Monday, September 17, 2012

food scraps = energy in Malmo: the food grinder

it's 6.30pm and you just arrived home from work.  it's time to make dinner.  it is a simple meal.  pasta with veggies and sauce.  you pull out the cutting board and your favorite knife.  you scrub all of the terrible pesticides and toxins off your vegetables, hoping that this shiny red pepper is not the one that puts one nano gram too much of whatever you don't want in your body.  you chop and cut and chop and suddenly you are sauteing it all in a pan.  the water is boiling for the pasta and voila! you have dinner.  it's delicious, by the way.

cleanup in this kitchen is almost as easy as making the mess.  you finished the pasta sauce so you splash some water around in the jar and dump it down the drain.  you open the door under the sink and deposit the jar into the clear glass recycling bin.  the scraps of vegetables go into the food grinder (what we used to call the garbage disposal).  you splash a little water on the plates and silverware and put it all in the dishwasher.  you always win the clean plate award so there are no scraps on the plate, but if there were any scraps or anything else that could be ground in the food grinder, you'd dump them into the sink and wash them "away" as well.
food grinder in kitchen sink
kitchen sink in the apartment.  pretty "normal" looking.  the silver button on the upper left turns on the food grinder.
then the magic starts.  you turn on the water and press the little silver button.  a loud gurgling sound emits from inside the sink drain, gradually getting more uniform and higher pitched.  when the last of the food remnants are gone, you press the silver button again and it's done.  your "wasted" food is on it's way to becoming energy.
food grinder in kitchen sink
it's a titan.  food grinder.
a separate piping system takes the water and ground food waste to a nearby storage tank.  it's surprisingly simple.  sedimentation allows the liquid to skim off the top inside the tank and join the rest of the waste water on it's way to a treatment plant in the harbor.  what settles at the bottom of the tank is pumped away to a nearby plant where they tank it all back together in a specific method that turns this "waste" into something called biogas.
separate pipes under sink collect food waste and water
pipes from both sink drains joining to go separately out of the building to a sediment and storage tank where the food waste separates and is pumped offsite for transformation from food waste to biogas
biogas, as you can imagine, is just like other gases that you know.  it can be burned like natural gas to heat your home boiler or hot water.  it can be refined into fuel to power your car.  it is basically like oil except we didn't have to dig for it or destroy anything like forests or water supplies or the environment to get it.  it is a natural byproduct of human consumption.  oh, and in case you are wondering (which I am sure you are) it is:
  • "clean" (meaning that the stuff that goes into the food grinder is food, not plastic or other undesirable items that dilute or destroy the biogas process)
  • hygienic for the inhabitant (what you put into the grinder is what you have already touched)
  • natural (no cleaning products, chemicals, or other stuff needs to be added)
  • simple (press a button and it's done)
  • cleaner burning (biogas is much lower emission and cleaner burning than many other fuels, especially oil based fuels such as gasoline and diesel)
if you are looking for an alternative to oil to power cars, buses, and other transportation, biogas could be a very successful option.  we've all seen how much food goes down the drain (which is, in itself, an area that needs some improvement).  the city of Malmo is making great strides to use food waste to produce energy and hopes to have the entire city bus fleet on biogas within ten years.  there is also a campaign to collect compost style food waste in all neighborhoods of the city as well as using the new grinder method.

want more info?
a company called vasyd is a main stakeholder in this process.  their (vasyd) website is also very informative (and has english translations).  I met with Mimmi Bissmont from the vasyd Malmo office.  she was extremely helpful and supportive.  thanks Mimmi!  her work focuses on connecting action, behavior, and sustainable efforts.  for more info on improved use of energy through behavior, check out this post on the psychology of energy reduction or this post about energy reduction through feedback loops.


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