New research from Cornell and UC Berkeley agriculture and engineering professors concludes that, when all of the elements required to produce biomass-based liquid fuels (such as ethanol and biodiesel) are added together, the energy requirements for production far exceed the energy produced.
...corn requires 29 percent more fossil energy than the fuel produced; [...] soybean plants requires 27 percent more fossil energy than the fuel produced [...]
In assessing inputs, the researchers considered such factors as the energy used in producing the crop (including production of pesticides and fertilizer, running farm machinery and irrigating, grinding and transporting the crop) and in fermenting/distilling the ethanol from the water mix.
What's notable about all of the production elements listed as "requiring" fossil fuels is that pretty much all of them are amenable to changes that would greatly reduce or eliminate fossil fuel use. Pesticide use can be cut with organic techniques (or even carefully-controlled bioengineering); algae-hydrogen fertilizers require no fossil fuel inputs; pumps and other electrical farm machinery can be solar-powered; and the tractors and transport can be biodiesel-fueled. And that's if there's no shift to more radical farming systems.
Then there are the improvements to the energy potential of the biomass itself. A variety of techniques are being developed to improve the efficiency of biofuel production, from engineered enzymes to biomimicry of the natural consumption of carbohydrates to up biofuel production to 75% of the dry plant weight.
The Cornell and UCB researchers have clearly lost sight of the wide array of changes now underway when it comes to worldchanging technologies. It may be true that, today, biofuel production is a net loser in terms of energy costs -- but that doesn't mean that it will be true tomorrow.
Nice to see the complexity of this issue being addressed. This is a good example of an alternative that could be green, if the right systemic conditions are met (in this case, more regenerative agriculture etc - as you point out). We run into the very same issues when talking about starch- or soy-based plastics, which don't necessarily come with any assurance that they're grown without an equal (or greater) amount of petrochemical inputs to produce them.
It's somewhat analogous to the way we used to automatically consider non-organic cotton to be ecologically-sensible solely on account of its being grown in soil. If we ignore the whole picture, we risk improving one stage of the life cycle while worsening another. And then congratulating ourselves for our cleverness.
Exactly right, Dawn.
Doesn't this completely contradict this USDA/DOE Study done awhile back?
(looks like everyone picked up on this story today.)
Some of the claims make me wonder. Biofuels from wood are energy-negative? If you're thinning a managed forest, you'd have to spend a lot of fuel on transport before you offset the takings; you'd do even better if you processed the wood on-site, such as by pyrolysis to bio-oil and then fuelled the equipment with the bio-fuel itself (only shipping off the excess).
I wonder if Pimentel didn't jump the shark this time.
If the comment here by Rahul Lyer is accurate, we can kiss Patzek and Pimentel goodbye as credible authorities.
A pity. This topic needs honest brokers very, very badly.
Christian, I suspect (without yet going back and reading the USDA/DOE study) that Pimentel, et al, are using a longer list of production components to determine overall footprint. In principle, I'm actually supportive of broader nets for this kind of research, in order to avoid missing out on a non-obvious problem down the road. In this case, as I suggest in the post, they took a worst-case scenario and didn't look at the ways it could be mitigated.
E-P, I'm not surprised the everyone picked up on this -- it has the potential to be a hard-to-root-out meme in the fossil fuel lobby's arsenal.
Looking at the comments over at GCC, it looks like this is a very poor bit of research. It also looks like the authors aren't as generally pro-alt.energy as the Cornell press release suggested; I'll edit my post accordingly.
Oh, fergodsake, is Pimentel still peddling this BS?
I guess I shouldn't be surprised. I think he must have some kind of corporate backing, because the media always gives his announcements lots of coverage; this suggests the presence of a PR apparatus. I recall hearing a rumor that he was being funded by Mobil Oil, but I can't find any confirmation... it's gotta be someone though.
His research is full of holes. Quite aside from leaving out new technology like cellulosic ethanol, he makes worst-case assumptions about current technology. He overstates the energy required to distill ethanol by a significant margin, ignores byproducts that improve the economics and energy balance of ethanol production, ignores alternate feedstock crops... I could go on and on.
I'm not even going to bother reading it this time; his name has no credibility left with me.
This doesn't really sound like a guy working for the petroleum industry:
The supposed lack of credibility of these researchers (versus, say, the government USDA/DOE) is being grossly overstated.
Some of the farther out green tech - like hydrogen from algae and bio-engineered plants - are not strictly in the bounds of the study. Not fair to compare a hypothetical to something that is specifically being produced in quantity now.
We are using corn ethanol now. If it is energy negative (takes more energy to create than it produces) than it is a loser, and should be dumped until we can get EROEI up to 25% or better.
Let's run a farm on only biodiesel and biodiesel products, and see if it can produce more than it takes in. (The brazilians have positive EROEI with sugarcane. They burn the leavings to power their conversion plants. They also use peasant farm labor -- it is organic alright.)
Finally -- cellulose ethanol -- hey trees are great. Anyone here want to tell me that if build an infrastructure to turn trees into liquid fuel, that we won't take it a bit too far? Here's to you, easter island.
I'm no expert but even if ethanol/biodiesel production from corn/soy/etc is very energy positive, it's not a solution to our energy problems. There is not enough farm land to replace even half our energy needs. And, we need that land to produce food!
Biodiesel and it's ilk are only useful if we can produce it using non-farm land, like a desert other currently non-productive, non-used landscape. That's why I was so excited when I saw this.
