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New Life Cycle Study Concludes That Biomass for Ethanol Is Not the Most Advantageous Energy and Emissions Use of the Feedstock
8 October 2008
A new life cycle study assessing the benefit of cellulosic ethanol in the context of projected feedstock constraints concludes that in terms of reducing greenhouse emissions and fossil fuel dependency, more is lost than gained when prioritizing biomass or land for bioethanol, rather than for use in technology pathways involving heat and power production and/or biogas, or natural gas and electricity for transport. The study was published online in the journal Environmental Science & Technology on 4 October.
The study by researchers in Denmark begins with the conclusion that toward 2030, the amount of biomass which can become available for bioethanol or other energy uses will be physically and economically constrained, regardless of whether of global or a European perspective is applied. This implies that the use of biomass or land for bioethanol production will most likely happen at the expense of alternative uses.
Specifically, the study compares the use in transportation of cellulosic ethanol produced from whole-crop maize by fermentation in several process configurations to alternative use of the feedstock in heat and power applications fueled by coal or natural gas.
Among the scenarios investigated, the researchers found that using willow in CHP production combined with using electric cars for transport yields the highest GHG mitigation and reduction in oil dependency.
They also found that the optimal biogas scenario is for biogas to substitute for natural gas in heat and power production and to use the displaced natural gas to substitute for oil in the transport sector.
In terms of greenhouse gas emissions, the ethanol baseline scenarios provide by far the lowest net GHG mitigation compared to the alternative utilizations of land for energy purposes. For example, use of the land to produce willow used for combined heat and power in substitution for coal provides GHG mitigation more than twice and high, and even higher if combined with electric cars.
Even when using fodder byproduct as fuels, the ethanol scenarios are still compared to the alternatives. The researchers attributed the low net GHG mitigation in the ethanol scenarios to the considerable amounts of steam and electricity consumed in the process of converting biomass into ethanol, especially for pretreatment, hydrolysis, extract concentration, distillation, and drying processes.
Less energy is required for catalyzing anaerobic digestion in the biogas process, for the thermal gasification of willow, or for wood pellet manufacturing. Other factors contributing to the difference in GHG mitigation across the scenarios include the high CO2 content of coal, which results in large GHG mitigation when biomass is used to displace coal, and the high energy efficiency of electric motors compared to combustion engines.
The ethanol scenarios also provide a low net fossil fuel displacement compared to several of the alternative technology pathways. Up to 2.5 times as high oil savings can be obtained with the alternative energy crop utilization pathways, for example.
Overall, for the case presented, the reductions in GHG emissions and fossil fuel dependency, obtained by producing whole-crop maize for bioethanol production happens at the expense of other land/biomass utilizations, which would provide considerably larger reductions. Thus, for this technology case and perspective, more is lost than gained when prioritizing land/biomass for bioethanol.
This is mainly caused by the significant energy conversion losses in bioethanol production compared to use of biomass in the energy sector. The losses lie in the need for pretreatment (lignocellulosic based production), the relatively low fermentation yield of ethanol, the need to dry and further process the byproduct and residual unconverted matter in order to make use of them, and the need to separate ethanol and water, implying distillation in all known cases. Such losses are not present in alternative technologies, e.g., biomass conversion to electricity and/or heat by incineration or conversion to biogas.
As long as fermentation-based conversion of biomass to ethanol implies these losses, bioethanol will come out disadvantageous to the alternatives studied heres and this is the case for presently known bioethanol technologies including both starch and lignocellulose based production. Thus, the results question the assumed justification for lignocellulosic fermentation based bioethanol: instead of reductions in GHG emissions and fossil fuel dependency, net increases will much more likely be the outcome, when considering the alternative biomass/land utilizations deprived on behalf of bioethanol.
—Hedegaard et al. (2008)
Resources
Karsten Hedegaard, Kathrine A. Thyø, and Henrik Wenzel (2008) Life Cycle Assessment of an Advanced Bioethanol Technology in the Perspective of Constrained Biomass Availability. ASAP Environ. Sci. Technol., doi: 10.1021/es800358d
October 8, 2008 in Cellulosic ethanol, Emissions | Permalink | Comments (79) | TrackBack (0)
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Comments
While it's true that, in the loooong run, producing biogas is more efficient than ethanol, the U.S. is, Today, powering the equivalent of 20 Million automobiles with the 10.6 Billion Gallons of ethanol it's, presently, producing.
With Non-Opec having already peaked, and Opec being not far behind our primary challenge, Today, is fueling the 240 Million vehicles on the road, at present.
We'll probably "ease" into the biogas thing with "fleet vehicles," initially.
Posted by: Kum Dollison | Oct 8, 2008 9:01:32 AM
Could it be that in our desire to keep our oversized gas guzzlers running with bioethanol intead of fossil fuels we are, once again, taking the wrong path?
Partial, followed by complete electrification of our vehicles and HVAC with clean electricity seems to be the best route.
We do not need more risky expensive OIL wars and financial turmoils.
Let us investment instead, in new clean technologies to locally produce more clean electrical energy and to locally mass produce PHEVs, BEVs and fully electrified high efficiency HVAC systems for our homes.
There are no acceptable reasons why USA should have to import OIL, NG and Electricity after 2020.
It is time to wake up.
Posted by: HarveyD | Oct 8, 2008 9:08:09 AM
This is exactly the point I've been making all along. Extracting H2 and methane from waste biomass is the most efficient way to harness this renewable and storable source of energy. This energy supply is quite limited so one must make the most efficient use of it.
Convert the waste biomass into a dense and easily-transportable form, and then gasify this form into H2 only when demand arises at or near the site of H2 distribution. H2 in FC and in an H2-optimized ICE is far more efficient than current ICE SI technology. However, until the H2 economy will arrive, bio-methane can be used as a bridge or stop-gap solution in the current transportation sector.
Methanol synthezized from the gasified biomass would also be efficient, but it is too corrosive and toxic for mass utilization. Ethanol, whether from grains or cellulosic, should be reserved for human consumption! :)
Posted by: Roger Pham | Oct 8, 2008 9:10:23 AM
@ Roger Pham -
why bother with hydrogen at all? Compressed or adsorbed natural gas will do nicely for next few decades, especially in Europe and if biogas is used to produce heat and electricity.
Posted by: Rafael Seidl | Oct 8, 2008 9:44:32 AM
As a result of the above conclusion that ethanol is not the best choice to meet our energy needs, one might ask: Should we be sorry about all the effort that has gone into ethanol up to this time?
My answer is no, and I'll explain why:
During the 1990's, we were making extensive use of methyl tertiary butyl ether (MTBE) as an oxygenated gasoline additive, to meet regulatory requirements for a little combined oxygen in gasoline to reduce hydrocarbon and carbon monoxide emissions.
MTBE did the job well. It blended with gasoline very nicely, had a very good octane boosting effect, and didn't adversely affect Reid vapor pressure, which has a bearing on evaporative emissions.
Unfortunately mother nature threw a frustrating showstopper in our faces when MTBE started turning up in water wells and surface waters. So, it was back to square one. We needed an oxygenated compound to meet the requirement I described above, and also we needed an octane enhancer. The oil-automotive industrial complex was also under pressure to use renewable resources.
Enter ethanol. Since fermentation is a part of mother nature's scheme of things, she doesn't object to ethanol. And, it has good octane rating. Ethanol is less corrosive than methanol, and doesn't create (at least not to as great a degree) the problems you get when you blend methanol into gasoline.
Finally, unlike compressed natural gas, ethanol can be used without extensive modifications to existing automotive designs.
So all in all, ethanol was the best we could do up to now. Should we consider using compressed NG instead? Unquestionably. As natural gas engines tend to be less pollution-intensive than Diesel engines, we are seeing more use of CNG in buses and commercial vehicles. In 1983 I was at a Society of Automotive Engineers dinner meeting where the topic was Ford's natural gas pickup truck. Ford has since decided to emphasize hydrogen.
Given that natural gas doesn't require as high a storage pressure as hydrogen to get the same range, I hope it will be possible to attain whatever emissions reduction performance (especially nitrogen oxides but also other hydrocarbons, particulates, and carbon monoxide) we need, without having to resort to hydrogen.
