Wholesale power prices in the US, with the exception of those in the West, decreased year over year in July amid an ongoing retreat in spot natural gas prices.

For the Lower 48 states, on-peak spot power prices fell 46.39% from July 2022 to an average of $57.42/MWh in July 2023, according to S&P Global Market Intelligence data.

Prices in the Electric Reliability Council of Texas Inc. had the largest year-over-year percentage decline, falling 58.41% to an average of $75.74/MWh, while prices in the US West ran counter to the wider downtrend, rising 14.19% from a year ago to an average of $93.02/MWh.

Month over month, prices rose 32.37% from June, with regional changes ranging from a 34.52% drop in ERCOT to a 158.37% increase in the California ISO.

Overall spot natural gas prices in organized US markets slipped 63.28% year over year to $2.620/MMBtu in July, led by PJM Interconnection LLC, where the prices were down 69% from a year earlier. Month over month, spot natural gas prices for the lower 48 states were up 24.74% from June, led by CAISO with a 71.59% surge in prices.

Across all US organized markets, gas-fired implied heat rates — the rate at which the market cost of power equals the spark spread, which is the cost of burning natural gas to generate electricity — rose 46% from the prior year to 21,919 Btu/kWh in July. The New York ISO had the largest year-over-year increase at 50.96% to 21,752 Btu/kWh, followed by CAISO at 47.59% to 14,743 Btu/kWh.

Year over year, coal-fired implied heat rates were up for Central Appalachia and down for the Powder River Basin in July. Compared to the previous month, implied heat rates were up for both Central Appalachian and Powder River Basin coal.

Year-over-year changes in monthly peak demand in organized markets in the US and Canada ranged between a 4.4% increase in CAISO and an 8.1% decline in ISO-NE.

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