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Cellulosic Ethanol Better Than Expected

New studies show that it takes less energy to grow cellulosic crops.
Tuesday, January 08, 2008
By Kevin Bullis

There's some more good news about cellulosic ethanol, a fuel derived from grasses and other nonfood sources. It's long been estimated that the amount of energy in such fuels will be much more than the energy required to make them--which is not the case with corn-grain-based ethanol. Now experimental results are in, and the ratio of energy produced to energy used is even better than expected. The renewable energy produced was 540 percent more than the nonrenewable energy used to make it. Previous studies estimated that the number would be more like 340 percent. The improvement comes, basically, from farmers using less energy than researchers thought they would to grow switchgrass, one of the proposed cellulosic sources.

The better ratio means that cellulosic ethanol could do more to reduce greenhouse-gas emissions than previously thought. That's particularly good news, since new legislation will require that some 21 billion gallons of fuel be made from such non-corn-grain sources. The trick now is to improve methods for converting switchgrass into ethanol--making the processes cheaper--and to get farmers to start growing switchgrass in large amounts.

Comments

  • What about the water?
    Daniel from SA on 01/09/2008 at 4:32 AM
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    In my limited knowledge of bioethanol processes, one of the major problems (and energy consumers) is removing the water from the ethanol.  The processes I know of use distillation, consuming a lot of the energy gained by making the ethanol.  Is there another way of separating ethanol and water?  (I am thinking polarity, reactivity, shape?)  I know this is a naive comment, but I hope to get some fresh thoughts on the topic.
    Rate this comment: 12345
    • Re: What about the water?
      RD on 01/09/2008 at 12:58 PM
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      Cellulosic feedstock should dramatically reduce the avg 123 gallons of water used to produce every gallon of ethanol from corn. But what of the coal used for many of the current and planned ethanol facilities. At about 300 tons of coal for each plant per day, does the heat input really make this an efficient and clean process just so that we reduce overall CO2, when science now is showing that CO2 ISN'T the problem?
      Rate this comment: 12345
      • Re: What about the water?
        Scottar on 03/10/2008 at 9:53 PM
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        RD:
        You are correct that more evidence is coming to light that climate change is not really driven by CO2 emissions. In fact one scientist showed that natural emission fudge uncertainties far overshadowed Anthropogenic CO2 emissions. And this scientist showed that the IPCC over- sensitized it's climate models to CO2's contribution and positive feedback elements in the climate system. I have read various other articles that support his findings:

        http://www.dailytech.com/Researcher+Basic+Greenhouse+Equations+Totally+Wrong/article10973.htm

        Researcher: Basic Greenhouse Equations "Totally Wrong"

        Michael Asher (Blog) - March 6, 2008 11:02 AM

        New derivation of equations governing the greenhouse effect reveals "runaway warming" impossible

        Miklós Zágoni isn't just a physicist and environmental researcher. He is also a global warming activist and Hungary's most outspoken supporter of the Kyoto Protocol. Or was. That was until he learned the details of a new theory of the greenhouse effect, one that not only gave far more accurate climate predictions here on Earth, but Mars too. The theory was developed by another Hungarian scientist, Ferenc Miskolczi, an atmospheric physicist with 30 years of experience and a former researcher with NASA's Langley Research Center........... Go to website for more.

        So what the government and research labs should be doing is developing more efficiency in energy usage as well as alternatives and quit worrying about the AGW CO2 factor. And they should allow more drilling for gas and oil as needed to keep the economy 'oiled' and energy prices reasonable until those alternatives can be properly developed and implemented. Rome wasn't built in a day and neither will the new energy economy.

        From what I have read best possibilities are solar produced energy alternatives both at the consumer as well as large commercial installations, electrical and hybrid type technology, diesel ICE's, bio fuels from engineered microbes and algee sources. Lets not rule out carbon fuel cell technology to take advantage of the vast resources of coal. Wind is more of a bandaid then real power source, it would be better utilized for production of hydrogen or other liquid energy form. And there are better designs then the tower type that are less intrusive. 4th generation nuclear plants that require less enriched uranium and use helium as a coolant instead of water could also be utilized with advanced transmutation of the nuke waste into fuel and short lived waste isotopes.

        When you remove the hysteria and fear mongering of the Envirocrats the energy scene becomes limitless, especially with technological innovation. It will be an ongoing diversified progression with no one winner, unless fusion becomes a viable reality.

        Rate this comment: 12345
  • Suprise suprise .....
    DJTal on 01/09/2008 at 5:11 AM
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    No doubt soon we'll discover that it's cheaper for farmers to grow biodiverse grasslands , and not to use herbicides or pesticides , and to not bother with ploughing the soil , and to reduce the amount of artificial fertiliser they use , and farmers can start using biofuel to power their vehicles to make the thing greener . 
    Rate this comment: 12345
  • calculate the land area and switchgrass is crazy
    killian on 01/09/2008 at 9:41 PM
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    At 7100kg/ha they found in the study, and their assumed 0.38L/kg, it would take 632,755 mi^2 to fuel the U.S. 2005 Vehicle Miles Traveled (VMT) of 2.7 trillion assuming the 2020 CAFE standards of 35 MPG (a lot more with our current fleet MPG). And of course in 2020, VMT will be much higher than 2.7 trillion miles. In contrast, it would take only 3,607 mi^2 of Concentrated Solar Power (CSP) to fuel the same VMT in 300 Wh/mi battery electric vehicles (such vehicles were designed and produced in the 1990s--not new technology). 632,755 mi^2 vs. 3,607 mi^2: which would you choose?

    (Wind is about 30,000 mi^2, more than CSP, but still much less than switchgrass, and about 95% of a wind farm can have a second use.)