Before I sign off I'd like to add that I hope we can improve the efficiency of processes to produce ethanol from biomass. Liquid fuels tend to be less of a packaging (i.e., space) problem than gaseous fuels, which have to be stored under high pressure. Perhaps the free market and not government arbitrarily choosing winners and losers, is the best way to determine what fuel is best for various applications.
Posted by: Alex Kovnat | Oct 8, 2008 10:08:25 AM
Well duh! This is such a no brainer I got to wonder why we're not doing this instead of going with ethanol... Oh wait, that's right, we've got leaders with no brains.
Posted by: ai_vin | Oct 8, 2008 10:15:56 AM
This study quantifies what I've said in the past. The most bang for the biomass buck comes from using it as a replacement for coal then using some of that electricity for EVs. Using biomass for IGCC is even better.
Posted by: tom deplume | Oct 8, 2008 10:44:48 AM
Hi Rafael,
Agree with you that adsorbed CNG will do nicely for the next few decades, that is, until FC technology and adsorbed H2 storage technology will be perfected and priced affordably, since FC promises nearly double the thermal efficiency of NG-ICE.
Posted by: Roger Pham | Oct 8, 2008 10:49:48 AM
Automakers really like ethanol because its dense (enough) and very easy to use with their existing technology (IC engines). Only about $50 more per care is needed to augment an existing car line to use E85.
I think range issues with PHEV-methane vehicles could be addressed by going tri-fuel and having a small E85 tank as well.
As with hydrogen, the automakers will avoid discomforting themselves if at all possible, even if it means pushing expensive, inefficient technologies up higher in the fuel production process.
I can see this inefficiency (at the expense of the consumers) being somewhat difficult to unwind in the near term. (Maybe Pickens should be supported to the extent that it serves this end?)
SOFCs using NG might make things more interesting as well.
Posted by: Jim | Oct 8, 2008 11:09:15 AM
"...assessing the benefit of cellulosic ethanol..."
"...ethanol produced from whole-crop maize by fermentation..."
Maybe I am misunderstanding, but the term "whole-crop maize" does not sound like cellulose ethanol.
"As long as fermentation-based conversion of biomass to ethanol implies these losses.."
They seem to mix things. There is grain fermentation and cellulose preparation and fermentation. As long as you go that route sure.
But if you gasify the cellulose biomass, you can make methane, methanol, ethanol or other hydrocarbons without fermentation.
Posted by: | Oct 8, 2008 11:28:31 AM
Keep in mind that NG is a petroleum-based business-as-usual scenario while cellulosic is entering the market via a wide variety of non-petroleum producers.
The old adage "Follow the money," applied here would indicate a pattern of oil and gas industries trying their damndest to limit entry of any non-petroleum energy resource.
The transition to non-fossil fuels is open to all offerings. And though NG and coal want to polish their image to be included in the "clean" energy cycle - the facts remain they are non-sustainable resources controlled by entrenched energy companies. Coal-bed methane wells in British Columbia are scarring pristine forest/valley habitat posing far greater environmental damage than the apparent difference in GHG release.
Ethanol has worked well in Brazil using cane feedstocks claiming 1:8 energy input. Coskata and Range Fuels and other entries in cellulosic from waste offer the real probability of low cost alternatives to fossils. Can we afford to nitpick efficiencies while petroleum pushes us into yet another energy monopoly? We think not.
Posted by: nrg nut | Oct 8, 2008 12:23:20 PM
@Alex
Thanks for the informative post.
“As a result of the above conclusion that ethanol is not the best choice ..”
Can you tell me what country the biomass is produced in from reading the LCA?
Posted by: Kit P | Oct 8, 2008 12:28:46 PM
@Kit P:
I can only speak from the perspective of the American experience. If the lead article was from Europe, maybe they have a different set of conditions. For example, they might not have as much of an issue with MTBE as we in America have. Also in Europe they have a higher percentage of Diesel cars, so bioDiesel might be a better option for them.
And then too, there are probably more natural gas vehicles, so biomethane might be a more logical choice for Europe than here in America.
There has been criticism of the American ethanol effort. One hopes that this was mainly due to the fact that first-generation ethanol plants were glorified whiskey stills, and that the most recent designs are more efficient.
We'll have to wait and see what happens with the cellulosic ethanol facilities now under construction. Novozyme seems to have a good handle on the enzymes issue involved with breaking down cellulose.
I've been interested in alternative fuels for over 30 years. At one time I was fascinated with the idea of gasoline and other liquid fuels from coal, but that may not be a good idea now that carbon dioxide has become such a hot issue.
Whatever, I'll keep reading Green Car Congress.
Posted by: Alex Kovnat | Oct 8, 2008 12:53:30 PM
I think you get about twice the fuel (energetically) when producing biogas (methane) from biomass compared with producing ethanol. And this doesn't take into account the added energies needing to produce ethanol (drying, distilling, etc.) so the overall disparity is probably even worse. The costs of the cellulosic ethanol production facility can't be discounted either. That said, a liquid fuel is much more convenient than a gaseous one.
Interesting for them to comment on burning biomass to produce electricity, which is then used in cars (I think that's what they meant). If burning biomass to make electricity is 30% efficient, then you are already beating the IC engine. The grid/transmission losses would be easily trumped by the processing and energy costs of the ethanol production.
Posted by: Jim | Oct 8, 2008 1:43:31 PM
If the lead article was from Europe, maybe they have a different set of conditions. For example, they might not have as much of an issue with MTBE as we in America have.Not using MTBE gets rid of the issue. MTBE was a response to a government demand for oxygenated fuels in the USA, not Europe.
Posted by: Reality Czech | Oct 8, 2008 2:07:49 PM
I agree that ethanol was and is an EXCELLENT replacement for MTBE, which was found to be too long-lasting when released into the environment.
MTBE (a chemical produced by the petroleum industry) was added to gasoline for cleaner emissions. American emissions standards have tended to be cleaner than European standards, which partly explains the lack of diesel engine penetration for autos in the U.S. After MTBE was found to be problematic, ethanol was used instead.
But it should be mentioned that there is big difference in 10% ethanol for emissions improvement, and 85% ethanol for the purposes of oil substitution. The economics of the two prospects, as well as the quantities involved, are completely different.
The fact that ethanol makes sense as a fuel additive doesn't mean it necessarily makes sense as a fuel substitute.
Posted by: Jim | Oct 8, 2008 2:26:47 PM
There is an interesting closed loop ethanol scheme using the methane from livestock manure to power grain -> ethanol production. The operation claims a 1:45 energy ratio.
http://www.e3biofuels.com/
Posted by: gr | Oct 8, 2008 2:27:04 PM
@Alex
I am astounded at the progress biofuels have made in the US in the last few years. However, there is a lack of LCA data using recent process numbers. Clearly, using biomass instead of oil for a district heating CHP is a winner when there is limited biomass like US and EU cities..
In the US we have lots more biomass than we have district heating. We will nominate ai_vin to live next to the power plant to save the planet.
The US is a very large and diverse country. There many many locations where different technologies would be the better choice.
Posted by: Kit P | Oct 8, 2008 3:26:58 PM
Not only biogas is more efficiently produced from biomass than ethanol but also it can be burned with a much better efficiency in an ICE thanks to very high octane index and gazeaous form, last but not least it is the least carboneous of all HC fuel and by fara the cleanest, what else can we ask ?? ha yes no complicated development since the process of methanisation is not new at all it can be produced at the farm then minimisation the transportation of biomass (prooblem that will plague the cellulosic ethanol) , but it requires a new infrastructe to transport an distribute that gas.
Posted by: Treehugger | Oct 8, 2008 6:50:25 PM
The bio methane can be put into existing natural gas lines. Just locate the plants near the farm fields and natural gas mains. It will clean up the present natural gas content. It is pure methane without the propane, butane or other substances.
