Ethanol energy balance
In response to furball's last post.
I concur that Pimentel states that it is a net energy loser, but the NDRC report seems to indicate that he assumed larger values for several of the energy input costs that go into ethanol as compared to the other studies. In reading that NRDC report, I got the same impression, that 5 of the 6 studies they read reported that (corn) ethanol yields more energy out than is put in the form of petro energy (the solar energy that is used by the plants would provide the "missing" energy input to balance the equation, but that is considered "free" by most analyses as all things we'll have more next year for free). I do question their numbers later in the report as well, as they said that gasoline returns 76% of the energy instead of the 80% number I've seen in other places. So perhaps (not surprisingly) the NRDC is biased toward the ethanol side as well. When you quoted the Wikipedia section with the "skeptics", be sure to follow the link (#8) to what those opinions are based on. Once again, it is the Pimentel studies that seem to come up with those land use numbers. I'm not trying to discredit him or insult the research, but it is odd that his name comes up quite frequently on the negative list. I agree that if you are harvesting a crop from the land without replenishing the soil, eventually you aren't going to get your yield. That cellulosic article is interesting. I hope more comes of it. -Jim |
Originally Posted by PSKSAM2
In response to furball's last post.
but the NDRC report seems to indicate that he assumed larger values for several of the energy input costs that go into ethanol as compared to the other studies. -Jim |
Agreed, but I guess time will tell whose estimate is more in line. The other thing to think about is that petroleum extraction and refining has been improved for the last several decades at the scale of fueling the nation and world. If ethanol was scaled to a larger level, engineering improvements will squeeze a lot of efficiency out of those supply chains and production, not to mention farming.
-Jim |
Read the whole article that Jim linked in the previous thread. I'll link it again.
http://www.rurdev.usda.gov/rbs/pub/sep05/running.htm It would appear to me that Pimental was thoroughly discredited. I would hardly call Pimental's study "all-encompassing." |
Maybe Pimental and Patzek were a _bit_ extreme; I don' tknow if I would personally include the ham and cheese sandwiches the farmer ate for lunch while combining. Not sure about that one.
As far as being "fully discredited" I don't think I'll believe that either; obviously there are differing opinions and the fact that that page has a political background, I'll believe it just as much as I believe the emperor has new clothes. Pimental and Patzek seem like they have good heads on their shoulders and I wouldn't be so quick to discredit them. But that's just MHO. I'm glad I was pointed to those folks' reports; makes me glad there's someone out there that thinks like I do and maybe I'm not so crazy after all. :) |
Here's a quote from David Morris's paper:
It often seems that every article, every interview, every public discussion about our most used and visible biofuel, ethanol, starts, and sometimes ends, with the question, “Doesn’t it take more energy to make ethanol than is contained in the ethanol?” In 1980, the short and empirical answer to this question was yes. In 1990, because of improved efficiencies by both farmer and ethanol manufacturer, the answer was, probably not. In 2005 the answer is clearly no. Yet the question will not go away. One might argue that this is because credible studies by one or two scientists continue to keep alive the claim that biofuels are net energy losers. Yet many grain and oilseed farmers wonder why it is that biofuels like ethanol and biodiesel are singled out for such an aggressive and persistent attack on the net energy issue. They compare the discussion of biofuels with that of hydrogen, a fuel that has captured the imagination of federal and state governments. Converting the transportation sector (and other sectors as well) to hydrogen has become a national priority. Thousands of articles have been written about hydrogen. Most are wildly enthusiastic. Some are negative. But very, very few even raise the net energy issue. A Lexis/Nexis search identified over 300 articles published just since 2000 that discuss the energy balance of ethanol, the vast majority with a negative slant; fewer than 5 even mention the net energy issue with respect to hydrogen. Yet for hydrogen the energy balance is not a controversial question. It is well documented that hydrogen's energy balance is negative: It takes more natural gas to make hydrogen from natural gas than is contained in the hydrogen. Another frustration by biofuels advocates is that the net energy discussion looks backwards, not forwards. Instead of focusing on the efficiencies of the best farmers and the newest facilities and a strategy to make these efficiencies the overall industry and agriculture average, the studies present averages largely reflective of the efficiencies of ethanol facilities that are 20 years old. This is not helpful to long range planning. Interesting discussion, rusty and furball, thanks for joining in. -Jim |
Example
Figured I should be the first to raise the Brazil question - any studies from that part of the world? Appreciate Brazil isn't the US. Sugar cane ain't corn or cellulose. I acknowledge they've spent some time getting their ethanol production up to current levels. Check the article below:
http://yaleglobal.yale.edu/display.article?id=6817 you might need to cut and paste. |
Pimentel spoke to a largely proethanol crowd of corn producers and their representatives. Ethanol, he said, is not a true renewable energy source, because it requires more energy in its production than is extracted from the finished product. According to his calculations, ethanol takes about 1.15 BTUs (British Thermal Units) of input for every 1 BTU of output. Lastly, then how come that Brazil is making so much ethanol to be used as a fuel? Source doesn't really matter because the distillation is the same in both cases whether one start with starch or sugar. Or is there a cheaper way to separate alcohol from water? |
One of the things most people forget about is the fact that oil has to be transported back and forth just as corn does. It takes energy to pull oil from the ground, as well as find it in the first place. Employees burn resources for oil as well. Oil does not produce positive by products.
This fact is NEVER brought up in the comparison between Ethanol and oil. |
Finally after some digging, I found Pimentel and Paztek's 2005 article:
Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soy bean and Sunflower Still searching for some others... -Jim |
Oil ground
Just a quicky - we could get down to the sandwich level on all this but my goodness. Can we not approach it by cost per comparable unit/volume? Then perhaps pull out numbers. The cost of transport (energy) is included in the pump price. Appreciate it isn't 100% accurate energy balance but is there some way to provide/substitute the missing info by looking at thte economic side of things?
For example - some wells are pressurized and don't require the same energy input as others. The sands up in Canada are a completely different animal. Perhaps price/cost could be a fair and universal standard to look at. |
Price/cost is even difficult because of subsidies at all levels and taxes.
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Patzek & Pimental
Just in case any of you didn't know, Pimental is not the ecology expert he claims to be. he is an entomologist, thats right, a bug expert. What makes him think he is even remotely qualified to comment on ethanol is beyond me. Could it be that the school at which he teaches, Cornell, has a shiny new campus in Qatar. Yes, Qatar, the little oil-soaked place. What industry's money do you suppose pays for his 'studies' ? And his frequent collaberator, T Patzek, he is a consultant for Shell Oil. There would seem to be more than just a little bias. I don't know why anyone would listen to these guys. They certainly seem thoroughly discredited to me. DF
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We could go back and forth with connecting dots all day (I'm sure that someone would find a link between some of the positive ernergy balance numbers and ADM/corn lobbies). It just serves to put more smoke in the air to cloud the facts about what. If either side is truly influenced by outside forces, then ultimately it will show up in their numbers or conclusions on the viability of an energy source. I think it's more productive to look at the numbers and decide who has the more scientifically supported case.
-Jim |
Here's is a paper by Shapouri at the USDA, the one that Pimentel refers to in his work. I believe this is a 2004 analysis based on 2001 data, since he refers to Pimentel's 2003 work.
THE 2001 NET ENERGY BALANCE OF CORN-ETHANOL -Jim |
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