<Open ThreadThe Oil DrumA little more on coal mining>

114 comments on A new thread for the weekend

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joule on January 14, 2006 - 2:46pm Permalink | Subthread | Parent | Comments top
I think you meant to say 11 billion gallons instead of 11 million gallons as the 2005 estimated global production of ethanol.  

It sounds like a lot, but 11 billion gallons a year works out to be approximately 0.66 million bbl per day, which is  equivalent to only about 0.8% of the yearly oil production of roughly 84 million bbl per day (and that's without even taking into account the fact that ethanol has a somewhat lower heat content than most refined petroleum products).

But it really much worse than that. Don't forget that even if we use the USDA's probably optimistic EROEI for ethanol-from-corn of 1.34, then that 0.66 million bbl per day of ethanol production is really only replacing about 0.23 million bbl per day of fossil fuel, equivalent to only 0.27% of global oil production.

While ethanol has made a start, I think these numbers illustrate how far we would have to go to make a signficant dent in global energy consumption by increasing the ethanol-from-corn option. I really don't see this as doing anything but nibbling around the margins of the overall energy problem. And that's without even addressing the issues of competition with food crops, strain on water resources, and soil depletion.

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Nate Hagens on January 14, 2006 - 3:14pm Permalink | Subthread | Parent | Comments top
Yes thanks for the correction - 11 billion gallons.

Another way to look at it is this:

Assuming 84mm bpd of oil and 660kbd of ethanol, we need (using aggressive USDA assumptions) 492,000 barrels of oil each day to create 660,000 barrels of ethanol. (660/1.34). We've 'created' 168,000 barrels per day.

The ethanol numbers show up in the 84 mbpd figures so the alternate equations are:

a) no ethanol => meaning we have 83,834,000 bpd of oil

OR

b)create ethanol => 660,000 bpd ethanol, which becomes part of 84,000,000 bpd oil equivalents + ecological externalities and some loss of food.

In this way, it can be seen that alternative energies, in an EROI circular fashion are adding to our energy supply by grossing up both sides of the energy balance sheet and adding other issues to the system that are not easily compared as apples to apples.

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LevinK on January 14, 2006 - 7:35pm Permalink | Subthread | Parent | Comments top
I suppose ethanol from sugar cane has much better EROEI otherwise it would have been a financial loser for Brazil for example. I also suspect that a great deal from the energy inputs ultimately comes from coal which is still quite abundant. If this is the case, one could argue that CTL would be a much more effective choice, which at least does not put a pressure on the food production.
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Magnus Redin on January 14, 2006 - 7:50pm Permalink | Subthread | Parent | Comments top
This is almost evil but a lot of rural europe would welcome pressure on the food production. Selling biomass for fuel production gives a better farmer life then living on subsidies. But this only works out well for the farmers if EROEI is high enough.
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Boof on January 14, 2006 - 9:38pm Permalink | Subthread | Parent | Comments top
CTL takes carbon from the ground and puts it into the atmosphere, exacerbating GW. One day even coal will run out. In an all-biofuels economy the carbon would be recycled indefinitely. Preferably the plant material would be leftovers from food production. Conservative estimates say to get both food and fuel we need at least 20 acres or 8 hectares of productive land per person. In the absence of new clean energy sources this probably requires a 50% reduction in the population.
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LevinK on January 15, 2006 - 12:20am Permalink | Subthread | Parent | Comments top
If I can recall correctly over the half of the energy needed to produce ethanol goes into the destillation process which by itself uses electricity. If the additional electricity comes from coal (the obviuos choice if you don't want nuclear) then with a 40% efficient power plant and EROEI of 1.34 we are going to need 0.5/0.4 = 1.25 Btu of coal energy to produce 1.34 Btu of ethanol energy; That is coal to ethanol EROEI is less than 1.1
On the other hand a Fischer-Trops conversion has an efficiency in the range of 70% so the coal to diesel EROEI is 0.7 which is not that far - again for ethanol I omitted the other energy inputs for fertilizers etc.

The CO2 arithmetics is even worse for ethanol because the ethanol itself is releasing CO2 in the atmosphere. If instead we yielded the farmland to forests the net result would be a reduction of C02 so I can not not agree that ethanol is costless on this point - there is an alternative cost here. My fear is that if we allow this idea to go to a really large scale, there may come a day when we will have all our forests replaced by energy crops just like it seems to be already happening in Brazil. No need to comment on the CO2 emissions effects from that prospect.

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