Barriers to cellulosic ethanol according to the DOE

[GliderGuider]

The list below is excerpted from the exceptionally thorough article on biofuels by Alice Friedemann, entitled Peak Soil: Why cellulosic ethanol, biofuels are unsustainable and a threat to America. The article was posted here last Wednesday by NoMoreMyths. I just finished reading it. I found it a thought provoking look past the faith-based, sound-bite-driven spin on biofuels in general and cellulosic ethanol in particular. The part that I found most sobering was her list in an Appendix of the hurdles identified by the US Department of Energy as still facing the deployment of biofuels. If the barriers are as formidable as they appear, then there's a good chance cellulosic ethanol may not come riding over the horizon to save the corn fields.

Department of Energy Biofuel Roadmap Barriers

This is a partial summary of biofuel barriers from Department of Energy. Unless otherwise footnoted, the problems with biomass fuel production are from the Multi Year Program Plan DOE Biomass Plan or Roadmap for Agriculture Biomass Feedstock Supply in the United States. (DOE Biomass Plan, DOE Feedstock Roadmap).

Resource and Sustainability Barriers

1) Biomass feedstock will ultimately be limited by finite amounts of land and water

2) Biomass production may not be sustainable because of impacts on soil compaction, erosion, carbon, and nutrition.

3) Nor is it clear that perennial energy crops are sustainable, since not enough is known about their water and fertilizer needs, harvesting impacts on the soil, etc.

4) Farmers are concerned about the long-term effects on soil, crop productivity, and the return on investment when collecting residues.

5) The effects of biomass feedstock production on water flows and water quality are unknown

6) The risks of impact on biodiversity and public lands haven’t been assessed.

Economic Barriers

1) Biomass can’t compete economically with fossil fuels in transportation, chemicals, or electrical generation.

2) There aren’t any credible data on price, location, quality and quantity of biomass.

3) Genetically-modified energy crops worry investors because they may create risks to native populations of related species and affect the value of the grain.

4) Biomass is inherently more expensive than fossil fuel refineries because:

a) Biomass is of such low density that it can’t be transported over large distances economically. Yet analysis has shown that biorefineries need to be large to be economically attractive – it will be difficult to find enough biomass close to the refinery to be delivered economically.

b) Biomass feedstock amounts are unpredictable since unknown quantities will be lost to extreme weather, sold to non-biofuel businesses, rot or combust in storage, or by used by farmers to improve their soil.

c) Ethanol can’t be delivered in pipelines due to likely water contamination. Delivery by truck, barge, and rail is more expensive. Ethanol is a hazardous commodity which adds to its transportation cost and handling.

d) Biomass varies so widely in physical and chemical composition, size, shape, moisture levels, and density that it’s difficult and expensive to supply, store, and process.

e) The capital and operating costs are high to bale, stack, palletize, and transport residues

f) Biomass is more geographically dispersed, and in much more ecologically sensitive areas than fossil resources.

g) The synthesis gas produced has potentially higher levels of tars and particulates than fossil fuels.

h) Biomass plants can’t benefit from the same large-scale cost savings of oil refineries because biomass is too dispersed and of low density.

5) Consumers won’t buy ethanol because it costs more than gasoline and contains 34% less energy per gallon. Consumer reports wrote they got the lowest fuel mileage in recent years from ethanol due to its low energy content compared to gasoline, effectively making ethanol $3.99 per gallon. Worse yet, automakers are getting fuel-economy credits for every E85 burning vehicle they sell, which lowers the overall mileage of auto fleets, which increases the amount of oil used and lessens energy independence. (Consumer Reports)

Equipment and Storage Barriers

1) There are no harvesting machines to harvest the wide range of residue from different crops, or to selectively harvest components of corn stover.

2) Current biomass harvesting and collection methods can’t handle the many millions of tons of biomass that need to be collected.

3) How to store huge amounts of dry biomass hasn’t been figured out.

4) No one knows how to store and handle vast quantities of different kinds of wet biomass. You can lose it all since it’s prone to spoiling, rotting, and spontaneous combustion

Preprocessing Barriers

1) We don’t even know what the optimum properties of biomass to produce biofuels are, let alone have instruments to measure these unknown qualities.

2) Incoming biomass has impurities that have to be gotten out before grinding, compacting, and blending, or you may damage equipment and foul chemical and biological processes downstream.

3) Harvest season for crops can be so short that it will be difficult to find the time to harvest cellulosic biomass and pre-process and store a year of feedstock stably.

4) Cellulosic biomass needs to be pretreated so that it’s easier for enzymes to break down. Biomass has evolved for hundreds of millions of years to avoid chemical and biological degradation. How to overcome this reluctance isn’t well enough understood yet to design efficient and cost-effective pre-treatments.

