Toyota, Mirai wonder: flush the toilet and fill your tank

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The Japanese automotive company launches a car powered by hydrogen obtained from sewage treatment.

The revolution of clean energy might be starting from the dirtiest place there is (at least in collective imagination): the toilet. According to Toyota, this could be the perfect solution for sustainable mobility. In addition to electric cars, there are also hydrogen powered cars. The problem is that nobody wants to buy them because nobody builds hydrogen fuel stations for them. But nobody builds hydrogen stations because there are no hydrogen powered cars around. The solution to this vicious cycle, according to the Japanese automotive company, could be a system that allows to produce hydrogen wherever there are human settlements. The solution, in theory, is at our fingertips. Precisely in our bathrooms.

Toyota’s Mirai is a line of hydrogen powered vehicles that take their fuel from sewage sludge. The process, explained by the U.S. online newspaper Quartz, is surprisingly simple. The automaker uses the wastewater treatment plant of Fukoka, Japan, to separate sewage into a liquid part and a solid part. Microorganisms are added to the solid part in order to decompose it, generating a biogas that is about 60% methane and 40% carbon dioxide. Then the CO2 is filtered out and water vapour is added, creating hydrogen and more CO2. The CO2 is extracted again, and what remains is pure hydrogen: a clean, efficient fuel which does not emit greenhouse gases.

Currently, the Fukuoka plant produces 300 kg of hydrogen per day, enough to fuel 65 Mirai vehicles. If all the biogas produced by the plant were converted to hydrogen, that number would jump to 600 cars per day.

We’re still far from achieving a hydrogen society that has no need for fossil fuels, but this is a good first step. Ideally, this process could be applied on an industrial scale in the wastewater treating plans of the world’s biggest cities. If it turned out to be feasible and convenient from an economic and environmental point of view, we could really say that the revolution starts from the toilet.

Source: Quartz