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Britain’s first ‘poo bus’ has gone into service. It runs a dedicated route between Bristol and Bath. It’s powered by a methane/propane mix, methane generated by anaerobic bacteria fed a mix of human and food waste.

The engine design is not much different from a diesel bus. The gas is stored in that bulgy bit on the roof; it’ll go 186 miles on a tankful.

Well. I dunno. I’m not opposed to things like this on principle, just on account of I’m a heartless gaia-h8r. I’m opposed to things like this because every time you look closer, it’s a shell game. Wonderful clean free energy comes out one end, but grubby wasteful things go on behind the curtain first.

There are clues in the article. It says the fuel burns with 30% less carbon emissions, for example. But it says earlier the methane is “upgraded” by removing carbon dioxide and adding propane. So, is the carbon comparable but simply unlocked during manufacture rather than use? Not that I object to a bit of good old CO2, y’unnerstand, I’m just doing a veracity check here.

It says one person’s annual food and personal waste will fuel the bus for 37 miles, so five people for a whole tank. A year’s worth of solid waste from five people for one refueling. That sounds like a big process. I mean, big tanks, big mixers, big energy consumption. Big investment.

The Bristol sewage treatment plant processes 35,000 tonnes (that’s a fancy British metric ton) of food waste and 75 million cubic meters of shit every year. In the process, they make 17 million cubic meters of this here biomethane. So, eh. Maybe they have figured out a way to do their sewage treatment job and squeeze some free energy out of it in the process. If so, good for them.

But I wouldn’t mind seeing some numbers on that.

November 20, 2014 — 5:55 pm
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