By Chris Mooney / The Washington Post

The Belridge oil field near Bakersfield, California, is one of the largest in the country. It has been producing oil for more than a century and last year produced around 76,000 barrels a day, according to operator Aera Energy.

Now the oil field is about to become even more remarkable. Its future production will be powered partly by a massive solar-energy project to make the extraction process more environmentally friendly, according to Aera and GlassPoint Solar, the firm that will create the solar project.

The Belridge field was discovered in 1911. Oil from the field flowed out of the ground because of natural pressure in the geologic reservoirs. Later, as the pressure declined, many companies said the field was exhausted. The field gained new life in the 1960s through a process known as enhanced oil recovery. But squeezing more crude oil from the Belridge requires large amounts of steam to loosen the heavy crude, which in turn requires energy.

Traditionally, Aera used natural gas to heat water to create steam. Now Aera and GlassPoint will use a large, 850-megawatt solar thermal array to evaporate the water that’s pumped into the ground to liberate more oil. The companies say this will offset 4.87 billion cubic feet of natural gas per year and avoid the emission of 376,000 tons of carbon. The water used emerges from the process of oil extraction itself and will be recycled and pumped back into the ground.

The project was made possible by the recent extension of California’s cap-and-trade system for carbon-dioxide emissions to 2030, said Christina Sistrunk, chief executive of Aera Energy, a company jointly controlled by Shell and ExxonMobil.

“We need some level of what I would call regulatory and legislative stability to be able to fund projects that really need a couple of decades worth of certainty to be economic,” Sistrunk said. “The extension of that program really underpinned our ability to make this long-term commitment.”

The solar thermal array will capture the sun’s energy using curving mirrors, then use that energy to heat water. A smaller, 26.5-megawatt solar photovoltaic installation will help power oil-field operations. The project should start operations by 2020, the participating companies said.

This is the second such megascale solar-oil project for GlassPoint, which is building the massive, 1-gigawatt Miraah project in Oman, on the tip of the Arabian Peninsula. (A gigawatt refers to the capacity to instantaneously generate 1 billion watts of electricity; a megawatt refers to the capacity to generate 1 million watts.) The Belridge project will be California’s largest solar project, the company said.

“From the day we start operating, Aera will see an enormous reduction in the amount of gas they consume in a given day,” said Ben Bierman, chief operating officer and acting CEO of GlassPoint Solar.

The combination of massive solar and massive oil is not what comes to mind when it comes to the global expansion of renewables, which generally has been led by wind and solar installations. But joint projects of various types between major oil producers and renewable energy players are growing, too. The Norwegian oil giant Statoil has announced plans to build solar arrays in Brazil with a clean-energy industry partner and made a major push into offshore wind energy; Shell is exploring a large solar project in Australia.

What’s different about the Belridge project is the use of renewables, which don’t emit greenhouse gases, to produce more fuel that will emit those gases. That could leave environmentalists feeling rather ambiguous. But this, too, has parallels — a recent major carbon-capture and storage project in Texas will capture most of the carbon dioxide emitted by a major coal facility, then pipe the gas in a liquid form to an oil field where it will, once again, be used in enhanced oil recovery.

What these examples show perhaps most of all is that as renewable energy becomes more and more a part of our lives, it will also become increasingly integrated into more traditional energy systems.

From an environmental perspective, Aera-GlassPoint project is a “good step,” said Simon Mui, director of California vehicles and fuels for the Natural Resources Defense Council, an environmental advocacy nonprofit. But Mui, who said his group had not yet fully evaluated that project, noted a distinction between reducing emissions from “fossil fuel infrastructure,” which the current project would do, and a more long-term project of reducing the emissions from transportation as a whole by substituting battery-powered vehicles or other technologies for cars that run on oil.

“I think it’s a false solution to think you can only do one or the other,” Mui said. “And I think the state policies are looking to do two things: one is accelerate the transition to electric-drive technologies and other alternative sources, as well as to clean up the existing fossil-fuel infrastructure. You kind of have to do both to meet both state and global air-quality and greenhouse-gas targets.”