[18][19] India-based Suzlon Energy is one of the world's largest wind turbine manufacturers.[20]

In December 2003, General Electric installed the world's largest offshore wind turbines in Ireland, and plans are being made for more such installations on the west coast, including the possible use of floating turbines.

On August 15, 2005, China announced it would build a 1000-megawatt wind farm in Hebei for completion in 2020. China reportedly has set a generating target of 20,000 MW by 2020 from renewable energy sources — it says indigenous wind power could generate up to 253,000 MW. Following the World Wind Energy Conference in November 2004, organised by the Chinese and the World Wind Energy Association, a Chinese renewable energy law was adopted. In late 2005, the Chinese government increased the official wind energy target for the year 2020 from 20 GW to 30 GW.[21]

Mexico recently opened La Venta II wind power project as an important step in reducing Mexico´s consumption of fossil fuels. The project (88MW) the first of its kind in Mexico, will provide 13 percent of the electricity needs of the state of Oaxaca and by 2012 will have a capacity of 3500MW.

Another growing market is Brazil, with a wind potential of 143 GW.[22] The federal government has created an incentive program, called Proinfa,[23] to build production capacity of 3300 MW of renewable energy for 2008, of which 1422 MW through wind energy. The program seeks to produce 10% of Brazilian electricity through renewable sources. Brazil produced 320 TWh in 2004. France recently announced a very ambitious target of 12 500 MW installed by 2010.
View of wind farm near Muppandal in India
View of wind farm near Muppandal in India

Over the 7 years from 2000-2006, Canada experienced rapid growth of wind capacity — moving from a total installed capacity of 137 MW to 1,451 MW, and showing a growth rate of 38% and rising.[24] Particularly rapid growth has been seen in 2006, with total capacity growing to 1,451 MW by December, 2006, doubling the installed capacity from the 684 MW at end-2005.[25] This growth was fed by provincial measures, including installation targets, economic incentives and political support. For example, the government of the Canadian province of Ontario announced on 21 March 2006 that it will introduce a feed-in tariff for wind power, referred to as 'Standard Offer Contracts', which may boost the wind industry across the province.[26] In the Canadian province of Quebec, the state-owned hydroelectric utility plans beside current wind farm projects to purchase an additional 2000 MW by 2013.[27]

[edit] Small scale
This rooftop-mounted urban wind turbine charges a 12 volt battery and runs various 12 volt appliances within the building on which it is installed.
This rooftop-mounted urban wind turbine charges a 12 volt battery and runs various 12 volt appliances within the building on which it is installed.

Wind turbines have been used for household electricity generation in conjunction with battery storage over many decades in remote areas. Household generator units of more than 1 kW are now functioning in several countries.

To compensate for the varying power output, grid-connected wind turbines may utilise some sort of grid energy storage. Off-grid systems either adapt to intermittent power or use photovoltaic or diesel systems to supplement the wind turbine.

Wind turbines range from small four hundred watt generators for residential use to several megawatt machines for wind farms and offshore. The small ones have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind; while the larger ones generally have geared power trains, alternating current output, flaps and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched and direct current generators are sometimes used.

In urban locations, where it is difficult to obtain large amounts of wind energy, smaller systems may still be used to run low power equipment. Distributed power from rooftop mounted wind turbines can also alleviate power distribution problems, as well as provide resilience to power failures. Equipment such as parking meters or wireless internet gateways may be powered by a wind turbine that charges a small battery, replacing the need for a connection to the power grid and/or maintaining service despite possible power grid failures.
Small-scale wind power in rural Indiana.
Small-scale wind power in rural Indiana.

Small scale turbines are available that are approximately 7 feet (2 m) in diameter and produce 900 watts. Units are lightweight, e.g. 16 kilograms (35 lbs), allowing rapid response to wind gusts typical of urban settings and easy mounting much like a television antenna. It is claimed that they are inaudible even a few feet under the turbine.[citation needed] Dynamic braking regulates the speed by dumping excess energy, so that the turbine continues to produce electricity even in high winds. The dynamic braking resistor may be installed inside the building to provide heat (during high winds when more heat is lost by the building, while more heat is also produced by the braking resistor). The proximal location makes low voltage (12 volt, or the like) energy distribution practical. An additional benefit is that owners become more aware of electricity consumption, possibly reducing their consumption down to the average level that the turbine can produce.

According to the World Wind Energy Association, it is difficult to assess the total number or capacity of small-scaled wind turbines, but in China alone, there are roughly 300,000 small-scale wind turbines generating electricity.[15]

There have been a number of recent developments of mini-windmills which could be adapted to home use with much less environmental impact compared to pole-mounted windmills, including:

* The AeroTecture vertical-axis turbine [28]
* The AeroVironment Architectural Wind Project [29][30]
* The piezoelectric windmill project [31]
* The Swift home wind turbine [32]. The Swift project peaked in 2004 and has had some implementation difficulties while promising to be a low-noise/safe roof-mount/low-cost alternative [33]
* The Motorwave micro-wind turbine [34][35][36]

[edit] Wind power: key issues

Wind power can be a controversial issue, and several main areas of dispute are debated between supporters and opponents.
Erection of an Enercon E70-4 in Germany
Erection of an Enercon E70-4 in Germany

