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Tuesday, July 21, 2009
 Scania (part of Volkswagen) builds modified, heavy-duty diesel engines designed to run on almost pure ethanol (E95, or 95% ethanol, with a 5% ignition improver).If that sounds weird, that’s because it is. US auto manufacturers make a big deal out of converting cars and trucks to run on ethanol/gasoline blends of up to 85% ethanol. Scania has done better than that for 15 years, and guess what, their engines can run on 100% biodiesel too, without any modification. Scania’s compression-ignition (CI) ethanol engine is a modified 9-liter diesel with a few modifications. Scania raised the compression ratio from 18:1 to 28:1, added larger fuel injection nozzles, and altered the injection timing. The fuel system also needs different gaskets and filters, and a larger fuel tank since the engine burns 65% to 70% more ethanol than diesel (whoa! see below). The thermal efficiency of the engine is comparable to a diesel, 43% compared to 44%. While Scania originally introduced this technology for “heavy commercial vehicles in urban operation” (city buses), they’re now extending it to trucks as well. Scania maintains that with existing technology, the transition to renewable fuels can be painless. Since in the last 15 years they’ve put 600 ethanol buses on the road (mostly in Sweden), the company seems to know what it’s talking about. Scania is also working to develop ethanol refueling infrastructure, which should make it easier for smaller transport companies to invest in ethanol-powered vehicles.  But why not use biodiesel, since ethanol requires about 1.5x more fuel usage? Scania’s answer may raise a few eyebrows: “the farming capacity [for biodiesel] is insufficient for the huge need foreseen for the transport industry.” Unless you take EU spokesman Michael Mann’s comments seriously (he said that Europe can grow enough fuel to meet 10% of it’s transportation fuel), Scania must be betting on cellulosic ethanol. The intensifying food vs. fuel debate isn’t taking this issue lightly, as I’ve written about here and here. In any case, Scania’s work seems to indicate it might not be as hard to create engines that run on alternative fuels as auto manufacturers maintain. Labels: biodiesel, ethanol diesel-engine, scania
posted by kEMe @ 11:00:00 AM 2 Comments:
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