One answer to lessening the country’s dependence on foreign fuel imports might be   hiding in the six-pack you carry home from the liquor store.

   At the Coors brewery in Colorado, the brewer and Merrick & Co. of Aurora, CO, are using beer waste to process 1.5 million gallons a year of the gas substitute ethanol.

   The 9-year-old plant that distills the residuals from beer making has been such a success, officials from the brewer and the engineering company said, that a second, $2.3 million plant will open later this month on the same site.  The second plant will double ethanol production at the brewery, partly by gathering millions of gallons of spilled beer and putting it directly into the process via and underground pipeline.  The ethanol — made in a maze of stainless steel pipes in much the same way as moonshine — is sold under a contract with Valero Energy Corp., which distributes the ethanol to Diamond Shamrock  stations.

   The beer waste accounts for only a fraction of the expected 4 billion gallons  of ethanol sold nationwide next year, but supporters say the plan illustrates the growing demand for gasoline substitutes as the country battles skyrocketing fuel costs and attempts to expand existing gasoline supplies.

   Alternative fuel sources are especially welcome in Colorado, where clean air laws mandate that ethanol be blended with gas during the winter to reduce vehicle emissions.  About 100 million gallons of ethanol are used in the state each year.

   Ethanol demand — already at an all-time high nationwide — has increased threefold since 1996 and will expand further after federal energy laws that mandate more use of alternative fuels go into effect in the near future.

   At least 7.5 billion gallons must be used in the U.S. by 2012, fueling nationwide interest in ethanol production.

   Nationally, at least 83 plants are currently in operation, more than 20 are being built and dozens more are in the planning stages.

   Opponents say ethanol can be costly — its price has jumped 40 percent in two years — and the market could bottom out if oil prices decreases significantly.  Ethanol opponents also argue that the fuel substitute reduces gas mileage and wouldn’t be economically feasible without federal tax credits for  producers.