Business Green: General Motors (GM) will today wade into the controversial debate surrounding the US biofuel industry, warning that without an urgent expansion in the country’s fledgling network of ethanol fuelling stations, millions of dollars of investment in biofuel technologies risk becoming “stranded”. GM vice chairman Tom Stevens will later today address a meeting of the Renewable Fuels Association (RFA), where he is expected to call on the government to increase support for the development of …