Archive for EROEI

Good Ethanol

I wrote a blog a couple months back talking about how environmentalists should avoid lumping all ethanol together as “bad” renewable energy because the Energy Return on Energy Investment (EROEI) is very low.  First of all, new ethanol plants being built today do have a net energy gain on a well-to-wheels basis (the critics are using decade old data), and so long as the energy inputs come from renewable sources, ethanol looks like a decent way to turn other forms of renewable heat energy into something we can put into our tank and drive around with.

E3 Biofuels is doing just that with a 25 million gallon “closed loop” ethanol plant in Mead Nebraska.  The distiller’s grain byproduct of the ethanol production is fed to cattle at an adjacent feedlot.  This saves energy by avoiding having to dry the grain and transport it to where the cattle are.  The manure from the feedlot is passed into an anaerobic digester which not only produces 100% of the energy necessary for the ethanol distillation process in the form of methane, but it also helps solve the nasty environmental problems caused by the massive supply of manure feedlots produce.  It was runoff from cattle manure that caused the problems with our spinach supply recently.

Other benefits are that by running the manure through the digester, odor is reduced, and methane from the manure decomposition does not escape into the atmosphere.  Methane is a much more potent greenhouse gas than is CO2.

If you believe the promoters that “This plant will make ethanol more than twice as energy-efficient as any other method of producing ethanol or gasoline,” I estimate that the well-to-wheels EROEI is between 2 and 4 (probably closer to 2.)  It’s not the great EROEI’s we get from Wind and geothermal, but it’s a liquid fuel we can use in our existing vehicle fleet (either as E85 in Flex-Fuel vehicles, or as E10 or E20 in standard gasoline engines.)

Without liquid fuel, we’re in great danger of economic disruption due to peak oil, but unless we get that liquid fuel in a manner less carbon intensive than conventional corn ethanol, we’ll be up to our ears in melted icecaps.

Obviously, what we really need is much more energy-efficient cellulosic ethanol which does not compete with our food supply for feedstock, and it will be great if that process is powered by renewable heat (methane form digesters, or solar thermal) but given that we’re unlikely to stop eating beef anytime soon, this is an elegant, closed process.

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There’s Ethanol and then there’s Ethanol

In the renewable energy community, Ethanol has a bad rap, due to some often-quoted, seldom checked studies on energy payback.

It’s received wisdom that ethanol from corn has an energy return on energy invested (EROEI) of somewhere between 0.8 and 1.0; i.e. you get less out than you put in.  The persistence of this idea is possibly due to some great cartoons.  I’m probably going to undermine my whole argument here, by including this one…

Then again, I expect that my audience is highly intelligent, and not easily distracted.  If you weren’t, you probably wouldn’t still be reading my extremely dense and often-tortured prose.  You deserve a good cartoon every now and then…

Back in the world of ethanol, times have changed.

Even though cellulosic ethanol is still very much in its technological infancy, a lot of companies and people are doing a lot of interesting things with corn ethanol to make the process more efficient, and, get those energy inputs in the form of “free” waste heat from some other process, or from renewable sources such as cow manure or landfill gas.

I’ve been educating myself a lot about this reading C. Scott Miller’s Bioconversion blog.  I admit I’m having to do a lot of catch up on this, because I was one of those people who believed ethanol was a total government subsidized boondoggle until recently.

All that said, even at an EROEI of 1.25 to 1.8, ethanol is not much of an energy “source.”  Sure, we’re getting a little energy out of the process, but one way to think about EROEI is how much effort it takes to get our energy. 

As a rough illustration, at an EREOI of 2, there has to be one person working to get energy for every person doing something else.  So if civilization were to exist one out of every 2 people would have to be employed in the energy sector… the other 50% would then have the energy they needed to do other useful things, like be doctors, politicians, soldiers, engineers, builders, investment advisers, bloggers, artists, manufacturers, scientists, psychologists, food farmers (as opposed to energy farmers), talk show hosts, etc.

 You might argue that some of those professions aren’t very useful (investment advisors and politicians perhaps), but even if we eliminate all those “useless” professions, I think the more useful professions like talk show hosts and artists might start finding themselves a little squeezed.

There is a reason that the human race was 95%+ farmers or hunter gatherers for most of of our history: the energy sources we were using were not powerful enough, with too low EROEI to sustain higher forms of civilization, such as talk show hosts.

If you don’t believe me, read this great article on “Peak Wood,” the cause of the iron age.

Back to ethanol: it’s not going to solve our world energy problem.  It’s a useful way to turn non-liquid fuels (manure, biogas, or coal) into something you can put in your car, but if we in the U.S. are  looking for a domestic source of energy that will wean us off the Middle Eastern oil teat, we can do it, only if we want to be a nation of farmers, witha much smaller population and lower standard of living than we have now.

Ethanol is big business these days, and it will make a tiny dent in our oil addiction, so all the investment is probably doing some good.  I predict that the biggest beneficiaries will be the farmers, and considering how hard farming is, that’s not a bad thing.  It’s probably better than out-and-out farming subsidies.

Basically, I’m no longer worked up about ethanol subsidies and mandates.  There are a ton of better ways we could be spending the money, but it’s hardly the stupidest thing our government does with our money.   I’d even be happy about it if they’d simply replace the money spent on all farm subsidies with subsidies for farm based energy.