5) Pretreatment reactors are made of expensive materials to resist acid and alkalis at high temperatures for long periods. Cheaper reactors or low acid/alkali biomass is needed.

6) To create value added products, ways to biologically, chemically, and mechanically split components off (fractionate) need to be figured out.

7) Corn mash needs to be thoroughly sterilized before microorganisms are added, or a bad batch may ensue. Bad batches pollute waterways if improperly disposed of. (Patzek Dec 2006).

Cellulosic Ethanol Showstoppers

1) The enzymes used in cellulosic biomass production are too expensive.

2) An enzyme that breaks down cellulose must be found that isn’t disabled by high heat or ethanol and other end-products, and other low cost enzymes for specific tasks in other processes are needed.

3) If these enzymes are found, then cheap methods to remove the impurities generated are needed. Impurities like acids, phenols, alkalis, and salts inhibit fermentation and can poison chemical catalysts.

4) Catalysts for hydrogenation, hydrgenolysis, dehydration, upgrading pyrolysis oils, and oxidation steps are essential to succeeding in producing chemicals, materials, and transportation fuels. These catalysts must be cheap, long-lasting, work well in fouled environments, and be 90% selective.

5) Ethanol production needs major improvements in finding robust organisms that utilize all sugars efficiently in impure environments.

6) Key to making the process economic are cheap, efficient fermentation organisms that can produce chemicals and materials. Wald writes that the bacteria scientists are trying to tame come from the guts of termites, and they’re much harder to domesticate than yeast was. Nor have we yet convinced "them to multiply inside the unfamiliar confines of a 2,000-gallon stainless-steel tank" or "control their activity in the industrial-scale quantities needed" (Wald 2007).

7) Efficient aerobic fermentation organisms to lower capital fermentation costs.

8) Fermentation organisms that can make 95% pure fermentation products.

9) Cheap ways of removing impurities generated in fermentation and other steps are essential since the costs now are far too high.

[Dogmudgeon]

1. Where's the Tribe?

The biofuel cheerleaders complain that there is a shortage of hard facts and sound science around here ... but when there is an excellent, informative piece posted, they don't even post in response to it.

Like nuclear power, biofuel has now become "tribalized". In just a few months, it has become impossible to discuss the uses and misuses of biofuels in most enviro/leftist circles. Considering the gravity of the crises that are gearing up, you'd think people would spend some time trying to discover whether they have forgotten anything before drawing their ideological lines in the sand.

Thanks for posting it. I haven't even seen the Friedemann article yet. I have a few days' reading to catch up on.

--p!

[jpak]

2. Gee, is that why the DOE is funding the development of 6 cellulosic ethanol plants??

http://www.doe.gov/news/4827.htm

Is that why the paper industry in Maine (and elsewhere) is developing wood ethanol biorefineries - that use xylans for ethanol feedstock and cellulose for paper and lignin for fuel and chemical feed stocks???

http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=115&topic_id=77997

Someone should tell them before it's too late.

And what about those three new wood pellet mills in Maine?? Maybe someone should tell them a thing or two while we're at it...

:evilgrin:

[NNadir]

3. Right now, biomass can do something few other systems can do,

fix atmospheric carbon dioxide.

Personally I think enzymatic methods suck, but pyrolysis methods involving waste biomass may have some utility. There are some excellent catalysts for these processes.

Thus one of the "ethanol showstoppers" is inappropriately placed:

Pyrolysis is not generally properly associated with enzymatic methods. They are different things more or less. In the pyrolysis case, one is producing syn gas (a mix of hydrogen and carbon oxides) and can make any of the traditional fuels including gasoline. There is no reason therefore to make ethanol, since the physical properties of ethanol are less than ideal as a fuel.

My pet favorite fuel is DME, which is under active development on an industrial scale in China and Japan and a few other places, regrettably from coal and natural gas. However the substitution of biomass, to the extent it is available is conceivable for producing some of this syngas. The Swedes have an extensively evaluated producing DME from wood. Their work in this regard seems to me to not be quite so "pie in the sky" as the ethanol industry. Clearly the potential for wood is limited, but on the other hand, it's hardly zero either.

DME is infinitely superior to ethanol, since its physical properties make its shipment by pipeline rather trivial. Existing infrastructure could be used in this case.

The link makes a point about nuclear aircraft development that is also misleading. It is worth noting that the exploration of nuclear aircraft lead to one of the greatest energy inventions ever, and one that the world will actively develop in the Gen IV nuclear program: The molten salt reactor. The reactor was abandoned out of government stupidity, but the experiments involved were so successful (though not for aircraft) that the idea is almost certain to be a major player in the future. This reactor design is rather remarkable I think. It will prove in the long run to be a real winner.

The separation of carbon dioxide from air can be industrially available in an equilibrium shift reaction that is a mimetic for the biological process. This may supplement or surpass biomass removal methods if there is a future, something that is now in doubt.