A new analysis conducted by the National Renewable Energy Laboratory and consulting firm AWS Truewind estimates that the energy potential of US wind resources has tripled since the last estimate in 1993. The report shows that current wind technology could generate 37 trillion kilowatt hours of electricity per year, which is more than a threefold increase from an estimated 10.8 trillion kilowatt hours from the previous analysis by the Pacific Northwest National Laboratory. No, the winds aren’t really blowing that much harder, the increase has come from technological advancements in wind turbines rather than a better understanding of the national windscape. The new data are from heights of 80 and 100 meters whereas the previous data was taken from a height of 50 meters. The most recent wind turbine designs have 80+ meter hub heights and are capable of generating more energy than shorter turbines because higher altitudes are less subject to wind shear effects from friction at Earth’s surface. And the designs are continually evolving – Norway is currently building the world’s largest wind turbine – a mammoth 10 megawatt, 162.5 meter machine.
The US wind resource map below shows the new predicted average annual wind speeds at a height of 80 meters.
In particular, Texas has the most abundant wind energy resource of any US state.
Despite this increase in our estimated wind resource, the many challenges of integrating more wind energy into our electricity generation mix still remain. Clearly, the estimated wind resource is abundant enough to supply a significant portion of electricity, yet the contribution of wind in the generation mix is very small (though is growing fast). In 2008, total US electricity net generation was 4.1 trillion kilowatt hours and wind contributed just 0.052 trillion kilowatt hours, according to the Energy Information Administration’s 2008 Annual Energy Review. The potential for substantial growth is well recognized, and in July 2008, the Department of Energy released a report analyzing a scenario to increase wind energy’s contribution to US electricity generation to 20% by 2030.
There are technical and policy barriers to achieving this scenario. One of the main technical barriers is transmission. As indicated on the above map, much of the wind resource is located in the middle of the country and away from urban population centers. New and substantial investment in transmission lines (around $43 billion!) is required to deliver the energy from where the wind blows to where it is demanded. Perhaps an even more difficult problem is the task of integrating a highly intermittent resource into the power grid without compromising stability. Investment in wind development is crucial, and can be stimulated by US policymakers extending existing production and investment tax credits or solidifying renewable portfolio standards.
Our national wind resource is abundant (even more so than previously was thought), yet significant technological innovation and forward-looking, long-term policy is needed before wind energy can become a major contributor to electricity generation.