I just don’t want it to distract from the important work we have to do to deal with the twin probems of peak oil and global warming:

  1. Improve energy efficiency (especially of our vehicle fleet.)
  2. Develop high ERoEI energy technologies: Wind, Solar concentrating, Geothermal.  PV will probably make it on this list as the technology improves.
  3. Displace some of that oil in transport with renewable electricity, via plug-in hybrids.  (Economic fuel cells are still too far away to make hydrogen a viable transportation fuel in the next 20 years)

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John Turner’s Renewable Energy Future; renewable technologies compared.

When you want an informed, but unbiased opinion, it’s usually best to ask someone John A Turnerwhose livelihood does not depend on coming back with the “right” answer.  When it comes to comparing different renewable energy technologies, one of the best experts I’ve heard from is John Turner.   Dr. Turner is a principal scientist for the Center for Electric & Hydrogen Technologies & Systems at the National Renewable Energy Laboratory (NREL), in Golden, Colorado.

The Hydrogen economy is that long hoped for world in which one day our cars will fill up at the corner hydrogen station, and combine that fuel with oxygen in the air, a process which will create electricity for the car’s motor, and with the only emissions being water.  It all sounds wonderful, but to reach that nirvana of zero emissions, the hydrogen itself needs to be produced with non-emitting technology.  That is because, contrary to oversimplified hype from politicians, hydrogen is not an energy source, but rather an energy carrier.  Like a battery, it has to be produced (charged) before it can be used.

Dr. Turner’s goal is to guide us to the hydrogen economy with as few missteps as possible, with missteps in his mind being the used of unsustainable technologies to get there.  Since he wrote his visionary 1999 article in Science, outlining a path to a “Renewable Energy Future” in which hydrogen serves as portable energy storage for an economy fueled solely by renewable sources of power.  The weak link in this chain is fuel cell technology.  Fuel cells are used to efficiently convert hydrogen and oxygen to electricity and water.  They have been around for well over a century, but are still too expensive for use in cars, although they are practical in some military and larger scale civilian operations.  A similar problem exists for hydrogen storage.

In contrast, hydrogen as a storage medium for electricity from intermittent power sources such as wind is a technology whose time has come. Norsk Hydro is currently doing a trial run of a wind/hydrogen combination system on a small Norwegian island, powering 10 homes.

What is most interesting to me about his presentation, is his unbiased comparison of different renewable technologies, along with nuclear, and Internal Gasification Coal Combustion (IGCC) with carbon sequestration.

He compares these technologies for robustness: the ability to meet our future energy needs; for expense, and for Energy Payback.  Energy payback and the related measure EREOI (Energy Return on Energy Invested) give us an idea of how much of our energy will have to be devoted to making more energy.

Here’s the run-down (with some additions of my own):

Technology

Energy Payback/ EROEI Robust? Price per kWh (approximate 2003 prices) Long term?
Wind

3-4 months; 20-30x

Yes

5-8 cents

Yes

Solar PV

3-4 years; 8x

Very

21-24 cents

Yes

Concentrating Solar

5 months; 40x

Very

8 cents

Yes

Biomass

varies

No

7 cents

Yes

Geothermal

varies by source

No

4-7 cents

Yes

Nuclear

1 year, not counting waste disposal. <20x

Yes

13-18 cents

?

Coal (w/ carbon sequestration)

16% of energy required for sequestration.

For now

5-6 cents

70 yrs, at current growth rates.

Energy efficiency

months; 50x +

Can never get all energy from efficiency

1-2 cents

Yes

(Items with links are from linked sources)

We’ll need all these energy sources, but Wind and concentrating Solar (CSP) stand out as near-term, robust, economical solutions, while Energy Efficiency and Geothermal will give us the most bang for our buck as we try to get started down the road.

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Ethanol vs. Biodiesel

A new study from the university of Minnesota comparing the lifecycle energy costs and emissions of corn ethanol to soy biodiesel is all over the press this morning. 

The results are no surprise to any of us who follow the industry: corn ethanol yields 25% more energy than it takes to produce it; while soy biodiesel yields 93% more.

The numbers for ethanol ar not new: people have been arguing about the EROEI (Energy Return on Energy Invested) for ethanol for years, and the numbers have slowly risen with improving technology from about -10% to today’s 25%.  What are new, are the EREOI numbers for soy biodiesel.  I had only heard one number for the EREOI of “biodiesel” before – and no mention of the feedstock was made, nor was I able to trace it back to a reputable source… I suspect it was a back of the envelope calculation by a biodiesel advocate.  That number was a 220% return, quoted to me twice, once by management at Blue Sun Biodiesel, and once by the person manning the booth for the International Center for Appropriate and Sustainable Technology, both of whom do good work, but who have an incentive to believe this highest number they hear.  Disclaimer: I too have an incentive to believe the highest number I hear because I have a Jeep that I use biodiesel in to minimize my carbon emissions.   Using the new numbers, my Jeep Liberty has about the same carbon footprint as my 2002 Prius, when running on B100.  On B20, which I use in the winter, the Prius still looks much better.   I’m pining for a plug-in hybrid diesel.

But I’m very happy to see reality injected into the whole biofuels debate.  Neither ethanol not biodiesel (nor both together) is going to save the US from having to import petroleum: if our entire corn and soybean output were shifted to these biofuels, that would only replace about 12% of gasoline demand, and 6% of diesel demand… are we ready to start talking about massively investing in increasing the efficiency of our vehicles yet?

One other new note in the article, which I like given my affection for biodiesel, is that soy is a much less fertiliser intensive crop than corn, and so growing it has fewer local environmental impacts. I hope these authors continue their work, and expand the study to include other feedstocks for both ethanol (sugarcane, cellulostic) and biodiesel (canola, algae, recycled oil).

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