Average coal-fired generation in the Midcontinent Independent System Operator (MISO) was at its lowest level for any September in at least 10 years following power plant retirements and continued gains in natural gas power in the grid's footprint.
Generators in the region dispatched 531,742 MW/d of coal power last month, down by 5.4pc from September 2022, according to MISO data.
Coal generation declined even as overall electricity demand in MISO inched higher. Generators dispatched 1.72mn MW/d of power into the grid in September, compared with 1.71mn MW/d a year earlier. Coal's share of generation dropped to 31pc from 33pc in September 2022.
September was the ninth month in a row that coal-fired generation in MISO fell from year-prior levels. Some of that reflects a reduction in coal capacity in the grid. MISO had 5,254MW less available nameplate coal capacity as of the end of August than it did a year earlier, according to estimates from the US Energy Information Administration. At the same time, the amount of natural gas and renewable generating capacity in the grid climbed by roughly 769MW and 5,249MW, respectively.
Renewable capacity in MISO has grown from zero in 2005 to roughly 25pc of the grid's installed generation this year and is expected to represent 85pc of installed capacity in MISO by 2040, the grid operator's vice president of system operations, Todd Ramey, said at a US House of Representative's subcommittee hearing last week.
Natural gas generation in MISO jumped by 16pc from a year earlier in September, to 679,654 MW/d, and its share of MISO's fuel mix rose to 40pc from 34pc. That's the highest September average for gas-fired generation since at least 2013.
Renewable generation dropped by 10pc from September 2022 to 234,704 MW/d, giving it a 14pc share of MISO's fuel mix. That is one percentage point less than renewable's share in September 2022.
The decrease in renewable generation was primarily a result of reduced wind and hydropower.
For the third quarter overall, average coal generation dropped by 13pc on the year prior to 593,232 MW/d and averaged 32pc of MISO' fuel mix, down from almost 37pc in July-September of 2022.
Last quarter, natural gas generation rose by 14pc on the year to 789,725 MW/d, or 42pc of the grid's fuel mix. A year earlier, natural gas accounted for 38pc of MISO's generation dispatch. Total generation in MISO inched down to 1.88mn MW/d from 1.89mn MW/d. Wind, solar and nuclear power increased.
