By installing solar arrays at the Roger Road Wastewater Treatment Plant, Pima County will reduce its electricity use over the next 20 years by an amount equivalent to taking 11,000 cars off the road.
This is Pima County's first step toward using renewable-energy sources to generate 15 percent of the county's energy needs by 2025, one of the county's sustainability objectives.
The arrays will generate 40 percent of the electricity needed for the sewage-treatment plant and 1.8 percent of the county's total annual power requirements.
Pima County has two master agreements with Solon America Solar Electric and Sun Edison that should have the county generating 6 megawatts of electricity from solar power over the next three years.
First up in those master agreements is the Roger Road project, which will produce 1 megawatt of power. The photovoltaic modules will be made in Tucson at Solon's plant here and be installed sometime in the next year.
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The 20-year contract will cost the county $3.5 million.
County officials estimate that buying the same amount of power over two decades from Tucson Electric Power would cost $5.5 million.
By not buying that power from TEP, the county avoids the generation of 64,000 tons of carbon emissions over the 20-year period. That's equivalent to taking 11,160 cars off the road over the same time period, said Tedra Fox, the county's sustainability manager.
Fox said the Roger Road facility was chosen because there is a large demand for power in one location that also has enough open space to accommodate the photovoltaic modules. The arrays will take up about 10 acres.
The location of the solar panels will be compatible with a plan to build a new sewage-treatment plant there and remove the old one to comply with new federal regulations on effluent.
Under the terms of the contract, approved last week by the Board of Supervisors, Solon will build, own and operate the facility. At the end of the contract, Pima County can buy the solar arrays for fair-market value, negotiate a new agreement or ask for the solar arrays to be removed, depending on the state of solar technology at that time.
