For a minute there I thought I had to get off my couch, when all the while the fact is we don't have to do anything much but keep things afloat for just a few decades more! In fact, we'd best shut up about PO, because if our offspring finds out we knew about it all along, they'll turn and wring our necks come 2036!
The technology seems to work, but I don't know how EROEI is. If biomass must be heated at 4 or 500 °C it must costs a lot of energy to produce the biooil. They are talking about using by product non-condensable gases (?) to fuel the plant in a closed loop. Have they found the "perpetuum mobile"? Has anybody more information on Bio-oil?
Posted: Fri Aug 27, 2004 6:56 am Post subject: Bio-fuels - EROEI
This has been debated at length. One of the people who argues against the benefits is Pimental who has studied the production of bio-ethanol in the USA and concluded an EROEI of 1 - i.e. no net gain. On the other hand there is study carried out by Strathclyde University in the UK which showed an EROEI of between 2 & 5. These processes are generally based on the production of ethanol and bio-diesel which are established but require the input of either sugary crops or vegetable oils.
Pyrolysis allows you to break down more complex organic materials to form liquid fuels - but requires heat and pressure. That said it is possible to process what would normally be agricultural waste - rather than using the land purely for an energy crop.
I assume in the Canadian process they are feeding in agricultural waste and using [probably] the dry gas to drive the process. There is no reason why the overall process shouldn't have an EROEI > 1 but it would be interesting to see the calculations.
If you want to see a truly high temperature conversion process have a look at this one http://www.magnegas.com/ - no ideas on EROEI...
Joined: Jun 20, 2004 Posts: 250 Location: California
Posted: Fri Aug 27, 2004 8:44 am Post subject: Ethanol
I've read Pimental's work carefully, and he makes a solid case against ethanol production as practiced in the USA. His most recent paper rebuts the points of his detractors (ADM, of course!).
1. He assumes you need to distill the fuel close to 100% purity, which is necessary for use as a gasoline additive. This wastes a lot of energy. For far less energy, you can produce 90% ethanol, which can be used directly in a suitable engine.
2. He assumes the crop input wasn't a waste product. Clearly, if the crop was otherwise going to be allowed to rot, any energy that went into producing it is wasted. So a more correct calculation would be to use the energy recovered or saved from the next-best use of the crop waste, rather than the energy consumed in producing the crop.
3. He didn't do the analysis for different types of fuel crops (although he mentions Brazil's experience with sugar beets).
so crunching the figures you would need to get 64,424.57 gallons per sq km or 0.0644 gallons per sq metre using all the arable land to keep the cars and trucks moving as usual. Don't know what the consequences of doing such a thing would be.
Joined: May 24, 2004 Posts: 3428 Location: California, USA
Posted: Sun Aug 29, 2004 3:09 am Post subject:
Also seen in today's BBC Internet news, something about the use of waste bananas in Australia, as a feedstock for methane production. This is a relatively low energy density system, if I recall correctly, about 4 lbs of bananas produce 1 KWH of electicity. But at least it's getting something usable from what would otherwise be a waste product.
This would be an example of "many small-increment improvements..." in the sense that it could provide an additional or supplementary source of energy in areas that are close to the points of production of the feedstock.
About 25 years ago, I heard something about growing energy crops along the verges of highways, rather than the otherwise-useless ornamental vegitation that is currently planted there. So you still have green groundcover next to the highways, it still gets watered and mowed. But the cuttings are collected and processed into alcohol, and so in effect you're getting energy from land-areas that are not viable for food crops.
Now this also suggests a wild idea, which may be completely stupid but what the heck. What about fallen leaves as a feedstock for alcohol production? I'm thinking of the fact that cities and especially suburbs spend large sums of money to collect the stuff each year in Autumn, so the material can already be brought to a central location for processing. The collection costs are the same as before; the only difference is the processing cost & energy balance, compared to the cost of depositing the leaves in a composting facility to turn into mulch.
Of, if the stuff can be composted, it could probably be used as an input to methane gas production.
Or, am I full of male bovine droppings? (which, themselves, are a potential input to methane production)
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. I would love to see a DeLorean fueled with domestic wastes.