Posted by: sjc | Oct 8, 2008 8:23:21 PM
As I have said this before, hydrolysis and fermentation are definitely not the most energy efficient use of lignocellulosic biomass. This is because, first, cellulose is a natural plastic that is practically unsusceptible to any low energy treatment like hydrolysis, and second, its content is only like 70 % on average in the lignocellulosic feedstock, the rest being lignin. These factors make it not suitable for fermentation to ethanol whatever clever scheme one might devise.
The most efficient way to deal with lignocellulosic biomass is thermochemical route. This includes combustion for heat production, and gasification. Gasification is particularly attractive because it yields gas that can be used for electricity production via a thermal engine, and can efficiently be converted into liquid fuels and chemicals.
Of course, there are feedstocks that are best fermented to methane even though carbon conversion will not be that high.
Posted by: black ice | Oct 8, 2008 10:50:36 PM
The real issue is that is not so easy to switch from one primary fuel source to another in case you try to make primary fuel accepted in automobile directly. That is very long lasting, expensive and tiresome process. You have to consider your strategy very carefully. And vice versa – it is not so complicated switching fuels for power generation. You just need to build new power plant which you would build in any case. It is just matter of consideration which fuel do you prefer. Therefore in order to be able to keep hands free and be able to switch to any fuel very quickly – coal, biomass, wind, NG, solar, nuclear or even fusion there is no other opinion to PHEV or BEV. You can charge in your battery which ever fuel is most economical, rational or “green” at any time!!! And this freedom of choice is just round the corner....
Posted by: Darius | Oct 9, 2008 12:45:38 AM
People who are losing their jobs, their homes, and in some cases their families, could care less right now about how “environmentally correct” ethanol is or isn’t. We are paying for an oil war sucking up $200 Billion a year and squandering 3% of our fuel supply. Add that to the price of your gasoline, diesel fuel, and your airline ticket. Our $500 Billion a year Foreign Oil Trade Deficit is paid for with debt instruments that we pay interest on. Thus, there is a Hidden Cost for fuels derived from imported oil. Stimulating Domestic Biofuels has a 10 to 1 payback, because it eliminates this “hidden cost” and stimulates our economy. Reducing our consumption of foreign oil has a higher priority than our carbon footprint.
A study by Iowa State University documented that ethanol lowers the cost of gasoline by 29 to 40 cents per gallon, which saves consumers $40 to $60 Billion a year and reduces imported oil. Our vehicles don’t run on biomass pellets or biogas, unless you want to spend $5-10K to convert them and fill them at home. Then spend extra time and expense finding a place to fill-up. No infrastructure.
There are two branches of auto-vehicles: (1) The 240 million vehicles we now have on the road valued at $6 Trillion, running on liquid fuels, which we will not be throwing away just yet. (2) And future vehicle designs that are under development, such as electric and plug-in hybrids, which will take 20 years to replace conventional vehicles. I agree that running electrics and plug-ins charged with electric power is the way to go. Electric is 1/7 the cost of operating a conventional vehicle. But in the mean time, we need Domestic Liquid Transition Fuels for the conventional vehicles we are phasing out.
The study described above is somewhat true but also flawed and inadequate. We are already using biomass burn power plants and converting some coal plants to biomass. We are already converting municipal solid waste, sewage and livestock manure into biogas for fuel and electric power. The authors are definitely not fully knowledgeable about ethanol, which now only consumes 23,000 BTUs to refine per gallon. Also, there are numerous sources of ethanol, and they’re all different: 2 to 1 Corn ethanol plus byproduct feed. 3 to 1 cattail ethanol plus biomass. 4 to 1 Sweet Sorghum based ethanol plus biomass. 5 to 1 cellulose ethanol, such as 30 ton miscanthus. 6 to 1 Jerusalem artichoke plus biomass. 7 to 1 integrated dairy: biogas, biodiesel, ethanol, plus milk and feed. 10 to 1 Algae based biodiesel, ethanol plus feed. And the list goes on. We have super sorghums that produce 40 tons per acre, and algaes that produce 100 tons per acre. And you can figure 100 gallons per ton ethanol. Yet the study uses “whole crop maize”. Get Real.
Cellulose ethanol does not consume natural gas or coal. It is self-powered from biomass, lignin or synth gas, depending on the process. Also many conventional corn ethanol refineries are switching to low heat distillation processes, biomass burn CHP, and renewables for production power. Efficiency evolution.
We do not have a food shortage or a shortage of land. We only use about 1/3 of our arable land, and we have millions of acres, not suitable for food crops, to grow biomass on. We fulfill all the orders for grain exports and could export more. This year we exported 20% more feed corn and double the amount of distillers grains livestock feed, after years of flat exports. If you count municipal solid waste and sewage, we have a billion tons of biomass waste available.
We are still discovering what ethanol can do. For example, Hydrous Ethanol: We can mix 4-5% water with ethanol and still blend it with gasoline. Or, we can eliminate gasoline altogether and blend ethanol only with water. Phil Ratte (Mechanical Engineer, BME University of Minnesota): “From 1981 to 1989, I worked with Herb Hansen, who had been an engineer on a WW II submarine, and a former captain of a nuclear submarine. We developed two prototype cars, a Ford Pinto Station Wagon and a Mitsubishi Sedan, that ran as well on 65 proof ethanol (2/3 water and 1/3 ethanol) as they did on unleaded regular gas.”
Posted by: Jeff Baker | Oct 9, 2008 1:04:20 AM
“Not only biogas is more efficiently produced from biomass than ethanol but also it can be burned with a much better efficiency in an ICE ..”
“The bio methane ...”
It is very obvious that Treehugger and sjc do not understand the engineering challenges with using biomass for energy.
Here is an example of good ideas: AGSTAR is a very successful program http://www.epa.gov/agstar/accomplish.html to reduce ghg and produce energy.
Producing biogas requires good engineering and experts to operated them.
Biogas is a dirty and low BTU fuel that is very a good stationary boiler to produce process steam. Clean biogas up a little bit to remove things like H2S and it can be used properly designed stationary ICE to drive a generator and make electricity for the local grid.
Clean biogas up a lot to produce pipeline quality methane, it can be compressed and put in a pipeline so Treehugger and sjc can burn it to make electricity in their backyard.
How green is that?
Here's the deal. If you are going to do something hard why not make ethanol? For those who did not take the time to look at gr's link http://www.e3biofuels.com/ go there and watch the video. The Mead facility is textbook industrial ecology. The most efficient use for biogas is too make process steam to make ethanol.
Posted by: | Oct 9, 2008 7:40:08 AM
Would it be possible to use the idea of vertical farming to grow large volumes of willow/hemp/bamboo on the exhaust stacks of CCGT / IGCC power stations with the resulting biomass being co-fired with the fossil fuel or turned into bio char.
Small natural gas powered range extenders for electric vehicles would double nicely as distributed combined heat and power units
Digestion of all suitable waste streams with some specialised crops could contribute a replacement for natural gas.
Concentrating solar for peak cooling requirements, efficient heat pumps powered by wind power for heating. Improvements in building insulation and thermal mass to reduce heating requirements in the first place.
The largest chunk of energy usage goes on heating / cooling and transport this is where the biggest efficiency savings are.
Posted by: Steve | Oct 9, 2008 9:04:15 AM
At least one person on this string of comments actually seemed to have read the journal article...
The authors are talking about Corn stover. Cellulosic ethanol is usually envisioned for wood chips and switch grass with some agricultural residues.
Of course corn stover ethanol does not make a lot of sense to address all of our needs. Shame on green car congress, that was a misleading article and not clearly presented.
Posted by: Don T | Oct 9, 2008 10:09:45 AM
Seems to be some pushback from ethanol supporters.
Say what you want, but 2 facts remain evident:
1) You can get much more energetically from a given amount of biomass with biogas than you can with ethanol. And with less physical plant overhead and less (added) energy input.
2) Given our thirst for oil, biomass resources are likely to be limited, not unlimited.
Again, no argument that liquid fuels are more easily stored and carried than gaseous ones. But if the liquid fuel costs twice as much, perhaps the customer would prefer a gaseous tank storage. It's not clear what's best for the consumer, but it is clear what's best for the ethanol producers (and biogas producers, for that matter).
