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Report: Coal-Powered Ethanol Plant CO2 Emissions 92% Higher than Gas-Powered

Des Moines Register. A report by Frontline BioEnergy in Ames, Iowa concludes that ethanol plants powered by coal release as much as 92% more carbon dioxide than those powered by natural gas.

The City Council of Des Moines, Iowa, is trying to decide between two competing proposals for a $200-million, 100 million gallon per year ethanol plant—one powered by coal, the other by natural gas—and is currently divided on which project to select. The report now goes into the decision mix.

Frontline’s analysis of a plant that would produce 50 million gallons of ethanol a year show a coal-powered facility would release as much as 207,000 tons of carbon dioxide a year while a natural gas-powered plant would emit 108,000 tons.

Des Moines’ proposed plants would produce at least 100 million gallons of ethanol a year. That means that the coal-powered plant would release as much as 414,000 tons of carbon dioxide a year, according to the report.

Frontline BioEnergy is a biomass gasification company. The company is currently working with researchers from Iowa State University to optimize a gasification process for the production of producer gas from biomass to replace the use of natural gas in ethanol plants. (Earlier post.)

Some backers of the coal-powered plant believe Lincolnway’s plan holds the most potential of someday using renewable energy sources such as switchgrass to power the plant. Some supporters of using coal also believe the large amount of natural gas used by ethanol plants could drive heating costs up for thousands of Des Moines-area families.

“This is about the future,” [Mayor] Cownie said Friday, noting that the city will use an independent consultant to evaluate the proposals before the Dec. 4 vote. “We all want to do the right thing.”


Rafael Seidl

I hope they factor in the risk of future legislation effectively mandating carbon sequestration for just about anything based on coal. Ignoring this risk would be penny-wise and pound-foolish.

Biomass gasification is a viable process for rural municipalities. It may make more sense to focus on GHG neutral electricity production from locally produced fuel than on ethanol production for E85. What matters is the aggregate GHG production, not the source.

The City Council in Des Moines might want to study the example of the town of Guessing in Austria.

Sid Hoffman

This shows the weakness of ethanol. If it really was as net energy positive as the claims are, they could self-power the plant, for example, use a few percent of the ethanol produced to power the plant for the ethanol extraction.


They can use corn stover for heat in the process. Bring the corn and the stalks to the same location. If they gasify the stover they could sell the energy products on the market as well...and all this would be CO2 neutral.




What is the point of using natural ga to produce ethanol, and then use ethanol to power vehicles? Is it not much simpler and cheaper to use directly natural gas to power vehicles? The technology is available since the '50s, and any gasoline-powered vehicle can be converted to nanatural gas at a quite reasonable cost.


I agree Max, it does not make much sense. In the U.S. we do not have an NG distribution network at fueling stations, so people would have to fill up in their garages. The utility of cars includes taking them on longer trips where they can fill up anywhere and ethanol does that.

tom deplume

Having just moved to a small town in iowa I can tell you that nat gas for cars won't work out here. What you see all over are propane tanks for home heating. Less than a mile from me is the site of a new biodiesel refinery.
Fueling a car at home raises the problem of fuel tax collection. It is easy to collect those taxes at the fuel pump.


Citroen and Gaz de France are testing a way to fill up the gas tank at home. In practice is a compressor. In winter it should be possible to use waste heat for gome heating.

As far as tax collection is concerned I trust the ingenuity of taxmen :-)


Starting with natural gas as a feedstock, what is the most efficient way of getting it to power a car ?
Compressed or converted into some other fuel -
If converted, why pick ethanol ?

Perhaps the group could suggest something better.
Rafael ???

Rafael Seidl

Mahonj -

direct use as CNG is the most energy-efficient option. It's most attractive for larger vehicles that can more easily accommodate the bulky tanks, e.g. city buses for which tailpipe emissions are a key concern. More general use of CNG is interesting mostly in those countries that have significant domestic reserves of natural gas and/or NG is taxed much more lightly than gasoline or diesel.

The picture might change a little bit if someone were to come up with a pick-up or truck-based SUV design in which the tanks double as structural members. If, big IF, the regulators permitted its use in on-road vehicles.

Wrt the ethanol plant in Des Moines: due in part to EPA's decision to withdraw its legal backing for MTBE as an oxygenate, demand for ethanol has gone through the roof and the town is looking at a potential employer and corporate taxpayer. Of course, mixing ethanol derived from fossil fuels into E85 is a total crock but as they say: you can fool some of the people all of the time, and those are the ones you want.

Max Reid

Natural gas can be used directly and there are 5 million + CNG vehicles in the World today.

Since Coal is cheaper, Coal based Ethanol will be able to compete easily with gasolene.


NG can be compressed to CNG or made into methanol. Cars can run on methanol and have in many trials, but ethanol has won out so far. The Phill device that Honda has for their Civic natural gas car is made by another company and compresses enough NG overnight to take the car 200 miles.


"..optimize a gasification process for the production of producer gas from biomass to replace the use of natural gas in ethanol plants."

