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Biodiesel From Sewage Sludge
MTorrice writes "Scientists have developed a way to convert lipids from sewage sludge into biodiesel. The low cost and high yield of the sludge process may make it economically feasible as a source of biofuel, the researchers say. Today, biofuel producers use lipids in vegetable oils to derive biodiesel, a mixture of fatty-acid-like molecules. Biodiesel is compatible with existing diesel engines, burns with less pollution than petroleum-derived diesel does, and comes from renewable resources. But current biodiesel feedstocks are expensive, limiting the fuel's widespread use. The researchers from South Korea found that sewage sludge, the semisolid material left over from wastewater treatment, can yield 2,200 times more lipids than soybeans and costs 96% less to process. To turn the sludge lipids into biodiesel, the researchers heated them with methanol."
Yeah, that's basically the way all biodiesel is made... But the problem with biodiesel isn't just the price of feedstock (used fryer oil is cheap enough already!), it's the price of removing stuff from the feedstock that would make the biodiesel of unacceptably low quality (free fatty acids, BCBs).
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Regarding Emissions:
Biodiesel is much better for the air. While it certainly does produce CO2 in nearly the same amounts per unit burned, it is unlikely to contain sulfur in measurable amounts. How much sulfur is in deep fryer oil, or sewage? Practically none, since it's poisonous. People don't eat it in more than trace amounts.
So while Biodiesel is still not great for greenhouse emissions (unless it's balanced. Plant a tree dammit!), it's great for the breathing air of critters like us, compared to petroleum derived diesel. And if you clean it so it burns better in your engine, it's going to be much lower in particulate emissions as well.
If sewage derived biodiesel is scalable, (and it looks like it might be), this could mean the end to all the shit we put up with going to war for petroleum.
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Actually for several decades now most sewage treatment plants have been separating out all of the solid particles and what can be is used for fertilizer. You can even go into some stores and buy bags of dried, treated sewage to use as spread on your lawn! My dad used to do it when I was a kid. It said so on the package but you could definitely tell exactly what it was when it got wet! I think they baked it or something like that to kill all the bacteria and make it safe first. I stayed far away from the lawn for a week or two whenever he did it but the grass loved it! It got very green very fast!