Ethanol: the net-energy debate returns

Is ethanol skeptic Pimentel right after all?

Posted by Tom Philpott at 9:49 AM on 16 Jan 2007

In 2004, the USDA came out with a study (PDF) claiming that corn-derived ethanol delivers 67 percent more energy than it consumes in production.

For many observers, including green-minded ethanol critics, the study delivered a resounding "case closed" to the decades-long debate about corn ethanol's "energy balance." Critiques began to focus more on the mounting environmental depredations of industrial-scale corn production.

But a study released by MIT -- the press release of which was ably skewered on Gristmill last week by Ron Steenblik -- to my mind reopens the net-energy debate.

First, a bit of context.

For years, as a series of studies has emerged crediting corn ethanol with positive energy balance, one major critic has clung to the opposite assessment: Cornell University professor emeritus David Pimentel (along with sometime collaborator Ted Patzak of Cal-Berkely).

Pimentel, whom I recently interviewed for Grist, began studying the question as a USDA consultant in the late 1970s.

Since then, Pimentel has come out with study after study claiming that when all of the inputs to corn-based ethanol are added up, the fuel is an energy bust: Producing it consumes more energy than the fuel delivers.

Pimentel's contention, if true, is devastating to corn-based ethanol's advocates: After 30 years of steady and generous government support, corn ethanol still isn't providing fossil-fuel conservation.

The common response to Pimentel's heresy is summarized over on the greenie site Journey to Forever: Pimentel is a crackpot who gets his results by relying on out-of-date input numbers.

Interestingly, Pimentel's work got an endorsement from an unexpected source: the recent MIT study, which as Steenblik's post shows has to perform rather tortured gymnastics to find value in corn-based ethanol.

The MIT press release summarizes researcher Tiffany Groode's research thusly:

Based on her "most likely" outcomes, she concluded that traveling a kilometer using ethanol does indeed consume more energy than traveling the same distance using gasoline.

Nor does Groode parrot the Pimentel-relies-on-ancient-data line. Here's how the the press release quotes her:

The results show that everybody [including Pimentel, mentioned by name] is basically correct ... The energy balance is so close that the outcome depends on exactly how you define the problem. [my emphasis]

This is precisely what Pimentel has long argued: that most ethanol energy-balance studies omit key factors like the energy required to manufacture farm equipment.

In our interview, Pimentel told me that his methodology is consistent with life-cycle net energy studies of other fuels. I'm not competent to comment on the accuracy of that statement, but the MIT researcher doesn't challenge it.

So if Pimentel is essentially right about corn-based ethanol's negative energy balance, how does Groode wind up tepidly supporting it?

She says what's known as the "co-product credit" -- the energy-saving value of distillers grains, an ethanol by product that can be fed to livestock -- pushes ethanol's energy balance into positive territory.

Incidentally, Pimentel told me he does account for distillers grains, but finds that other researchers tend to overestimate the energy they save.

Again, I'm not competent to comment on this point, but I can say this: The MIT study is telling us that the entire case for corn-ethanol as a net saver of fossil fuel rests on a product -- distillers grains -- whose only market is industrial meat producers.

That group operates under a kind of bizarro triple bottom line: it profits by generating social, environmental and animal-welfare horror.

Indeed, the FAO recently declared that feedlot meat production spews out more greenhouse gases globally than cars!

Distillers grains as cheap feed for the CAFO industry, it seems to me, represents a thin reed on which to hang the green case for corn ethanol.

Might it be time to take a fresh look at Pimentel's work?

For story: Ethanol: the net-energy debate returns
11 Comments | Post a Comment

You don't even have to go that far

Good point, but forget about the energy balance for a minute and wake up to the larger reality:

Just as war is politics by other means, ethanomania is nothing but a scheme to continue the carburban enterprise by other means (in this case by taking land away from providing food and fiber or environmental services and turning it toward fuel production for SUVs).

Remember, the oil industry is just one of many that depend entirely on carburbia--and none of them want the party to end.

The point of ethanol isn't to replace fossil fuels--it's to scam the rubes for a while longer so that they don't realize they've been sold a $200,000-300,000 bag of crap with a 30 year mortgage and no future.

The suits are quite worried about one thing: the instant the proles figure out that the future they've been sold is going to turn on them like a badly trained pitbull, they are going to stop giving a damn about the "social contract" and having a spotless police record.