[edit] Scalability

A key issue debated about wind power is its ability to scale to meet a substantial portion of the world's energy demand. There are significant economic, technical, and ecological issues about the large-scale use of wind power that may limit its ability to replace other forms of energy production. Most forms of electricity production also involve such trade-offs, and many are also not capable of replacing all other types of production for various reasons. A key issue in the application of wind energy to replace substantial amounts of other electrical production is intermittency; see the section below on Economics and Feasibility. At present, it is unclear whether wind energy will eventually be sufficient to replace other forms of electricity production, but this does not mean wind energy cannot be a significant source of clean electrical production on a scale comparable to or greater than other technologies, such as hydropower. Most electrical grids use a mix of different generation types (baseload generating capacity and peaking capacity) to match demand cycles by attempting to match the variable nature of demand to the most economic form of production; with the exception of hydropower, most types of production capacity are not used for all production (hydropower usage is limited by the presence of appropriate geographical sites). For example, nuclear power is effective as a baseload technology, but cannot be easily varied in short timeframes, and gas turbine plants are most economically used as peaking capacity; coal generation is primarily considered appropriate for baseload generation with some capacity to cycle to meet demand.

A significant part of the debate about the potential for wind energy to substitute for other electric production sources is the level of penetration. With the exception of Denmark, no countries or electrical systems produce more than 10% from wind energy, and most are below 2%. While the feasibility of integrating much higher levels (beyond 25%) is debated, significantly more wind energy could be produced worldwide before these issues become significant. In Denmark, wind power now accounts for close to 20% of electricity consumption[37] and a recent poll of Danes show that 90% want more wind power installed.[38]

[edit] Theoretical potential

Wind's long-term theoretical potential is much greater than current world energy consumption. The most comprehensive study to date[39] found the potential of wind power on land and near-shore to be 72 TW (~54,000 Mtoe), or over five times the world's current energy use and 40 times the current electricity use. The potential takes into account only locations with Class 3 (mean annual wind speeds ≥ 6.9 m/s at 80 m) or better wind regimes, which includes the locations suitable for low-cost (0.03–0.04 $/kWh) wind power generation and is in that sense conservative. It assumes 6 turbines per square km for 77-m diameter, 1.5 MW turbines on roughly 13% of the total global land area (though that land would also be available for other compatible uses such as farming). This potential assumes a capacity factor of 48% and does not take into account the practicality of reaching the windy sites, of transmission (including 'choke' points), of competing land uses, of transporting power over large distances, or of switching to wind power.

To determine the more realistic technical potential it is essential to estimate how large a fraction of this land could be made available to wind power. In the 2001 IPCC report, it is assumed that a use of 4% – 10% of that land area would be practical. Even so, the potential comfortably exceeds current world electricity demand.

Although the theoretical potential is vast, the amount of production that could be economically viable depends on a number of exogenous and endogenous factors, including the cost of other sources of electricity and the future cost of wind energy farms.

Offshore resources experience mean wind speeds about 90% greater than those on land, so offshore resources could contribute about seven times more energy than land.[40][41] This number could also increase with higher altitude or airborne wind turbines.[42]

To meet energy demands worldwide in the future in a sustainable way, many more turbines will have to be installed. This will affect more people and wildlife habitat. See the section below on ecology and pollution.

[edit] Economics and feasibility
Some of the over 6,000 wind turbines at Altamont Pass, in California. Developed during a period of tax incentives in the 1980s, this wind farm has more turbines than any other in the United States, producing about 125 MW. Considered largely obsolete, these turbines produce only a few tens of kilowatts each.
Some of the over 6,000 wind turbines at Altamont Pass, in California. Developed during a period of tax incentives in the 1980s, this wind farm has more turbines than any other in the United States, producing about 125 MW.[43] Considered largely obsolete, these turbines produce only a few tens of kilowatts each.

Wind energy in many jurisdictions receives some financial or other support to encourage its development. A key issue is the comparison to other forms of energy production, and their total cost. Two main points of discussion arise: direct subsidies and externalities for various sources of electricity, including wind. Wind energy benefits from subsidies of various kinds in many jurisdictions, either to increase its attractiveness, or to compensate for subsidies received by other forms of production or which have significant negative externalities.

Most forms of energy production create some form of negative externality: costs that are not paid by the producer or consumer of the good. For electric production, the most significant externality is pollution, which imposes costs on society in the form of increased health expenses, reduced agricultural productivity, and other problems. Significantly, carbon dioxide, a greenhouse gas produced when using fossil fuels for electricity production, may impose costs on society in the form of global warming. Few mechanisms currently exist to impose (or internalise) these external costs in a consistent way between various industries or technologies, and the total cost is highly uncertain. Other significant externalities can include national security expenditures to ensure access to fossil fuels, remediation of polluted sites, destruction of wild habitat, loss of scenery/tourism, etc.

Wind energy supporters argue that, once external costs and subsidies to other forms of electrical production are accounted for, wind energy is amongst the most cost-effective forms of electrical production. Critics may debate the level of subsidies required or existing, the "cost" of pollution externalities, and the uncertain financial returns to wind projects — that is, the all-in cost of wind energy compared to other technologies. Intermittency and other characteristics of wind energy also have costs that may rise with higher levels of penetration, and may change the cost-benefit ratio.

