Heating greenhouses with biogas increases yields.
Biogas is a byproduct of organic waste. It is usually flared or ignited onsite to destroy toxic contaminants and then left to disperse into the atmosphere. Biogas can provide an inexpensive, though imperfect, option for heating horticultural greenhouses. Does this Spark an idea?
Concept
You can ferment greenhouse waste, municipal solid waste, wastewater sludge, biodegradable feedstock and energy crops in an anaerobic digester to produce biogas, which can then be recirculated through the greenhouse as a heating source. Plant biogas contains approximately 80 percent methane, a greenhouse gas that traps heat.
Benefits
In addition to producing heat, biogas can also provide a beneficial carbon dioxide supplement, as well as nitrogen supplement if animal waste is included in the biogas production process. In 2002, French researchers demonstrated that by converting a commercial boiler to biogas and purifying carbon-dioxide-rich combustion exhaust gases of toxic residues, crop yields were much higher than those in a control group. The researchers also found that the economics of heating greenhouses with biogas outweighed the heating cost-savings from burning up biogas onsite.
Drawbacks
Predicting the exact chemical composition of biogas is nearly impossible. You can measure it only after it has been produced. Biogas is less abundant in winter, when a greenhouse needs heating the most.
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