The 5% Project

by JMG at 10:35 AM on 16 Jan 2007

quibbles over details

Whether the EROEI is 0.8, as Pimtel would have it, or 1.6, as the USDA claims, is really irrelevant. The EROEI on crude oil production is 10:1 or better. The EROEI on gasoline production from crude oil is also about 5:1. Corn ethanol doesn't get anywhere near those numbers, which means that it can't ever be more than a marginal fuel, even with the most optimistic assumptions (which include, among other things, the notion that the market for distiller grains would not become quickly saturated).

Our energy future is going to have to include significant conservation, so I am not by any means suggesting that the only alternatives worth considering are those with EROEI values as high as gasoline: I'm not sure there are any such options from renewable sources. But I do believe that any source that is so close to the breakeven point that we have to argue about whether or not it is positive at all are a waste of time. I would look for an EROEI of at least 2, hopefully 3-4.

by GreenEngineer at 10:42 AM on 16 Jan 2007

Solar heat has an EROEI @ 25:1

by sunflower at 10:58 AM on 16 Jan 2007

Re: Quibbles over details

>But I do believe that any source that is so close to the breakeven point that we have to argue about whether or not it is positive at all are a waste of time.

Yes. This. Should have been all caps, cause it deserves to be shouted.

Oh and a side note. Wind has an EROI of 18X to 24X. I think even the EROI on PV is 3.5X to 6X. (PV takes 18 months to 3 years to pay back its energy investment. But the question therefore is lifespan, which can be as low as 12 years, and as high as 30. Production drops towards the end of lifespan - which why the worst case is 3.5X on the extremely unlikely assumption that you combine a three year payback and a 12 year lifespan.)

by Gar Lipow at 12:45 PM on 16 Jan 2007

Gar...

Thanks for the support.

Regarding PV lifetime, the modules themselves are usually under warrantee for 25 years, nowadays. A 30-year service life is considered a conservative assumption. 50 years is a probably reasonable upper end. Anyone who only got 12 years from their system would be rightfully pissed off, and calling the manufacturer.

Now, inverters don't usually last more than 7-15 years, but they are not the majority of the embodied energy.

by GreenEngineer at 2:24 PM on 16 Jan 2007

SunCube EROEI

The SunCube is a concentrating solar PV system with 2-axis tracking. Here's an Excel spreadsheet that lists the system's EROEI at 9.12, and the time for energetic payback at 2.74 years.

Ped Shed Blog

by Laurence Aurbach at 4:06 PM on 16 Jan 2007

"Connect the output to the input"

Almost everyone has long known that whether or not a study concludes corn ethanol has a positive or negative EROEI depends solely on how big a circle the studier chooses to draw around the process. The smaller the circle the fewer the energy inputs and the better the EROEI of ethanol; draw a bigger circle for the study (as does Pimental), the greater the energy inputs and the less favorable the EROEI.

The truth is that all along there has been a simple way to test the claim of agribusiness and the ethanol industry that they produce more energy than they consume.

The US Patent Office Test

Since its inception, the US Patent Office (USPO) has received a steady stream of patent applications for perpetual motion machines -- machines that theri inventors claim will produce more energy than it consumes.

As part of their patent review process, the USPO sometmes asks a board of esteemed scientists to evaluate claims for inventions that sound too good to be true. Very early in its history, those scientists recommended to the USPO a simple test for all of the perpetual motion machine patent applications: Ask the inventor to connect the output of the machine to the input and see if it keeps running.

So that's what the USPO did. Ever since, when they receive an application for a supposed perpetual motion machine, they ask the inventor to, "Please connect the output to the input and let's see if it keeps running."

The inventors who understand the Second Law of Thermodynamics turn and walk away knowing they can't pass the test. Others who are more naive, do as the USPO asks, and then walk away after their machines sputter to a stop and the USPO patent reviewer smiles and waves goodbye.

To this day, the USPO has issued no patents for a perpetual motion machine.

A Question and a Proposal

That raised my curiosity: Why has no one in a position of power to hand out tax credits, subsidies, mandates, and pass protective tariffs ever asked the ethanol industry to pass the "Please connect the output to the input and let's see how long it keeps running." test?

Wouldn't it be nice if before Congress passes the next Farm and Energy Bills they asked agribusiness and the ethanol industry to step up to the plate and demonstrate they can connect the output of the ethanol production cycle to the input and keep running?

WHy has no one asked the ethanol industry to show they can provide all the energy an industrial corn farm and ethanol plant needs, using only the ethanol the plant produces? (When I say all, I mean all: Everything from powering all farm equipment; to supplying the energy to grow and harvest the seed corn; to using ethanol as the feedstock and energy source for the nitrogen fertilizers they need; to using ethanol as the feedstock for for the pesticides, herbicides, and fungicides essential to industrial corn farming; to providing the energy for cultivation, harvesting, and transporting the corn; using ethanol to dry the corn if necessary; and of course using ethanol as the sole energy source at the ethanol plant to mill, ferment, and distill the corn and reform it into ethanol.)

