Denver Post: The market for renewable energy — driven by big corporate buyers like Pepsico and Intel Corp. — has tripled since 2004, according to a analysis by the Golden-based National Renewable Energy Laboratory. In 2007, 18.1 billion kilowatts of green power — such as wind, hydro, landfill methane gas — were sold and business customers made up three-quarters of those sales, the report says. There were a total of 860,000 electricity customers across the country purchasing green power …