The Renewable Fuels Association, the ethanol industry’s major lobbyist, works out of cramped offices that it shares with a lawyer near Capitol Hill. Pictures of ethanol plants from its 61 board members hang everywhere. “We’re about to run out of wall space,” said Bob Dinneen, the association’s president. [...] After three decades of surviving mostly on tax subsidies, the industry is poised tonight to get its biggest endorsement from on high that it has a long-term future as a home-grown alternative to gasoline.