I certainly don't propose that as a working business model -- we all know ethanol is too expensive for farmers and ethanol plants to use routinely as their energy source. But if the energy studies the ethanol industry likes to cite are true, they should be able to do it as a demonstration.

Making the ethanol industry perform that test by asking them that simple question would settle the three decades long debate of whether making ethanol consumes more energy than it consumes.

What I'd like to ask the ethanol industry is why they have never done their own demonstration to prove they can connect the output to the input?"

If the ethanol barons really felt deep in their hearts they could pass that test, wouldn't they have done that long ago just to silence the naysayers? (Of course they would have.)

I can tell you my suspicions on why they will never voluntarily attemp the connect the output to the input test: They know if they tried and it failed, their industry would be turned on its head, and I suspect they must secretly understand they couldn't pass.

Instead, they would rather wave around paper studies from the USDA and the Argonne National Lab. Studies that may or may not be correct, but that they are afraid to try and substantiate.

Write your Congressperson

Please take the time to write your representative and senator and ask them to make agribusiness and the ethanol industry pass the USPO test before sending any more money their way:

Please connect the output to the input and let's see how long it keeps running.

by Gary Dikkers at 9:28 PM on 16 Jan 2007

Energy and Net CO2

South Dakota State University last week presented an analysis that showed that using the farm ground in eastern South Dakota for corn ethanol requires that at least 45% by weight of the corn be returned to soil in order to not deplete the soil in order to keep the energy balance positive by not requiring excessive nitrogen for fertilizer and in order to maintain the CO2 storage level that soil has historically maintained. This 45% figure can vary considerably depending upon the nature of the soil and rainfall. Areas with less rainfall will require more of the corn be left in the field. That part of the state gets about 18 inches of rain a year.

I have not seen the report as it was just presented at a conference last week. The University of Minnesota Cedar Creek research facility has done similar work and has shown the importance of leaving significant amounts of the plant matter in the field and that the energy balance requires responsible management in order to keep it positive.

I suspect that regulation will be required in order to keep production levels at substainable levels and avoid over farming.

by ffletcher at 11:36 PM on 16 Jan 2007

Great comments

I agree that corn-based ethanol's EROI is so paltry even in the USDA's rosy view that it should be scrapped, since it can never seriously offset energy-rich gasoline.

But, a positive net energy balance is a powerful rhetorical tool, and a case could be made that combined with serious conservation (and not, say, a bunch of flex-fuel Hummers) that a fuel with an EROI of 1.6 has a place in a broad mix of alternatives,

However, a fuel with an EROI of 0.8 has no place at all and clearly should be scrapped.

That's why i think it's important info that Pimentel may well be right, after all. Yes, Gary Dikkers, the discrepancy between Pimentel and USDA do involve boundary definitions, but Pimentel's critics has for years now been trying to discredit him by claiming his data is inaccurate (an altogether different charge). Well, is it or isn't it? The MIT study does not make this claim.

Furthermore, the reason I ended my post with the "fresh look at Pimentel's work" line is this (and I should have made it explicit): The guy claims that cellulosic ethanol's EROI is "even worse" than the corn-based stuff.

Whoa! If that's true, then we're really hurtling down the path of folly. Lester Brown says switchgrass-based ethanol has an EROI of 4; Pimentel says its less than 0.8.

Gar, GreenEngineer, JMG--what do ya'll think?

Victual Reality

by Tom Philpott at 6:04 AM on 17 Jan 2007

Please excuse...

... the egregious typos above; I shouldn't try to write before coffee.

Victual Reality

by Tom Philpott at 6:06 AM on 17 Jan 2007

Great!

Bust switchgrass too.

It is nice to see universities noticing the soil depletion of chemical agriculture. But maintaining the soil is not enough. It is in a very sad state right now. A drought year or two and a huge dustbowl is about to form, one laced with toxic ag chemicals this time around.

Farm land should be built up with organic agriculture, it sequesters cO2. And conservation reserve land ought to be storing 1.8 tons of cO2 per acre per year with natural prairie grasses (a Minnesota university study confirms this figure)rather than growing switchgrass for fueling gas guzzling ICE vehicles.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

by amazingdrx at 7:35 AM on 17 Jan 2007

ADVERTISING POLICY

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