For similar reasons that Las Vegas homebuilders look to build in the city’s outlying areas, solar developers often seek federal public land when looking for where to place large-scale projects. The land is easy to develop. It is open. It stretches on for miles. But these solar projects routinely run into roadblocks, conflicting with other uses of federal land, which belongs to all Americans.

Recent solar and wind projects, proposed to operate on the federal land that comprises most of Nevada, have come into conflict with wildlife corridors, public access and conservation areas. That tension has split environmental groups, allies united by tackling climate change but divided over how to deploy massive amounts of clean energy without squeezing natural habitats. And it has led many organizations to ask: What if solar developers are looking in the wrong places?

Last year, the Nature Conservancy and the Nevada Mining Association proposed and helped pass a regulatory change to make solar arrays an option for cleaning-up and closing old mines, disturbed land unburdened by the conflicts that exist on untouched federal land. The idea is to direct new solar projects to brownfield sites while giving companies another option for reclamation. Mines also have existing roads and transmission, easing some of the barriers for energy development.

“We can scale up redevelopment of mine lands,” Jaina Moan, an external affairs director for The Nature Conservancy focused on climate, said during a panel on Saturday. “Renewable energy deployment can be an alternative to reclamation, and it can also support mining operations.”

The panel, part of the mining association’s annual meeting in Stateline, dug into the proposal, focusing on what it would take to actually locate renewables on operating or closed mines. As with prioritizing infill development in cities, what is often seen as a “win-win” by land use experts faces a challenging uphill battle when it comes to permitting, financing and economics.

Although renewables have been placed on brownfields elsewhere in the country — and the world (there is solar on an old coal plant in Canada) — the idea has not fully taken hold in Nevada, though some projects have been proposed. In 2004, the Environmental Protection Agency looked at the Bullfrog mine near Beatty as a pilot project to test solar arrays on scarred land. And Moan said the conservancy is exploring other opportunities.

Although developers can potentially amplify the environmental benefits of solar by building on brownfields, they face several challenges. One is that solar contracts usually require a long-term commitment from an offtaker, often through a contract known as a power purchase agreement, for a term that can last as long as two decades. Permitting solar fields can also be a challenge because mining companies are required to outline a closure strategy before operations begin. Finally, it can be more difficult to entice solar developers to consider brownfields because the sites often require more technical expertise to build on and there are concerns about taking on additional liability.

Moan said some of these issues can be dealt with early in the process, including in permitting. She emphasized that there were also opportunities to integrate solar into existing mining operations. Those could potentially be expanded — or scaled up — once a mine went out of operation.

“These considerations can also be made from mining companies who are in the exploration phase in thinking about their operating plans — and thinking about their reclamation and closure plans — and including renewable energy on that,” she said during the panel discussion.

John Seeliger, a regional energy manager for Nevada Gold Mines (a newly formed joint-venture between Barrick and Newmont), said renewables are taking a “higher priority” for the company. He suggested on-site renewables could also help with some transmission issues in Northern Nevada.

In part, the interest in renewables is a recognition of the economics. Energy analysts expect the cost of generation for solar to decrease in Nevada and the cost of natural gas to gradually rise through the next two decades. Although those estimates rely on a metric — the Levelized Cost of Electricity — that does not take into consideration external issues, the cost of intermittency (in the case of solar) or the cost of greenhouse gas emissions (in the case of natural gas), they provide a rough estimate for the lowest cost option for constructing new power generation. And in Nevada, that option is solar.

Mines have traditionally sourced their power from an electric utility or power plants that are able to produce electricity regardless of whether the sun is shining. (Nevada Gold Mines owns one of the state’s last two coal plants.) That's because reliability is integral to mining operations, Seeliger noted.

“A mining process is a 24/7 operation, and we can’t afford to look at lowering [power supplies] at night because obviously our process has to continue to move forward,” he said.

But he added that the costs and technology for battery storage technology is changing rapidly. Batteries can store excess solar energy produced during the day, which allows power users to access those electrons at night.

Part of the challenge in getting operations to adopt renewables — both for on-site use and at legacy sites — are competing interests within a company, said Ned Harvey, a managing director for industry and heavy transport at the Rocky Mountain Institute, which advocates for clean energy.

“I think the biggest problem is the barrier between corporate interests and operating interests,” he said.

Harvey explained that mining firms have a structural incentive to meet immediate performance metrics. That can make it difficult to convince companies to commit to a project perceived as new, technical or risky.

But it’s not just about solar. Jim Faulds, who directs the Nevada Bureau of Mines and Geology, argued that there is a potential to include geothermal in mining operations. Because of the Great Basin’s dynamic geology, there is a significant amount of untapped geothermal, a renewable resource that taps into energy stored in hot underground water. Potential for geothermal energy often overlaps with mineral deposits, Faulds said, making it an option for heating or renewable energy, if the economics penciled out.

Las Vegas Rep. Dina Titus, who spoke after the panel, offered an update on federal mining legislation and said she was concerned about how the Trump administration’s trade war with China could affect the industry.

“Regardless of what the administration may think, our economy is globally linked,” she said. "Your industry does not stop at the border."