After vaulting almost fivefold in August, wholesale power prices in the Electric Reliability Council Of Texas Inc nearly quadrupled year over year in September, once again spurred by extreme heat.
Day-ahead on-peak power prices in ERCOT averaged $152.42/MWh in September, a 374.1% jump from the index of $32.15/MWh in the previous year. The average spot power price for the U.S. was up only 23.5% over the same period at $43.36/MWh.

Spot power prices in Texas spiked into the $970s/MWh to as much as the $980s/MWh on Sept. 5 before pulling back but remaining elevated in the $840s/MWh to as much as the $850s/MWh on Sept. 6, just on the heels of a conservation appeal from ERCOT as the grid operator expected extreme temperatures to result in tight grid conditions.
"Some areas of Texas are expected to see the highest temperatures experienced so far this summer. Temperatures are expected to exceed 100 degrees in all major Texas metropolitan areas through Sept. 7," the grid operator said in a statement.
ERCOT load during the month peaked on Sept. 6 at 68,817 MW, which became the grid operator's new load record for the month of September. That load level was 6.5% higher than in the prior year, while September peak load was mostly lower year over year for the other independent system operators in the country.

Underlying gas prices for the Texas grid operator fell 16.1% year over year to an index at $2.262/MMBtu in September. That was in line with a 17.2% decline in the national average pegged at $2.256/MMBtu.

Implied heat rates, or the efficiency rates at which the market cost of power equals the cost of burning fuel to produce electricity, surged 465.3% year over year in September for gas-fired generators in ERCOT. Coal-fired implied heat rates in the region soared 194.2% to as much as 230.6% over the same period, depending on the type of coal used.


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