Catherine Schladweiler, P.E.Principal, Environmental Policy and Sustainability, Tucson Electric Power Company
With the goal of greater sustainability, Tucson Electric Power Company (TEP) is taking steps to conserve as much water as possible in our power generation operations, as well as throughout its office facilities and grounds. Water is a precious resource in the Sonoran Desert, so everything our electric company can do to reduce our water consumption makes good sense from both an environmental and business perspective.
In late June, TEP submitted a bold Integrated Resource Plan to state regulators that calls for more than 70 percent of its power to be derived from wind and solar resources, and an 80 percent reduction of carbon emissions by 2035. TEP will achieve this with the eventual retirement of two units at our Springerville Generating Station in 2027 and 2032, and our coal-fired units at Four Corners Power Plant and San Juan Generating Station.
Our cleaner, greener energy portfolio also will reduce surface and groundwater use by 70 percent over the next 7-12 years.
The company’s steam-operated fossil fuel plants boil water to create steam that drives turbines to create electric energy. This steam is then collected and sent through a condenser that circulates cool water through pipes to convert the steam back into water. The process repeats many times for the generation of electricity, but TEP attempts to use and recycle every drop of water to the fullest extent.
At TEP’s H. Wilson Sundt Generating Station in Tucson, for example, water from waste sumps is recycled seven times for use in the cooling towers, explained Dylan Bearce, Director of Tucson Power Production.“We do everything we can to take our condensed water and storm water and use it in our processes. We also repair leaks quickly and adhere to good maintenance practices to reduce water use,” he said.
With TEP’s replacement of two units at the Sundt plant with 10 new water-efficient, natural gas-firedreciprocating internal combustion engines (RICE) in early 2020, the facility expects to reduce its annual water use by nearly 70 percent. “The RICE engines have a closed-loop system that results in low water losses and makeup requirements,” Bearcenoted.
The new RICE generators are not only 40 percent more efficient than the units they replaced, but also reduce nitrogen oxide emissions by 60 percent – contributing to cleaner air – and provide flexible power generation to support the company’s use of intermittent wind and solar energy.
“All of the water that we take and use is pH balanced and put into holding ponds,” said Walter Yosin, SGS Environmental Superintendent. “In ourponds, you’ll see ducks and water fowl. We do everything in our power to be responsible with our water use and protect the environment.”
TEP’s water conservation efforts also extend to our office facilities and grounds. Built in 2011 to LEED Gold standards, the company’s headquarters building in downtown Tucson features low-flow toilets, motion-sensor faucets and a 170,000 gallon cistern for capturing rainwater and water from the building’s cooling tower basin for irrigating landscaping.
Each year, about 191,000 gallons of rainwater and recycled water from the cooling tower basins is captured in the cistern and used to water landscaping. Using the basin water as a backup for the cistern reuses water that would normally drain to the city sewer.
Water in the Tucson basin is carefully managed to ensure there is enough water to serve our population for at least the next 30 years, but TEP still needs to do its part to conserve this valuable commodity. With the dramatic shift away from fossil resources to the expansion of renewable energy in coming years, TEP will continue to realize even more significant water savings.