Washington ? The Obama administration renewed its commitment Tuesday to speed up investments in ethanol and other biofuels while seeking to deflect some environmentalists’ claims that huge increases in corn ethanol use will hinder the fight against global warming.

President Barack Obama directed more loan guarantees and economic stimulus money for biofuels research and told the Agriculture Department to find ways to preserve biofuel industry jobs. The recession, as well as lower gasoline prices, has caused some ethanol producers to suffer, including some who have filed for bankruptcy.

Obama said an interagency group also would explore ways to get automakers to produce more cars that run on ethanol and to find ways to make available more ethanol fueling stations. “We must invest in a clean energy economy,” Obama said in a statement.

The reassurances to the ethanol industry came as the Environmental Protection Agency made public its initial analysis on what impact the massive expansion of future ethanol use could have on climate change. Rejecting industry and agricultural interests’ arguments, it said its rules — which will take months to develop — will take into account increased greenhouse gas emissions as more people plant ethanol crops at the expense of forests and other vegetation and land use is influenced worldwide by the demand for biofuels.

When Congress in 2007 required a huge increase in ethanol use — to as much as 36 billion gallons a year by 2022 — it also required that ethanol — whether from corn or cellulosic crops like switchgrass or wood chips — have less of a “lifecycle” impact on global warming than does gasoline. It set the threshold at 20 percent climate-pollution improvement for corn ethanol and 60 percent for cellulosic ethanol, although ethanol made from facilities already operating would be exempt.

EPA Administrator Lisa Jackson said the analysis shows corn ethanol emitting 16 percent less greenhouse gases than gasoline, even taking into account global future land-use changes.

But that’s true in only one of the scenarios the EPA examined; another showed corn ethanol would account for 5 percent more greenhouse gases than gasoline. The scenario Jackson cited assumes future environmental benefits over a period of 100 years will more than pay back the initial increase in greenhouse gases from land-use changes; the second assumes a shorter payback period of 30 years.

Frank O’Donnell, president of the advocacy group Clean Air Watch, said the Obama administration was “walking a tightrope” to try to reconcile the expansion of corn ethanol with its determination to aggressively address climate change. He called the assumption of a 100-year ethanol payback to make up for early greenhouse emission increases “nothing but an accounting trick to make corn ethanol look better.”