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Topic: Electric cars not biofuels
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| UGoGirl | Posted – 7/27/2007 9:06:59 AM | show profile As far as transportation goes, the future (and near-term future I'm talking about rather than 50 years down the road) must go electric. Biofuels will never be able to fully replace petroleum-based fuels (not even close). And we're no way near ready to turn coal into liquid fuels (without huge climate change impacts). So we should be forgetting about hydrogen fuel cells (for the next few decades anyway) and stop wasting time and energy turning corn (especially) into highly inefficient fuels, and figure out how we're going to get more electricity to support electric cars, plug-in hybrids, and more electrified public transportation. And that energy source will have to be very low in greenhouse gases (wind, solar, tidal, and yes unfortunately we're going to need nuclear too). Time to get real. *** "There are approximately 4 billion arable acres in the world. There are many different feed stocks from which to make renewable diesel, but most biodiesel is made from rapeseed oil. Rapeseed is an oilseed crop that is widespread, with relatively high oil production. "Consider how much petroleum could be displaced if all 4 billion acres of arable land were planted in rapeseed, or an energy crop with an oil productivity similar to rapeseed. The average rapeseed oil yield per year is 127 gallons/acre. On 4 billion acres, this works out to be 33 million barrels per day of rapeseed oil. The energy content of rapeseed oil is about 10% less than that of petroleum diesel, so the petroleum equivalent yield from planting all of the world's arable land in one of the more popular biofuel options is just under 30 million barrels per day. This is just over a third of the world's present usage of petroleum, 85 million barrels per day. Yet this is the gross yield. Because it takes energy to grow, harvest, and process biomass into fuel, the net yield will be lower, and in some cases may even be negative (i.e., more energy put into the process than is contained in the final product)." http://www.theoildrum.com/node/2812#more |