* Conventional and nuclear power plants receive substantial direct and indirect governmental subsidies. If a comparison is made on total production costs (including subsidies), wind energy may be competitive compared to many other sources.[citation needed] If the full costs (environmental, health, etc.) are taken into account, wind energy would be competitive in many more cases. Furthermore, wind energy costs have generally decreased due to technology development and scale enlargement. However, the cost of other capital intensive generation technologies, such as nuclear and fossil fueled plants, is also subject to cost reductions due to economies of scale and technological improvements.
* Nuclear power plants generally receive special immunity from the disasters they may cause, which prevents victims from recovering the cost of their continued health care from those responsible, even in the case of criminal malfeasance. In many cases, nuclear plants are owned directly by governments or substantially supported by them. In both cases, nuclear plants benefit from a lower cost of capital and lower perceived risk, as governments take on the risk charge directly. This is a form of indirect subsidy, although the size of this subsidy is difficult to ascertain precisely.
* To compete with traditional sources of energy, wind power often receives financial incentives. In the United States, wind power receives a tax credit for each kilowatt-hour produced; at 1.9 cents per kilowatt-hour in 2006, the credit has a yearly inflationary adjustment. Another tax benefit is accelerated depreciation. Many American states also provide incentives, such as exemption from property tax, mandated purchases, and additional markets for "green credits." Countries such as Canada and Germany also provide other incentives for wind turbine construction, such as tax credits or minimum purchase prices for wind generation, with assured grid access (sometimes referred to as feed-in tariffs). These feed-in tariffs are typically set well above average electricity prices.
* Many potential sites for wind farms are far from demand centers, requiring substantially more money to construct new transmission lines and substations.
* Intermittency and the non-dispatchable nature of wind energy production can raise costs for regulation, incremental operating reserve, and (at high penetration levels) could require demand-side management or storage solutions.
* Since the primary cost of producing wind energy is construction and there are no fuel costs, the average cost of wind energy per unit of production is dependent on a few key assumptions, such as the cost of capital and years of assumed service. The marginal cost of wind energy once a plant is constructed is close to zero.
* The cost of wind energy production has fallen rapidly since the early 1980s, primarily due to technological improvements, although the cost of construction materials (particularly metals) and the increased demand for turbine components caused price increases in 2005-06. Many expect further reductions in the cost of wind energy through improved technology, better forecasting, and increased scale. Since the cost of capital plays a large part in projected cost, risk (as perceived by investors) will affect projected costs per unit of electricity.
* Apart from regulatory issues and externalities, decisions to invest in wind energy will also depend on the cost of alternative sources of energy. Natural gas, oil and coal prices, the main production technologies with significant fuel costs, will therefore also be a determinant in the choice of the level of wind energy.
* The commercial viability of wind power also depends on the pricing regime for power producers. Electricity prices are highly regulated worldwide, and in many locations may not reflect the full cost of production, let alone indirect subsidies or negative externalities. Certain jurisdictions or customers may enter into long-term pricing contracts for wind to reduce the risk of future pricing changes, thereby ensuring more stable returns for projects at the development stage. These may take the form of standard offer contracts, whereby the system operator undertakes to purchase power from wind at a fixed price for a certain period (perhaps up to a limit); these prices may be different than purchase prices from other sources, and even incorporate an implicit subsidy.
* In jurisdictions where the price paid to producers for electricity is based on market mechanisms, revenue for all producers per unit is higher when their production coincides with periods of higher prices. The profitability of wind farms will therefore be higher if their production schedule coincides with these periods (generally, high demand / low supply situations). If wind represents a significant portion of supply, average revenue per unit of production may be lower as more expensive and less-efficient forms of generation, which typically set revenue levels, are displaced from economic dispatch. This may be of particular concern if the output of many wind plants in a market have strong temporal correlation. In economic terms, the marginal revenue of the wind sector as penetration increases may diminish.

[edit] Intermittency and variability

Main article: Intermittent Power Sources

Electricity generated from wind power can be highly variable at several different timescales: from hour to hour, daily, and seasonally. Annual variation also exists, but is not as significant. This variability can present substantial challenges to incorporating large amounts of wind power into a grid system, since to maintain grid stability, energy supply and demand must remain in balance.

While the negative effects of intermittency have to be considered in the economics of power generation, wind is unlikely to suffer momentary failure of large amounts of generation, which may be a concern with some traditional power plants. In this sense, it may be more reliable (albeit variable) due to the distributed nature of generation.

[edit] Grid management

Grid operators routinely control the supply of electricity by cycling generating plants on or off at different timescales. Most grids also have some degree of control over demand, through either demand management or load shedding. Management of either supply or demand has economic implications for suppliers, consumers and grid operators but is already widespread.

Variability of wind output creates a challenge to integrating high levels of wind into energy grids based on existing operating procedures. Critics of wind energy argue that methods to manage variability increase the total cost of wind energy production substantially at high levels of penetration, while supporters note that tools to manage variable energy sources already exist and are economical, given the other advantages of wind energy. Supporters note that the variability of the grid due to the failure of power stations themselves, or the sudden change of loads, exceeds the likely rate of change of even very large wind power penetrations.

There is no generally accepted "maximum" level of wind penetration, and practical limitations will depend on the configuration of existing generating plants, pricing mechanisms, capacity for storage or demand management, and other factors.

A number of studies for various locations have indicated that up to 20% (stated as the proportion of wind nameplate capacity to peak energy demand) may be incorporated with minimal difficulty. These studies have generally been for locations with reasonable geographic diversity of wind; suitable generation profile (such as some degree of dispatchable energy and particularly hydropower with storage capacity); existing or contemplated demand management; and interconnection/links into a larger grid area allowing for import and export of electricity when needed. Beyond this level, there are few technical reasons why more wind power could not be incorporated, but the economic implications become more significant and other solutions may be preferred.

At present, very few locations have penetration of wind energy above 5%. Germany, Spain, and Portugal all have penetration levels above 20%, however, and Denmark's penetration is over 40%, demonstrating that the technical issues are manageable at relatively high levels.

