OREANDA-NEWS. The share of coal in the generating fuel mix of major southwest US utilities has been stable this month compared with a year earlier, even though overall generation fell as unseasonably cool weather moderated demand.

Coal in the first half of June accounted for 41pc of generation in the Southwest Variable Energy Resource Initiative members' territories, which cover most of Arizona and New Mexico and parts of neighboring states. Natural gas accounted for 26pc of generation. Both numbers were unchanged from the same period last year.

Coal-fired generation in absolute terms fell by 2.6pc year over year to an average of 5,226MW. Gas generation was down by less than 1pc, renewable output fell by 10pc while nuclear generation was stable. Nuclear plants in the first half of June accounted for 23pc of southwest power output. Renewable resources' share was 10pc.

Arizona and New Mexico cooling degree days — a measure of cooling demand — in the two weeks ended on 13 June were lower than a year earlier, according to the National Weather Service. Average load, at 14,083MW, was 4pc lower than a year earlier. Total generation decreased by 2pc, cutting imports from neighboring power grids.

Prompt quarter Powder River Basin (PRB) coal delivered prices this month were assessed about 8pc lower than a year earlier. Southwest natural gas spot prices so far this month are down by 45pc on the year. But PRB coal still remains competitive in southwest balancing areas.

The Southwest Variable Energy Resource Initiative aggregates load and generation data from eight utilities: Arizona's Generation and Transmission Cooperatives, Arizona Public Service, El Paso Electric, California's Imperial Irrigation District, Public Service of New Mexico, Salt River Project, Tucson Electric Power and the Western Area Power Administration's desert southwest region.

Coal-fired generation in the those utilities adds up to more than 11GW. About 1GW of that capacity will retire in 2016-17, covering units at the Cholla plant in Arizona and San Juan Generating Station in New Mexico, according to Argus' power plant retirement database.

Southwest US coal plants last year accounted for 26pc of installed capacity and 39pc of total generation in the region, according to a report issued this week by electric grid reliability coordinator Western Electric Coordination Council.