I am not real comfortable with the way Dr. Pimentel's numbers are disputed in blog comments by non-numeric talking points.
We know there have been a number of efficiency concerns building, and that they are already taken seriously in environmental and governmental circles.
These numbers may be somewhat more negative, but it's not like we've never heard of this stuff before.
By the way - I totally disagree that this sort of study is in the fossil fuel industry's favor. You've got it precisely backwards. If we do not have viable alternatives, we must clamp down on conservation - and their profits - very soon.
Did you know that gasoline is a net energy loss? So is petroleum-based diesel fuel. It takes more energy, for extraction, refining and transport, to create gasoline and diesel, than each fuel provides. For gasoline, the net energy balance is 74% - that is, there is a net loss of 26 Btu's (Kcal, or whatever) for each 100 Btu's of gasoline; for petro-diesel, the energy balance is 83%. (Source: www.mda.state.mn.us/ethanol/balance.html) Dr. Pimental and the USDA disagreed about the energy balance of ethanol. According to the USDA, it was a positive energy balance of 134%; according to Dr. Pimental the energy balance for ethanol is only 77%. Of course, I have no idea who's right. According to the National Renewable Energy Laboratory in a 1998 study, pure biodiesel has an energy balance of 320%. I have no idea how far into the input-output matrix they peered. B20 biodiesel, by the way, has an energy balance of 98%. (Source: NREL< "An Overview of Biodiesel and Petroleum Diesel Life Cycles, May, 1998.)
I agree with odograph's last statement. It seems to me that regardless of the fuel, efficiency in its use is Priority #1. We need Factor 2 efficiency improvements in the next 10 years, Factor 4 in 20 years and Factor 10 in 30 years. That's a very high-tech challenge, a task worthy of the finest minds. If we pull that off, we'll buy enough time to investigate the merits of alternative fuels, and bring them on line in ways that best make sense. Trying to invent other fuels to waste the way we waste our current ones seems sad and dumb, like a junkie who, lacking heroin, is guzzling Paragoric.
David - conventional drilled petroleum from light sweet crude is about 10 to 1 (at least) on the positive ledger. Maybe I am misunderstanding what you mean though.
When you start to get into low grade oil, oil from high capital cost areas (offshore) or tar sands, EROEI invested does start to drop dramatically.
Tar sands is really a way to convert natural gas into oil (indirectly).
To relate this back to ethanol / biodiesel, the possible energy gains are demostrably small compared to conventional oil (2/1 using USDA boosterish numbers) - and as Eric pointed out, it isn't much of a replacement as framed because immense amounts of cropland (currently being used for food) would be required to substantially replace current fuel supplies of 25 million barrels of oil A DAY. (U.S.)
I'd rather see serious investment into things like hydrogen emmitting algae and such, and again these won't be small enterprises if we are looking to replace conventional liquid fuels.
Jon, I'm saying that our principal automotive fuels - gasoline and diesel - do not yield net energy. My number for gasoline was wrong; it's energy balance is .805, or a net 19.5% loss of energy. For diesel the energy balance is .843, or a net 15.7% loss. That's obviously not the case for light sweet crude, but it is for its refined products that we put in our cars. This is according to the study cited above, which in turn references other studies. If they're wrong, I'll stand corrected, but in the meantime, I'm going to really have a pause each time I go to the filling station.
My main point is this: whether the fuel is gasoline, diesel, B20, ethanol, or electricity, it takes an enormous amount of effort and environmental stress to put it in our tanks, and we should use it as efficiently as possible.
While oil itself is a net gain gasoline refining is EXTREMELY energy intensive. Specialy the refining going on these days that gets larger amounts of gasoline out of each barrel.
Thats why the fuel companies know they can get hydrogen to work in the long run. They already know the energy sources they will use and THIER costs for using those energy sources and they have a good idea how much hydrogen they can produce. Simple economics get the cost of production below the price you can sell it at and your good to go.
The production of ethanol from wood products is not a new concept, Germany tried this during WWII. The process then was called sacrification of wood; the idea is to generate fermentable sugars from wood (or better yet wood base products, i.e. paper). It seems to me that we dispose of millions of tons of wood product daily and that these supplies are not used to there fullest.
Mr. Foley: You might want to consider the implications of the Second Law of Thermodynamics and what it means versus your misimpression of what it means. I'm serious about this; using it your way, you'd look at the huge amount of sunlight which yields a comparatively trivial amount of firewood, and call the woodlot "energy negative".
Dan: There are a number of prospects for fuel production from waste. Off the top of my head, there are:
E-P, I respect the contributions you make to these ongoing discussions, enough that I wondered what I had written that would make you think I don't understand thermodynamics.
I see your point, and you're right - a woodlot concentrates solar heat, yet only collects 0.7 W/sq.M (with a theoretical limit of 4.7 W/sq.M.) And that's not particularly efficient - to produce one terrawatt from crops, we'd need approximately 500,000 square miles of vegetation, an area about 1/7 the size of the United States. (Source: Tyler Volk, NYU Biology Dept.) Of course, the rest of the solar energy isn't going to waste, since it maintains Earth's energy balance. But from an efficiency standpoint, it's better to heat my house with sunlight through windows than with firewood, because the energy conversion is much more efficient. If I had a finite amount of sunlight, you bet I'd be looking at the "energy balance" of the woodlot.