[edit] Energy storage

See article: energy storage.

One potential means of increasing the amount of usable wind energy in a given electrical system (penetration rates) is to make use of 'wind energy storage systems'. Effectively, "surplus" wind energy would be used to store electricity in usable form, e.g. pumped storage hydroelectricity. Storage of electricity would effectively arbitrage between the cost of electricity at periods of high supply and low demand, and the higher cost at periods of high demand and low supply. The potential revenue from this arbitrage must be balanced against the installation cost of storage facilities and efficiency losses.

Many different technologies exist to store usable electric energy, including air ballast, battery technologies, even flywheel energy storage, etc. For large energy grids, pumped storage hydroelectric has been implemented at large scale, but capital requirement include accessing the acreage of the potential area sites as suitable for such facilities. Most storage technologies are currently unproven commercially at large scale - often dependent on government induced environmental credits, and renewable energy subsidies.

One solution currently being piloted on wind farms is the use of rechargeable flow batteries as a rapid-response storage medium [1]. Vanadium redox flow batteries are currently installed at Huxley Hill wind farm (Australia), Tomari Wind Hills at Hokkaido (Japan), as well as in other non-wind farm applications. A further 12 MWh flow battery is to be installed at the Sorne Hill wind farm (Ireland) [2]. The supplier concerned is commissioning a production line to meet other anticipated orders.

An alternate solution is to use flywheel energy storage. This type of solution has been implemented by EDA [3] in the Azores on the islands of Graciosa and Flores. This system uses a 18MWs flywheel to improve power quality and thus allow increased renewable energy usage.

V2G (Vehicle to Grid) offers another potential solution. In 2006, several companies (Altairnano, A123 Systems, Electrovaya) announced lithium batteries which could power future EVs (Electric Vehicles) and PHEVs (Plug-in Hybrid Electric Vehicles). A feature of these batteries is a high number of charge/discharge cycles per battery lifetime (Altairnano claim 15,000 cycles). By plugging thousands of cars to the grid when they are not in use (95% of the day on average), the electric car becomes an asset to the grid, rather than a drain only. Each participating vehicle would require upload as well as download capability. The vehicle owner would presumably be rewarded for energy uploaded at the market peak rate. Download (charging) would preferably take place during periods of excess wind (or solar) generation.

A chicken/egg problem exists in getting V2G off the ground. V2G capability would add to the cost of an already expensive electric car. Until such time as V2G cars are numerous enough to make the concept viable, there is no financial return on V2G investment. A successful launch of V2G will likely require government sponsorship of the startup period. World governments also have a role to play in regulating standard plugs and standard communication protocols between vehicles, billing aggregators and power utility companies. Without such standards, a repeat of the unfortunate situation which sees so many different plugs on appliances throughout the world could eventuate. -->

[edit] Predictability

Main article: Wind Power Forecasting

Related to but essentially different from variability is the short-term (hours - days) predictability of wind plant output. Like the other electricity sources wind energy must be "scheduled" - a challenge because of the nature of the energy source. To this end wind power forecasting methods are employed by utilities or system operators, which methods are essentially similar to the more general weather forecasting methods used by met offices. To date for various reasons the predictability of wind plant output is limited.

[edit] Ecology and pollution

[edit] CO2 emissions and pollution

It is sometimes said that wind energy, for example, does not reduce carbon dioxide emissions because the intermittent nature of its output means it needs to be backed up by fossil fuel plant. Wind turbines do not displace fossil generating capacity on a one-for-one basis. But it is unambiguously the case that wind energy can displace fossil fuel-based generation, reducing both fuel use and carbon dioxide emissions.[44]

Wind power consumes no fuel for continuing operation, and has no emissions directly related to electricity production. Wind power stations, however, consume resources in manufacturing and construction, as do most other power production facilities. Wind power may also have an indirect effect on pollution at other production facilities, due to the need for reserve and regulation, and may affect the efficiency profile of plants used to balance demand and supply, particularly if those facilities use fossil fuel sources. Compared to other power sources, however, wind energy's direct emissions are low, and the materials used in construction (concrete, steel, fiberglass, generation components) and transportation are straightforward. Wind power's ability to reduce pollution and greenhouse gas emissions will depend on the amount of wind energy produced, and hence scalability, as well as the profile of other generating capacity.

