Jim Frederickson, a senior research fellow at The Open University’s Faculty of Technology, has found that worms may not be as environmentally friendly as many think. Research at large commercial worm composting beds shows that worms give off nitrous oxide, a greenhouse gas 296 times more powerful than CO2. As commercial ‘wormeries’ become more common and landfill sites get smarter about trapping methane, worms’ contribution to climate change is set to increase.
Says Frederickson: “We know from research in Germany that a third of the nitrous oxide emissions coming from the soil are associated with worms. What we found from looking at large worm composting systems is that their emissions could be comparable in global warming potential to the methane from landfill sites.
“The amount of worm composting is very, very small and the amount of landfill is huge. But landfill sites are quite well run these days and it is possible to extract about half the gas they generate and use it for electricity generation.”
As the Government wants to increase the amount of household waste that is composted and recycled to 40% in 2010 and is thinking about financial incentives for recycling and setting a new national target for the reduction of commercial and industrial waste going to landfill, it could mean more domestic and commercial worm composting.
“The amount of nitrous oxide emitted by large scale worm composting is something we should be looking at before we go further down that route. In addition, we also need to investigate emissions from domestic-scale worm bins as there are tens of thousands of these being used.”