Fortunately, solar energy is renewable and virtually endless (by the human time scale). That's not the case with petroleum, so using 100,000 Btu's of petroleum to create 80,500 Btu's of gasoline isn't a long-term proposition. I think it should also change how we account for CO2 emissions caused by driving, freight transport, flying, etc.
I was trying to make 2 points. First, our current automotive fuels have a negative net energy balance, the charge that Dr. Pimental and others level at biofuels. Second, we can't afford to use petroleum or biofuels wastefully, and I strongly doubt that our next energy sources will allow for the profligate use we make of our current ones. So consider this a strong endorsement of efficiency first, then renewables. It's just plain dumb to waste oil; it will be just as dumb to waste alternative fuels.
Is there something about the 2nd Law that negates this?
I was trying to make 2 points. First, our current automotive fuels have a negative net energy balance...That's only true if you do not define petroleum, coal, etc. themselves as energy inputs. That's a very disputable definition.
When it takes 2 BTU of energy from other sources to pump, refine and deliver 1 BTU of petroleum, I will agree 100% that it is energy-negative. (If the application is valuable enough, such a cost might still be worth it.)
... the charge that Dr. Pimental and others level at biofuels.You're committing the Fallacy of Ambiguity here. Pimentel et al. are saying that the biofuels cannot deliver enough energy to run their own production and delivery, a charge which appears to have an uncomfortable amount of merit. This charge is patently false when applied to petroleum.
I was VERY excited to see this post. I will have to go back and check the links to make sense of it all and, I have to admit, I start to get a little boggled with the numbers.
I am working on a project with urban High School students in NJ where the kids will make biodiesel in their chemistry labs to use in an old school bus. All the points raised are valid ones and I look forward to more lively debate on this as the years go by. Till then, I'll be teaching kids to make it themselves.
The best part of this is hard to figure. Urban at-risk kids taking a waste product and turning it into a fuel that, unlike hydrogen, requires no infrastructure change and that yeilds a usable by product as waste (glycerine). Not only is this fuel renewable and carbon neutral, it improves air quality in their city, less acid rain (I think) and in its virgin manufacture, money to farmers not third-world dictators and royal families.
I don't know what THE answer is, but I'm looking for an old diesel Mercedes if you have one.......
This goes to show how in the dark we are concerning energy.
Remember, those photovoltaics used to run the pumps or whatever, also take a great deal of energy to produce in the first place. And this study didnt take into account all the energy needed to produce the various machinery needed to make all of this happen. Where do we start? At the fuel needed to survey the mountain where the iron ore will be mined?
Fortunately newer photovoltaics will return new energy more quickly because they require less to produce. This is something to look forward to.
The worry about transporting the feedstock long distances is avoidable. The equipment needed to produce biofuels does not need to be gargantuan and centralized. Both biodiesel and ethanol production lends itself to smaller scale, distributed production facilities. There are even mobile turnkey biodiesel facilities on the market today. The advantages of distributed, local production go well beyond transportation costs.
Its not easy to think about doing everything differently but thats what was needed when we first began using electric energy to do work. That change was not very long ago, and look where its gotten us so far.
Without getting into questions about the professional credibility of Pimental (seems to me to be the Fred Singer/Patrick Michaels of the ethanol debate), it is worth noting that virtually all other lifecycle analyses (LCAs)of ethanol and biodiesel show positive energy balances, typically ranging from 0.5 - 0.8 (energy in/energy out)compared to Pimentel (2001) value of -1.62. That's a pretty significant difference, and put's Pimentel's results way out in left field comparatively speaking. As mentioned earlier, Pimentel's previous work has been criticised extensively by others for its questionable methodological assumptions (e.g. using outdated crop efficiency estimates, not including credits from co-products such as dried distiller grains, etc.)
LCAs are notoriously complex because so many assumptions have to be made throughout the analysis (e.g. extent of fertilizer use, corn yield per hectar, conversion efficiency, extent of irrigation, transport, etc.) and so it isn't suprising that there are different results being put out. However, I am suprised that Pimentel is still going at it after having been soundly discredited by other academics in the field--time will tell if this latest attempt is the third and final one.
An excellent summary of the current understanding and research on LCAs for ethanol and biodiesel can be found in a report put out by the International Energy Association, "Biofuels for Transport: An International Perspective". Unfortunately, not available on the web, but definitely worth reading for those looking for an unbiased assessment.
David - your updated numbers on gasoline make more sense. To restate it, for every 100 gallons of gasoline produced, 20 gallons are spent in refining, transporting, etc, according to your reference -
but - the study you mentioned:
-- has some issues which mobjectivist deconstructed a while back:
He's pretty critical of the framing of the government supported USDA studies. I encourage those looking for deeper analysis on ethanol and biodiesel to check it out.
Pimentel is quoted in the Cornell press release as favoring using biomass to create electricity (burning it). This is a much more sensible plan than conversion to ethanol or biodiesel, as far as net energy balance goes. And it would even impact the transportation market with a switch to plug-in hybrids or fully electric cars.
Bio-fuels have exactly the same problem as hydrogen, for transportation: way too much energy is lost in the conversion to the fuel, transport of the fuel, and then in the internal combustion (or fuel cell) process. Whether or not the EROEI for any of the bio-sources is negative or positive, it'll be strongly positive if you convert to electricity as soon as possible in the process.
On the other hand, like hydrogen, biofuels may make sense for energy storage; they're easily transported and have high energy density.
