The Sucking Sound? Just A Little Biogas

This nifty little shed on a suburban street in Gothenburg, Sweden is filled with microbes busily eating household garbage in a pilot project to dry up compost before it's turned into methane at the local biogas plant.

Brainchild of Lars Smedlund, the Somnus Hus is a system that helps remove 75 percent of the moisture, and most of the odor from compostable food waste. About 180 families in a condominium complex in the pilot will share the shed and deposit their paper bags with food scraps into the green shute (each family has a key to the shute). After the scraps are shredded, moisture is sucked away via a wet filter system filled with odor-eating bacteria. In 4-5 days the scraps resemble finely-chopped wood chips (photo after the jump).

Unlike other compost systems, which are subject to rot when too wet, the Somnus system is designed to control the humidity and smell, and the smaller resulting volume of compost only requires a pick-up once or twice a year, versus the once a week or every two weeks for food compost collection systems such as San Francisco's.

Even better, the dried-up compost can be redistributed in community gardens, or it can be collected by what Smedlund described as 'sucking cars' (industrial vacuum trucks) where it is then deposited as raw material at the local biogas plant - at least in places like Gothenburg where there actually are 'local biogas plants.'

By Smedlund's reckoning, each bag of household food scraps can make enough methane to drive a car 3.2 kilometers. If only Volvo hadn't killed their bi-fuel methane model last year!

Smedlund says each shed uses about 6,500 kWh of electricity per year - about the same as a TV on stand-by. The Gothenburg pilot will last 1.5 years. ::Via Smedlund.se