Analysis: MISO coal burn declines in May

OREANDA-NEWS. June 19, 2015. Dispatched coal generation in the Midcontinent Independent System Operator (MISO) territory fell in May from a year earlier but by a less substantial amount than in neighboring coal-reliant power grids.

Coal-fired power plants in MISO generated about 6pc less electricity last month than in May 2014, based on the latest monthly operations data reported by the grid's market monitor. That compares with double-digit declines in the PJM Interconnection and the Southwest Power Pool.

Many coal generators in MISO have received a one-year reprieve from the April 2015 compliance deadline for the federal mercury and air toxics rule. So the bulk of retirements will occur next year.

MISO coal capacity retirements total 1.5GW this year and 3.2GW in 2016, based on Argus' coal plant retirement database.

By contrast, the bulk of PJM coal retirements happened in April-June. MISO is the second-largest wholesale power market in the US after PJM and covers all or parts of 15 states, stretching from the Canadian border to the Gulf coast.

Earlier this year, grid dispatchers made little use of coal plants scheduled for retirement in MISO, Energy Information Administration data show. By contrast, more than half of PJM coal plants marked for retirement ran in the first quarter.

Coal-fired power plants in May accounted for 69pc of generation in MISO's central region, similar to the share in May 2014 and up slightly from April 2015. Cleared load in that region, which includes Michigan, eastern Wisconsin and parts of Illinois, Missouri and Indiana, fell by 1.1pc year over year. Most of MISO's coal capacity is in that region.

The year-over-year decline was more significant in the MISO south region, where coal's load share fell to 16pc in May. But the four-state region covering parts of Arkansas, Louisiana, Mississippi and Texas already relies mostly on natural gas and nuclear power for generation. Gas amounted to 50pc of the load in MISO's southern region. It was only was only 13pc of the supply mix in the midwest segment of the grid.

Coal accounted for 54pc of generation in MISO's northern region, which includes Iowa, Minnesota, North Dakota and western Wisconsin, in May. Wind power in that region accounted for 29pc of the total.