41 comments on A Life Cycle Assessment of Energy Products: Environmental Impact Assessment of Biofuels
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No, all these studies show an EROFEI--Energy Returned on Fossil Energy Input--of 8 to 10. The steam and electricity in the refinery is raised from burning bagasse--which is energy--but this is not included as in input energy. Moreover, the surplus electricity is all credited back to the ethanol production. Think logically--ALL ethanol is produced by fermentation and distillation--and the bulk of the energy used in the process is simply raising the beer to the point of vaporization--1 BTU per pound of water per degree Fahrenheit. When you start with a dilute 15% beer mix and need to achieve 99.8% purity through distillation and dehydration, physical laws set the limits. So even if no other energy were used in the process from planting, harvesting, and transport, then the most sugarcane ethanol could achieve is 2.7:1 return. The CO2 consequences of using bagasse over fossil fuels of course is much better (which is the main focus of this analysis), but it shouldn't cloud the understanding of the energy consequences of sugarcane ethanol.
The issue of crediting is disputatious, but asserting you get an energy return of 10:1 on sugarcane ethanol is ludicrous. That would mean that only 8,000 BTUs would be required to produce a gallon of ethanol. Try offering a sugarcane ethanol producer 8,000 BTUs of energy per gallon and see what he could produce, when the absolute minimum distillation energy requirement is on the order of 15,000 BTUs per gallon, not to mention dehydration and other processes in the chain.
I'm all for moving beyond intellectual dishonesty as well.
Doesn't seem like it. I didn't claim an EROEI of 10 for sugar cane. I pointed to a set of reports that document how they reached that conclusion. I did say that the studies were not equal to US corn studies. I have cited reports from the Worldwatch Institute, German governmnet, and the World Bank. You have just offered opinion.
We can discuss EROFEI. Fine. That is more accurate, but the distinction is small. Sugar cane does produce bagasse and it is used to provide the heat for distillation. So, there is no theoretic reason why you couldn't distill ethanol at far less than 8000 BTUs of fossil inputs if 100% of the energy that goes toward providing the heat comes from bagasse.
Almost all of the energy input to sugar cane production comes from fertilizer. I don't need to offer sugar cane producers any BTUs. They already have a similar deal and have been producing in Brazil since before I was born.
So, Mr. Logic, how then does sugar cane based ethanol reduce GHGs by 50% and why is that not a good reason to use it as a fuel?
The promotion of sugarcane ethanol based solely on its lower fossil fuel needs is intellectually dishonest. I don't know you or your orientation, so I can't comment on that.
I didn't offer an opinion. I offered basic science facts, since I'm a scientist and that's what I do.
What I said is that you couldn't produce a gallon of sugar-cane ethanol with 8000 BTUs of energy of any form, including bagasse. These studies make the energy return of sugarcane ethanol look so high because they both omit the non-fossil fuel inputs as energy (which they are) and because of co-production credits. From a CO2 point of view, this is fine, but not from an energy point of view.
Sugarcane ethanol reduces CO2 emissions over petroleum gasoline because of the non-fossil fuel inputs to its production, but it doesn't take any less energy to produce it than if you only used fossil fuels.
CO2 isn't the only thing to be concerned about.
Sparaxis
You’re not doing too well here. If you are not being dishonest then you are very confused.
1. "The promotion of sugarcane ethanol based solely on its lower fossil fuel needs is intellectually dishonest."
I don't see where Jack is doing this. He started out with this:
“Your statement that "fossil fuels are necessary to produce biofuels with a real return of less than 1" is either an intentional falsification, or displays ignorance inconsistent with the time you have spent at TOD.”
This relates to the EROEI, nowhere did he say that he was doing an exhaustive comparative study.
2. “I don't know you or your orientation, so I can't comment on that.”
What does this even mean? What are you talking about? What orientation? North-South, East West, sexual, does it matter?
3. “I didn't offer an opinion. I offered basic science facts, since I'm a scientist and that's what I do.”
Anyone can cite facts, but not everyone understands their relevancy.
“These studies make the energy return of sugarcane ethanol look so high because they both omit the non-fossil fuel inputs as energy (which they are) and because of co-production credits.”
Uh, but the EROEI calculation for oil doesn’t? Try including the oil energy as an input and see what kind of EROEI you get. Are the oil co-products given credits?
4. “CO2 isn't the only thing to be concerned about.”
Earlier you accused him of being concerned only about EROEI.
Yikes!
I'm not accusing Jack of anything. I don't know him. I'm sure he's a fine upstanding person. I'm accusing studies and reports that promote sugarcane ethanol based solely on its lower fossil fuel needs as being intellectual dishonest, in part because they tend to conflate fossil fuel energy with just "energy". Perhaps my pronouns were vague? Should have I used "one" instead of "you"?
