Natural gas-fired generators fared better than coal-fired generators in December 2019 as power and gas prices fell sharply.

U.S. average implied heat rates, or the efficiency rates at which the market cost of power equals the cost of burning fuel to produce electricity, climbed 18.3% year over year for gas-fired generators in December 2019. Implied heat rates fell 8.9% to as much as 25.5% over the same period for coal-fired generators, depending on the type of coal used.

Independent system operators across the country saw underlying gas prices decline at a faster pace than wholesale power prices during the month. On a nationwide basis, the on-peak spot power price index was 26.2% lower year over year in December 2019 at $30.90/MWh, while the average gas price at hubs serving power generators was down 37.6% over the same period at $2.668/MMBtu.

Demand firmed up in December 2019, with the monthly peak load higher by 0.7% year over year in the California ISO to as much 7.8% in the Electric Reliability Council Of Texas Inc.

Market prices and included industry data are current as of the time of publication and are subject to change. For more detailed market data, including power and natural gas index prices, as well as forwards and futures, visit our Commodities pages.