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By Robert Rapier on Jul 19, 2010 with 31 responses

Biomass to Fuel via the MixAlco Process

Previously, I described a portion of my role in the early development of the MixAlco Process. Developed in the laboratories of Professor Mark Holtzapple at Texas A&M University, the process has undergone significant further developments, which I report on in this essay.

Details of the MixAlco Process

Here I will describe the process in a nutshell, but Wikipedia describes the process in significant detail. In fact, the details there are so thorough I suspect it was written at least in part by Professor Holtzapple’s graduate students.

The MixAlco process utilizes naturally occurring microbes to convert cellulose into chemical intermediates and fuels. The focus of the early work was to identify organisms that utilize cellulose as an energy source, and then to select microbes that are hardy and efficient for use in industrial fermentation. Unlike a conventional cellulosic ethanol process, the MixAlco Process does not add enzymes to break down cellulose. Cattle, for instance, host a mixture of microbes that produce their own enzymes that break down cellulose and convert it into primarily acetic acid. Think of a cow’s stomach as an industrial reactor, and you start to get the picture of what the process is attempting to accomplish.

From an economic point of view, the process has several advantages over conventional cellulosic ethanol. First, as noted, the process requires no enzyme addition. Second, because a mixed culture of hardy microbes is used, the process does not require sterile conditions. As you might imagine, the rumen digestive system is not a sterile environment. Finally, the process ultimately yields mixed alcohols or hydrocarbons, which have a higher energy content than does just ethanol.

The Present Status of the MixAlco Process

A company called Terrabon was formed in 1995 to commercialize the MixAlco process (and two other technologies). I graduated that same year, and plans were being formulated to construct a pilot plant based on the process. Construction of the pilot plant, designed to process up to 200 pounds of biomass per day, started in 2000. Because funding was scarce in those early days, it took several years to complete the pilot plant, but it has been in continuous operation since 2006.

Construction of a larger demonstration plant began in 2008, and was started up less than one year later. The demonstration plant is designed to process up to 10 tons of biomass per day, and has been in continuous operation since early 2009.

In 2009, the company attracted two large strategic investors. Valero invested in Terrabon in April 2009, and Waste Management followed in August. These investments bring together the technology in Terrabon, a refining and distribution capability with Valero, and lots of municipal solid waste to feed the reactors from Waste Management.

The Hard Questions

To evaluate this process objectively — admittedly more of a challenge than normal because of my history with the process and with Professor Holtzapple — I have to ask tough questions around the energy balance, conversion efficiency, capital costs, etc. If I look at the process completely objectively, it has characteristics that I do like, but also some that I don’t. One of the things I don’t like is the large quantities of water in fermentation processes that must be dealt with. That isn’t a show-stopper; after all Brazilian ethanol is a fermentation process that contains a lot of water. But they remove that water by using very low-cost biomass as fuel. Still, if the water wasn’t there in the first place, the energy efficiency could be a lot higher.

Professor Holtzapple sent me a number of presentations and papers (some linked below), which I have slowly worked through. These answered some questions — and triggered many more — so I have exchanged several e-mails with Professor Holtzapple in order to gain better insight into some areas. I present portions of the exchanges below.

Q&A with Professor Mark Holtzapple

RR: We were talking about a pilot plant in 1995, the year I graduated. What took so long to get it built?

MH: The pilot plant was started with seed funding of about $300,000. The funding was VERY welcome and resulted from initiatives taken by Jack Hopper at the Texas Hazardous Waste Research Center, which got its money from EPA. Unfortunately, this was not sufficient to build the entire pilot plant. We got some free equipment (e.g., steam-jacketed kettles) when Texaco shut down its research facility. Terrabon also provided major pieces of equipment over the years (e.g., vapor-compression dewatering system) and support structures. Recently, the pilot plant was upgraded for the DARPA project, the goal of which is to produce 100 L of jet fuel. We have added a centrifuge and driers, so the pilot plant is an evolving facility. It took a long time to build it because funding was hard to get, particularly in the early years when oil prices were low.

The demonstration plant was started in early 2008 and first became operational in early 2009…LESS than one year after construction began. To me, this is quite remarkable because it is quick for the first plant of any process. The detailed engineering was done by a company that designs waste water treatment plants and it was built by a general contractor that constructs buildings on campus and elsewhere. Much of the equipment was purchased from Grainger and McMaster-Carr. The reason I mention these points is that the design skills, construction skills, and equipment are commonly available, which makes scale-up easy. In contrast, biological processes that require sterility require specialized skills more commonly found in the pharmaceutical industry. They need sanitary valves, pumps, heat exchangers, and tanks, all of which are specialty items. Further, there are only a limited number of engineering and construction companies who have the skills…this makes scale up expensive and difficult.

The demonstration plant continues to evolve. Initially, it was only capable of doing pretreatment and fermentation. This summer, they are installing equipment that can do downstream processing. If you want more details, it is best to ask the Terrabon folks.

