Each year, the US produces about four billion metric tons of waste which has about half the energy content as the same weight of coal. Bill Davis and his company, Ze-Gen, has found a way to liberate hydrogen gas from that waste.

Using technology from the steel industry, where oxides and carbon contamination are a largely solved problem, Ze-Gen is taking the wood from construction waste and dumping it into liquid iron in an oxygen-free environment. It gets out a mixture of carbon monoxide and hydrogen gas. Although there’s a significant energy cost here, Davis quipped that “keeping iron molten doesn’t take as much energy as you’d think.”

The technique can be translated, with lower efficiencies, to household waste. There’s a chance that this could provide a secondary revenue stream for landfills and dumps, although Davis emphasized that the company hopes to ensure that the process pays for itself purely in energy terms.

On the environmental front, this winds up being being carbon-neutral, since the original source of the hydrocarbons is a typically a tree. Keeping waste out of landfills also has some obvious benefits, although getting everything to a Ze-Gen plant may entail burning some energy that shipping to landfills doesn’t. The other notable aspect of this approach is that Ze-Gen may wind up competing for waste material with other green technologies, like wood recycling and landfill methane production. The fact that there will be winners and losers as these technologies mature is overlooked far too often.