You can do a lot better than burning biomass to make electricity; use it to reduce zinc oxide to metal and sequester the CO2 product. The consequence is that your energy system is carbon negative.
Land is not a renewable resource. In fact, we have lost aout 75% of our top soil and we are losing what's left at a frightening pace. We are also due to lose a lot of productive land in and near coastal areas due to rising sea levels and salt water intrusion in the decades ahead. It's going to take a heck of a lot of land to grow enough biomass to displace the amount of petroleum we are accustomed to using (and wasting) even if the biomass and/or oil seeds can be grown, processed and distributed in such a way that they provide a positive energy balance.
Water is also in short supply where most of the biomass is likely to be grown in the U.S., and climate change models show that it will become increasingly scarce and less reliable during this century. Crop damage is also increasing due to ever more violent storms as global warming sets in. Capturing and pumping water, of course, is energy intensive, leaving in doubt that energy balance, again.
Meanwhile, worldwide, production of food peaked several years ago, but the growth of the population did not. Given a choice, I would rather have land and water used to produce crops feed us than feed our cars, and it won't be long before we will need to be making such a choice.
Hey, I have a couple ideas. Maybe we could learn to be more efficient and get by on less. Maybe we could take responsibility for promoting a decline in human population by making sure the people alive today don't need to rely on their kids to do enough manual labor to keep them barely alive. Then, perhaps, we might have a shot at a planet that wasn't about to be driven into an eco-collapse that will wipe out most of our grandchildren in a rather brutal and pathetic manner, if not doing the same to ourselves.
Based on earlier comments in this thread, I suppose some of you are ready to dismiss this as the ranting of yet another friend of the petro-chemical companies before hopping in your car or SUV to grab some more "healthy" snacks and sodas to munch when you return to your computer for more shared pipe dreams about techno-fixes that will allow the perpetuate the continuation of a shakey economy that has even the few so-called winners within it freaked out about their futures. If so, here's a little reading for you to do when you get back:
Still wanna try growing enough veggie oil and biomass to continue business as usual?
E-P wrote: "That's only true if you do not define petroleum, coal, etc. themselves as energy inputs. That's a very disputable definition."
E-P, I completely understand your point, but here's my weird perspective: I don't think fossil fuels are energy inputs. I think they're the accumulated stock of the only energy input of consequence - the sun. I'm distinguishing a stock from a flow, a savings account from an income. If you're living off of your savings account, it's not an "input" to your income. This may be irrelevant to the points you're making, but it's central to the point I'm making. We need eventually to learn to live within current solar income. To do that, we need to focus on radical efficiency improvements first and foremost. I think that trying to invent a substitute fuel to substitute for fossil fuels, consumed at our current rate, is very unlikely to succeed.
Jon S., your statement seems right, but the way I'd express it is this: to obtain 100 gallons of gasoline takes energy equivalent to 120 gallons of gasoline.
It's as if we're living off of a savings account, and for every dollar we withdraw, the bank charges us 20% in service fees. Actually it worse, because we also incur a future debt to clean up our CO2 mess.
I'm optimistic that we can solve this problem, but we need to define the problem correctly. My opinion is that the problem is first and foremost how to retool our society to function on about 10% as much energy as it uses today, while still providing a decent life to people. Second, the problem is how to obtain that energy from current solar income to the greatest possible extent. If that's not possible, the third part of the problem includes how to mitigate the harm done by reliance on fossil and nuclear fuels. I also think that if you define the problem another way, solving it becomes virtually impossible.
Of course other people see it differently. I respect that, and welcome the opportunity to learn from other points of view. This is a group discussion, not combat.
My opinion is that the problem is first and foremost how to retool our society to function on about 10% as much energy as it uses today, while still providing a decent life to people.Setting an arbitrary target of 10% is counterproductive.
Second, the problem is how to obtain that energy from current solar income to the greatest possible extent.The solar energy hitting the typical home's roof is several times as much as the energy used by or on behalf of the occupants of that home. The only reason you'd want to slash energy consumption to an even smaller fraction of what's cleanly and easily (and fairly cheaply) available is out of ideology.
Energy isnt the problem converting it into useful forms and getting those forms where its needed cheaply enough is.
Once you have an energy carrier that you can work with and use all you need is a cheap enough energy source to create it. This can be as simple as harvesting kudzo and converting it to bio or harvesting seaweed and doing the same or harvesting algae or any number of thingers that grow... To bullding massive hyper hot nuke plants and using the heat to both generate power on a grand scale and crack water. To someday harnessing the power of fusion energy. To someday controlling gravity/going after fundamental forces.
Right now we need a few easy to use energy carriers. We have good ones lined up and we are making amazing progress in making them cheap.
So its not a big deal just takes time and money and minds.
I am a bit confused with this whole conversation. It seems to fly in the face of the DOE study showing the energy yield is higher in biofuels than petroleum fuels http://www.b100fuel.com/archives/2005/07/biodiesel_has_v.html.
How are these two reconciled? Biodiesel looks like very energy efficient in that study.
"The solar energy hitting the typical home's roof is several times as much as the energy used by or on behalf of the occupants of that home."
I've yet to do this calculation, so I'll try it now.
My house is a standard urban home on a 20 ft by 30 ft foundation. The 20 ft face is the one facing south.
Forget for a moment that I don't have a simple roof surface (two sides, pitched), that the angle may not be optimal relative, and that there isn't a 100 year old tree full of leaves (6-8 months a year) towering over my house providing cooling in a house without air conditioning. Let's also forget any thermal considerations for the moment.
