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About 200 sheep were released on the 45-acre OCI Solar Power Alamo 2 solar farm at 8203 Binz-Engleman on Tuesday, April 2, 2019. Their release is an effort control vegetation, which if left unchecked, can begin to block the sun from the solar panels, which produce enough power for about 1,000 homes.

Fields of solar panels at OCI Solar Power's Alamo 1 Solar Farm are seen Sept. 23, 2020 as CPS Energy's coal-powered electric plant is seen in the background.

Renewable sources of electricity have contributed more than a third of the power on the Texas grid so far this year, dwarfing the amount generated by wind and solar farms just a year ago.

Renewables are slowly edging out fossil fuels on the state’s electric grid, as well.

Solar power has grown exponentially in Texas over the past few years. In the first three months of this year, solar farms generated 85 percent more power than in the same period last year. In March alone, solar produced more than 1,800 gigawatt hours of electricity in Texas — more than twice the amount it generated in Texas in all of 2016.

On ExpressNews.com: End of San Antonio’s last coal-fired power plant in sight; CPS likely to rely more on natural gas

With more than 4,600 gigawatt hours generated in the first quarter, solar farms contributed an all-time high of 5 percent of the state’s electricity. That was nearly four times the amount they generated in the first quarter of 2020.

Meanwhile, wind turbines generated 29 percent of the state’s electricity so far this year. That was second only to natural gas, which is still the primary fuel used for electric generation in Texas.

After overtaking coal as a state power source in 2020, wind continued expanding its lead over the fuel. Coal plants contributed 19 percent of the state’s power in the first quarter, unchanged from a year ago. But the ratios have flipped from five years ago. In 2017, coal generated nearly one-third of Texas’ electricity while wind turbines contributed 17 percent.

While natural gas remains the most common generation fuel in Texas, wind and solar power apparently have supplanted some gas-fired generation in 2022. Natural gas plants have produced 35 percent of the state’s power so far this year, continuing a downward slide from 42 percent last year and 46 percent in 2020.

The same trend is being seen in San Antonio, where city-owned CPS Energy generated nearly 30 percent of the city’s electricity using natural gas, more than any other source. But that was a decline from 33 percent a year earlier.

The most recent yearlong data that’s available for CPS generation covers the period from October 2020 through October 2021.

Over that period, CPS got 13 percent of its power from renewable resources and 28 percent from its nuclear power plant in South Texas. Statewide, nuclear power plants have contributed 12 percent of power in Texas so far this year, a slight increase from the first quarter last year.

On ExpressNews.com: CPS Energy partners with Bill Gates-backed startup Quidnet on underground energy storage system

CPS Energy’s J.K. Spruce coal-fired power plant, meanwhile, generated 23 percent of San Antonio’s power in that yearlong period, but it is also among the largest sources of air pollution in the region.

And CPS could be changing how it produces power over the next few years.

The utility is expected to sign contracts by midyear to purchase power from several solar farms, which could add 900 megawatts of solar capacity for the pubicly owned utility. It currently has 500 megawatts of solar capacity.

CPS also is preparing to shutter its Braunig and O.W. Sommers gas-fired power plants, which were built in the 1960s and early 1970s. The utility will close those in 2025 or 2026, likely replacing the power they produce by contracting to buy electricity from an existing gas-fired plant in South Texas.

By about 2028, CPS is expected to close one of the coal-fired units at the Spruce plant and convert the larger second unit to run on cleaner-burning natural gas.

CPS interim CEO Rudy Garza has said the utility will examine the future of the Spruce coal plant this year and ask it’s five-member board of trustees to vote on a plan by the end of the year.

“We’ve got to have access to natural gas capacity that can be turned on when solar is not there,” Garza said. “That’s the trick we’re trying to figure out.”