Biogas: It’s not a waste of energy.

While some cities are staring to get savvy with organic waste management in municipal composting programs, rarely do you see an integrated approach to sewage or other…less desirable…animal byproducts that creates energy. Biogas is a time-tested technology for the anaerobic processing organic waste to create two very valuable byproducts: methane gas (energy) and nutrient rich sludge (fertilizer). The energy can be piped and used in stoves, heating systems, refrigerators – basically anything that runs from gas (including machines like generators that produce electricity).

A basic biogas system. Thanks to the Unesco Training Manual for this diagram!

Some clever communities, like Bern, Germany, are even compressing the gas and using it as fuel for buses. Although Vancouver’s Olympic Village does deserve credit for passively extracting heat from sewages for a district heating system, the organic waste still ends up at a large centralized plant that depends on an extensive infrastructure system and costly processing. Many cities’ solid waste systems are reaching capacities – this is also occurring to stormwater systems as well – more often than not, these systems are combined sewers that cause overflow during storm surges, spilling rainwater and raw human waste into the ocean.

Rather than expanding traditional facilities, we should incentivize biogas plants in both urban and rural contexts. Based on current biomass production we could provide around 3% of North America’s energy needs from biogas. The US is already getting .6% of it’s natural gas consumption from landfill gas (which is the same biogas) and cities are profiting from the sale of the methane. New York City makes $11 million dollars a year selling the methane extracted from the Fresh Kills Landfill on Staten Island.

A biogas digester is buried beneath this garden and parking lot in Accra, Ghana. Photo by Author.

The best part is that it is not a new idea either, it is an ancient technology that is being used around the world from India to Switzerland. The US Department of Energy estimates that China has 8-17 million individual biomass digesters.  Biogas is especially popular in developing countries where centralized systems are unfeasible.

 Even Accra’s finest gated communities and luxury condominium towers have their own biogas plants, discretely buried under gardens and parking lots. The sewage is piped into a chamber where it takes about 7-20 days to convert into methane, which then flows into a balloon where the gas is stored and then piped back into kitchens or mechanical rooms for energy. The beautiful part is that the digester chamber can function for 20 or more years without with low maintenance.

Biogas plans for a school in Ghana. Photo by Author.

As an advocate of distributed or decentralized systems, the biogas digester system is a necessary technology because it can be constructed at many scales and is extremely cost effective. While currently most applications of biogas are in rural, agricultural or developing contexts, there is a huge potential for biogas productions in dense and regenerated urban areas, like new multifamily or commercial developments.

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One Response to “Biogas: It’s not a waste of energy.”

  1. Vanessa said:

    Jul 15, 10 at 7:35 pm

    At the risk of sounding immature, can I point out how awesome that explanatory diagram is?

    Seriously though, my region of Metro Vancouver is looking into a (long-overdue) composting program. It looks like biogas could be a real possibility here in the near future!