The relevancy of the facts I cited is that it is thermodynamically impossible to get a 10:1 ENERGY return on sugarcane ethanol. It is possible to get a 10:1 FOSSIL energy return on sugarcane ethanol. Further, I distinguished that the focus on FOSSIL energy is fine if you are concerned about CO2.
I don't understand your point about "oil" EROEI. Are you talking about crude oil, in which case there are no coproduction credits involved? Or an oil product, which is the combination of a crude oil EROEI and a conversion efficiency?
I didn't accuse anyone about anything. I'm not the ad hominem type.
Ok, maybe I was too harsh, but here is my point: Do we really care about the EROEI of "ethanol" or do we care about the EROEI of sugar cane?
Wouldn't a lot depend on how the EROEI is defined?
Jack attacks a statement that fossil fuels were required to get an EROEI of greater than one. You respond by saying: No, it's EROFEI.
I really haven’t looked at the studies too much yet, but I don’t need to because your argument doesn’t make sense.
You can’t just say that EROEI can’t be 10 because it takes more than 8000 btu to distill it. If the energy to distill the ethanol comes from bagasse, then you do not count it as an input.
Please show why the studies are wrong, i.e. show that energy in the ethanol is less than ten times the energy that was invested. Use a starting point of a bare field and an endpoint of ethanol. Lets say I had a field, with an ethanol plant on it. The EROEI is the energy out of the field divided by the energy into the field.
Thank you for keeping this going while I was asleep here in Thailand.
It seems clear that the original comment tacked on to Prof Goose's call to promote the story was an uneducated hit piece that doesn't show any evidence that the author even read the study.
However, Sparaxis does have a point, although it doesn't directly contradict mine. Yes, sugar cane-based ethanol looks very different on EROEI and EROFEI metrics, largely because of the use of bagasse to provide heat and sell power externally (which provides an offset).
If there were a perfect regulatory environment and significant use of energy in transport, things could be quite different. In that case, demand for electricity for bagasse could compete directly with demand for ethanol as a transportation fuel. Then, maybe the energy is bagasse would not belong to the sugar cane alone, but would be already a part of the energy system. Then, it would not be included in the ethanol EROEI calculations.
I am not a huge advocate of liquid biofuels. Over time, it seems to be crop acreage will be a base resource that goes into fuel production, like it or not. In that case, I think electricity is a far better pathway. But we are not there yet.
It seems that for developing countries in tropical regions, sugar-cane based ethanol makes sense economically and environmentally in the meantime. I don't have any problem with diverting sugar from the food chain. I do not think tropical forests are being impacted much by ethanol (although they may be for soy and palm oil) and do think that sugar cane for fuel will be largely unirrigated.
Corn-based ethanol seems to be completely bankrupt and would not even be looked at without subsidies in the forms for cash, free water and externalization of environmental damage. I don't think all ethanol sources combined will ever provide much more than 5% of liquid fuels.
But in the right environment and until transportation moves to electricity as a fuel source, I do think some ethanol can make sense.
Good remarks Jack, I share your opinions (electricity, Brasil-EtOH, USA-EtOH) as one of the authors of the study. Biofuels may be ok under very specific conditions, but for the future we have to look at alternatives with much higher efficiencies (yes, sunlight-to-electricity!). Biofuels produced out of organic wastes look very promising, but produced out of food it's not only problematic from an ethical point of view.
Thank you. I do think we are on the same page. I tend to agree that there are disturbing potential ethical issues related to competition between fuel and food. However, it is not as clear cut as some make it out to be.
One could make an argument that the poor benefit more from fuel than from sugar, tobacco, alcoholic beverages, etc. So, we would have to infer that there could be ethical issues involved in using so much land for these products. Likewise there is so much waste in processed foods and meat consumption.
Why do some people consider diverting sugar to ethanol as evil, when diverting corn to livestock feed is just fine?
"ALL ethanol is produced by fermentation and distillation"
Nice try. I'll give you a 'E' for effort though. Even make it scratch and sniff just for you Spar =]
Wouldn't it be possible to use a heat engine to suck heat energy out of the condenser to pre-heat the beer? Under these circumstances, I would expect you could reduce energy requirements by at least the 3:1 typical efficiency you get from an air conditioner. Its not like you need to keep the de-alcoholized beer hot. All you need to do is move the heat around some.
Besides, simple heat is easy to get. Locate the place next to a generating facility, or use concentrated solar power.
Why not use a counter-flow heat exchanger to recapture the heat of vaporization from the distillery and use it to evaporate incoming beer? The necessary heat input could probably be reduced a lot, since you want the output to be cool eventually, anyway.