RR: Do you have a good idea of the energy returns of the process? I presume you will burn lignin (but probably aren’t in the pilot plant), but am curious about the fuel output/fossil fuel input ratio.

MH: The attached paper (Reference 2) shows the energy return can be as high as 18:1.

RR: OK a follow-up to that. I believe the 18:1 you mentioned is theoretical, but am really interested in what you have actually observed to date. My biggest concern is the amount of water that has to be removed from the process, and while I could envision scenarios that would yield a very high energy return, it would be at the expense of yield of final product (because I would have to burn much of the biomass for process heat).

MH: The main purpose of the demonstration plant is to prove that the fermentation works.  Most engineers who have reviewed our process believe the downstream processing steps will work.  Most of the uncertainty involves the fermentation, which is reasonable because no one has ever operated a mixed-acid fermentation for this purpose.  As much as possible, Terrabon wants to use conventional, off-the-shelf technology for the downstream steps.  The philosophy is to pursue one invention at a time.  At the moment, the fermentation is the “invention” being pursued.

Currently, the demonstration plant does not employ our advanced vapor-compression desalination technology. Instead, Terrabon opted to use a less sophisticated, off-the-shelf technology that can be put in place rapidly.

Terrabon has built a large advanced vapor-compression distillation (AdVE) system for the City of Laredo, which be used to desalinate brackish water. It is still in the debugging stage, but will be shipped in late July.

We have put a LOT of effort into dewatering.  This step can be very energy and capital intensive if not done properly.  We have made some remarkable breakthroughs (in my opinion) that related to promoting dropwise condensation on the heat exchanger surface.  In our laboratory apparatus, we have measured heat transfer coefficients as high as 42,500 Btu/(h ft2 F).  For comparison purposes, a conventional heat exchanger at the same operating conditions would have a heat transfer coefficient of 3000 Btu/(h ft2 F).  I am in the process of preparing the patent application, so the patent has not yet been filed.  Unfortunately, I cannot give more details at this time.

RR: I generally view water as something I would rather exclude from my process, due to the energy required to remove it. In a conventional ethanol process (e.g., corn or sugarcane) a lot of the process energy is devoted to removal of water. There is also the issue that water resources are a problem in many areas. Can you comment?

MH: Regarding the water issue:

1. The fermentation water is recycled, so the process does not consume much water (other than for cooling towers).

2. If the feedstock is wet, water must be purged from the system. Because we distill water from the salt, we can purge distilled water from the system, which can be used for irrigation or industrial purposes.

3. All biological processes involve water in the fermentation. Critical issue are (1) concentration and (2) ease of separation. Brazilian ethanol tends to be pretty concentrated (~10%) whereas we tend to be more dilute (2 to 5%).

4. Although we must separate more water per unit of product, our separation process is easier. With ethanol, both water and ethanol are volatile, so multiple-stage distillation with reflux is required. Further, they have an azeotrope, which creates a complex separation step to reach purity. In contrast, we are separating a volatile component (water) from a nonvolatile component (salt). This allows the separation to occur in a single stage, rather than the multiple distillation stages needed with ethanol. In our process, because the temperature of the condensing steam and boiling salt water are very similar, it is amenable to heat pumping, which dramatically lowers the energy input. In contrast, with ethanol, the boiling and condensing occur at widely different temperatures, so heat pumps are not as effective.

RR: What have been some of the biggest challenges to overcome in the piloting?

MH: I think anyone who works with biomass will say that solids handling is a big challenge. Also, mixing is an issue. I believe these issues are tractable when scaling up.

We do NOT have any issues with maintaining sterility…all bugs are welcome to the table…may the best bugs win!! Our process is driven very close to the low-energy state (acetic acid) whereas sugar or ethanol are reactive intermediates that want to become acetic acid. The only other product of a lower energy state is methane + carbon dioxide, which are produced by methanogens. Fortunately, methanogens are ‘fragile” microorganisms… they are strict anaerobes so small amounts of oxygen wipe them out. Also, they do not grow well at low pH or at high ammonia concentrations. We put inhibitors into the system to kill the methanogens. We have had good luck with iodoform, but there are MANY other known inhibitors such as monensin, BES (bromoethanesulfonic acid), chloroform, etc.

RR: What is the yield of product from a ton of biomass? (e.g., gallons of alcohols, ketones, acids)

MH: The yield depends upon the route taken.

Using the acid route (see Reference 2), the reported yields are

Mixed alcohols = 141 gal/tonne = 127 gal/ton (from Table 1)

Hydrocarbons = 0.635 × mixed alcohol = 89 gal/tonne = 80 gal/ton from Page 551

Using the ketone route (see Paper submitted version)

Hydrocarbons = 81 gal/tonne = 73 gal/ton (from Table 1)

Mixed alcohols = 0.8 lb digested/lb fed × 0.65 lb acid/lb digested × 0.583 lb ketone/lb acid × 1.0225 lb alcohol/lb ketone × gal/6.6 lb × 2000 lb/ton = 94 gal/ton = 104 gal/tonne (from Table 1)

(Note 1: tonne = 1000 kg, ton = 2000 lb)

(Note 2: yields are quoted on an ash-free basis)

(Note 3: Yields are based upon laboratory studies. They must be confirmed at industrial scale.)