Posted by: Jim | Oct 9, 2008 11:23:46 AM
@Jim:
Your second point is important. Because biomass is not unlimited and there are costs to conversion and transportation. Bio-methane, in any scenario going forward will be a supplement to the huge installed NG infrastructure. That infrastructure is owned and operated by the petroleum industry.
Oil will pay lip service to a "bio-methane" expansion for CNG vehicles, knowing full well that their market share via coal-bed methane wells will grow.
The downside of the Pickens Plan is his insistence that we convert/manufacture cars to CNG. 99% NG comes from oil field operations. Any bio-methane industry will be dwarfed by the installed oil and gas infrastructure and its expansion will expand our reliance on fossil NG.
While there are some advantages to bio-methane from an engineering perspective - it is a poor political choice. At least for now.
Posted by: nrg nut | Oct 9, 2008 1:01:09 PM
The renewable liquid and battery electric fuel pathways have plenty of policy support, in the form of mandates, incentives and grant subsidies, and this policy support has stimulated hundreds of millions in capital investment in RD&D and production and distribution infrastructure. The gaseous fuel pathways, however, have been badly neglected by federal and state policy, not to mention funds for RD&D and incentives to stimulate capital investment. Like E10 natural gas motor fuels in the form of CNG offers a renewable fuel pathway via both biomethane from waste AND blended natural gas/renewable hydrogen motor fuels for use in existing internal combustion engines. The few vehicles using these nethane/hydrogen mixtures have been branded with fancy names such as Hythane, HY5 or H20. But the technology itself is universally available -- and affordable.
Posted by: david e bruderly | Oct 9, 2008 2:25:37 PM
From the unnamed above post: “The most efficient use for biogas is to make process steam to make ethanol.” Good Point. This is what several new ethanol plants are doing in the Texas Panhandle. Ethanol producers are replacing natural gas by taking manure from local feedlots and converting it to biogas for combined heat and electric power (CHP) to run the plant. This is efficient use of biogas, consumed onsite. Some municipal solid waste and dairy and livestock based biogas plants are either generating electric power for the grid or feeding cleaned biogas into natural gas pipelines. And yes these are good applications for converting biomass into biogas, especially from waste and byproducts.
Don T: “Of course corn stover ethanol does not make a lot of sense to address all of our needs.” Good Point. The above study’s use of “whole crop maize” (corn stover?) is not a good efficient feedstock for ethanol. You get 4 tons of corn stover per acre of corn. Normally, it is advantageously plowed under in preparation for the next crop. Experts say you should only remove no more than half the stover. This stuff is bulky and is a logistical nightmare to transport it to the refinery and store it and handle it, etc., which would also consume fossil fuels. It would be better to take 50% of the stover and convert it into biogas or pyrolysis bio crude in the middle of the field for the farmer’s onsite use. However, Poet Ethanol is adding cellulose ethanol capability to one production scale plant, where they will initially convert corn cobs to ethanol, and later supplement that with local biomass crops such as highly productive 10 ton switchgrass, 20 ton super sorghum, and 25 ton miscanthus. This will also enable them to replace natural gas with a portion of the biomass for production power, derived from synth gas. As to whether biomass burn, synth gas for production power, or biogas from biomass digestion is more efficient, that remains to be seen. Also depends on the process and the feedstock used.
Jim: I agree that biogas is efficient for specific applications, such as (1) sewage and landfill processing, (2) dairy, poultry and livestock manure processing, (3) and onsite biomass waste processing, where the feedstock is closeby, and (4) local biomass to CHP for ethanol production (and more). This is a thriving industry. But for the millions of vehicles we already have on the road, mass produced Liquid Fuels are the bomb. Biogas on the other hand is a bulky, much lower BTU gas that has infrastructure limitations and cost restraints setting up a used conventional vehicle to run on it. For me, I want a vehicle that I can fuel-up anywhere, but a biogas-methane-natural gas infrastructure is inadequate.
It does Not just boil down to what can be produced more efficiently. What’s more important is how biogas is best applied, and how ethanol is best applied. Also how biogas is managed and integrated, compared to how ethanol is managed and integrated. And the two don’t have to be separate. Biogas and ethanol can be advantageously integrated as noted above.
Regarding your comment about biomass being limited: Yes, if we use petroleum fuels to produce biomass, it’s limited. But we’re not locked into that. On waste land, algae is going to produce more biomass than we can possibly use. Algae can also be efficiently digested into biogas, if that’s what you want.
We can also use domestic biofuels to produce biofuels. More and more farmers are making their own biodiesel from their own oil crops. About 8% corn oil is being extracted from distillers grains and sold back to local farmers for biodiesel.
Check out the “Cyclone Green Revolution Engine”. This engine opens up a whole new world. It can run on any combustible fuel: Any combination of gaseous or liquid fuels, and notably, slurries of ultrasound fractionated oil rich algae, ethanol enhanced biomass and bio crude, even raw biogas and powdered biomass.
Fast growing algae, cattails, seaweed, invasive plants, and whatever else we can exploit, which can be grown locally in our waste water and graywater, are over 100 tons per acre per year. The success of biomass will also hinge on how we exploit our waste products into value added biomass, fuels, and energy. 4/5 of the planet is ocean. We are not limited.
With basic engine modifications, one part high octane ethanol can be diluted with two parts water, converted into a gaseous form onboard the vehicle, and still be an effective combustible fuel. This is what we need to do with our ethanol, as a transition fuel.
Posted by: Jeff Baker | Oct 9, 2008 2:56:01 PM
To who said I don't understand the challenge in using biomass for energy should do his research, I am perfectly aware that you need to remove the H2S from the biogas but it is still way simpler and cheaper than making cellulosic ethanol, cellulosic ethanol is one of the most challenging project ever developped by man and it is still unclear if it will work.
2nd the german who are pragmatic people came to teh conclusion that biogas was better than cellulosic ethanol from an efficiency point of view, and it is also cleaner once the H2S haas been removed.
So do your research before saying that people don't understand what you believe you understand but that you don't
Posted by: Treehugger | Oct 9, 2008 7:59:41 PM
Jeff
There is millions of cars across the world that run on NG, they are way more efficient and cleaner that all thsi cars that you want to run on E85 where you are going to burn the ethanol with a poor efficiency because, the millions cars you are talking about are not designed to run on ethanol given the poor mileage of the american car fleet this is a shame to use ethanol, plus their emission will be worse. Ethanol can not be distributed by gazoline pipeline, so where is the conveniency that you are talking about ? Ethanol is certainly not the ideal fuel you are picturing,
Posted by: Treehugger | Oct 9, 2008 8:07:52 PM
Quoth Harvey D:
Could it be that in our desire to keep our oversized gas guzzlers running with bioethanol intead of fossil fuels we are, once again, taking the wrong path?Some of us have been saying this for years, and saying that CAFE regulations should have been replaced or assisted by fuel taxes since the 1980's.
There are no acceptable reasons why USA should have to import OIL, NG and Electricity after 2020.The USA may have nobody willing to sell any of those things to it much earlier than that. :(
Quoth Roger Pham:
Extracting H2 and methane from waste biomass is the most efficient way to harness this renewable and storable source of energy.Going to H2 is generally a waste of energy unless it is required for e.g. chemical synthesis.
Posted by: Engineer-Poet | Oct 9, 2008 8:24:42 PM
And quoth Jeff Baker:
We are paying for an oil war sucking up $200 Billion a year and squandering 3% of our fuel supply....We're squandering a lot more than 3% with wasteful driving and idiotic "lifestyle" vehicles such as Hummers. We can fix both of them without a cent of subsidies, often at a large savings; "eco-driving" can save upwards of 20% at zero cost, and the "lifestyle" vehicles cost more than the efficient alternatives.
A study by Iowa State University documented that ethanol lowers the cost of gasoline by 29 to 40 cents per gallon, which saves consumers $40 to $60 Billion a year and reduces imported oil.
There are ... (1) The 240 million vehicles we now have on the road valued at $6 Trillion, running on liquid fuels, which we will not be throwing away just yet.Do not forget that the value of each vehicle falls by about 20% when it is driven off the lot, and half the lifetime mileage is typically driven in the first 6 years (in the USA). We're going to replace those vehicles anyway, it's just a question of what the replacements will be like.