    NREL estimates the CSP potential in U.S. West rated "premium" or "excellent" at 1,642 TWh on 6,091 sq. mi. (they also have another 456 TWh in the "good" category).  The NREL survey excludes a long list of places, including sensitive areas.

    Oh, and by the way, there are only 1,137,504 mi^2 of "cropland pasture, grassland pasture and range, and forest land grazed" in the U.S.  Are we going to use 60% of this land to fuel our cars?  What about the species that depend upon that land?

    Let's not destroy our prairies when a much saner alternative exists.
    Rate this comment: 12345
    • Re: calculate the land area and switchgrass is crazy
      hachi on 01/10/2008 at 9:02 AM
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      You could grow the switchgrass on the wind farm land, ;)
      Rate this comment: 12345
      • Re: calculate the land area and switchgrass is crazy
        killian on 01/10/2008 at 3:17 PM
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        Good one!  Let's see, if wind is 432 GJ/ha, and ethanol is 57 GJ/ha (60 GJ/ha in the PNAS article on 95% of the wind farm), then we're picking up 13%, which isn't bad.  Too bad internal combustion is so inefficient.  If we replaced the U.S. 2006 fossil electricity of 2,868 TWh (10 EJ) with wind, it would take 23.9 million hectares (92,278 mi^2).  On this land we could produce only 1.4 EJ of ethanol.  That ethanol would take us 350 billion miles (assuming the 2020 CAFE of 35 MPG).  Now, what to do about the other 2350 billion miles we travel?
        Rate this comment: 12345
        • None are perfect.
          DJTal on 01/12/2008 at 6:33 AM
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          No source of energy is perfect , whiich is why we need a balanced mix of renewables . Bioenergy is ideal in areas that are perfect for plant growth etc.
          Rate this comment: 12345
          • Re: None are perfect.
            killian on 01/18/2008 at 4:51 PM
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            It may not be perfect, but electricity as a passenger vehicle fuel stands so far above the other choices that it is unclear what role the others will eventually have in such vehicles.  Biofuels (e.g. algae biodiesel) are most likely useful for things like long-distance freight.
            Rate this comment: 12345
            • Re: None are perfect.
              DJTal on 01/20/2008 at 5:31 AM
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              There are ALWAYS going to be applications where transportable liquid fuels are needed . I wouldn't be so sure about the cheap price of electricity , biofuels do have the potential to be much cheaper .
              Rate this comment: 12345
              • Re: None are perfect.
                killian on 01/21/2008 at 11:25 AM
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                On the price of electricity, Stirling Energy's FAQ says they are already "less than 0.10/kWh" and NREL suggests we'll get to 0.07.  Where is the price increase going to come from?  Concentrated Solar Power doesn't have a fuel cost.  Almost all of the cost is depreciation on the capital, so once deployed, you won't see price increases like you do with natural gas.

                Using 0.07/kWh, 300 Wh/mi, and 92% efficient grid, one gets 0.023/mi driving cost for BEVs.  To match this driving cost, ethanol would have to have a cost of production of 0.54/gallon at 35 MPGge, and 0.92/gallon at 60 MPGge.  How likely is this?  I also expect the retail markup of regulated electricity to be less than that of ethanol.
                Rate this comment: 12345
                • Re: None are perfect.
                  Siphon on 04/01/2008 at 6:36 AM
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                  The above comments seem to suggest strongly that a plugin-hybrid & liquid fuel combo would be best, as long as the balance is strongly shifted towards electric propulsion and the small remainder is used for the non-plugin (liquid fuel) part.

                  Plugins can reduce automotive liquid fuel consumption up to about 80% fairly cost-effectively. Increased electric rail transportation could increase the electric portion considerably. However, this leaves little for airplaines, although high speed rail could drastically reduce shorter distance and intracontinental flights. Building the infrastructure takes a long time though.

                  And we still have to deal with ships.

                  Without algae, I'm afraid there's going to be liquid fuel problems. That leaves liquefying coal, which isn't an enticing proposition.
                  Rate this comment: 12345
    • Re: calculate the land area and switchgrass is crazy
      ronwagn on 02/20/2008 at 7:16 AM
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      Switchgrass can be grown on land that has never been used for farming. It has a much deeper root system, and can be grown on wasteland, highway meridians, and roadsides. We have millions of acres of land that are not productive. Also timber waste, and all the weeds that burn out west every summer. It would stop all the wildfires, if we would just harvest the brush.

      I am amazed by the negativity of some comments. Is it that everyone has their favorite technology. I think we need them all, and let the natural winners evolve. Energy independence is the most important goal, to me.
      Rate this comment: 12345
      • Re: calculate the land area and switchgrass is crazy
        killian on 04/22/2008 at 2:14 PM
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        Sorry about the perceived negativity.  My goal is really to place some of these articles in context.  People can get complacent thinking "problem solved" when in fact the solution cannot scale well.  I agree that cellulosic ethanol can be part of a solution; my intent is to point out that it is not an entire solution.

        You mention that energy independence is your primary interest.  Mine is eliminating our greenhouse gas emissions.  Argonne's estimate is that E85 from cellulosic ethanol is 64% lower emissions than gasoline.  That's not good enough.

        Rate this comment: 12345
  • Dubious Comparison
    MakeSense on 01/10/2008 at 11:49 AM
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    Comparing renewable energy out to nonrenewable energy in is always dubious. What about the renewable energy in? Doesn't it count? Also, these assessments tend to discount energy generated by byproducts within the process, another less than perfect assumption.
    Rate this comment: 12345
  • This is good news
    Solar John on 01/13/2008 at 8:22 PM
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    Maybe now the price of corn will drop, and I can once again use it for heating my home as nature intended. 

    sj
    Rate this comment: 12345

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