Slashdot Mirror
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."
Emission production as you state it is only a problem on a local level where the emissions are most concentrated (dense cities). Even electric cars will have emissions (either in production or at whatever plant is making the electricity for it). It's the part about digging up materials which have been locked underground for millions of years and then releasing those emissions into the atmosphere that is the global problem. If all of the energy and consumables your vehicle used during it's entire lifetime (including manufacture) were harvested from plants or otherwise scraped off of the surface of the biosphere instead of from within the ground you would essentially be close to net-neutral impact on the planet as far as emissions are concerned (not that there is no impact, it would just be ridiculously low impact).
Biodiesel (as usable in my VW Jetta) is only a little less efficient than petrol / oil based diesel. Mileage is about 5mpg lower or so, but you have to make sure the biodiesel is clean of other contaminants which can be a bit laborious depending on the original source. Of course most people I am aware of will typically use an 85/15 blend for better performance (15% regular diesel).
As far as emissions go, I don't think it's too much different but I don't know much about that. I guess it would entirely depend on how "clean" and viable the input is.
In any case, if we can turn something which truly does not have a better use other than to be cleaned (at great expense) and sent back into the biome into a usable fuel at less expense I fully support research into it. It seems to be much smarter than ethanol where suddenly the price of fuel becomes linked to the price of food. We honestly don't currently have a better use for human sewage anyways considering it is not considered fit for fertilizer either. Besides, if this comes to America just think of how much fatty acids are already present in the McSewage, or how we could just re-introduce Olean oil if we needed to increase production (how's that for a disgusting thought?).
- Toast
To expand on this, in new TDI's from Audi/VW at certain intervals raw diesel is injected into the cylinders post burn to heat up the particulate filter and burn off collected carbon. Because of this the raw diesel fuel mixes a little with the oil. For petroleum based fuels this is not a problem as the synthetic oil is designed to allow this to happen. Unfortunately biodiesel is a really great engine cleanser. The problem is that when biodiesel above 5-10% mixes with the synthetic oil the oil is diluted and loses its ability to adhere to the cylinder wall and prevent friction. I think most people understand the basic concept of running an engine without oil. My understanding is that a person could run up to 20% biodiesel if they are willing to make very frequent oil changes, say every 5k miles. But at ~$60 a change it may seem pricey for you.
There is or can be built a machine that can simulate any physical object. -Church-Turing principle
The issue I see is that newer VW TDIs (with the common rail system) is not designed to run on anything higher than B5 (95 Diesel/5 Bio). With my 2012 Jetta, if I use anything higher, they can void my warranty, and they are able to tell. Which sucks cause the station right near me that does Diesel does anywhere from B1 to B11, no notice as to what it is at that time. The problem here is the point in which biodiesel combusts, as compared to straight diesel. To be "clean burning", which VW Diesels are, they do a direct injection of diesel into the exhaust system to burn off the soot and other impurities that are/were common with diesel engines. Biodiesel doesnt ignite the same, leaving the impurities/soot, causing it to clog part of the exhaust system up, requiring expensive replacements.
This is to say, annoying, at the least. Now, I've heard of people having good luck with mod kits adding a second (heated) tank to use with filtered waste vegetable oil, with a cutover switch in the cabin. Start on diesel, switch over to WVO, then switch back later, but those were with pre-2010 VW Diesels.
OMG... I have a sig?
Problem with this is heavy metals. Lots of heavy metals that would be processed out of industrial waste just goes down the drain in household sewage. They used to spread sewerage solids on corn fields in Michigan when I was growing up, but they had to stop because the metals were ending up in the corn in levels too high for human consumption. For years those fields were only usable to grow animal feed, until finally the metals were leeched out of the soil (and probably into the water table).
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin