From Kitchen Scraps to Biogas - Stockholm Embraces Garbage Disposals
by April Streeter, Gothenburg, Sweden on 09.29.08
From the 'everything that goes around comes around' department: in Sweden it is a rare thing to find a kitchen equipped with a garbage disposal, those noisy finger hazards that are extremely commonplace in American kitchens. And while many TreeHuggers eschew the garbage disposal habit for composting of kitchen scraps, a surprising counter-trend is occurring in Sweden's larger cities.
From a hefty fee to a discount for garbage disposals
Previously, a high annual fee discouraged apartment dwellers from thinking about owning a garbage disposal - municipal engineers were worried about gas build-up in sewer lines and other blockages from running liquid garbage through regular pipes. So only about 40 apartments in the entire city went through the expensive hassle of getting and owning a garbage disposal. In the U.S. 50 percent of ALL homes have a disposal - it increases a home's water consumption and electricity usage and forms more of a burden to municipal sewage treatment. Why are the Swedes encouraging it, then? They want to mine the waste stream for biogas.
An increase in organic material in Swedish sewage lines is now considered a positive, so the fee for the garbage disposals reduced by more than half to U.S.$65 dollars - purchase and installation of a machine will still cost around $800.
Competition for the national composting goal?
In Sweden there's a national goal of 35 percent of waste material being composted or by 2010. That may be a tough goal to reach as many people toss everything into the trash, knowing that most of it gets burned in large incinerators Sweden invested in in the 70's and 80's. One study showed Swedes tossing 225 pounds of edible food each year.
By using garbage disposals, Stockholm Water reckons they can turn that waste into methane gas. Scores of methane stations dot the Swedish roadsides and methane is used in many city buses - though Volvo discontinued its dual methane/gas powered car two years ago. Stockholm Water has now tested the pipes, so to speak, and determined that the system can absorb a lot more of the waste stream in the municipal system and turn it into methane gas, so that an even larger goal recommended by the Green party could be reached. The Greens say 70 percent of the waste stream could be either composted or turned to biogas by 2015. Today Stockholm Water can produce 8 billion cubic meters of methane, though just half of it goes to vehicles.
Methane or biogas use on the rise
Last year demand for methane rose 18 percent, but in Stockholm it rose a full 40 percent. Stockholm can't make enough of its own biogas currently, and imports from nearby municipalities. Sweden's Environmental Protection Agency lists biogas as the most environmentally friendly vehicle fuel - there's even the biogas-powered train.
Read more
Trash Talking the Garbage Disposal: Examination of a Not So Green U.S. Export
Sweden's Green Car Explosion
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Quick question: when people refer to volumes of methane or natural gas, what pressure is that at?
100.000 kPa / 14.696 psi most likely as per SPE definitions.