July 17, 2017 Read More →

On the Blogs: ‘Capacity Factor’ for U.S. Wind Fleet Exceeds That of Coal Plants

Greentech Media:

Seasonal trends, favorable conditions and ever-improving technology all came together in April to help America’s wind turbine fleet spin past coal’s capacity factor.

The Energy Information Administration’s Electric Power Monthly put wind at 44.8 percent, slightly above coal’s 43.4 percent — and just below the 45.7 percent of the nation’s combined-cycle natural-gas plants.

The United States’ wind fleet saw its highest capacity factors around April, roughly corresponding to the nation’s lowest period of electricity demand (Electric Power Monthly, Table 1.2.A). This pushes down on dispatchable generation, causing fossil generators to experience their turbine capacity factors reaching annual lows around this time.

Last year, these factors pummeled coal’s capacity factor below 40 percent in both March and April, allowing wind to slip ahead of it, largely unnoticed, for a brief stretch.

Wind has not yet topped coal’s capacity factor in the fall months, though it made its closest approach in November 2015 (39.0 percent versus 43.6 percent). A combination of mild weather and low natural-gas prices will probably be needed for wind to hit this next milestone.

That said, coal’s capacity factor remains well above that of wind on an annual basis (52.7 percent versus 34.7 percent in 2016), and grid modelers generally take pains to distinguish between intermittent and dispatchable power.

While technology has improved, capacity factors have crawled upward very slowly. This is partly due to year-over-year variations in the wind resource adding significant noise to the data set, and partly thanks to cost reductions making once-marginal projects (with lower capacity factors) economic for developers.

The increasing deployment of turbine designs optimized for lower wind speed regimes, even in high-wind areas, has provided a boost. The shape of wind speed distributions means there are advantages to being able to harvest more energy in gentler winds, even in the blusteriest locales. An analogy might be made with advances in solar module design that allow photovoltaics to convert more indirect or low-angle light; the panels can provide more kilowatt-hours even if their peak kilowatt rating doesn’t change.

Wind Breezed Past Coal’s Capacity Factor in April

Comments are closed.