U.S. House lawmakers are targeting a 20% reduction in greenhouse gases from 2005 levels by 2020 in a draft climate bill unveiled Tuesday that promises to raise energy costs for the country, but leaves many of the most important details for later negotiations.

The draft document, published by the Energy and Commerce Committee, omitted specifics on the percentage of carbon dioxide credits to be auctioned off versus given freely to industry, a key determinant of how much such a program will cost.

Facing a fierce political fight over a measure that will have a wide-reaching impact across the economy, the decision by House Energy and Commerce Committee Chairman Henry Waxman, D-Calif., will buy time for further negotiations on the issue.

The draft bill - the American Clean Energy and Security Act - establishes a decreasing cap on greenhouse gases and creates a market where businesses could buy and sell the right to emit those gases.

It also includes a federal mandate for an increasing percentage of electricity to come from renewable sources, an efficiency standard and new performance standards for coal-fired power plants.

"This legislation will create millions of clean energy jobs, put America on the path to energy independence, and cut global warming pollution." Waxman said. "Our goal is to strengthen our economy by making America the world leader in new clean energy and energy efficiency technologies," he said in a statement.

Industry groups such as the U.S. Chamber of Commerce believe that too aggressive emission cuts without safety valves that can alleviate price pressures could force businesses overseas and will raise energy prices to unsustainable levels.

Waxman's omission indicates that President Barack Obama's plan for an auction of 100% of the credits is unlikely, and a later version of the bill will most likely include allocation of credits to energy-intensive industries such as the steel, aluminum, paper and chemicals. In the President's 2010 budget proposal, Obama estimated the auction could have raised nearly $650 billion in climate revenue over the course of eight years, though Treasury officials estimated it would likely raise two to three times that amount.

Lawmakers - particularly those from manufacturing and coal-powered states - are likely lock horns over the percentage allocations distributed to industry and the distribution of climate revenue.

Few believe that the Senate, where the biggest battle looms for a climate change bill, will pass legislation this year to cut greenhouse gases even if the House approves a version of Waxman's bill.

But House passage would give the president substantial leverage in international climate treaty talks to be conducted through the year. Waxman has said he wants to pass the bill out of his committee by the end of May, and the House could approve the bill before a meeting of major economies in July, leading up to the December United Nations negotiations in Copenhagen.

One of the key measures to mitigate costs will be the "offset" program, which allows firms to offset their emissions through other emission-reduction projects such as re-forestation or updating technology at foreign power plants. The offset program is designed to leverage greater emission reductions, however, and requires a certain amount of emission cuts to buy offset credits.

Waxman's draft includes:

- A new source performance standard for coal-fired power plants that cuts carbon dioxide emissions by 50% by 2015 and 65% by 2020

- Renewable electricity standard from 6% by 2012 up to 25% by 2025

- An energy efficiency standard, up to 15% in electricity savings and 20% in natural gas savings by 2020.

- A low-carbon fuel standard designed to drive development of electric vehicles and biofuels

- A required $10 billion utility charge to fund carbon dioxide sequestration projects

- A mandate for a 30% increase in building efficiency for new buildings by 2012 and a 50% increase by 2016

- By Ian Talley, Dow Jones Newswires, 202-862-9285; ian.talley@dowjones.com