Tucson Electric burns its last coal – over two years early – at Sundt Unit 4

Tucson Electric Power (TEP), which had been mulling this decision for a while, said Aug. 13 that it is ending the use of coal at its largest local power plant, the Sundt facility, as part of a plan to diversify the resources it relies on for generating capacity.

The coal inventory at the H. Wilson Sundt Generating Station is expected to be depleted as of Aug. 13. The last remaining chunks will be pulverized and fed into the boiler of Unit 4, a multi-fuel unit that now will rely primarily on natural gas, supplemented by renewable landfill gas and a unique “solar boost” system.

“Eliminating the local use of coal is an important part of our plan to build a cleaner, more diverse energy portfolio,” said David G. Hutchens, TEP’s President and Chief Executive Officer.

The Sundt plant has been a focus of changing federal energy and environmental policy. In 1982, the U.S. Department of Energy (DOE) ordered that all four units at the natural gas-fired plant be converted to coal under the Power Plant and Industrial Fuel Use Act of 1978, which sought to preserve domestic supplies of natural gas during the energy crisis. That law was repealed in 1987, and the DOE later rescinded its order after TEP had completed the conversion of Unit 4.

Now the plant is subject to new federal requirements that require reductions in coal-fired emissions. The U.S. Environmental Protection Agency (EPA) accepted TEP’s proposal to end the use of coal at the plant as an alternative to the installation of costly emission controls to limit regional haze.

TEP is ending its use of coal at the plant more than two years ahead of the Dec. 31, 2017, deadline in its agreement with the EPA. The transition also will help Pima County comply with stricter ozone standards that take effect later this year while reducing the plant’s CO2 emissions, contributing toward compliance with the final Clean Power Plan, issued in August by the EPA and designed to take effect beginning in 2022.

TEP typically fueled Unit 4 with coal when natural gas prices were higher. While Unit 4 will lose that flexibility, it can produce 30% more power when fueled by natural gas.

TEP’s Integrated Resource Plan (IRP) calls for cutting the company’s coal-fired capacity by more than 30% and reducing greenhouse gas emissions by 25% over five years. TEP is increasing its use of natural gas and relying more heavily on its expanding renewable energy portfolio, which now includes more than 400 MW of solar, wind and other resources.

Tucson Electric said in its IRP filed in April 2014 at the Arizona Corporation Commission that it anticipated permanently eliminating coal at Sundt Unit 4 and operating the unit on natural gas starting in 2018. Sundt is a four-unit station located in Tucson. Units 1, 2 and 3 are gas- or oil-burning units with capacities of 81 MW, 81 MW and 105 MW, respectively. Unit 4 has a capacity rating of 156 MW burning gas and 125 MW burning coal.

TEP provides safe, reliable electric service to more than 414,000 customers in southern Arizona. TEP and its parent company, UNS Energy, are subsidiaries of Fortis Inc., which owns utilities that serve more than 3 million customers across Canada and in the United States and the Caribbean.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.