25 comments on Anaerobic Digestion (AD) in Ontario – A Regulatory Obstacle Course
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I made a floating gasometer connected to a methane digester running on cow manure and chopped grass. However I haven't scaled it up as it seems like a lot of work for modest amounts of gas. Biomethane appears to be a niche for energy recovery, not a prime time energy source. Away from 'hot spots' like dairies, landfills and sewage farms it is unlikely that methane could power the materials handling requirement. How many of these places run their vehicles on methane?
Remember that we already pay for garbage and sewage removal, subsidised fuel in a sense. Those fees help buy diesel for trucks and grid electricity for large pumps. That's what makes it economic to generate small amounts of electricity onsite and recycle some leftover solids to farmland.
Some claim that methane 'needs' to be burned as it is a stronger greenhouse gas than CO2. Large human assisted methane emitters (ie not natural swamps) should be carbon taxed and let them work it out, maybe passing the tax on to customers.
As Stoneleigh pointed out, burning the methane to produce power lowers the emissions from what would otherwise be a total waste. Methane released to the atmosphere has 21 times the warming potential of CO2, so reducing even small-scale emissions is worthwhile. In BC, the Environment Ministry estimates that methane release from landfills accounts for 9% of provincial GHG emissions on a CO2 equivalent basis. Recovering methane from municipal landfills has become standard practice.
Sewage treatment is another potential source of electricity. Most of Canada has completely ignored this possibility because treatment systems were designed when the resource values in sewage weren't important. Victoria, where I live, has had only quarter-inch screens on their effluent for decades and is finally moving towards wastewater treatment. Since the region is starting from scratch, there's a movement to extract energy from the sludge in much the same way as Stoneleigh has described. Several cities in Sweden produce methane and/or electricity and/or district heat from sewage sludge, fuelling the municipal bus fleet and making a profit in the process.
The obstacles to AD at Ontario farms do look discouraging. What may emerge is a more centralised approach to agricultural waste disposal at the district level.
Indeed biomethane is energy recovery not an energy source, but there is a great deal of energy available to be recovered, especially if high energy off-farm wastes such as chicken fat can be digested.
Running vehicles on the methane produced (once it has been cleaned) is being done in Europe, and the idea is being discussed here as well.