Topeka ? A proposal imposing the state’s first tax on carbon dioxide emissions won first-round approval Monday night in the House, but some members didn’t see it as a sincere effort to combat global warming.

The proposal’s sponsors drafted it so that its tax of $37 on each ton of excess CO2 emissions probably would apply only to the Board of Public Utilities in Kansas City, Kan.

Some House members interpreted the measure as an attempt to punish Wyandotte County legislators who have opposed two proposed coal-fired power plants in southwest Kansas.

Its sponsors said they want to encourage utilities to limit greenhouse gas emissions that many scientists link to climate change. They also said they are showing a willingness to compromise on energy policy.

Three Republicans who support the southwest Kansas plants proposed the new carbon tax. They offered their plan as an amendment to a Senate-passed bill making relatively minor changes in various tax laws.

The House approved the amendment 78-42, then advanced the entire package on a voice vote. Final action is expected today, when approval would return the bill to the Senate, which must consider the House’s changes.

“This is truly designed to get carbon dioxide emissions reduced,” said Rep. Tom Sloan, a Lawrence Republican, one of the amendment’s sponsors.

House action was part of a larger debate triggered by the state’s denial in October of an air-quality permit for Sunflower Electric Power Corp. The utility wants to build two coal-fired plants outside Holcomb, in Finney County.

Many legislators support Sunflower’s $3.6 billion project, viewing it as much-needed economic development. In denying the permit, Roderick Bremby, secretary of health and environment, noted the plants could produce 11 million tons of CO2 a year.

Sunflower’s supporters drafted a bill to allow the coal plants and strip the secretary of some power. Gov. Kathleen Sebelius, who appointed Bremby, vetoed it.

Supporters drafted a second bill, and some are trying to build the two-thirds majorities necessary in both chambers to override Sebelius’ veto. They’re short in the House, where six members from Wyandotte County opposed the bill she vetoed.

Six weeks ago, the House voted 66-49 against a proposal to impose a tax of $3 a ton on excess CO2 emissions. Some legislators who opposed that plan, arguing it would hurt the state’s economy, voted Monday for the carbon tax of $37 a ton.

“I question the sincerity of this,” said Tom Thompson, a lobbyist for the Sierra Club’s state chapter. “It stirred the pot.”

But supporters said the new proposal was more acceptable because of how it was drafted.

First, it would apply only to utilities with a total generating capacity of more than 350 megawatts. That’s Kansas City’s BPU, Sunflower, Westar Energy Inc. and Kansas City Power & Light Co.

Any money raised would be used to finance a tax credit for the utility with the state’s lowest CO2 emissions in tons per megawatt hours of electricity.

“It’s just almost a sin tax,” said Rep. Clay Aurand, a Courtland Republican and another sponsor of the amendment. “If they clean up a little, there won’t be any.”

The tax also would apply only when a utility’s emissions are 10 percent greater than the statewide average for all utilities. That provision narrows the list of utilities likely to pay it to Kansas City’s BPU.