A growing body of scientific research suggests that shit might save the world from climate doom—or at least contribute to saving it, along with other crap humans routinely generate and throw away.
A new report on this was launched in the European Parliament in Brussels on Tuesday on behalf of the European Networks Association (ENA) and GEODE, an industry association representing 1,200 plus independent energy companies across the EU.
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The report explores the immense potential for “green gas” produced from renewable sources to supply low carbon heat and especially transport.
Green gas is produced from waste such as sewage, manure, food waste, and fuel crops, as well as byproducts from chemical processes, according to the report.
Unlike solar or wind energy, green gas suffers from no intermittency problems, can be produced 24 hours a day, and easily stored, providing a useful complement for any renewable energy mix.
Carbon dioxide generated by burning green gas does not increase CO2 emissions because, unlike fossil fuel energy, the carbon source of green gas was previously in circulation above ground, and is therefore merely part of the natural carbon cycle.
Biomethane could be used as a supplementary fuel for electric vehicles to create overall “truly zero-emission driving.”
The most promising type of green gas is biomethane—specifically the methane produced from the anaerobic digestion of organic matter, including human or animal excrement—which is already being produced and injected into the gas grids of 10 European countries.
The new report explains how the voluminous quantities of shit produced by both humans and animals can be used to generate clean energy with almost zero carbon emissions:
“Anaerobic digestion (AD) is the straightforward natural breakdown of organic matter into carbon dioxide, methane and water, by micro-organisms (bacteria and archea)… At the end of the process there is a mixture of methane and carbon dioxide gases (biogas), water and some organic material (digestate).”
The report provides a helpful diagram showing that the shit produced by five cows over a single year can heat a typical home in Denmark.
“Biogas can be burned to produce both heat and electricity, or upgraded to biomethane which can be used as vehicle fuel or injected into the gas grid,” says the report.
Biogas can also be produced from waste organic materials, including biomass from, for instance, forestry waste. The report emphasises that it is not advocating that land be set aside to grow crops for biofuels, but that the focus must be on re-mobilising agricultural waste like straw or husks.
The report notes, for instance, that one lorry full of household-produced organic waste is sufficient to heat about 30 typical homes in Denmark for a month.
Last year, a report by the International Gas Union concluded that 1 TWh (terawatt per hour) of biogas can be produced for every million people. With 500 million people in the EU, that gives a potential of 500 TWh.
“That means that biogas could theoretically account for over 10% of non-fossil fuelled transport in Europe,” the IGU concluded, noting this could be achieved by 2020—within five years—with the right policies.
In the US, the Union of Concerned Scientists agrees that the potential, though modest, is significant: As much as three quarters of natural gas used in transport (or 7 percent of natural gas consumed by the electricity sector) could be completely replaced with US-waste-derived biomethane.
This has major implications for therapidly expanding electric vehicle (EV) market, where biomethane could be used as a supplementary fuel, completely replacing traditional petrol, to create overall “truly zero-emission driving.”
Sweden is leading the way in the technology. The proportion of biomethane in natural gas fuel sales for gas-run vehicles in the country is now 73 percent. But there are projects popping up in the US, too.
In the Colorado city of Grand Junction, the Persigo Wastewater Treatment Plant processes 8 million gallons of the city’s human shit into biomethane, which then fuels about 40 fleet vehicles—garbage trucks, street sweepers, dump trucks and transit buses. The project is reducing carbon emissions by 60 to 80 percent, and will pay for itself in around seven years.
The lesson is clear. Human beings produce an awful lot of shit. Our mistake is thinking that shit is useless.
Of course, shit power by itself cannot solve all our energy challenges. But it looks like Europe is catching on to the fact that there’s no point letting good shit go to waste—the health of the planet’s climate may well depend on it (at least partly, anyway).