For example, Hydrous Ethanol: We can mix 4-5% water with ethanol and still blend it with gasoline.No you can't. Any significant amount of water in ethanol separates it from gasoline, causing "emulsification". This has been a headache for decades.
Ford/MIT worked on a downsized dual-fuel engine a while back which used direct-injected ethanol to do charge cooling, allowing extreme turbocharging and a halving of engine displacement for the same peak output. The secondary fuel system would have run nicely with hydrous ethanol (cheaper) but this fuel would not mix with gasoline.
Posted by: Engineer-Poet | Oct 9, 2008 8:25:54 PM
Well said, Engineer-Poet!
Posted by: Ron Steenblik | Oct 9, 2008 9:43:49 PM
"The USA may have nobody willing to sell any of those things to it much earlier than that. :( "
Only a fool underestimates the power of greed throughout the universe.
Posted by: | Oct 9, 2008 11:36:56 PM
I am reporting that Brazil is running hydrous ethanol mixed with gasoline, and they have been for years. All regular gasoline in Brazil is blended with 24% ethanol, in solution with 4% water. If you blend the ethanol and the gasoline first and then add the water, it does Not work. The water must be bonded into the ethanol first, and then it blends freely with gasoline. The State of Louisiana is using 4% hydrous ethanol blended with gasoline in a pilot program with a company called Renergie. Preliminary tests conducted in Europe have proven that the use of hydrous ethanol, which eliminates the need for the hydrous-to-anhydrous dehydration processing step, results in an energy savings of between ten percent and forty-five percent during processing, a 4% product volume increase, higher mileage per gallon, a cleaner engine interior, and a reduction in greenhouse gas emissions. Dautzenberg and Netherlands-based client Process Design Center BV were investigating new ways to dry ethanol and stumbled across unexpected interactions among water, ethanol and gasoline. “We knew of the problems in drying ethanol,” he said, referring to the capital- and energy-intense employment of molecular sieves in dehydration. “We tried to find another way, so we asked ourselves, ‘Why not use gasoline to dry the ethanol?’ The hydrous ethanol and gasoline mix should not have been miscible, but it was fully miscible.” As a result, a ternary equilibrium diagram was formed. “We went to Shell in Holland with this information, and they said, ‘This cannot be true,’ but they investigated it further only to arrive at similar results,” Dautzenberg said. References: “Testing the Water” by Ron Kotrba; and “Ethanol Solution: Just Add Water” (Ethanol Producer Magazine).
What I advocate goes beyond 4% hydrous ethanol as described above: Taking ethanol to the next level, by modifying existing engines to run on 30% ethanol and 70% water (no gasoline). And I referenced above two researchers who accomplished that.
Ethanol and water as a fuel is nothing new. In the 1920's, the model A Ford cars and trucks ran on 165 proof ethanol: 17.5% water and 82.5% ethanol. ‘Makes you wonder why most cars on the road today are not allowed to do what a Model A could do 90 years ago. Time to change that.
Recently, a Pratt Community College engine testing team lead by instructor Greg Bacon, mixed 20% water with pure ethanol, and efficiency in the combustion chamber doubled. When the ethanol explodes, the water instantly turns into additional power in the form of steam and, can also provide hydrogen and oxygen inside the cylinder, under the right conditions.
Dongfeng, a major Chinese auto maker is introducing a car this year that runs on 65% ethanol and 35% water (no gasoline). This is a standard internal combustion engine equipped with a compact fuel processing device attached to the intake. They claim hydrogen is formed. Toyota also has a similar hydrous ethanol add-on prototype for a standard engine that produces on board hydrogen. Internal combustion engines can be highly efficient running on ethanol and water. A 50-50 blend of pure ethanol and water will ignite. But if more than 50% water is used in the blend, it will need to be heated and vaporized prior to combustion.
Posted by: Jeff Baker | Oct 10, 2008 12:32:29 AM
Treehugger:
Prior to this response, I never referred to E85 or conveniency as you claim. Ethanol is still evolving. And I don’t suggest using E85, unless you have an engine that is optimized for it. The Saab 9-5 Biopower engine, which IS optimized for ethanol, outperforms gasoline, getting 20% more power, 16% greater torque, and 10% better mileage. The Lotus Exige 265E “Flexi” gets 45 more horse power on E85 than it gets on gasoline. Next year, Ford is introducing the EcoBoost gasoline engine, with an option for ethanol injection that will rival diesel power for a much lower cost. Within the next two years, Suzuki, Ford, GM and numerous other car makers will introduce engines which exploit the advantages of ethanol. Pure ethanol has higher octane, faster flame speed, lower emissions, lower burn temperature and less heat loss than gasoline. Major automakers are scheduled to produce smaller, lighter, high compression, turbocharged ethanol optimized engines, with high power to weight ratios, that are a lot more efficient than current gasoline and diesel engines. And the fuel will be cheaper, cleaner and made from domestic resources. Most importantly, ethanol mixes readily with water, a source of hydrogen and oxygen.
I’m not completely sold on combining ethanol with gasoline. Ethanol got in the fast lane, because we needed a replacement for MTBE, the oil industry oxidant for gasoline that was poluting our ground water. Aside from that, blending gasoline and ethanol is not neccesary. In the U.S., that was how politicians created an incentive for oil companies to distribute ethanol, by giving them a 51 cent per gallon tax credit to blend it with gasoline. Problem is, ethanol is more efficient when it’s mixed with water rather than gasoline.
Again, what I advocate is modifying existing engines to run on a blend of 30% pure ethanol and 70% water.
Posted by: Jeff Baker | Oct 10, 2008 2:01:25 AM
@Treehugger
“To who said I don't understand the challenge in using biomass for energy should do his research, I am perfectly aware that you need to remove the H2S from the biogas ..”
That was ENGINEERING challenge. Do you? Are you an engineer? No, you are not. H2S is not hard to remove but CO2 is a large component of biogas and hard to remove. The only easy and cheap way to remove CO2 from CH4 is too burn it an ICE or boiler. However, as the concentration of CO2 increases, the BTU content decreases and the mixture will not support combustion.
So Treehugger, if you know of an easy and cheap way of removing CO2 from biogas, let me and the rest of the world know.
Posted by: Kit P | Oct 10, 2008 3:23:51 AM
There's a couple easy ways of removing CO2 from biogas. One is to simply let the gas 'settle' in a vertical tank. (CO2 is about 3 times denser than methane; 44 grams per mole versus 16 grams per mole).
The other is to bubble the biogas through water. Water readily dissolves CO2. There is an issue with regenerating the water, but one way of doing this is to grow algae in it; they can make quick use of dissolved CO2.
I'd say removing CO2 from biogas is much easier than separating ethanol from water; and less energy is needed.
There are other components in biogas, but they are predominantly CH4, CO2 and H2S.
Posted by: Jim | Oct 10, 2008 7:22:46 AM
So Treehugger, if you know of an easy and cheap way of removing CO2 from biogas, let me and the rest of the world know.
Easy, easy answer!!! You use biogas to make electricity for an all electric society and recycle the CO2 into growing algae in a closed loop to make more fuel to generate electricty and so on and so on.........................!!!
Posted by: solar nano | Oct 10, 2008 8:07:28 AM
So Treehugger, if you know of an easy and cheap way of removing CO2 from biogas, let me and the rest of the world know.
Easy, easy answer!!! You use biogas to make electricity for an all electric society and recycle the CO2 into growing algae in a closed loop to make more fuel to generate electricity and so on and so on.........................!!!
Posted by: solar nano | Oct 10, 2008 8:32:43 AM
There's a couple easy ways of removing CO2 from biogas. One is to simply let the gas 'settle' in a vertical tank. (CO2 is about 3 times denser than methane; 44 grams per mole versus 16 grams per mole).
Completely impractical. First, the tank would have to be on the order of a CO2 scale height in height to get a significant separation factor. In one gravity, this is several kilometers. Second, the time for the gas to come into this equilibrium would be the molecular diffusion time, which for a kilometers-tall tank would be outrageously long (centuries).
