The American Le Mans Series (ALMS) and its technical operations affiliate, International Motorsports Association (IMSA), has formally approved a butanol blend as the fifth energy source for race cars in the series. ALMS entrants are already running on E10 (10 percent ethanol), cellulosic E85, diesel and hybrid-electric power. The first team expected to use butanol on a full-time basis will be Dyson Racing with its Mazda-powered Lola prototypes. Dyson first used butanol on an experimental basis in one of its cars during the Petit Le Mans and Laguna Seca races at the end of the 2009 season.
For now, the approved fuel is a blend of 20 percent biobutanol and 80 percent ethanol (iBE20) and only prototypes will be allowed to use it. For the first two races at Sebring and Long Beach, cars running iBE20 will have to carry an extra 30 kilograms of ballast until the performance impact is assessed. From the Laguna Seca race in May, the extra weight will be removed.
The butanol fuel is being supplied by Dyson's primary sponsor, British Petroleum. Butanol has a number of advantages over ethanol as a fuel, starting with energy density. Gasoline has 32 megajoules per liter while butanol has 29.2 MJ / L and ethanol has only 19.6 MJ / L. Butanol also has a much lower heat of vaporization than ethanol, allowing for easier cold starts. Because its characteristics are closer to gasoline, it can be used without resorting to stainless steel fuel lines and higher flow injectors. However, its high melting point requires it to be blended with gasoline to prevent gelling in cold weather.