Coca-Cola Co. plans to produce billions of bottles from recycled plastic this year, but officials of the nation's biggest soft drink company say they have been constrained by a scarcity of recycled plastic.Jeff Foote, director of corporate environmental affairs for the Atlanta-based soft-drink giant, said Monday that Coke plans to use 10 percent recycled plastic in its bottles this year.About 20 college students protested outside the World of Coca-Cola, the company's Atlanta tourist attraction, on Saturday. They accused Coke of breaking a promise in 1990 to use 25 percent recycled plastic in bottles.But Foote said the effort to use recycled material has been ongoing since the early '90s."We had some technology that we used in the early '90s that was very aggressive and very expensive," Foote said. "What we decided to do was go back to the drawing board to see what other technologies could be created or used."He said Coca-Cola spends more than $2 billion a year on recycled materials and supplies.GrassRoots Recycling Network, an environmental group in Athens, Ga., called Coke's announcement "genuine progress," and acknowledged that recycling of plastic soda bottles must increase to meet the demand for recycled plastic.Foote said a major increase in Coke's use of recycled plastic would force other businesses to make new plastic because supplies are so limited."We don't want to displace their supply," he said. "If we took away from them, they'd have to use virgin (plastic) anyway."Other products made from recycled plastics include auto parts, carpet fiber and clothing.Pepsi-Cola spokesman Larry Jabbonsky said Monday the nation's second biggest soft drink company is committed to using bottles with recycled plastic."As we speak, we're studying several different technologies to make that happen in as useful and cost-effective manner as possible," Jabbonsky said.