The only way this kind of separation could be even remotely feasible would be in a centrifuge, since the time required scales inversely as the square of the acceleration. Even then I doubt it would be competitive.
Posted by: Paul F. Dietz | Oct 10, 2008 3:41:07 PM
@Pual
“this is several kilometers”
Ye of little imagination and low of out of the box thinking. Just put a few wind turbines and solar PV on the tower. Some of this is not new technology either. My Grandmother was always promoting different uses of space hooks.
Posted by: | Oct 10, 2008 6:20:38 PM
Paul,
If what you say was true, then radon would not collect in basements, and the Lake Nyos eruption would not have killed thousands of people with its CO2 plume (just like the dry ice mist you see on Halloween).
Further, methane and hydrogen leaks would not disperse harmlessly upward (which they do).
Since CO2 is denser than ambient air, methane should disperse upward even faster.
And then there's helium balloons.
I think you are discounting bouyancy in your calculations.
Posted by: Jim | Oct 10, 2008 7:39:02 PM
...and then there's the farmers that collect methane from cows in their barns - by collectors built in the roofs.
Posted by: Jim | Oct 10, 2008 7:49:15 PM
Kit
It happens that I am an enginer with some successfull achievement in his area. But anyway, compressing the biogas above 30 bars and cooling it to room temperature should liquefy the CO2 while the CH4 should be still in gazeous state so separating liquid from gaz shouldn't be that difficult my friend. Also if they can do membrane that can separate CO2 from N2 and O2 it should also worh for CO2 and CH4 though the CH4 might stick to the membrane because of the polarity of H in CH4.
Centrifugation should also be able to remove most of the CO2.
Posted by: Trehugger | Oct 10, 2008 10:12:48 PM
If what you say was true, then radon would not collect in basements, and the Lake Nyos eruption would not have killed thousands of people with its CO2 plume (just like the dry ice mist you see on Halloween).
You are wrong. Neither of the situations you describe there involve gases that are initially completely mixed, then separating under gravitational acceleration.
Posted by: Paul F. Dietz | Oct 11, 2008 5:46:46 AM
...and then there's the farmers that collect methane from cows in their barns - by collectors built in the roofs.
No, they don't. Where did you get this silly notion? Farmers collect methane/CO2 mixes produced in waste pits, collecting the gas from the pit without allowing it to be highly diluted by air.
Posted by: Paul F. Dietz | Oct 11, 2008 5:49:55 AM
@ Treehugger
“So Treehugger, if you know of an easy and cheap way of removing CO2 from biogas, let me and the rest of the world know.”
Can I assume that you are a German engineer? I have a great deal respect for German engineering but let me explain the KISS principle. Keep It Simple Stupid.
What we have Treehugger is a failure to communicate. I need easy and cheap. I understand all the methods of gas separation Treehugger described, they are not easy or cheap.
Treehugger is making statement that are not universally true about biomass. It may be true in the EU. It is not true in the US. LCA must be adapted to each location.
In a location where large amounts of corn (or other biomass) is grown and large numbers of animals are fed the corn, then there is a large amount of manure and crop waste. This is an environmental issue in rural communities.
I can show a huge improvement by processing the waste using an common engineering solution called an anaerobic digesters (AD). AD are not generally an easy or cheap. Cooking with cow dung that dries in the barnyard is easier and cheaper than collecting it putting it in a simple AD to produce cooking gas. The huge sanitary improvement by processing animal waste justifies the increased cost.
So AD are used to treat waste. Biogas is a low BTU dirty byproduct gas. It almost universally flared or used as boiler feed. Biogas is a significant industrial safety hazard.
The debate here is akin to which is better for producing milk, cows or horses. As it turns out cows are much more efficient at converting the energy in grass than horses. Milk has lots of fat in it to supply humans with energy.
Being more efficient, can we assume Treehugger rides a cow to work? Why are the loons here never discussing EROI comparing cows, horses, NGV, and EVs.
Furthermore I know that dried woods has a high energy content. Why are those stupid farmers not feeding wood to cows and horses? Surly the teach EROI at AG colleges.
I get to work using an ICE POV. Ethanol, vegetable oil, animal fats have all been proven to useful fuels ICE fuels as have NG.
For all those who want to milk your horse and ride your cow to work based on the EROI, I hpoe you do not have an expectation many will follow.
Posted by: Kit P | Oct 11, 2008 7:49:58 AM
Jeff Baker repeats one of the favorite misconceptions of ethanol and especially E85 advocates - that the Saab BioPower gets higher mileage on E85. Verifiably false by looking at information from 1) Saab, and 2) DoE NREL testing. Ethanol is playing and can continue to play an important (but not major) part in reducing fossil fuel consumption, but no one is well served by overstating its benefits. The low energy content of ethanol is just a fact of life that will always limit its potential.
Go to GM / Saab website -
http://www.gm.com/experience/fuel_economy/news/2007/adv_engines/saab-biopower-100-030707.jsp?exist=false (scroll down about 2/3 down the page)
"The overall fuel consumption of the current Saab 9-5 BioPower engine using E85 is about 30% higher than on gasoline and the optimized BioPower 100 engine is expected to yield a near 10% gain against this."
What they mean that is that the 9-5 can improve the mileage penalty by about 10%, so that there is only a 27% penalty instead of 30%. This was also noted in:
Optimizing the Saab BioPower 100 Concept Engine for E100
7 March 2007 http://www.greencarcongress.com/2007/03/optimizing_the_.html#more
DoE is a huge ethanol proponent, but their research shows the same thing, as noted in a recent presentation - "Benchmarking the Ethanol-Optimized Saab 9-5 BioPower" Slide 9 says:
"Saab BioPower Fuel Economy Data Shows that E85
Fuel Economies 23-27% lower than Gasoline"
West, B., et al, Oak Ridge National Laboratory, presentation to the Society of Automotive Engineers,
Government/Industry Meeting, May 1416, 2007
Posted by: bjb | Oct 11, 2008 11:50:53 AM
Kit
I can understand that for some reason you are a strong Ethanol proponent, after all in US a lot of american men care more about their liquid fuel based SUV or bulky cars than about their own wife, but that deosn't change the pysics of the whole thing, right? This study just confirm what have been observed elsewhere : biogas is more efficient path than ethanol, period. And I think efficiency is critical when it comes to scale biomass for powering 200 millions of cars. And I maintain that an AD biogas digester can be implemented at the farm level even with the CO2 and H2S scrubber when a Ethanol cellulosic processing unit can simply not.
Posted by: Treehugger | Oct 11, 2008 12:56:03 PM
"Whole crop maize" appears to be the use of grain corn, corn cobs and stover (corn stalk) for conversion to ethanol. This still leaves us with annual grain crop agriculture, which is a high input process.
Cellulosic biomass production from perennial grasses and trees is an animal of quite a different nature. This is low input, low fertility agriculture. Output/input ratio is significantly higher than grain crop agriculture. (See field trials studies done by the University of Illinois Urbana-Champaign.) The concentration of edible resources into a seed head, that is done by annuals, is a very energy intensive process and requires high fertility and soil disturbance. Removing corn cobs and stover from the field will result in soil degradation, reduction in soil organic matter, and increased soil erosion.
We won't be able to make a breakthrough on biomass fuel production if we rely on annual grain crops. That's a dead end.
Although personal transportation can be converted to stored electrical energy "fuel" source, movement of cargo by this method is limited to very short run pickup and delivery. Biomass fuel should be saved for cargo, not general, transport. Hydrogen based transportation is so low, from a total system basis, it really should be discarded as an alternative.
Posted by: fred schumacher | Oct 11, 2008 2:25:39 PM
Oops. I meant to say hydrogen based transportation is so low in efficiency, on a total system basis. See: Proceedings of the IEEE Vol. 94, No. 10, October 2006 "Does a Hydrogen Economy Make Sense?" by Ulf Bossel. It's available online as a pdf.
Posted by: fred schumacher | Oct 11, 2008 2:34:30 PM
Paul,
Maybe we should just agree to disagree, until a test can be performed.
