The background: The United States alone annually produces 1.4 billion tons of waste, and most winds up in landfills. Not everything can be recycled and incinerators emit dioxins and toxic ash.

The solution: Montreal-based PyroGenesis has refined a process, called plasma arc gasification, in which solid waste is fed into a furnace. There, extreme electrical charges break it down into three marketable byproducts: a gas that can be converted into steam or electricity; metal ingots that can be resold; and a glassy solid that can be processed into material for floor tiles or gravel.

The payoff: Carnival Cruises uses a PyroGenesis system to shrink tons of cabin waste into a few pounds of harmless sand. The U.S. Navy has hired PyroGenesis to develop plasma waste systems for new industrial aircraft carriers.

The opportunity: An estimated $40 billion is spent annually to transport, incinerate, recycle, and store waste in the United States alone. Most industry experts say the technology is still several years away from widespread commercial use. Dozens of early-stage startups, meanwhile, are developing related products in niche markets for medical and other hazardous wastes.