* A study by the Irish national grid stated clearly that "Producing electricity from wind reduces the consumption of fossil fuels and therefore leads to emissions savings", and found reductions in CO2 emissions ranging from 0.59 tonnes of CO2 per MWh to 0.33 tonnes per MWh.[45]
* Wind power is a renewable resource, which means using it will not deplete the earth's supply of fossil fuels. It also is a clean energy source, and operation does not produce carbon dioxide, sulfur dioxide, mercury, particulates, or any other type of air pollution, as do conventional fossil fuel power sources.
* Electric power production is only part (about 39% in the USA[46]) of a country's energy use, so wind power's ability to mitigate the negative effects of energy use — as with any other clean source of electricity — is limited (except with a potential transition to electric or hydrogen vehicles). Wind power contributed less than 1% of the UK's national electricity supply[6] in 2004 and hence had negligible effects on CO2 emissions, which continued to rise in 2002 and 2003 (Department of Trade and Industry); the growth of installed wind capacity in the UK has been impressive (installed wind capacity doubled from 2002 to 2004, and again from end-2004 to mid-2006), but from low levels. Until wind energy achieves substantially greater scale worldwide, its ability to contribute will be limited.
* Groups such as the UN's Intergovernmental Panel on Climate Change state that the desired mitigation goals can be achieved at lower cost and to a greater degree by continued improvements in general efficiency — in building, manufacturing, and transport — than by wind power.[47]
* During manufacture of the wind turbine, steel, concrete, aluminum and other materials will have to be made and transported using energy-intensive processes, generally using fossil energy sources.
* The energy return on investment (EROI) for wind energy is equal to the cumulative electricity generated divided by the cumulative primary energy required to build and maintain a turbine. The EROI for wind ranges from 5 to 35, with an average of around 18. This places wind energy in a favorable position relative to conventional power generation technologies in terms of EROI. Baseload coal-fired power generation has an EROI between 5 and 10:1. Nuclear power is probably no greater than 5:1, although there is considerable debate regarding how to calculate its EROI. The EROI for hydropower probably exceeds 10, but in most places in the world the most favorable sites have been developed.[48]
* Net energy gain for wind turbines has been estimated in one report to be between 17 and 39 (i.e. over its life-time a wind turbine produces 17-39 times as much energy as is needed for its manufacture, construction, operation and decommissioning). A similar Danish study determined the payback ratio to be 80, which means that a wind turbine system pays back the energy invested within approximately 3 months.[49] This is to be compared with payback ratios of 11 for coal power plants and 16 for nuclear power plants, though such figures do not take into account the energy content of the fuel itself, which would lead to a negative energy gain.[50]
* The ecological and environmental costs of wind plants are paid by those using the power produced, with no long-term effects on climate or local environment left for future generations.

[edit] Ecology

* Because it uses energy already present in the atmosphere, and can displace fossil-fuel generated electricity (with its accompanying carbon dioxide emissions), wind power mitigates global warming. While wind turbines might impact the numbers of some bird species, conventionally fueled power plants could wipe out hundreds or even thousands of the world's species through climate change, acid rain, and pollution.
* Unlike fossil fuel or nuclear power stations, which circulate or evaporate large amounts of water for cooling, wind turbines do not need water to generate electricity.

[edit] Ecological footprint

Large-scale onshore and near-shore wind energy facilities (wind farms) can be controversial due to aesthetic reasons and impact on the local environment. Large-scale offshore wind farms are not visible from land and according to a comprehensive 8-year Danish Offshore Wind study on "Key Environmental Issues" have no discernible effect on aquatic species and no effect on migratory bird patterns or mortality rates. Modern wind farms make use of large towers with impressive blade spans, occupy large areas and may be considered unsightly at onshore and near-shore locations. They usually do not, however, interfere significantly with other uses, such as farming. The impact of onshore and near-shore wind farms on wildlife—particularly migratory birds and bats—is hotly debated, and studies with contradictory conclusions have been published. Two preliminary conclusions for onshore and near-shore wind developments seem to be supported: first, the impact on wildlife is likely low compared to other forms of human and industrial activity; second, negative impacts on certain populations of sensitive species are possible, and efforts to mitigate these effects should be considered in the planning phase. Aesthetic issues are important for onshore and near-shore locations in that the "visible footprint" may be extremely large compared to other sources of industrial power (which may be sited in industrially developed areas), and wind farms may be close to scenic or otherwise undeveloped areas. Offshore wind development locations remove the visual aesthetic issue by being at least 10 km from shore and in many cases much further away.
A wind turbine at Greenpark, Reading, England
A wind turbine at Greenpark, Reading, England

[edit] Land use

* Clearing of wooded areas is often unnecessary, as the practice of farmers leasing their land out to companies building wind farms is common. In the U.S., farmers may receive annual lease payments of two thousand to five thousand dollars per turbine.[51] The land can still be used for farming and cattle grazing. Less than 1% of the land would be used for foundations and access roads, the other 99% could still be used for farming.[52] Turbines can be sited on unused land in techniques such as center pivot irrigation.
* The clearing of trees around onshore and near-shore tower bases may be necessary to enable installation. This is an issue for potential sites on mountain ridges, such as in the northeastern U.S.[53]
* Wind turbines should ideally be placed about ten times their diameter apart in the direction of prevailing winds and five times their diameter apart in the perpendicular direction for minimal losses due to wind park effects. As a result, wind turbines require roughly 0.1 square kilometres of unobstructed land per megawatt of nameplate capacity. A 2 GW wind farm, which might produce as much energy each year as a 1 GW baseload power plant, might have turbines spread out over an area of approximately 200 square kilometres.
* Areas under onshore and near-shore windfarms can be used for farming, and are protected from further development.
* Although there have been installations of wind turbines in urban areas (such as Toronto's exhibition place), these are generally not used. Buildings may interfere with wind, and the value of land is likely too high if it would interfere with other uses to make urban installations viable. Installations near major cities on unused land, particularly offshore for cities near large bodies of water, may be of more interest. Despite these issues, Toronto's demonstration project demonstrates that there are no major issues that would prevent such installations where practical, although non-urban locations are expected to predominate.
* Offshore locations, such as that being developed on a large underwater plateau in eastern Lake Ontario by Trillium Power use no land per se and avoid known shipping channels. Some offshore locations are uniquely located close to ample transmission and high load centres however that is not the norm for most offshore locations. Most offshore locations are at considerable distances from load centres and may face transmission and line loss challenges.
* Wind turbines located in agricultural areas may create concerns by operators of cropdusting aircraft. Operating rules may prohibit approach of aircraft within a stated distance of the turbine towers; turbine operators may agree to curtail operations of turbines during cropdusting operations.