OK, assuming a simple roof at an optimal angle, the south-facing surface would be about 323 ft2 or roughly 30 m2. According to the NASA EOSWeb site you mentioned (thanks for that, btw - awesome site!), we get 3.61 kWh/m2/day in the Twin Cities.
So, with 15% efficient panels covering the whole roof surface (forget about lower efficiency because it doesn't track), that surface should be able to generate 16.25 kWh on an average day, or a little less than 500 kWh per month.
I took a random 12-month sample and found we used 3,148 kWh during that period, or about 262 kWh per month.
So, it seems like it would be possible if the roof were to change and the tree were to come down, and somehow I found passive means of thermal control which didn't require electricity for cooling or heating.
I also did some calculations of what an average household uses. According to Census data, there were about 109 million households in 2000. In 2001, residential retail sales of electricity were about 1.2 trillion kWh. That comes out to about 11,000 kWh per household, or a little over 30 kWh per day.
So, for an average household getting insolation numbers for the Twin Cities, one would need a 55 m2 (about 600 ft2) surface to generate that much power at 15% efficiency. That 600 ft2 is the same as a square with about 25 ft sides. Using a simple roof with one side facing south at an optimal angle, the foundation of the house would have to be about 1,160 ft2.
So, I'm not sure what conclusions can be drawn from it other than the amount of energy it's possible to generate with PVs (at this point in time) is treading a close line in terms of self-sufficiency. I wouldn't say it's safe to say there's "many times" the energy available given current technology. Certainly there are wide variations in siting, tree cover, climate, roof types, space, etc, which wouldn't easily allow for generalizations.
I have to say I agree with Martin's comments that the comments on this post seem to be a little off topic. The central question is whether or not biofuels are C02 negative or positive. The real story here is that the vast majority of research (wang, Levelton, Levy, Maceto et al) shows that they are positive -- by varying degrees, depending on technologies and production processes (20-90%)-- and yet one contrarian (i.e. Pimentel) continues to get published. The analogue here is the climate change debate, where a handful of people get an inordinate amount of coverage and credibility from the press by rehashing old arguments using questionable assumptions...same thing is happening here with biofuels.
Now that's not to say that there aren't any controversies surrounding biofuels (there are several), or that all biofuels are "sustainable". Again this depends on production processes, feedstocks, soil/water conservation methods, use of pesticides/fertilizers, etc.
I'm also surprised that people haven't been talking about some of the other environmental aspects and technical barriers of biofuels.
Specifically, it is fairly well known that the environmental benefits of ethanol in particular have been declining over time. Originally, it was prommoted because of its ability to reduce carbon monoxide (by increasing the amount of oxygen in the fuel-air mixture)-- this is why denver, colorado (thin air) which was then a CO non-attainment area was the first jurisdiction to use ethanol in the early 80s. Since then vehicle technologies have improved and greatly reduced CO emissions. On the down side, ethanol increases the volatility of the final fuel, and increases VOC emissions which lead to smog. FOr these reasons, California has been seeking a waiver from the federal oxygenate requirement. In the post-911 era, a number of people are also framing biofuels in terms of homeland security, specifically as a means of reducing dependence on foreign oil.
Biodiesel, while less problematic still faces significant technical hurdles, the most significant of which is the fact that it doesn't flow at low temperatures (e.g. the same way olive oil condenses in the fridge).
Given all these issues, the next question is: are biofuels a viable GHG mitigation strategy? If that is the only thing that you are considering I would say no, unless it is produced using cellulosic feedstock, switchgrass, or sugarcane -- because the GHG benefits using these feedstocks are significantly higher compared to corn, and less ecologically damaging.
Joseph Willemssen: I said that enough energy fell on a typical roof to fulfill your needs, not that you could necessarily manage that with today's technology.
Your 20 by 30 foot roof gives you 600 ft^2; call it 60 m^2 to account for the extra area shaded by the vertical relief. (You wouldn't have to put this on the roof of the house, of course; anything would do.) At 3.61 kWh/m2/day, you'd intercept 216.6 kWh/day, or 9.0 kW average. This makes your situation very marginal, because US energy consumption over all sources is about 12 kW/capita. On the other hand, your house is both atypically small and rather far north. An average American house just about anywhere in a band from Arizona across to Florida and Georgia would probably have a considerable surplus.
Current commercial PV panels run 10-17% efficiency, depending on technology. Lab tests of quantum dot converters hold out the possibility of 65% efficiency... there's a lot of potential that we have not yet begun to tap.
"Joseph Willemssen: I said that enough energy fell on a typical roof to fulfill your needs, not that you could necessarily manage that with today's technology."
Well, perhaps I misunderstood. This is what you wrote:
"The solar energy hitting the typical home's roof is several times as much as the energy used by or on behalf of the occupants of that home. The only reason you'd want to slash energy consumption to an even smaller fraction of what's cleanly and easily (and fairly cheaply) available is out of ideology."
So, if you're talking about potential not really realizable with current technology, then you're basically speculating about how far that technology can be pushed, how much it will cost, etc. I think David's coming from a position of knowing that we *know* we can make huge advances in efficient utilization with *existing* technology. It's a lot less risky than betting on technology which may not come to fruition economically or in a timely fashion.
