Coal's share of Southwestern Public Service Co.'s generation mix was 27.2% in August, the largest slice of the pie the fuel has achieved in 2019, while natural gas and oil contributed 33.6% of the stack, according to a regulatory filing published Tuesday.
The regulated utility, a subsidiary of Xcel Energy Inc. that serves 400,000 customers in Texas and New Mexico, told the Public Utility Commission of Texas that it burned $13.7 million worth of Powder River Basin coal in August at its 1,018-MW Harrington power plant in Amarillo and its 1,065-MW Tolk Station facility in Muleshoe in the state.
However, in the year-ago month, the utility burned $17.19 million worth of coal at a 59.1% capacity factor, resulting in a 31.3% share of its generation stack.
The two plants generated 757,056 MWh of power in August, or 8.1 million MMBtu, while operating at a 48.9% capacity factor. The company's six gas and oil-fired plants generated 934,799 MWh of power in August, or 10.7 million MMBtu, while running at a 57.6% capacity factor.
On a cost per million British thermal units basis, the coal plants achieved $1.69/MMBtu, while the gas plants ran at $1.05/MMBtu. The average dispatch price for coal was $18.14/MWh, compared with $12.01/MWh for gas and oil.
In August, Southwestern Public Service bought 453,048 tons of coal from Tuco. Over 56%, or 255,683 tons, of the 8,825 Btu/lb coal went to the Harrington plant, while the remainder went to Tolk Station.
On a million British thermal units basis, the company bought over 8.04 million MMBtu of coal in August, while gas purchases totaled 10.74 million MMBtu.
Through the first seven months of 2019, Southwestern Public Service bought 2.18 million tons of 8,879 Btu/lb PRB coal at an average delivered cost of $30.30/ton, according to data from the U.S. Energy Information Administration. The Harrington plant took delivery of 1.3 million tons at an average price of $28.30/ton, while 876,922 tons was shipped to Tolk Station at $32.31/ton.
The coal, which was also supplied by Tuco, came from two mines — Arch Coal Inc.'s Black Thunder and Peabody Energy Corp.'s North Antelope Rochelle — in Wyoming, according to the data.