U.S. Coal Capacity Factors

Coal capacity factors vs renewable capacity and generation

U.S. Coal Capacity Factors
Photo by Nikolay Kovalenko / Unsplash
A common refrain in the fossil versus renewable power debate goes something like this - wind & solar are subsidized, thus displace reliable baseload coal, which would otherwise run at high capacity factors

While there is some truth to that urban legend, coal power generation has largely been displaced by natural gas generation in the U.S.

We took a look at monthly generation for five of the largest coal plants in the U.S., all of which reside in states with relatively low renewable power generation, to test the hypothesis

The results may surprise. As always, energy and power markets are more complex than 280 character tweets or political soundbites

Coal Country

We selected five of the largest coal plants in the U.S. to look at coal capacity factors

Monthly generation for the five plants was pulled from EIA datasets

Aggregate power generation was calculated

Monthly generation was compared to capacity to calculate capacity factors:
--— >  monthly generation / (capacity * 24 hours * 30 days)
Then rolling 12-month capacity factors were calculated

Record scratch. The combined capacity factor for these five coal plants has been consistently under 60% since late-2015 and under 50% since late-2019.

As shown on the chart, capacity factors began to slide as the U.S. experienced surplus natural gas and low gas prices.

Now for the kicker.  The combined wind & solar power generation in the states where the five plant sample is located is only 5.7% of total power generation.

Regional dynamics, RTOs and ISOs surely impact power prices in these states, but blaming wind & solar for low coal capacity factors looks like a stretch based on this small sample.

More to come...