NEVADA: A refinery designed to make ethanol from cornstalks, leaves and cobs — not the grain itself — opened on Friday in central Iowa, the culmination of a $225 million construction project and millions more invested in its engineering and design. The plant, owned by chemical and biotechnology company DuPont, will use the same bacteria that tequila distillers use to make ethanol instead of yeast, which is most prevalent in the ethanol industry. It’s one of the new innovations DuPont said it has incorporated into the plant, touted as the world’s largest cellulosic ethanol plant; DuPont expects it to eventually make 30 million gallons of the fuel additive a year.