Local opinion: Data centers must use solar power

Despite citizens’ objections and concerns about increasing cost for electricity and water scarcity, both the Pima County Board of Supervisors and Marana’s city government have given approval for building data centers. Beale Infrastructure has already begun site preparation near the Pima County fairgrounds. Preliminary work near Veterans Memorial Park in Marana may soon follow. Both the Pima County Board of Supervisors and the Marana City Council must require data centers to be powered by sunshine, not fossil fuels and be net water positive.

Data centers are incredibly energy-intensive, consuming an estimated 4% of U.S. electricity, with that number growing rapidly as AI and cloud services expand. When powered by fossil fuels, they worsen climate change and place massive demands on scarce water supplies. Those environmental costs should not be borne by residents and can be avoided if Beale provides its own electricity by building a solar farm coupled with battery storage for nighttime power. Beale can also be required to be net water positive.

Arizona sunshine is free and plentiful; water is not. That is especially true now, as dramatic reductions in water supply will soon be imposed by the Bureau of Reclamation. Beyond emissions reductions, one of the strongest arguments for solar-powered data centers is water conservation. Because most water use in the data center lifecycle comes from electricity generation, shifting to solar dramatically reduces total water demand.

Utility-scale solar in the U.S. Southwest typically produces electricity at $0.02–$0.04 per kWh, according to the U.S. Energy Information Administration (EIA). This makes it the cheapest source of new power generation. Solar is, of course, intermittent, and large-scale battery storage is essential for data center reliability.

Consequently, Beale would need to invest either in Lithium iron phosphate (LFP) batteries or in gravity batteries, and the cost to do that would be significant. This would mean upfront costs for solar would be greater than the cost of a gas-fired power plant. It would also incur significant costs for land purchase. But once built, the cost to provide power is negligible. Sunshine does not need to be purchased, mined or refined, and it does not pollute.

Additionally, storing power in batteries provides multiple advantages, including cutting reliance on water for cooling, cutting dirty emissions and noise, and providing reliability during nighttime hours or during grid outages. But the critical advantage of a solar-powered data center is its very limited use of water.

Traditional fossil fuel and nuclear power plants use enormous volumes of water for steam generation and cooling. Studies from the National Renewable Energy Laboratory (NREL) show that both coal and natural gas plants consume roughly 2.5 billion gallons of water annually for cooling and steam generation. By contrast, solar PV uses nearly zero water to generate electricity. The only significant water use comes from panel washing.

If Beale were required to buy land for a solar farm from land that had been used for growing cotton, water use would be cut to less than 1/100th of the water formerly used.

Powering data centers with solar panels and battery backup is technically feasible, economically competitive, and environmentally advantageous. While upfront capital costs for building a solar farm and utility-scale batteries are significant, the operational cost to power a data center with solar panels is very low, and the water savings — especially in our area — are vital. Our water supply is already imperiled, and that problem will become worse with time.

As data center demand accelerates, solar plus storage systems offer a path to sustainable, water-efficient digital infrastructure. Both the Pima County Board of Supervisors and the city of Marana must demand nothing less.