Production and share of global electricity supply


Individual wind turbines have been steadily growing in terms of their nameplate capacity – the maximum electricity output they achieve when operating at full power. While the average size of turbines still differs dramatically from country to country, there has been a market trend towards bigger turbines across all markets. For the purposes of the GWEO scenarios, this trend is expected to continue over the next few decades.

It is also assumed that each turbine will have an operational lifetime of 20 years, after which it will need to be replaced. this 'repowering' or replacement of older turbines has been taken into account in the scenarios.


A wind turbine's 'capacity factor' refers to the percentage of the nameplate capacity that a turbine installed in a particular location will deliver over the course of a year. This is primarily an assessment of the wind resource at a given site, but capacity factors are also affected by the efficiency of the turbine and its suitability for the particular location. For example, a 1 MW turbine operating at a 25% capacity factor will deliver 2,190 MWh of electricity in one year.

From an estimated average capacity factor today of 25%, the scenario assumes that improvements in both wind turbine technology and the siting of wind farms will result in a steady increase. Capacity factors are also much higher at sea, where winds are stronger and more constant. The growing size of the offshore wind market, especially in Europe, will therefore contribute to an increase in the average. As a result, across all three scenarios, we assume that the average global capacity factor will increase to 28% by 2015 and then 30% by 2036. Although capacity factors will vary from region to region, we have assumed these same global averages for the regional scenarios as outlined below.


While it is of interest to calculate how much power would actually be generated by wind energy in the three scenarios, putting this into the context of global electricity demand is even more relevant, as it will give us an idea of the share that wind power can have in satisfying the world's increasing hunger for power. The three GWEO scenarios are therefore set against two projections for the future growth of electricity demand: a 'Reference Demand Projection'; and an 'Energy Efficiency Demand Projection'.

Maranchón wind farm, Guadalajara, Spain

© Wind Power Works

Reference demand projection

The more conservative of the two global electricity demand projections is again based on data from the IEA's 2009 World Energy Outlook, including its assumptions on population and GDP growth, extrapolated forwards to 2050. It takes account of policies and measures that were enacted or adopted by mid-2009, but does not include possible or likely future policy initiatives.

The IEA's estimation is that in the absence of new government policies, the world's electricity demand will rise inexorably. Global demand would therefore almost double from the baseline 15,000 TWh in 2005 to reach nearly 29,000 TWh by 2030.

Energy efficiency demand projection

The IEA's expectations on rising energy demand are then set against the outcome of a study on the potential effect of energy efficiency savings developed by DLR and the Ecofys consultancy2. This study describes an ambitious development path for the exploitation of energy efficiency measures, based on current best practice technologies, emerging technologies that are currently under development and continuous innovation in the field of energy efficiency.

In reality, of course, constraints in terms of costs and other barriers, such as resistance to replacing existing equipment and capital stock before the end of its useful life, will prevent this 'technical' energy efficiency potential to be fully realised. In order to refect these limitations, we have used the more moderate energy efficiency demand projection from the study, which is based on implementing around 80% of the technical potential.

This scenario results in global demand increasing by much less than under the Reference projection, i.e., to 25,000 TWh in 2030, which is 14% (or 4,000 TWh) lower.


On the basis of these energy demand projections, the share of wind power in the global electricity demand can be calculated.

In the reference scenario, wind power would produce 1,000 TWh of electricity by 2020, a trebling from the estimated 350 TWh produced by the 158.5 GW of wind capacity in 2009. Depending on the demand projection, this would cover between 4.5-4.8% of the world's electricity needs, about the same share as is currently achieved in Europe. By 2030, 1,400 TWh would account for 4.9% to 5.6%. Overall, the contribution of wind power to the global electricity supply would remain small.

Cerro Becerril wind farm, Spain

© EDP Renovavies

Under the Moderate scenario, the situation would look considerably different. In 2020, wind energy would produce 2,000 TWh, twice as much as under the reference scenario, and this would meet 8.9%-9.5% of the world's power demand – already a substantial contribution. By 2030, 4,300 TWh would be produced by wind energy, taking the share up to 15%-17.5%, depending on how demand develops over the next two decades.

The Advanced scenario paints a picture in which wind power would become a central player in global power generation. By 2020, the world's combined installed wind feet would produce 2,600 TWh of clean power, which would account for 11.5%-12.3% of global electricity supply. This would rise to 5,400 TWh by 2030 and a share of 18.8%-21.8% – a fifth of the world's power needs could thus be satisfed by wind power alone.