Page 22 - GBC winter 2015

Our mess often provides the ingredients, potential, and a trajec- tory to make biogas. But why are we so reticent in acknowledging our complicity in this tawdry affair. To date, biogas is the only techno- logically fully established renewable energy source that is capable of producing heat, steam, electricity and vehicle fuel. Even so, it has no boundaries, is definitely suspect and loves to be in your face, espe- cially when you choose to ignore her. Society has to stand-up, and resolve this messy affair. We all produce waste and we all have the responsibility to manage waste in a sustainable manner.
411 ON BIOMETHANE
So, what is biogas? Biomethane is the unwanted product that will always be around as long as there will be life on this planet and waste. She represents a paradox. As a free agent, she is indeed reckless and 21 times more potent than carbon dioxide as a greenhouse gas1. When she is constrained and rehabilitated (tamed), society is better off.
As a carbon neutral fuel, she becomes environmental friendly. Many natural gas companies are making a concerted effort to befriend this black sheep of the family as she is a safe alternative to natural gas. One cautionary note: although not as simple as hydro- gen gas, she certainly is ubiquitous and definitely just as explosive.
Of all the types of renewable energy, biomethane systems can fulfil multiple goals when rehabili- tated properly and as such can become a celebrated, versatile resource. Biomethane can be directly combusted in an internal combus- tion engine to produce electricity and heat or fed directly into a boiler for heat.
Source: Canadian Biogas Study. “Benefits to the Economy, Environment and Energy.”
Technical Document. December, 2013
When electrical and thermal energy is produced by biogas plants, the amount of carbon diox- ide (CO2) produced during biogas production is more or less equal to the amount absorbed by the energy crops during growth or the amount which escapes as waste decays.
In addition, biogas can be cleaned up and used as a source of transportation fuel or fed into the natural gas grid as a direct replace- ment for natural gas. Biomethane, when stored as either a compressed natural gas (CNG) or a liquefied natural gas (LNG), can be trans- ported across great distance where no grid is available.
In the setting of a golf course, grass clippings, food waste from
the club house, and sewage could all be fed into a small affordable digester to produce heat, steam, electricity, and vehicle fuel.
Such adoption would decrease both the club’s carbon footprint and its overall energy expenses. Who would not want to get off the grid?
Biomethane from waste is produced by either a biochemical process (e.g., anaerobic microbial fermentation in a digester) or through thermochemical means (e.g., gasification). Detailed knowl- edge on the functioning of the fermentation process is key for optimizing this process; however, the vast majority of the microbes involved remain unknown and cannot be cultivated in laborato- ries.
The anaerobic process kills many pathogenic and fecal micro- organisms, often responsible for the foul stench associated with rotting organic biomass, lowers the chemical oxygen demand (COD), and leaves behind another gift: a high-quality fertilizer. Further removing nutrients and fibers from digestate/fertilizer leaves behind relatively clean water that can be recycled for many uses short of human consumption.
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1One tonne of methane is equivalent to 21 tonnes of carbon dioxide, in terms of global warming potential.
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