WASHINGTON –– Energy Secretary Rick Perry has ordered 60-day study of the U.S. power grid, which will examine whether policies that favor wind and solar energy are accelerating the retirement of coal and nuclear plants critical to ensuring steady, reliable power supplies.

Regulators increasingly wonder how to balance the grid’s reliability with state policies that prioritize less-stable renewable energy sources.

In a memo, Perry highlights concerns about the “erosion” of resources providing “baseload power” – consistent, reliable electricity generated even when the sun isn’t shining and the wind isn’t blowing.

“We are blessed as a nation to have an abundance of domestic energy resources, such as coal, natural gas, nuclear and hydroelectric, all of which provide affordable baseload power and contribute to a stable, reliable and resilient grid,” Perry wrote in the memo to his chief of staff. But in recent years, grid experts have “highlighted the diminishing diversity of our nation’s electric generation mix and what that could mean for baseload power and grid resilience.”

President Trump has already moved to dismantle Obama-era policies that discouraged coal-fired power plants – regulations Perry said destroyed jobs and “threaten to undercut the performance of the grid well into the future.” Perry’s effort suggests that the administration may be looking for other ways to keep coal plants running.

Perry asked his chief of staff, Brian McCormack, to develop a plan for evaluating to what extent regulatory burdens, subsidies, and tax policies “are responsible for forcing the premature retirement of baseload power plants.” He also wants to know whether wholesale energy markets adequately compensate some of the attributes that coal and nuclear plants provide, such as on-site fuel supply, that strengthen grid resilience.

Conservatives – including some advising the Trump administration – have long taken aim at subsidies for renewable power, including a recently renewed production tax credit that helps offset the cost of wind and solar installations. Beyond federal tax policy, some states have enacted renewable power mandates that encourage their use.

As governor of Texas, Perry presided over a big expansion in wind power, driven in part by a requirement that the state derive some electricity from renewable sources.