Re: Even the best biofuels aren't cost effective

Bob Eldred wrote: 
"Morgan" <yrmastr@xxxxxxxxxxx> wrote in message
news:0g_Ce.1979299$Xk.931215@xxxxxxxxxxx

"Bob Eldred" <nsmontassoc@xxxxxxxxx> wrote in message
news:_jZCe.850$Fk4.520@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx

"The Phantom" <phantom@xxxxxxx> wrote in message
news:ercod1do64rqeedsrhn0ejq6797osj7jh5@xxxxxxxxxx

http://seattletimes.nwsource.com/html/nationworld/2002387520_ethanol18.html


In the case of ethanol they claim that it takes 29% more fossil energy 

to

make ethanol than one gets out of it. I take that to mean that it takes 

129

BTU's input to get 100 BTU's of ethanol output. I don't know
if that is an accurate number or not, but taking it at face value, what


if

the 129 BTU's came from ethanol or other bio-fuels to net 100 BTU's of
ethanol product. Would not the yield be 100/129 X 100% = 77.5%. In
otherwords, using their numbers and using green fuels to power the


process,

the yield of ethanol is 77.5%. That sounds pretty damn good to me. I'll 

bet

it is as good or better than gasoline from petroleum using the same
rational.


You misunderstood the gist of the argument.  Making 100 Btu's of ethanol
fuel value requires an input of 129 Btu.  This means that for every 100
Btu's of ethanol you get, you've already used 129 Btu's of something else.
If you assume you use ethanol as the fuel for the process, then you keep
losing ethanol.

The efficiency isn't 77.5% because you've done the math wrong.

Eff = (output - input)/input = (100-129)/129 = -22.5%

Negative efficiency means you are putting more in that you are getting 

out.

The 100 Btu's they talk about in the article are NOT net.  They are GROSS.
Therefore you are LOSING 29 Btu's for every 100 Btu's of fuel you made.


Not

a very good business model - unless you have a subsidy. 


I don't by that. I think you are right that is the implication but it makes
little sense. It's basically saying that even with all of the solar input it
still takes more energy to produce than you get out. Why should that be?
Numbers from the USDA that I have seen say that there is about 30,000
BTU/gal net positive from corn ethanol which makes more sense for a "solar
enhanced" product than a net negative. Admittedly those are different than
the numbers in the article no matter how you calculate it. How do you
reconcile their 57% statement about wood?

While I think that the use of food seeds for fuel makes little sense, I
believe that appropriate plants can be used to produce positive energy gain
fuel. Certainly wood did that in the 19th century with no oil or coal. Am I
wrong?
Bob


Hi Bob,
Let me see if I can explain it. To get ethanol from corn, first you have to grow the corn. This is an energy gaining stage, because, even though you have used diesel tractors to till and harvest the corn, you get more value out (in corn) than you put in via diesel and fertilizers.

But now, you decide to make it into ethanol, for energy consumption and not human consumption. To make ethanol, you have to mix the corn with water and yeasts, and this will naturally create the ethanol. Again, it takes a little energy to do this, but since we are relying on biological processes, you don't loose too much since nature is working for you. However, after all this fermenting is done, you have a problem. You have this 'mash' composed of water, corn leavings, and a little ethanol. What you want to do is seperate out the alcohol from the rest, and this is a VERY energy intensive process. First, you filter out the leavings, which can be used as hog feed, a plus. Then you have to HEAT the water/ethanol mixture and distill out the alcohol. Theoretically, you could use solar heating to do some of the energy in this step, but it is generally not done for mass production. Solar heat is too diffuse to make it profitable, so they use natural gas or electricity to heat the mixture and then cool it to distill out the ethanol. By the time you have done this last energy intensive step, you put in 4 units of energy for every 3 units of ethanol energy you extracted. If you are drinking the result, then you can make a nice profit. If you are burning the result, you just increased your losses unless the government has subsidized the whole process to support you.

Charlie
.

Relevant Pages

  • Re: Using E85 Yet ?
    ... A move to grain-based fuel supply is debated ... Farmer Jim Robbins was riding high last week in a damp corn field near ... produce ethanol, the nationwide demand for the grain-based fuel is ...
    (soc.senior.issues)
  • Re: OT: The big lie. Or is it
    ... and soybean crops are dedicated to fuel. ... Beef prices will go up. ... sources but using ethanol based blends seems at ... In the past 2 years, feed corn prices have skyrocketed, up over 400%, ...
    (alt.smokers.pipes)
  • Re: Ethanol (The Corn Lobby Corn Holes America)
    ... 15 years ago I put in a 1000 gallon fuel storage tank to get me ... supporters of ethanol had argued that the volatile organic compound ... ethanol in our gasoline supply will alleviate our need for foreign oil. ... its energy salvation is at hand. ...
    (rec.outdoors.rv-travel)
  • Another reason ethanol is a bad idea
    ... an energy difference of about 3.4 percent. ... a blend containing 85 percent ethanol that can be used ... even though E-85 is about 60 cents per gallon ... is affecting average fuel economy in the United States. ...
    (misc.transport.road)
  • Re: Marine diesels, turbines, and alternate fuels?
    ... different fuel types, so I was wondering if the kind of Ethanol Brazil ... Graphic shows bushels of corn used for ethanol production. ... replacing gasoline, most researchers agree. ...
    (sci.military.naval)