The microwave oven belongs on the list of consumer innovations—like the TV dinner or the widespread use of polyester in clothing—that seemed really nifty at first but have since fallen somewhat out of style. Sure, a lot of people still own microwaves, but crunchy types tend to dismiss them as symbols of America’s instant-gratification food culture, and scientists have revealed that microwave popcorn—hands down the best use of the appliance—gives off a chemical vapor that causes lung disease. But what if it turned out that giant microwave ovens could help us sequester carbon—large amounts of carbon, enough to make a dent in global warming? That would surely help refresh the microwave’s fading gee-whiz factor.
As it turns out, there’s a company in New Zealand that’s figured out how to use microwaves to turn wood, agricultural waste, and other forms of biomass into charcoal—a process that helps keep carbon out of the atmosphere because charcoal, unlike other forms of biomass, is slow to decompose and return its carbon to the air. This charcoal (which often goes by the fancier name of “biochar”) could be added to farmers’ soil to improve fertility and water retention, or even just buried in pits or dumped in the ocean. It’s possible to create charcoal by heating the biomass in conventional ovens, but using microwaves improves the efficiency of the process, allowing up to 50 percent of the starting biomass to be converted to charcoal.
Of course, just how much of an impact this would have on the global climate is a matter of some debate. Over at the Guardian, George Monbiot accuses biochar advocates of peddling false hope for an easy solution to global warming, pointing out that it would be a really bad idea to cover huge swaths of the planet in tree plantations just so that those trees could be converted into carbon-sequestering charcoal. James Lovelock agrees that charcoal tree plantations would be silly, but notes that agriculture already generates a huge amount of biomass—the stems of wheat or corn plants, for example—that is currently left to rot. If farmers were given incentives to start turning this waste into biochar, the resulting carbon sequestration could start to add up.
It’s something that we may be hearing a lot more about in the relatively near future. There’s a growing movement to get biochar included in the post-Kyoto climate treaty being negotiated this year in Copenhagen as a way for countries to offset their emissions. If that were to happen, then the market for biochar cookers just might take off. And that could be the best thing to happen to the microwave since the invention of leftovers.