Until now, researchers making biogas from the
anaerobic digester at the University of Guelph’s
Ridgetown Campus have been using liquid manure to
feed the operation. Their next step is to add other materials,
such as used oil or grease from fast-food restaurants or
food processing activities. In Ontario, there is currently only one operating anaerobic
digester on a farm, while in Germany there are almost 4,000. In
several European countries, farmers are allowed to add other
materials to the manure in their anaerobic digesters. For example,
some farmers are permitted to put up to 20 per cent of
organic materials obtained outside the farm into their digesters.
Adding this amount of these materials might lead to a doubling
in the output of methane, Fleming notes.
Products like spent oil from restaurants can’t be digested on
their own. However, blending the oil with pig manure should
result in a boost in gas production. This small addition of product
could result in double or triple the gas output, depending
on the material being added.
Along with mixing the pig manure with fats and oils,
researchers will try using corn silage or vegetable waste from
crops high in sugar, such as sugar beets or sweet potatoes