By Tom Kleckner

ERCOT on Monday approved Luminant’s proposal to dispose of nearly 2,300 MW of coal-fired generation capacity in Texas.

The ISO’s reliability assessments determined that none of the four units at the company’s Big Brown and Sandow plants was “required to support ERCOT transmission system reliability.”

Luminant, the generation subsidiary of Vistra Energy, announced the retirements of both plants last month. (See Vistra Energy to Close 2 More Coal Plants.)

ERCOT said the Texas grid is undergoing “significant change,” with new technologies “changing the role that some older generation resources play in grid and market operations.” The ISO said lower natural gas prices have been reducing revenues for all generators in recent years, and wind and solar resources continue to flood the market.

As of Oct. 30, ERCOT has nearly 48 GW of new generation projects under study, and more than 21 GW of new projects have interconnection agreements. That includes more than 10 GW of proposed gas-fired projects, 2 GW of utility-scale solar and more than 8.7 GW of wind projects.

ERCOT has said it will have almost 81 GW of total capacity available this winter, more than enough to meet a projected peak of more than 61 GW. It will update the expected reserve margins for 2018 and the next several years in the next Capacity, Demand, and Reserves Report, scheduled for Dec. 18.

The Public Utility Commission of Texas has also directed the ISO to study and consider the appropriate level of reserves needed to maintain reliability while minimizing costs in its energy-only market.

Big Brown’s two units date back to the early 1970s and are capable of 1,150 MW of output. Vistra has said it is exploring a sale of the site north of Houston, but the plant will be shut down if it hasn’t been sold by Feb. 12, 2018.

Sandow’s units date back to 1981 and 2009 and have 1,137 MW of capacity. They will be closed Jan. 11.

Combined with the earlier retirement of Monticello’s three coal units, Luminant will have shuttered 4,167 MW of coal capacity by early next year — more than half of its 8,000 MW of available capacity. The company has only two coal plants left: Martin Lake (2,250 MW) in East Texas and Oak Grove (1,600 MW) in the southern part of the state.