[edit] Impact on wildlife

* Onshore and near-shore studies show that the number of birds killed by wind turbines is negligible compared to the number that die as a result of other human activities such as traffic, hunting, power lines and high-rise buildings and especially the environmental impacts of using non-clean power sources. For example, in the UK, where there are several hundred turbines, about one bird is killed per turbine per year; 10 million per year are killed by cars alone.[54] In the United States, onshore and near-shore turbines kill 70,000 birds per year, compared to 57 million killed by cars and 97.5 million killed by collisions with plate glass.[55] Another study suggests that migrating birds adapt to obstacles; those birds which don't modify their route and continue to fly through a wind farm are capable of avoiding the large offshore windmills,[56] at least in the low-wind non-twilight conditions studied. In the UK, the Royal Society for the Protection of Birds (RSPB) concluded that "The available evidence suggests that appropriately positioned wind farms do not pose a significant hazard for birds."[57] It notes that climate change poses a much more significant threat to wildlife, and therefore supports wind farms and other forms of renewable energy.
* Some onshore and near-shore windmills kill birds, especially birds of prey.[58] More recent siting generally takes into account known bird flight patterns, but some paths of bird migration, particularly for birds that fly by night, are unknown although a 2006 Danish Offshore Wind study showed that radio tagged migrating birds traveled around offshore wind farms. A Danish survey in 2005 (Biology Letters 2005:336) showed that less than 1% of migrating birds passing an offshore wind farm in Rønde, Denmark, got close to collision, though the site was studied only during low-wind non-twilight conditions. A survey at Altamont Pass, California, conducted by a California Energy Commission in 2004 showed that onshore turbines killed between 1,766 and 4,721[59] birds annually (881 to 1,300 of which were birds of prey). Radar studies of proposed onshore and near-shore sites in the eastern U.S. have shown that migrating songbirds fly well within the reach of large modern turbine blades. In Australia, a proposed onshore/near-shore wind farm was canceled before production because of the possibility that a single endangered bird of prey was nesting in the area.
* An onshore/near-shore wind farm in Norway's Smøla islands is reported to have destroyed a colony of sea eagles, according to the British Royal Society for the Protection of Birds.[60] The society said turbine blades killed nine of the birds in a 10 month period, including all three of the chicks that fledged that year. Norway is regarded as the most important place for white-tailed eagles.
* The numbers of bats killed by existing onshore and near-shore facilities has troubled even industry personnel.[61] A study in 2004 estimated that over 2200 bats were killed by 63 onshore turbines in just six weeks at two sites in the eastern U.S.[62] This study suggests some onshore and near-shore sites may be particularly hazardous to local bat populations and more research is urgently needed. Migratory bat species appear to be particularly at risk, especially during key movement periods (spring and more importantly in fall). Lasiurines such as the hoary bat (Lasiurus cinereus), red bat (Lasiurus borealis), and the semi-migratory silver-haired bats (Lasionycteris noctivagans) appear to be most vulnerable at North American sites. Almost nothing is known about current populations of these species and the impact on bat numbers as a result of mortality at windpower locations. Offshore wind sites 10 km or more from shore do not interact with bat populations.

[edit] Offshore and Ocean Noise

As the number of offshore wind farms increase and move further into deeper water, the question arises if the ocean noise that is generated due to mechanical motion of the turbines and other vibrations which can be transmitted via the tower structure to the sea, will become significant enough to harm sea mammals. Tests carried out in Denmark for shallow installations showed the levels were only significant up to a few 100 metres. However sound injected into deeper water will travel much further and will be more likely to impact bigger creatures like whales which tend to use lower frequencies than porpoises and seals. A recent study found that wind farms add 80-110dB to the existing low-frequency ambient noise (under 400Hz) and this could impact baleen whales communication and stress levels, and possibly prey distribution. [4]

[edit] Aesthetics and safety

On the issue of safety, the British Wind Energy Association has said:

"...wind energy is one of the safest energy technologies, and enjoys an outstanding health & safety record. In over 20 years of operating experience and with more than 50,000 machines installed around the world, no member of the public has ever been harmed by operating wind turbines. High standards exist for the design and operation of wind energy projects as well as close industry co-operation with the certification and regulatory bodies in those countries where wind energy is deployed."[63]

* Recorded experience that onshore and near-shore wind turbines are noisy and visually intrusive creates resistance to the establishment of land-based wind farms in many places. Moving the turbines far offshore (10 km or more) mitigates the problem, but offshore wind farms may be more expensive and transmission to on-shore locations may present challenges in many but not all cases.
* Some residents near onshore and near-shore windmills complain of "shadow flicker", which is the alternating pattern of sun and shade caused by a rotating windmill casting a shadow over residences. Efforts are made when siting onshore and near-shore turbines to avoid this problem.
* Large onshore and near-shore wind towers require aircraft warning lights, which create light pollution at night, which bothers humans and can disrupt the local ecosystem. Complaints about these lights have caused the FAA to consider allowing a less than 1:1 ratio of lights per turbine in certain areas.[5]

Wind power is nothing new. Windmills at La Mancha, Spain.
Wind power is nothing new. Windmills at La Mancha, Spain.