It seems that CO2 is dense enough to pile up and kill someone in just a half hour:
http://www.osha.gov/dts/hib/hib_data/hib19960605.html
I dunno. This might not fit your definition of a mixed gas, but it certainly doesn't seem likely that a tank kilometers in height would take centuries to settle either, based on this behavior.
Deep pits in factories, buildings, etc. are routinely noted as hazards for collecting CO2, even if the CO2 sources are not located in the pits themselves. Again, this is not indicative of a centuries settling time.
Posted by: Jim | Oct 11, 2008 4:26:08 PM
It seems that CO2 is dense enough to pile up and kill someone in just a half hour:
Yes, if you have large parcels of gas of different compositions, the parcels of the denser gas can sink down below those of the lighter gas. If the parcels are sufficiently big, diffusive/turbulent mixing is not efficient and they remain distinct.
But once those gases are mixed, unmixing them involves separation at the molecular level. The physics of this is well understood; indeed, there's a section on it in Feynman's lectures on physics. The way it works is that in a state of complete thermodynamic equilibrium, the partial pressure of each gas decreases with altitude as an exponential function, decreasing by a factor of e over a 'scale height'. The scale height is inversely proportional to the molecular weight. For methane and CO2 the scale height is measured in kilometers (indeed, for a gas of MW ~29, the average MW of air, the scale height is a bit less than the thickness of the troposphere.)
The *time* for this equilibrium to be established is given by the diffusive mixing time, which is (linear dimenions)^2 / diffusion constant. For typical gases at 1 bar the diffusion constant is on the order of 1 cm^2/sec. So, for a 3 km tower, the time is about 10^11 seconds, or about 3000 years. In the real atmosphere, turbulence remixes the air much faster than this, so air does not separate according to molecular weight except in the very high atmosphere where the diffusion constant is much larger (since molecular mean free paths are longer).
Posted by: Paul F. Dietz | Oct 11, 2008 9:08:07 PM
@ Treehugger
I am a strong advocate of using AD to treat animal waste in semi-arid regions where the organic fertilizer can be used to reduce soil erosion. I am a strong advocate of pyrolysis or gasifiers to process excess biomas from semi-arid forest because the excess biomass results in intense fires that destroys the forest and causes soil erosion.
Look for the root cause of environmental problems and match technologies to fix the problem,
“This study just confirm what have been observed elsewhere : biogas is more efficient path than ethanol, period.”
That is just not true and Treehugger did not read the LCA. I have read many LCA for EU systems. They are very informative for the EU but Treehugger the EU is not the US.
“I think efficiency is critical when it comes to scale biomass ...”
So Treehugger, Germans should be riding cows to work instead of overprices fast cars.
No, efficiency is not critical. Selecting the correct process for the problem you are trying to solve.
As Fred suggests the 'total system basis' must be evaluated. Again look at the Mead plant. Biogas is produced to heat boilers to make ethanol and the AD returns much of the organics to the soil to grow more corn.
Posted by: Kit P | Oct 11, 2008 10:05:07 PM
Paul,
This is perhaps a different form of "public education".
:)
You are probably right about this one. The literature is pretty clear about gas distribution in the atmosphere. Scale heights are higher for lighter gases, which mostly explains why they diffuse out faster. (Because more of them, proportionally, are higher up, they have a better chance of getting knocked out; plus less energy is needed to accelerate them to escape velocity. Which all leads to weird theories by creationists citing helium concentrations as proof the earth is only 7000 years old, but I won't go there.)
I guess I can't reconcile this fact with reality of stable accumulation of dense gases in certain circumstances, such as radon in basements and co2 in deep pits. I appreciate that something with such a small (or large?) Reynolds number can essentially ignore gravity, but obviously it doesn't at the macro level. It's POSSIBLE that gas in a tall narrow tube might act a bit differently (wall strikes ?) than gas in a more typical atmospheric situation.
It just seems odd that tiny leaks of radon (hardly a dense parcel) can nonetheless accumulate in a basement instead of occupying its nominal distribution of its scale height as it should. Somehow the walls of the house contain it. (I'm not trying to defy Feynman, just basically confused.)
Oh well. This thread was about ethanol; and I was just trying to point out that separating CO2 from CH4 is not a big deal. As others have mentioned, absorbants or membranes would probably work fine.
Efficacy of methane for transportion depends on cost and density of storage. The charcoal briquette-like substrate apparently provide good density at low total pressure. Probably promising. Since ethanol can never compete with methane with respect to production costs, this is the only remaining weak point.
The infrastructure argument is a sham as we are already plumbed nationwide for NG, whereas gas stations owned by oil companies have to be dragged kicking and screaming into supplying E85 pumps.
Posted by: Jim | Oct 12, 2008 12:05:50 AM
Quoth solar nano:
if you know of an easy and cheap way of removing CO2 from biogas, let me and the rest of the world know.You fractionally distill the gas under pressure, removing CO2 as a liquid and recovering it as a saleable product; this also removes the H2S and siloxanes. This is the essence of the CO2 Wash process.
Paul: Good note on diffusion. Very valuable.
Posted by: Engineer-Poet | Oct 12, 2008 10:59:02 AM
@E-P
Thanks for the link. That was Kit P. you were quoting. What part of ‘easy and cheap’ do you not understand?
Biogas from a farm anaerobic digesters can be used in an ICE to make electricity or boiler without removing CO2. No compressors, no refrigeration systems.
KISS
Posted by: Kit P | Oct 12, 2008 3:08:13 PM
Kit,
I don't think it's that simple. Generators and engines runs somewhat poorly on biogas. I think you at least need to scrub the H2S out of it.
Cost is an issue with all biomass related technology because you are forced to have many little plants, as the cost of transporting feedstock becomes onerous pretty quickly. (Another problem the ethanol folk tend to ignore.)
-One who now understand gas diffusion a bit better
Posted by: Jim | Oct 12, 2008 4:33:52 PM
@Jim
You are right, there is nothing simple about biomass especially AD. Lot of ICE have been destroyed over the years. Several manufactures have engines designed for biogas. Removing H2S and moisture for farm application is relatively simple. WWTP and LFG require much more complicated systems because of the bad stuff in the gas.
The point is to keep as simple as possible. There are compelling reasons beyond producing a little energy. Every concentrated animal feeding operation has a zero discharge permit under the CWA. Taking the data from a manure handling plan for a 1000 head dairy farm and adding a AD provides the following benefits as a result of reducing air emissions:
- 5.5 ktons of methane captured
- 1.0 ktons of nitrogen compounds (mostly ammonia) captured (1.6 ktons of methane displaced from ammonia production)
- 60 tons phosphate
- 60 tons potassium
CAFOs can not pollute the water directly but blowing away is okay because you can used to your eyes watering.
Posted by: Kit P | Oct 12, 2008 6:28:39 PM
Kit,
Agreed. According to Gail the actuary (theoildrum.com) peak Phosphorus happened around 1990. But the Nitrogen/ammonia savings are probably more important.
Expensive energy means driving is expensive, which is not good. But it also means Haber-Bosch is more expensive, which is REALLY not good.
Without cheap Haber-Bosch (for fixing Nitrogen) we can only sustain about half the people on earth we have now. So DEFINITELY a problem. This should motivate more AD more than than anything.
Posted by: Jim | Oct 12, 2008 6:36:00 PM
If CO2 Wash isn't easy and cheap (requires pressurization and refrigeration, pretty trivial stuff), pray tell... what is?
CO2's triple point is at 5.2 bar, IIRC. Single-stage centrifugal compressors can hit about 10:1, so there you are. How this relates to biomass-to-ethanol I don't know, we've gotten a ways from there.
Posted by: Engineer-Poet | Oct 12, 2008 8:40:02 PM
E-P,
I think it all started with a comment by Kit on Oct. 10.
I didn't start it; I just posted a bunch of stuff that didn't make much sense; which is slightly different.
Posted by: Jim | Oct 12, 2008 9:02:42 PM
“what is?”
Not separating the biogas and using it directly in a boiler or ICE to make electricity is simpler.
“How this relates to biomass-to-ethanol”
Did you read the whole thread?
Posted by: Kit P | Oct 13, 2008 3:24:24 AM
I guess I can't reconcile this fact with reality of stable accumulation of dense gases in certain circumstances, such as radon in basements and co2 in deep pits.