Now this is the right idea, even though the earlier post indicates a very odd bit of research involved. Just gasify the stover..a proven method.

Rick Thurman

A couple of ideas for making any thermal process for producing a chemical fuel suitable for use in today's car fleet (which is, after all, the point of using ethanol):

1. Iowa is also home of a lot of windfarms so far, with most of the electric production coming in fall, winter, and spring. If I remember correctly, a 50 million gal/yr facility could use around 20 MegaWatts to power it, when the wind is available. What size windfarm would produce sufficient electric power to cut the chemfuel requirements down to size?

2. A previously proposed windfarm project in Iowa included a CAES (Compressed Air Energy Storage) facility; in other words, when the windfarm produced too much electricity, the excess would power compressors that would pump air into a sealed-up old mine. When electric power was needed, the compressed air would be let out through regular gas-fired turbines, which would provide two-thirds of the turning power needed by the turbine generators; the rest would be provided by the thermal fuel (natural gas, biogas, or what have you).

3. A Toronto company has a hydrogen-fuel injection process for increasing the fuel-efficiency of any combustion process for any fuel. So far, they have concentrated on after-market installs on diesel trucks for the over-the-road market. They guarantee a 10 per cent increase in efficiency and power, but more may be possible. It doesn't sound like there should be any problem in using this style of "after-burner" on either gas- or coal-fueled heaters for ethanol production. For that matter, it sounds like it should work equally well on gas and coal-fired electric geneation plants.

If you use wind when available for electricity, then biogas-fired electricity when the wind is lower (with both CAES-assistance and hydrogen-fuel-injection), how low can you take the CO2 production?

One step further... not now, but with further research...
algae-based oil production is still in the research stages. That typically mentions bubbling CO2 from coal-fired electric generation plants through water (coolant from the plant, still pretty warm) via clear panels exposed to sunlight. Algae in the water in the panels (specially selected varieties) produce oil. When harvested from the water, the oil can be processed (with methanol or ethanol) to produce biodiesel. So...
any CO2 from the thermal-heaters, plus CO2 from the fermentation process (a major ethanol by-product) could be further processed with some of the ethanol to make biodiesel. This could be especially attractive to Midwestern ethanol producers, since most of the farmers, truckers, etc most closely associated with these plants use diesel in their workaday vehicles. The Iowa economy needs biodiesel as much, maybe more, than it needs gasoline substitutes. Last time I checked, diesel is more expensive than gasoline anyway.

Rick Thurman

One take currently being developed on biogas: a Texas-based company is building a couple of ethanol plants next door to cattle feedlots. They feed the post-ethanol distiller's grain to the livestock, then take back the manure produced thereby to get the methane by fermentation. I don't know how big of a feedlot operation is needed to balance with a plan for a 50 million gal/yr ethanol operation.


I say just burn all the coal in open pits and forget about the environment. Why bother with the P.R. bull on this coal project. In reality this with CCS would just make the ethanol a carrier fuel. That would be OK.



This is a great project. And it is just initial step to utilize synergy of food/fuel production.

Cow manure should be composted or digested in order to be used as organic fertilizer any way. In that respect collection of biogas from manure anaerobic digestion is pure surplus. Due to high nitrogen/carbon ratio of manure, anaerobic digestion is severely suppressed. This problem could be solved by addition of high C/N ratio plant residue – agricultural waste. It does not require future break-through technology as for cellulosic ethanol, anaerobic microorganisms eat plant biomass fiercely right now. Speed and yield of anaerobic digestion per unit of volume of digester could be tripled this way. Excess of biogas (close to 65% methane, 35% CO2, and some H2S – by volume) could be directly used in lean-burn diesel generators to generate electricity with very high thermal efficiency of about 38%. Additional CO2 effectively serves as cooled EGR, and as a result emissions of NOx are very low. For medium-size electricity generation lean-burn gaseous fuel diesel generators are the cheapest technology currently possible. Such technology is widely utilized on sewage treatment plants.

High-temperature exhaust (with some portion of biogas burning to increase temperature beyond sulfuric acid dew point after heat exchanger) could be used for distillation of bioethanol, and further after dry desulphurization to heat-up anaerobic digesters. If temperature of digester is raised from 35C (mesophilic digestion) to 55C (thermophilic digestion), productivity of digester is doubled further. Excess of biogas could be washed from CO2 and fed into local NG system.

Now, anaerobic digestion produces highly concentrated pumpable organic fertilizer – anaerobic process retain all nitrogen and other nutrients, unlike aerobic composting. This fertilizer will be used on adjacent fields.

High concentration stream of CO2 is potential candidate for purification and sale. Excess of CO2 could be fed to adjacent hot houses for carbon fertilization of the grown vegetables. Currently most greenhouses use ridiculously wasteful practice of burning NG, cooling exhaust, and feeding it to greenhouse to maximize the yield. Note, that due to controlled environment hot house production is free from pesticides and herbicides. It could be fertilized from the anaerobic digestors, and could return waste biomass back to digestion.

