Generator margins narrowed in the U.S. year over year in May as power and underlying fuel prices trended lower with demand.

U.S. independent system operators saw average hourly load shrink 4.9% to as much as 7.3% versus the year ago in May.

Year-over-year losses prevailed at the power hubs, driving the national average wholesale power pricing 21.1% lower to $25.63/MWh from $32.47/MWh.

Nationally averaged spot natural gas prices at hubs serving generators declined 7.9% over the same period to $2.287/MMBtu from $2.484/MMBtu.

Natural gas-fired implied heat rates in May, or the efficiency rates at which the market cost of power equals the cost of burning fuel to produce electricity, were 14.3% lower on a nationwide basis year over year. Coal-fired implied heat rates were down 13.1% to as much as 28.0% depending on the type used.

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.