The Trump administration has mangled the costs and benefits of one of the most significant climate regulations of the Obama years in an effort to justify its repeal, which Scott Pruitt, the administrator of the Environmental Protection Agency, announced on Monday.

In a leaked series of new analyses, the agency claims that jettisoning the Clean Power Plan, which limits planet-warming carbon dioxide emissions from the nation’s power plants, will save electric power producers up to $33 billion annually by 2030. But just two years ago, the agency estimated that the plan’s emissions goals could be achieved at less than a fifth of that price.

Have the economics of decarbonizing the power sector really deteriorated so badly, so quickly? Only by sleight of hand, using numerical smoke and mirrors.

The reality is that since the E.P.A. conducted the analysis that accompanied the 2015 plan, the costs of zero-carbon wind and solar energy have fallen substantially, as have price forecasts for lower-carbon natural gas. Accordingly, any new E.P.A. analysis of the Clean Power Plan’s costs should have found — as at least three outside assessments, including one by the American Petroleum Institute, have — that the rule’s pollution targets can be achieved even more cheaply than the agency initially thought.