I brought up real world data to get some context about where we are and how far we'd need to go to get towards a solar self-sufficiency point (at least with electricity and assuming that average consumption levels don't change). The point of making the latter assumption is to isolate David's argument for efficiency from your argument for ramping up production of clean renewable energy.
"Your 20 by 30 foot roof..."
My foundation is 20x30. If I had a simple roof structure (which I don't, but again, let's drop that), the surface on the south-facing side would be the size I mentioned -- about 323 ft2. It might be a little off because I didn't stop to calculate what the pitch height would have to be to get an optimal angle, so I just assumed 6 feet. Taking half the depth of the house as the length of the base of a right triangle, it would be:
c^2 = 15^2 + 6^2
East-West dimension is 20 ft, as I said.
c * 20 = 323.2
My apologies if I worded that in a confusing manner.
"On the other hand, your house is both atypically small and rather far north. An average American house just about anywhere in a band from Arizona across to Florida and Georgia would probably have a considerable surplus."
Well, for an urban home, it's not that small. And we actually do pretty well in terms of insolation, considering how far north we are. But you're right - a spawling single level home in Arizona etc is going to have much more roof surface with far fewer obstructions and much better insolation.
So, there may be enough solar for the electricity in certain cases, but that then gets offset by what we were discussing on another thread about density, efficiency, and so forth. There's also all thermal issues to consider, among other things.
I'm am with you 100% in terms of the idea that we can live off of our daily solar diet, though I am also sympathetic to David's argument for radical improvements in efficiency making that easier, being quicker, and in many cases cheaper than simply ramping up production. I'm sure you agree on that as well.
And we always need to keep in mind that this is the real, messy world, with all kinds of people with all kinds of priorities, with all kinds of expertise and different time on their hands. And we also have a legacy of building stock and infrastructure that needs to be worked with, even though we all might wish for a clean slate onto which we could graft clean, efficient, and elegant ideas.
I have manged full scale LCA studies on two industrial commodity products. From that experience I understand that LCA studies are extremely imprecise and vulnerable to bias or (more often) ignorance of the investigators and poor underlying data sets. This is not the same as inaccurate: e.g. corn grown in central Minnesota using apray irrigation, marginal soils, and heavy inputs characeristic of food grain production will result in a poor energy balance whereas other cropping systems might lend themselves to a more postive one. Some LCA inventory sofware in common use commonly uses European data published decades ago to characterize energy and material burdens. Other LCA sofware might use US or even EU/US aggregate burden basis units making the result comparisons 'apple and orange': hence the low precision.
I find it problematic that engineers with no life science backround and no apparent peer review from life scientists "diagnose" energy systems that are fundamentally life driven. I have a similar problem with the USDOE which is entirely too corporate focused (look at the miserable slog of getting an organic food standard published if you need and example).
Having read several of the independent studies myself, I am optimistic that biodiesel fuel can be made with postive energy outcome. It is definitely not possible however, to meet the projected 40% increase in liquid fuel demand by 2030 with either fossil or "living" fuels. Effficiency is paramount.
John L, glad you pointed out the big picture.
Using either Pimental's numbers (and he admits, incidentally, that biodiesel can be energy positive - see below) or the USDA / DOE numbers, there is not enough cropland available to realistically replace even 10% of current liquid fuel usage without shorting the food crops.
"David Pimental, a professor of ecology and agricultural sciences at Cornell University in New York, has studied several alternative energy sources, and gives biodiesel a good rating. "It turns out that with soybean oil, energetically (in terms of energy), you get a positive return. In other words, you get about a gallon and a half (5.7 liters) for every gallon (3.8 liters) of oil that you invest in that. So it is positive in that sense. However, the cost is significant," he says. "The data that I have indicate that it costs you about a one dollar and eighty cents per gallon (per 3.8 liters). That's for production and it's not distribution and so forth. So that is a significant price.'
David Pimental is not as fond of a similar alternative fuel called ethanol..."
Why is that? Net positive or not...
"So nearly 4 times the amount of ethanol available for net over-the-counter sale needs "extracting" as a gross overhead. Essentially, this means 4 times the size of corn fields needed for our "home-grown" energy independent solution, than if we used fossil fuels as a production energy source."
The same calculations show that you'd need to harvest 3x the amount of soybean oil that could be sold as net product; 2/3 of the total would have to be used to run the farming operation in one way or another.
Biofuels from crops are clearly not going to help enough to be worthwhile. Biofuels from crop byproducts may be another matter. Biofuels from waste that's otherwise headed for landfills is a pure win.
The entire production chain for biodiesel can be a green one, with no need for any petro-inputs whatsoever.
Of course, if you use lousy crops for biodiesel (like soy), you're asking for trouble.
Biodiesel only makes sense when it is produced from high yielding oil trees like jatropha, avocado, coconut and drought tolerant oil palm. These crops yield between 5 and 20 times more than soybeans. New oil palm hybrids have to potential to produce 70 barrels of oil per hectare, about 35 times more than soybeans!
In fact one of the largest potential feedstocks for biodiesel right now is "rendered" livestock (see Rothsays in Canada for example). With concerns over Mad cow and the like, this source is likely to increase considerably in the future.
A couple of other observations. First, I think we're setting up a bit of a straw man here by saying that there isn't enough corn to meet the fuel demands of 2030. As far as I'm aware nobody is saying that we should take the Brazil 1980s approach and strive for complete substitution. Biofuels are simply part of a basket of solutions (hybrid, electric, transportation demand management, etc.)-- nothing more, nothing less.
