Air Pollution Control Equipment Services, Coal, Emissions

Tucson Electric Power to add fourth coal unit

11 May 2006 — A fourth unit will be added to Tucson Electric Power’s Springerville Generating Station (SGS), the company announced yesterday, expanding the availability of coal-fired power in the region. Salt River Project (SRP), a Phoenix-based utility, will own the 400-MW unit and control its output. The unit is expected to begin commercial operation in late 2009.

The new unit will stand alongside SGS Unit 3, which is under construction and is expected to be placed online during the third quarter of this year. That 400-MW unit will be leased from a financial owner by Tri-State Generation and Transmission Association, a wholesale power cooperative that will control the unit’s output. Tucson Electric Power (TEP) will operate both new units along with the two existing 380-MW units at SGS.

“This project gives us another opportunity to generate additional value from our existing investments and plant operating experience,” said James S. Pignatelli, chairman, president and CEO of TEP and its parent company, UniSource Energy Corp.

Pignatelli said that both new units at SGS will contribute to the diversity of Arizona’s energy supply, which is increasingly reliant on plants fueled by natural gas.

As for pollution controls, TEP said that like Unit 3, Unit 4 will use best available control technologies and equipment to limit emissions. The units will employ dry scrubbers for sulfur dioxide reduction, selective catalytic reduction and low NOx burners to control oxides of nitrogen, and baghouses to capture particulates. Fly ash and bottom ash — byproducts from the coal combustion process — will be collected and stored on-site in sealed landfill facilities.

This equipment combined with recent emissions control upgrades to Units 1 and 2 will ensure that total emissions from all four units will be significantly less than previous emissions from the two existing units.

TEP and SRP have formed a project team to oversee construction of Unit 4, which is expected to cost SRP between $600 and $650 million.