The reason radon is elevated in basements is that the radon is being produced in the soil and rocks under the basement (from the decay chains of uranium). As it diffuses out it goes through the basement before escaping to the atmosphere. Since there is a net flow of radon from the basement out to the atmosphere, the concentration of radon must be higher in the basement than in the outside air. If there is a lot of radon being produced, and the basement is not well ventilated, significant concentrations of radon can be reached.
The density of radon has absolutely nothing to do with this -- the same effect could be observed if (say) helium were diffusing into the basement from the underlying soil and rock.
Similarly, situations where concentrations of CO2 develop are because CO2 is being produced (either volcanically or biologically) and is accumulating, not because CO2 is separating itself from the air. High concentrations of CO2, once developed, can remain stable in low spots because density inhibits macroscopic mixing.
Posted by: Paul F. Dietz | Oct 13, 2008 9:38:35 AM
Paul,
Not (really) doubting you. But check out this fact sheet, which has the seal of the Department of Energy on it. They seem to confuse hydrogen's rapid diffusing with it's lightness. They say some other stuff that you clearly would not agree with.
www.hydrogenassociation.com/general/factSheet_safety.pdf
Posted by: Jim | Oct 13, 2008 11:22:51 AM
I see nothing in that link that I would disagree with. Note that hydrogen, when it leaks, is not initially mixed with air, and so there are macroscopic density differences that can cause the hydrogen to rise.
Once the hydrogen is mixed into the air at the molecular level, it does not then spontaneously separate up near the ceiling, as I suspect you are thinking it could do.
Posted by: Paul F. Dietz | Oct 13, 2008 11:50:16 AM
No, I don't think that.
But I think it would diffuse rapidly enough to then be essentially individual molecules. By the time a plume got to a ceiling (depending on the size of the plume) the molecules should be pretty much dispersed. I don't think ceilings have much to do with it (again, depending on the size of the plume) as the safety sheet implies.
In fact, it makes no mention of plumes at all, nor does it specify radically different behavior of the gas based on its concentration.
Most of the safety points imply (or straight out say) that hydrogen is safe because it rises so quickly, when it is actually safe because it diffuses so quickly. (Again, based on the size of the plume.)
Posted by: Jim | Oct 13, 2008 12:19:23 PM
@Jim
Small concentrations of gases in air and water is a complex topic. Since I was a certified “gas free engineer' in the navy, let me provide some "public education".
You were not reading a 'safety sheet' but a carefully written propaganda piece. It is called lying.
Hydrogen has unique physical and chemical properties that has not substitutes. However, it is very difficult to handle.
“nor does it specify radically different behavior of the gas based on its concentration”
You mean like explosive range, detonation range, difficulty detecting, difficulty containing, difficulty compressing, difficulty transporting, difficulty containing, and metal embrittlement.
There are many hazards associated with producing and using energy. They must be mitigated to an acceptable level of risk. Assuming that a hydrogen leak will not collect in a roof and result in a detonation of sufficient force to displace the roof to the neighboring roof, would be an incorrect assumption.
Posted by: Kit P | Oct 13, 2008 3:06:54 PM
Quoth the troll:
Not separating the biogas and using it directly in a boiler or ICE to make electricity is simpler.Not if your LFG contains silanes, it isn't. The silanes burn to SiO2, which coats engines and boilers and requires costly rebuilds. H2S has its own problems.
Since you have to separate the silanes and H2S to run engines anyway, you might as well upgrade the LFG/biogas to pipeline quality. This lets you use it as compressed fuel gas in vehicles, export via pipelines, or otherwise serve the same markets as natural gas.
Now how come the soi-disant "expert" didn't know this... or wouldn't admit to it? No prizes for guessing.
Posted by: Engineer-Poet | Oct 13, 2008 8:46:29 PM
I agree with Engineer-Poet.
First, why waste biogas on a boiler? Just burn the biomass instead.
Second, why have special equipment to use the biogas, when if cleaned properly, it can be integrated into our existing NG infrastructure and its myriad applications and technology?
So, the cleaning problem is not an unreasonable one to ponder, in my view. I appreciate Mr. Poet's comments on CO2 Wash, but wonder if something yet cheaper is possible.
Posted by: Jim | Oct 14, 2008 7:23:22 AM
@E-P
You drop into middle of a discussion without understand the topic or having the curtsey to read the entire thread. If you note several times I have qualified the source of biogas such as:
“Removing H2S and moisture for farm application is relatively simple. WWTP and LFG require much more complicated systems because of the bad stuff in the gas.”
E-P linked a DOE funded demonstration project for a new method if converting biogas from WWTP and LF to pipeline gas but it has not been commercially proven.
What E-P does not understand, just because you can do something, does not mean you should do it?
Based principles of minimizing environmental impact based on LCA or reducing dependence on foreign fossil fuel; there is no reason to put biogas into pipelines.
Posted by: Kit P | Oct 14, 2008 7:40:42 AM
At the least, methane has its placce. But storage (both CNG and LNG)has problems. So what about adsorption? Is metal-organic frameworks key?
For example:
http://www.sciencedaily.com/releases/2008/01/080121101027.htm
Please email me directly at mekrebs@i1.net, as well as responding here, if you would be willing to provide an update.
Thanks
Posted by: Mark | Oct 14, 2008 9:41:35 AM
The charcoal-like stuff seems promising to me:
The metal frameworks (also touted for Hydrogen) seem way too theoretical to me. Not sure they can make it in quantity any time soon.
I'm annoyed with how much effort has been made to store hydrogen which could've been directed to methane instead. The hydrogen proponents push their strategy, but when asked about NG, complain about the storage (and infrastructure!) problems of NG. Ridiculous.
Posted by: Jim | Oct 14, 2008 10:45:28 AM
Thanks Jim. Seems an elegantly simple alternative for avoiding SCUBA tank pressures or liquefacation.
Overall, this is pretty impressive too.
http://www.ecofuel-world-tour.com/9.0.html?&L=2
Posted by: Mark | Oct 14, 2008 12:24:20 PM
Interesting discussion. One thing that is often overlooked is that there are numerous valuable products that can be made from cellulosic biomass other than ethanol and methane. Our analysis has concluded that the best combined GHG and value creation use cellulose to gasify it to syngas and then produce any of the following three products: anhydrous ammonia, dimethyl ether (DME) or H2 gas. Done correctly, each of these can be made relatively cheaply. The ammonia replaces the use of NG in the making of virtually all of the US nitrogen fetilizer. DME can be used as direct replacement for diesel fuel in low pressure tanks and can even be used during a transition period in a dual-fuel scenario. H2 is still problematic because of transport, storage and distribution. its unfortunmate because we can already make H2 gas at $1.30/Kg.
I agree that in the near and medium terms, making fuels and products that are direct replacements for our existing processes and activities make a great deal of sense. And in most cases that still allows us to use biomass and create better products that can still flow through the same distribution systems. Our view is that we should focus biomass conversion toward: (1) nitrogen fertilizer, (2) DME for diesel replacement and (3) butanol for gasoline replacement. Burning biomass to make electricity is among the least beneficial uses of the material.
Posted by: JackO | Oct 29, 2008 7:40:34 AM
Quoth JackO:
Our analysis has concluded that the best combined GHG and value creation use cellulose to gasify it to syngas and then produce any of the following three products: anhydrous ammonia, dimethyl ether (DME) or H2 gas.H2 is the essential precursor to NH3, so those options are the same except for the last step. DME for diesel fuel may be the best motor fuel, but I think you're wrong about value per se. The consumption end of the system must also be considered; diesel engines will not remain the power supply of choice if the fuel is "high value" and thus expensive.
Burning biomass to make electricity is among the least beneficial uses of the material.If the feedstock supply is limited, achieving the maximum field-to-wheels efficiency is probably going to yield the most value also. Making electricity to run an electric vehicle (e.g. Smith Newton truck) is not only more efficient than conversion to liquid followed by ICE, the vehicle has a much broader selection of energy supplies.
Posted by: Engineer-Poet | Oct 30, 2008 12:40:53 PM
