Save public lands: Put solar on Walmart!

Parking lots and big-box store roofs could generate oodles of clean power.

On a sunny day in early December, Interior Secretary Deb Haaland stood on a dais outside the Phoenix exurb of Buckeye, Arizona, where about 3,000 acres of desert had been scraped clean and leveled to make way for the Sonoran Solar Project, which will soon provide power to some 91,000 homes. 

Haaland came with good news for utility-scale solar and climate hawks: The Bureau of Land Management would review three massive solar projects proposed in Arizona and hoped to expedite permitting for solar energy on federal lands in Arizona, California, Nevada, New Mexico and Utah. “Solar energy projects on public lands will help communities across the country be a part of the climate solution, while creating good-paying jobs,” Haaland said. 

 

 

But these projects could also potentially uproot imperiled Joshua trees and cactus, kill or displace threatened desert tortoises, block wildlife migratory paths and harm local communities. This puts conservationists and policymakers in the difficult position of having to choose between saving the desert — or the planet. 

There are other ways, however, and other locations for solar panels, from residential rooftops to farm fields fallowed by drought. France, for instance, recently required large parking lots to be covered by solar canopies that shade cars and provide up to 11 gigawatts of new generating capacity, equivalent to about 10 times the three proposed projects in Arizona. 

This inspired us to ask: How much power could be generated by slapping solar panels not only over the West’s vast parking lots, but also on its 21,000 big-box store rooftops? We did the math, and this is what we found out.  

1,155 megawatts
Estimated generating capacity if solar panels covered all 370 miles of the Los Angeles Aqueduct, as LA officials propose.

37,500 gigawatt-hours per year
Energy output of solar canopies if all of Phoenix, Arizona’s 12.2 million parking spots were covered. 

139
Number of desert tortoises relocated to make way for the Yellow Pine Solar Project in southern Nevada in 2021. Within a few weeks, 30 of them were killed, possibly by badgers.

4,200 (215,000 acres)
Grazing leases bought and retired in the Mojave Desert in California by Avantus this year to protect wildlife habitat and Joshua trees. The Onyx Conservation Project is a partnership with federal and state land management agencies to “offset” the impacts of the company’s developments elsewhere in the region.

1.3 million
Estimated number of Joshua trees destroyed by the 2020 Dome Fire, thought to be exacerbated by climate change, in the Mojave National Preserve in California. 

 

An array of solar panels on top of an Ikea store in Carson, California.
Bing Guan/Bloomberg via Getty Images

Note: We worked from two figures that were calculated by Greta Bolinger and Mark Bolinger in “Land Requirements for Utility-Scale PV: An Empirical Update on Power and Energy Density,” published in the IEEE Journal of Photovoltaics in March 2022:

Power density: .35 megawatts per acre for utility-scale, fixed-tilt photovoltaics. Most residential solar systems are about 400 watts, or .0004 megawatts. 

Energy density: 447 megawatt-hours per year per acre for utility-scale fixed-tilt photovoltaics. An average American household uses about 10 megawatt-hours of electricity annually. 

We used Environment America’s figures and Google Earth’s measurements to determine that an average big-box store has 3.25 acres of rooftop. We used American Planning Association calculations to estimate that one acre contains about 145 parking spaces. 

Additional sources: BLM, EIA, Basin & Range Watch, UC Davis, Berkeley Lab, Avantus, Primergy, American Planning Association, USGS, Environment America, Google Earth.

Infographic by Luna Anna Archey/High Country News

Jonathan Thompson is a contributing editor at High Country News. He is the author of Sagebrush Empire: How a Remote Utah County Became the Battlefront of American Public Lands.