All in all, the system could involve into near closed loop system (with energy of sun as major contributor), with yield of meat, milk, near organic vegetables and crops, electricity, NG, and biofuels. With minimal addition of synthetic fertilizers and energy, if any.

Emerging technologies, such as cellulosic ethanol, biobutanol (having very beneficial synergy if blended with ethanol for use as gasoline additive), CO2 enhanced algae ponds, biodiesel fuel feedstock extraction from corn used for ethanol production, tallow conversion to biodiesel, etc., could add to the complex additional benefits and flexibility.

I believe that such incredibly beneficial for farmer’s communities industrial/agricultural complexes are way more efficient and promising way to spend money then for fashionable BS such as corn E85, pure organic farming, or geological carbon sequestration.



One of the interesting things about alternative energy sources and green vehicles is the multidisciplinary nature of the technology (EE, ME, ChemE, and now AgE). It's interesting that the largest agribusiness in the Pacific Northwest is JR Simplot, which was progressive enough to fund Micron Technology. If there's a profit to be made in energy technology agribusinesses will do it -- a hopeful sign. Some tax credits for early developers could jump start investment. Thanks for the detailed post.


Would it make sense to use the waste heat from a conventional, coal fired power plant, to boost efficiency of an ethanol producing plant, which could use biomass as feedstock?


Sure, but you would have to locate the ethanol plant hear the power plant and haul the corn. It might not be practical. However, using the corn stalks as a heat source might make sense. If you have to get the corn to the ethanol plant you could also get the corn stalks there.

P Schager

With friends like these, why does the ethanol industry need enemies? That is, assuming it isn't in fact renewables' enemies behind this, in key measure. I can tell you right now that out here in California where the customers are, when people hear of ethanol being made using coal (spewing mercury, SOX, NOX, thorium etc.) they are going to ask why don't we redirect the money and cut out the farmer.

Assuming tons not tonnes that's 8.28 lbs CO2/gallon of ethanol; CO2 positive, but not by a lot. Coal-to-liquids is more likely to have the pollutants removed, even CO2.

A plant with a coal heater can have it replaced in the future, but one with a natural gas heater can't? That's the marketing you need in order to slip through a coal plant. But natural gas isn't that much better, since we're running out and when we have to depend on imports we'll need to change again.

Using any kind of fossil fuel to inefficiently distill ethanol is an obscenity. You don't need the high-temperature heat that fossil fuel is good for. You only need a temperature rise of a few tens of degress C, and that is easily achieved by several more benign methods. Easy solar, cogeneration, process by-product heat, other fuel synthesis byproduct heat, heat pump heat, geothermal, or combinations thereof.

Why is it that people in India seem to know what they're doing, but Americans don't? Solar ponds work, and are a cheap solution.

The best solution would be set up a PV farm next to this thing using cheap solar cells, probably with concentrators and let them heat up a bit, liquid cool them and use the 'losses' to distill the ethanol. Solar cell efficiency goes down maybe 12% (low pressure distillation at 50 C) but the free heat should be worth it. Use a giant heat tank so you can distill around the clock. The cells'll be cheap soon. Less than 1% of the land needed to grow the corn, and the electricity is probably worth more than the ethanol.

The only way to save the renewable industry from pre-obsolete solutions is to institute a 'virtual carbon tax' that subtracts from their subsidies if they are emitting carbon in the process as if the carbon tax were already here. Otherwise when we finally get the tax we will have to start all over.


Ethanol distallation can be accomplished with relatively low temperatures. I'm thinking cogeneration. Given sufficient vaccuum, even solar energy.

My technical fantasy is converting my washing machine into a fermenter, throw in some grass clippings and a cup of enzymes and start brewing. Then violate several ATF laws and distill my own fuel-grade ethanol.

Cheryl Ho

There are developments in DME in China:

Currently, the market trend today is such that many Chinese coal chemical companies are moving towards optimising low cost and abundant coal feedstock for expansion into DME production.

If you would like to know more on COAL to Syngas to DME developments, join us at upcoming North Asia DME / Methanol conference in Beijing, 27-28 June 2007, St Regis Hotel. The conference covers key areas which include:

DME productivity can be much higher especially if
country energy policies makes an effort comparable to
that invested in increasing supply.
National Development Reform Commission NDRC
Ministry of Energy for Mongolia

Production of DME/ Methanol through biomass
gasification could potentially be commercialized
Shandong University completed Pilot plant in Jinan and
will be sharing their experience.

Advances in conversion technologies are readily
available and offer exciting potential of DME as a
chemical feedstock
By: Kogas, Lurgi and Haldor Topsoe

Available project finance supports the investments
that DME/ Methanol can play a large energy supply role
By: International Finance Corporation

For more information:,


iowa can suck my balls iowa sucks we don't even have a pro football team!

Prajith damodar

How can convert Biogas to electricity in cheaper method .
I hav a biogas plant hav a capacity of 4 metre cube.

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