Still, the orders could be reversed by a future administration. And the plan does not cover purchasing by the Department of Defense, which accounts for a large portion of the government’s energy spending. Clean energy purchases could also cost the government more money in the short run, and many of the components like electric charging stations for an all-electric federal vehicle fleet have not yet been built.

Republicans already are mounting opposition to the plan. On Wednesday Senator John Barrasso of Wyoming, the top Republican on the Senate Committee on Energy and Natural Resources, denounced it as “disgraceful” and said the plan would harm workers in the fossil fuel sector.

“This is not build back better,” he said in a statement. “It’s another backbreaking move to build bigger bureaucracy.”

The plan Mr. Biden set forth presents significant challenges for the administration.

Just 40 percent of the electricity purchased by the federal government now comes from renewable sources like wind and solar. The goal is to ramp that up to 100 percent in less than a decade. The federal government currently consumes just 1.5 percent of the nation’s energy, although it is a major player in certain states where it has significant operations, such as Virginia, California, Georgia and North Carolina.

In converting its power to wind, solar and other sources that don’t produce planet-warming emissions, the government intends to follow the path set by companies like Google, Apple and Wal-Mart, which established tariffs or developed power-purchase agreements with local utilities to achieve their goals of 100 percent renewable energy, a senior administration official said.

The requirement to purchase only zero-emissions vehicles by 2035 is even more difficult.

Currently electric vehicles represent only about 1.5 percent of the government fleet. In fiscal year 2021 the administration purchased 650 electric vehicles, according to the administration, a number it hopes to increase several-fold this year and beyond. The government buys about 50,000 vehicles a year, many of those are replacements.

“That’s about half the annual output of one factory, about half of one percent of all vehicles sold every year,” said Steven Koonin, a physicist who was an under secretary of energy under President Barack Obama and who is now a climate policy fellow at the American Enterprise Institute, a conservative research organization. “It’s small potatoes.”