* Improvements in blade design and gearing have quietened modern turbines to the point where a normal conversation can be held underneath one. In December 2006, a jury in Texas denied a suit for private nuisance against FPL Energy for noise pollution after the company demonstrated that noise readings were not excessive, with the highest reading reaching 44 decibels, which was characterized as approximately the same noise level as a wind of 10 miles per hour.[6] The suit was initially for visual intrusion,[7] but that was disallowed, so it concentrated on noise, which with the large spreads involved, was bound to fail). Texas civil case law requires proof of personal injury in a suit against a neighbor's activities (Klein v. Gehrung, 25 Tex. Supp. 232), so even if the plaintiffs had presented data showing more substantial noise, they would not have prevailed unless they could prove injury.

Wind turbines at Magrath, Alberta, Canada.
Wind turbines at Magrath, Alberta, Canada.

* Newer wind farms have more widely spaced turbines due to the greater power of the individual wind turbines, and to look less cluttered.
* The aesthetics of onshore and near-shore wind turbines have been compared favorably to those of pylons from conventional power stations.
* Offshore sites have on average a considerably higher energy yield than onshore sites, and generally cannot be seen from the shore even on the clearest of days.

Biography

Biography

Biography (from the Greek words bios meaning "life", and graphein meaning "write") is a genre of literature and other forms of media such as film, based on the written accounts of individual lives. While a biography may focus on a subject of fiction or non-fiction, the term is usually in reference to non-fiction. Pat Shipman however, says "I think a good biographer has to write fiction some of the time to make apparent a significant event in someone's life." This is sometimes debated. As opposed to a profile or curriculum vitae, a biography develops a complex analysis of personality, highlighting different aspects of it and including intimate details of experiences. A biography is more than a list of impersonal facts like birth, education, work, relationships and death. It also delves into the emotions of experiencing such events.

Early forms

The first known biographies were written by scribes commissioned by the various rulers of antiquity: ancient Assyria, ancient Babylonia, ancient Egypt, ancient Mesopotamia, among others. Such biographies tended to be chiseled into stone or clay tablets, a method called cuneiform.

The Jewish holy scripture is an anthology of some of the earliest biographies in existence, detailing the lives of chiefs, kings, tribes, patriarchs and prophets. However, the dates of these written accounts are disputed.

Classical forms

Ancient Greeks developed the biographical tradition which we have inherited, although until the 5th century AD, when the word 'biographia' first appears, in Damascius' Life of Isodorus, biographical pieces were called simply "lives" (βιοι: "bioi"). It is quite likely that the Greeks were drawing on a pre-existing eastern tradition; certainly Herodotus' Histories contains more detailed biographical information on Persian kings and subjects than on anyone else, implying he had a Persian source for it.

The earliest surviving pieces which we would identify as biographical are Isocrates' Life of Evagoras and Xenophon's Life of Agesilaos, both from the fifth century BC. Both identified themselves as encomia, or works of praise, and that biography was regarded as a discrete entity from historiography is evidenced by the fact that Xenophon treated King Agesilaos of Sparta twice in his works, once in the above-mentioned encomium and once in his Greek History; evidently the two genres were conceived as making different demands of authors who enrolled in them. Xenophon could present his Cyropaedia, an account of the childhood of the Persian King Cyrus the Great now regarded as so fabulous that it falls rather into a novelistic tradition than a biographical one, as a serious work, without any disclaimers or caveats.

Whereas Thucydides set the benchmark for a historiographical tradition comprising 'conclusions ... drawn from proofs quoted ... [which] may safely be relied upon' (Thuc. 1.21), and offering little explicit judgement on the men with whom he dealt, biographers were quite often more concerned with drawing a moral point from their investigations of their subjects. Parallel Lives by Plutarch, a Greek writing under the Roman empire, is a series of short biographies of eminent men, ancient and contemporary, arranged in pairs comprising one Greek, one Roman, in order that a broad educative point might be extraced from the comparison (for example Mark Anthony and Demetrius were paradigms of tyranny, Lysander and Sulla examples of great men degenerating into blood-thirsty corruption).

However, although their moralising approach is not in fashion in the current intellectual climate, Greek biographies still have much to offer the modern reader, and for the most part it is reasonable to assume that while authors may have suppressed details which did not fall in with the general theme which they wished to convey, they are unlikely to have fabricated much. Not least, they were instrumental in developing the modern idea of the person. The traditional Greek attitude to individuals was to 'reduce them to types'; the Peripatetic tradition records various categories into which men might fall: the flatterer, the superstitious man and so on. Greek rhetorical handbooks give advice on 'ethopoia', that is creating a character, one of a recognised type, to win favour in the law courts.

The biographical tradition does draw on these types, but it also gives explicit recognition to the importance of individual ideosyncrasies in defining a man, and places the emphasis firmly on a man's personality rather than merely listing his accomplishments. As Plutarch says in the introduction to his Life of Alexander the Great, 'in the most illustrious deeds there is not always a manifestation of virtue and vice, but a slight thing like a phrase or a jest often makes a greater revelation than battles where thousands fall, or the greatest armaments, or sieges of cities'. Thus the individual is recognised as having some value and interest irrespective of the impact of his actions on the broader sweep of history.

Under the Roman Empire, the biographical and historiographical traditions converged somewhat, likely due to the nature of government, whereby the state was dominated by a single emperor with totalitarian power and whose character and actions set the tone for the period; Tacitus's History and his Annals, as well as Dio's History contain much of the same material as the biographer Suetonius's Lives of the Twelve Caesars. However, although Tacitus in particular was extremely critical of the regime, his disapproval emerges in subtle characterisation and arrangement of his material, in contrast with Suetonius' vicious authorial comment.

