First the solids and liquids, i.e. untreated human excreta, are collected from homes and taken to the sewage station by the city council. There the solid and liquid parts are separated, or in some cases the stuff may even arrive separated, as is the case with Micke’s urine-diverting loo that separates the products literally “at the source”!
The liquid component is sanitised to render it safe for agricultural use; urine is rich in urea and can be fantastic as fertiliser. The solid waste, however, provides the raw materials for another kind of magic ;)
The solids are transferred to larger tanks and dried; in Micke’s case, the extractor fan installed near the poo box beneath his toilet has already set this process in motion. Once the solid excreta are dry, they are deoxygenated in the same way as for animal manure, and eventually this process results in the production of methane gas.
However, the most exciting use I see for biogas is as car fuel! Given a) our current levels of petrol/diesel consumption, b) the fact that hydrogen-powered cars are still out of reach for most people and c) the lack of sense (in my view) of growing crops such as soy to make biofuel for cars when there’s scarcely enough space to grow all we need to feed ourselves as a species, I LOVE the idea of using a limitless resource like human poo to run cars! Micke has a “vision” that one day, everyone in his eco-passionate circle (at least a hundred people living nearby) will join a scheme to use solid-separating toilets like his, and run their cars on biogas... well, if anyone can make it happen, it’s him!
In Finland there are about 350 service points, many bearing the “Gasum” brand name, where consumers can choose to fill their car with biogas fuel. It’s funny really that there are so many, as there are only about 250 biogas-fuelled cars in Finland... yet! At many of these service stations, normal petrol and diesel are also available. And there’s yet another option: natural gas, from Finland’s neighbour Russia.
So, are you tempted to go down the biogas route? Maybe you’ve already made the positive switch over to an electric car; in fact one thing I’ve noticed on my travels is that charging stations are becoming more visibly present, e.g. in car parks and at garages. But if you’re still looking for a more economical and ecological alternative to petrol, might biogas be for you?
If so, how do you feel about buying a Volvo? They’ve been making biogas-compatible cars since 1980 – and if that’s not forward thinking I don’t know what is! Apparently there were a couple of slightly irksome decades where the cars contained a single huge fuel tank, which got in the way; however, since 2001 Volvo have been producing cars with three smaller fuel tanks, which are more sensibly accommodated to deliver a far more comfortable journey :)
Micke’s biogas car is a 2003 factory-produced Volvo V70. You would NEVER know – from its speed, comfort, handling or anything else – that you weren’t in a petrol or diesel car. Unless you happen to be standing next to Micke at the fuel pump and you see how much (or little!) it costs him to fill the tank! It’s entirely possible to convert a car so that it can run on biogas; however, since the methane needs to be kept pressurised at 200 bar in the engine, it makes for a pretty complex machine. The cost is likely to be in the region of £1600... possibly well worth it for those who cover a lot of miles.