By any measure, Waste Management is a giant in the U.S. garbage collection and recycling business, but its future might lie in a different service: turning trash into energy. If we lose the waste, we’ve certainly lost the business, said Carl Rush, vice president of the company’s organic growth group, the chief vehicle for its energy investments. The shift in thinking comes at a time when U.S. landfill collections are hitting a plateau as Americans recycle more, consumer products makers reduce packaging and many large corporations adopt “zero waste” goals. Demand for renewable energy and fuels also is increasing, in response both to regulations requiring them and to public concerns about the nation’s reliance on fossil fuels and their environmental impact. Waste Management also has its own pilot plant in Oklahoma that converts landfill gas to diesel fuel for its trash collection trucks. […] it’s in a joint venture with Linde in an Altamont, Calif., plant that turns landfill gas into liquefied natural gas and powers 1,000 garbage trucks there. The company now has a portfolio of nearly 30 acquisitions, joint ventures and investment projects at various stages of development.