by Bytesmiths » Fri 10 Dec 2004, 01:01:08
$this->bbcode_second_pass_quote('BILL_THA_PHARMACIZT', 'w')hats the EPR of Hemp based fuels?
heating oil biodiesl etc etc ????
Hemp produces about 300 kg/ha of oil. This is much lower than many other oilcrops, but hemp fiber is a useful byproduct.
Biodiesel is about 80% feedstock oil, 20% OH radical, typically contributed by methanol. (Ethanol can be used as an oxidizer, but it is hydrophilic, and the 5% water it holds makes things more difficult.)
Making biodiesel reduces the ERoEI of an oilcrop. Diesel engines can and should be converted to use the oil directly for maximum efficiency.
For comparison, rapeseed oil (Canola) produces about 1,000 kilograms per hectare, jojoba or jatropha about 1,500, and avocado about 2,000, and oil palm up to 5,000. <i>(Multiply by 0.89 if you live in a backward country that hasn't learned the SI system yet.)</i>
By these measures, hemp is a poor source of energy oil.
As far as ERoEI, my best estimate is that a hectare of rape will produce enough oil for a diesel tractor to cultivate and harvest 16-19 hectares of cropland. (Assuming 40-50 liters/hectare for all tractor input, and vegoil energy at 90% of petro-diesel.) This is currently a better ERoEI than many oil wells, but it does not include irrigation, fertilizer, or transportation to markets.
Hemp would be only 30% of that, or an ERoEI of about 5.