In recent years, wind energy has grown to become one of the most plentiful sources of renewable energy in the United States. Between 1998 and 2015, the United States added nearly 74 gigawatts of wind energy generation capacity — roughly equivalent to 37,000 average-sized modern wind turbines or over 60 times the 1.21 gigawatts required by Doc Brown’s time machine in “Back to the Future” (great Scott!). Today, wind provides a major portion of the U.S. electricity supply, with eleven states producing over 10 percent of their electricity from wind in 2015.

Approximately 73,992 megawatts of wind energy capacity were installed in the United States between 1998 and 2015. Credit: U.S. Department of Energy 2015 Wind Technologies Market Report

As more and more wind turbines were produced and installed, the cost of wind electricity steadily declined. Between 1980 and 2015, U.S. wind energy’s levelized cost of electricity (LCOE), or the total capital, operation, and maintenance cost per unit of electric energy produced, fell from a high of nearly $600 per megawatt-hour (60 cents per kilowatt-hour) to approximately $50 per megawatt-hour (5 cents per kilowatt-hour) — less than the cost of a new gas or coal plant.

The levelized cost of electricity (LCOE) of U.S. wind energy fell from a high of nearly $600 per megawatt-hour in 1980 to just less than $50 per megawatt-hour in 2015, at a “learning rate” of 17.8%. Credit: Lawrence Berkeley National Laboratory

While wind energy has experienced significant gains since the 80s and 90s, some have speculated that wind energy might have reached its limit when it comes to cost reductions and technological improvements. But a survey of wind industry experts by the U.S. Department of Energy’s Lawrence Berkeley National Lab suggests otherwise.

The study, also published in the peer-reviewed journal Nature Energy, surveyed a diverse set of 163 wind energy experts from industry, research institutions and academia. The survey sample included 22 pre-identified “leading experts” judged to have unique qualifications to forecast the future direction of the wind energy industry. The results of the survey showed that experts expect the cost of onshore wind energy to decline by approximately 24 percent by 2030, and 35 percent by 2050. Interestingly, the anticipated cost reductions aren’t driven by some fundamental change to wind turbine technology, but rather by the trend toward larger and larger turbines.

The first wind turbines installed in the 80s and 90s had a generating capacity of just 0.1 megawatts and a height from the central hub/generator to the ground of just 18 meters. Today’s typical turbines have a generating capacity of 2.0 megawatts and a hub height of 82 meters. A taller tower means that modern turbines can capture steadier, faster winds at a higher altitude. Furthermore, the rotor diameter can be increased to capture more wind overall. The amount of wind energy produced is proportional to the turbine’s rotor area multiplied by the wind velocity cubed, so taller towers and larger rotors make a big difference. The experts surveyed by Lawrence Berkeley National Laboratory anticipate that by 2030 the typical wind turbine will have a hub height 115 meters and a rotor diameter of 135 meters, for a total generating capacity of 3.25 megawatts.

Experts anticipate wind turbines will significantly increase in size by 2030, leading to a 24 percent reduction in the cost of wind energy. Credit: Lawrence Berkeley National Laboratory

The results of the expert survey are important because they show that professionals on the ground in the wind industry with skin in the game believe that manufacturing and transport limitations will not constrain the size of wind turbines, and costs will fall.

If the cost of wind energy continues to decline, wind will fully outgrow the need for policy support in the form of the federal production tax credit and take on a market dynamic that makes wind the preferred energy generation technology for economic reasons alone — at least in regions where adequate sites exist, like the plains of U.S. Midwest and Texas.

The greatest U.S. wind resource lies in the plains of the U.S. Midwest and the Texas panhandle. Pumping wind energy from the plains to the coasts will become increasingly important as the price of wind energy falls, and it becomes a more valuable resource. Credit: NREL

The challenge associated with pumping wind energy from the plains to the rest of the country will become increasingly important as the cost of wind energy declines, and the benefit of tapping the energy of the wind-swept plains increases. High-voltage transmission lines can get the job done, but they face many of the same NIMBY (not in my backyard) issues as contentious oil and gas pipelines and have to overcome permitting in every state they cross. That’s why I’ve argued for the need to build transmission lines. If we don’t, then the great American wind belt will never be tapped to its full potential.