Second, it is important not to use Pimental's arguments as a broad indictment against biofuels in general. It is true that from a holistic perspective, ethanol from corn provides dubious benefits at best. The same cannot be said of ethanol made from cellulosic feestock (e.g. wood waste, corn stover)--google Iogen--or from sugarcane as in Brazil, where the bagasse is used to fuel the plant.
In the real world the bottom line is money. Brazilian ethanol is currently far cheaper than corn ethanol produced in the States--which is why there is a 52c/gallon tarriff on it (so much for free trade). Cellulosic ethanol technology still hasn't matured to the point of being cost competitive (which presumably why it's given a 1.5-2.5 extra credit in the latest U.S. energy bill), but it seems likely that it could be viable within the next 5-10 years, in which case ther will likely be an enormous potential for ethanol to replace conventional gasoline considering the volume of wood waste from the North American forestry sector.
Why stick to simply calculating the tangible benefits of biofuels?
There's a list of indirect advantages which you have to take into account:
-the mere fact that biofuels exist makes people more conscious about their energy consumption and habits (probably the single most important factor to arrive at a sustainable future)
-you don't have to colonize, slaughter, kill, and butcher people to get your oil, and consequently, you don't need to train terrorists to defend your oil and who will later attack you, making you illegally invade another country full of oil (heavy social costs of a barrel of oil)
-biofuels have the capacity to transform the political attitude of people, indirectly (reducing or taming the neofascist impulses of the American people, embodied by those who drive military style vehicles for pleasure)
-biofuels have the capacity, no matter how small, to reduce the totalitarian grip of the American military-industrial-media complex on society (because petroleum is the ultimate driving force of this horror complex)
-biofuels are "grown", which is a very feminine way of producing things; while petroleum is "pumped" out by "drills" "penetrating" "holes"; this mere metaphoric difference has effects on the subsconscious; ultimately, it contributes to an ecofeminist outlook on life, and gets rid of the patriarchal, authoritarian and modernistic way of thinking.
These and many other indirect effects of biofuels are of immense value.
After all, we must ask ourselves why 4% of the people on this planet have both the largest army, go to war most often, kill more people than anyone else, and consume 25% of all energy on the planet. It's a cultural thing. And biofuels indirectly help change that disastrous, horrible culture.
"After all, we must ask ourselves why 4% of the people on this planet have both the largest army, go to war most often, kill more people than anyone else, and consume 25% of all energy on the planet. It's a cultural thing."
Whoa. I don't think this country "goes to war" the most often - not by a long shot. We may screw around with the internal workings of other countries a lot (now), but that's not the same as going to war. Put it in historical perspective, and what we do isn't that extraordinary.
America isn't the way it is because somehow the earth is being penetrated with drills and it's reinforcing patriarchal society. That's a bit of a stretch, don't you think?
If you look at energy, for example, the amount we use is a factor of a number of things - the GDP (and the degree to which we have energy-intensive industries), population, population dispersion, climate, the timing of our country's growth relative to the industrial and automotive ages (influencing development patterns), etc., and just general inertia of inefficiency.
Far as I know, there isn't an economically advanced nation (or any nation for that matter) that seems to be anywhere near a point of living in balance with nature. So though you may be right about a certain type of violence that permeates American culture, it certainly isn't unique (especially in historical terms) and is reflective of the general violence and imbalance that all of humanity has been living with for pretty much all of history.
People are so far removed from the processes that go on to make their daily lives work, so I don't really see how if they drive their car down paved earth to a fueling station and take a metal and rubber pump and let some biofuel go in to their metal tank (and never seeing or smelling it), that somehow this is going to rub off on them the healing power of nature.
I like that you're thinking beyond the rational and scientific merits of biofuels, but we need to be real about the fact that there are sucky, selfish people well dispersed across the planet (as well as great, positive, relatively selfless ones).
"After all, we must ask ourselves why 4% of the people on this planet have both the largest army, go to war most often, kill more people than anyone else, and consume 25% of all energy on the planet. It's a cultural thing. And biofuels indirectly help change that disastrous, horrible culture."
Oh no Lorenzo - that's what people from Texas oil money call an 'enternality' --
As to the hilarious terra cotta solar story - that's a political question and an aesthetics question.. on the one hand people need to organize for rational solutions and make these sorts of ludicrous limitations on healthy alternatives terribly UNFASHIONABLE... solar/wind needs better PR.
Also engineers need to hire designers at the begining of the product cycle -- beauty is importatant to the propogation of ideas and innovation. Though it may not be critical to the function -- the fuction will not be adopted if the form is offensive to most people.
For good or evil beauty matters.
(For those who haven't read Cradle to Cradle - I suggest picking up a copy)
Instinctively, the idea of doing anything with food other than eating it -- or with cropland other than producing food -- does not seem to me like a long-term solution to any problem. When I think of the opportunity of biodiesel, I think of it as an opportunity to extract value from what are now merely waste products. The Frito-Lay company could convert its used fryer oil into diesel to fuel its delivery trucks, for example. But production of vegetable oil on an industrial scale -- which entails all the features of industrial agriculture; monoculture, fertilizer, and so on -- simply to change the input to our system of producing fuel for general private consumption -- well, I don't need "net energy analysis" to decide how I feel about this.
biofuels are "grown", which is a very feminine way of producing things; while petroleum is "pumped" out by "drills" "penetrating" "holes"; this mere metaphoric difference has effects on the subsconscious; ultimately, it contributes to an ecofeminist outlook on life, and gets rid of the patriarchal, authoritarian and modernistic way of thinking.If I had any doubts that the "loony left" still existed, that would have put them to rest.