Middle Ages and Renaissance

The Early Middle Ages (AD 400 to 1450) saw a decline in awareness of classical culture. During this time, the only repositories of knowledge and records of early history was the Roman Catholic Church. Hermits, monks and priests used this historic period to write the first modern biographies. Their subjects were usually restricted to church fathers, martyrs, popes and saints. Their works were meant to be inspirational to people, vehicles for conversion to Christianity. See hagiography. One significant example of biography from this period which does not exactly fit into that mold is the life of Charlemagne as written by his courtier Einhard.

By the late Middle Ages, biographies became less church-oriented as biographies of kings, knights and tyrants began to appear. The most famous of these such biographies was Le Morte d'Arthur by Sir Thomas Malory. The book was an account of the life of the fabled King Arthur and his Knights of the Round Table.

Following Malory, the new emphasis on humanism during the Renaissance promoted a focus on secular subjects such as artists and poets, and encouraged writing in the vernacular. Giorgio Vasari's Lives of the Artists (1550) was a landmark biography focusing on secular lives. Vasari created celebrities of his subjects, as the Lives became an early "best seller." Two other developments are noteworthy: the development of the printing press in the fifteenth century and the gradual increase in literacy.

Biographies in the English language began appearing during the reign of Henry VIII. James Foxe’s Acts and Monuments (1563) essentially was the first dictionary of biography, followed by Thomas Fuller’s The History of the Worthies of England (1662), with a distinct focus on public life.


Modern biography

The "Golden Age" of English biography emerged in the late 1700s, the century in which the terms "biography" and "autobiography" entered the English lexicon. The classic works of the period were Samuel Johnson's Critical Lives of the Poets (1779-81) and James Boswell's massive Life of Johnson (1791). The Boswellian approach to biography emphasized uncovering material and letting the subject "speak for itself." While Boswell compiled, Samuel Johnson composed. Johnson did not follow a chronological narration of the subject's life but used anecdotes and incidents selectively. Johnson rejected the notion that facts revealed truth. He suggested that biographers should seek their subject in "domestic privacies", to find little known facts or anecdotes which revealed character. (Casper, 1999)

The romantic biographers disputed many of Johnson's judgments. Jean Jacques Rousseau's Confessions (1781-88) exploited the romantic point of view and the confessional mode. The tradition of testimony and confession was brought to the New World by Puritan and Quaker memoirists and journal-keepers where the form continued to be influential. Benjamin Franklin's autobiography (1791) would provide the archetype for the American success story. (Stone, 1982) Autobiography would remain an influential form of biographical writing.

Generally, American biography followed the English model, however, incorporating Thomas Carlyle's view that biography was a part of history. Carlyle asserted that the lives of great men were important to understanding society and its institutions. While the historical impulse would remain a strong element in early American biography, American writers carved out their own distinct approach. What emerged was a rather didactic form of biography which sought to shape individual character of the reader in the process of defining national character. (Casper, 1999)

The distinction between mass biography and literary biography which had formed by mid nineteenth century reflected a breach between high culture and middle-class culture. This division would endure for the remainder of the century. Biography began to flower thanks to new publishing technologies and an expanding reading public. This revolution in publishing made books available to a larger audience of readers. Almost ten times as many American biographies appeared from 1840 to 1860 than had appeared in the first two decades of the century. In addition, affordable paperback editions of popular biographies were published for the first time. Also, American periodicals began publishing series of biographical sketches. (Casper, 1999) The topical emphasis shifted from republican heroes to self-made men.

Much of late 19th-century biography remained formulaic. Notably, few autobiographies had been written in the 19th century. The following century witnessed a renaissance of autobiography beginning with Booker T. Washington's, Up From Slavery (1901) and followed by Henry Adams' Education (1907), a chronicle of self-defined failure which ran counter to the predominant American success story. The publication of socially significant autobiographies by both men and women began to flourish. (Stone, 1982)

The authority of psychology and sociology was ascendant and would make its mark on the new century’s biographies. (Stone, 1982) The demise of the "great man" theory of history was indicative of the emerging mindset. Human behavior would be explained through Darwinian theories. "Sociological" biographies based their subjects' actions as the result of the environment, and tended to downplay individuality. The development of psychoanalysis led to a more penetrating and comprehensive understanding of the biographical subject, and induced biographers to give more emphasis to childhood and adolescence. Clearly, psychological ideas were changing the way Americans read and wrote biographies, as a culture of autobiography developed in which the telling of one's own story became a form of therapy. (Casper, 1999)

The conventional concept of national heroes and narratives of success disappeared in the obsession with psychological explorations of personality. The new school of biography featured iconoclasts, scientific analysts, and fictional biographers. This wave included Lytton Strachey, André Maurois, and Emil Ludwig among others. Strachey's biographies had an influence similar to that which Samuel Johnson had enjoyed earlier. In the 1920s and '30s, biographical writers sought to capitalize on Strachey's popularity and imitate his style. Robert Graves (I, Claudius, 1934) stood out among those following Strachey's model of "debunking biographies." The trend in literary biography was accompanied in popular biography by a sort of "celebrity voyeurism." in the early decades of the century. This latter form's appeal to readers was based on curiosity more than morality or patriotism.

By World War I, cheap hard-cover reprints had become popular. The decades of the 1920s witnessed a biographical "boom." In 1929, nearly 700 biographies were published in the United States, and the first dictionary of American biography appeared. In the decade that followed, numerous biographies continued to be published despite the economic depression. They reached a growing audience through inexpensive formats and via public libraries.