Friends, for some reason this topic has touched a nerve. We're in danger of forgetting to be kind to one another. We won't make much progress this way. I'm one of those guilty of veering off-topic here, and for writing some provocative things. I apologize. Perhaps it's time to take a breather, think about what we've learned from this discussion, and carry on when we're in a more compassionate frame of mind?
Bite me, David, you bastahd!!
I'm just kidding, just kidding. :-)
On solar panels as I said way back a few months ago they need to think of ways to make solar panels that blend in better. People pay massive amounts of money for homes whose property value does realy rely on how the area looks and as such an UGLY solar job will get you in deep poop for a very good reason it costs everyone around you money.
Now having said that they DO make solar panels that are close to the color of ceramic roof tiles. They even make ones that LOOK like them.
Wow. This has to be one of my all-time-favorite posts. You can FEEL the passion. Mr. Foley, E-P, Lorenzo, all of you totally rock.
It is important to remember that everyone has a valid perspective and no one really knows what the !@$#%^ is going to happen.
I only know what I know, but I also know that I don't really know. My perspective is only one point. When we share in 'a good way' it is then possible to truly see and transform.
Thank you all for sharing your insights on this topic.
This study is biased because the most obvious source for biofuels is NOT taken into account. Alcohol from Sugarcane is already a serious mass-produced energy positive biofuel, yet somehow it is missing from this study. It's like taking only the worst examples from the lot and leaving the best ones on the shelf.
I imagine the new study by Pimentel and Patzek in Natural Resources Research showing negative energy value in all biofuels is a repeat of what these advocates have been saying for the past 15 years. Hopefully, scores of respectable scientists will tear it apart, limb by limb, even though it may contain some useful and important analyses on water table depletion and contamination.
Perhaps the biggest technical problem in Patzeks works is the value used for the fossil energy input in production of fertilizer. This energy requirement has been steadily decreasing over the past 35 years. The theoretical minimum for NH3 is around 25 GJ (HHV) per ton of NH3. The mean for plants built in the 1960s was 75 GJ/t, and for new plants constructed in 1997 it was around 33 GJ/t. The average for all U.S. plants in 1995 was 40 GJ/t, or 11.1 MWh/t, or 17,600 BTU/lb. Patzek (in a 2003 paper) mentions this 1995 U.S. average number, then inflates it (unnecessarily) 10% for transportation and handling. He then jumps to an energy value for urea (which is more energy intensive than ammonia and accounts for about 50% of nitrogen application) from the 1980s (28,800 BTU/lb), inflates it by 10% for transportation and handling, and applies this number to all fertilizers.
A more realistic number for mean fossil energy per pound of fertilizer just 5 years from now is about half of what Patzek assumes. And of course, 20 years from now, it could easily be just 20% of what Patzek assumes if there is aggressive support of production of renewable fertilizers on wind farms.
Then there is the question of how much fertilizer is used. Are the reported numbers in pounds of NH3 or pounds of nitrogen? Pimentel assumes agricultural reports are always quoting nitrogen fertilizer amounts in nitrogen content, whereas in some cases they were reporting ammonia amounts and nitrogen would be 14/17 as large. He then consistently uses the highest reported fertilization rates from various studies. His phosphorus application rates, for example, are at least 30% above more commonly reported mean rates, which are steadily decreasing.
There are similar problems in his analysis of energy required for processing the corn into ethanol, where he relies heavily on data from the 80s, which he then inflates by 20% to account for the energy required to make the concrete and steel in the ethanol plant (even though the plants may have a 40 year design life). His credits for the value of co-products are unrealistically low by even greater proportions. His analysis of ethanol from cellulose and hemicellulose is not even worthy of comment.
Finally, for special effects, Patzek likes to report the total energy input, including the solar energy, just after hes been summing fossil energy input and net energy output in an attempt to mislead the unwary reader into thinking the total ethanol energy output is 35% of the fossil energy input though he is careful not to actually state that.
Pimentels support of solar and wind is commendable, but that is no excuse to distort the case for biofuels. It is certainly quite possible that analyses by biofuel supporters are rather optimistic for current standard practice; but this is excusable, as there has been a significant trend toward improving efficiencies over the past 15 years, even though fossil energy costs have been very low during most of that period. With fossil energy costs now rising rapidly, we can expect rapid strides in all efficiencies over the next five years.
In fairness, the above brief comments on previous works by Patzek and Pimentel may not apply to their most recent article in Natural Resources Research. If anyone has a copy, I'd be interested in seeing it - though not interested enough to buy it.
See Shapouri, http://www.ethanolrfa.org/net_energy_balance_2004.pdf , for a balanced analysis of corn-ethanol.
See U.N. report #26, http://www.fertilizer.org/ifa/publicat/pdf/part1.pdf , for all you ever wanted to know about the fertilizer industry.
See Greene, Growing Energy, NRDC, http://www.bio.org/ind/GrowingEnergy.pdf for serious analysis on cellulosic ethanol.
See Patzek, http://petroleum.berkeley.edu/papers/patzek/CRPS416-Patzek-Web.pdf , for some extremely biased rambling based on obsolete data.
F. David Doty, PhD, physics