RR: Related to the above, have you used the leftover lignin in a biomass boiler? I have glanced through various information on the demo plant, but haven’t see whether this piece in integrated.

MH: The boilers in the demonstration plant are gas- or propane-fired. This reduces capital and hassle. In my opinion, biomass boilers only make sense at large scale.

RR: What are you doing with the product coming out of the pilot/demo plants?

MH: The product from the early runs has been stored for later processing. The stored product and the currently produced product will be converted into ketones using newly installed downstream equipment.


As always, readers are strongly encouraged to ask their own critical questions before forming strong opinions on a particular technology. As I have stressed many times, there are no silver bullets in the world of energy. Every energy production process comes with baggage of one sort or another. The key to successfully transitioning away from fossil fuels in the most sustainable manner will be to develop technologies in which the excess baggage is minimized.

The MixAlco technology discussed here does address many of the negative aspects related to certain other cellulosic technologies. I think the keys to their success in the long run will be how well they are able to integrate the combustion of leftover biomass for process heat into their process. If that aspect is successful, then the process should be able to produce liquid fuels with relatively low fossil fuel inputs.

Additional Resources

There are numerous resources that describe the MixAlco process. Professor Holtzapple has made a couple of presentations available:

MixAlco Presentation at the Indo-US Conference on Bioprocess & Bioproducts – Technology Trends & Opportunities (3.5 meg PDF)

MixAlco Presentation at the 32nd Symposium on Biotechnology for Fuels and Chemicals (7.5 meg PDF)

Terrabon’s site has a detailed process description:

Process Description from Terrabon Site

The Wikipedia site is also very informative:

Bioconversion of biomass to mixed alcohol fuels

Finally, one can go to the Professor Holtzapple’s lab website to read about the latest developments:

Holtzapple Research Group


1. Granda, C., Holtzapple, M., Luce, G., Searcy, K., and Mamrosh, D. (2009). Carboxylate Platform: The MixAlco Process Part 2: Process Economics Appl Biochem Biotechnol, 156:537–554.

2. *Granda, C., Zhu, L., and Holtzapple, M. (2007). Sustainable Liquid Biofuels and Their Environmental Impact. American Institute of Chemical Engineers. Environ Prog, 26: 233–250.

3. Holtzapple, M., and Granda, C. (2009). Carboxylate Platform: The MixAlco Process Part 1: Comparison of Three Biomass Conversion Platforms Appl Biochem Biotechnol, 156:525–536.

  1. By moiety on July 19, 2010 at 6:11 am

    Been very busy lately but this is an interesting topic.

    A question I have is has an alternative to VCD (vapour compression distillation) been considered? How dry does the final product have to be? Reverse osmosis is the most common method but multiflash distillation (similar to VCD maybe even the same) where waste heat is available is prefered.

    For desalination projects information can be gotten from…..s/shuaiba/


  2. By Wendell Mercantile on July 19, 2010 at 3:08 pm

    Finally, the process ultimately yields mixed alcohols or hydrocarbons, which have a higher energy content than does just ethanol.

    Better than ethanol. I like the sound of that. But of course that will lessen any chance of support from the 42 farm state senators, Big Corn, or the ethanol lobby.

  3. By paul-n on July 19, 2010 at 3:24 pm

    Interesting stuff, to be sure, though I am a little dissapointed at the slow pace of progress here.  For something that started in 1995 it has had a long gestation period, mostly, it seems, due to lack of funding.

    The “one invention at a time” approach will also slow things down, though there are valid reasons for taking this approach.

    The most positive thing here is that Valero and Waste Management are getting involved – that is a great sign.  Valero has been buying up ethanol distilleries, and has more than a bilion gpy of capacity.  Presumably, product from this process could be mixed into the ethanol stream.  At the very least, they have experience, equipment, distribution and retail for handling alcohol fuel.


    Sounds like an ideal next step is a fleet trial of Waste Management trucks and vehicles running on mixed alcohol fuel supplied by Valero!


    Also sounds like a good process for a warm weather climate – solar assisted heating for the distillation would help.


    Will be interesting to see the continued performance of the demonstration plant.  From everything that has been said, this looks like a process than can be done on a small scale – ideal for biomass and waste.

    A plant located at a landfill seems ideal.  Process that municipal waste, which is as far from sterile as you can get, use methane from the old parts of the landfill for the boilers, and the residual solids/ash can be landfilled, with a >95% volume reduction.  No wonder WM stepped up!

  4. By paul-n on July 19, 2010 at 3:29 pm

    Wendell, the ethanol industry may not like this, but the corn farmers should be happy.  This process can take their corn just as easily as conventional ethanol.  But it can also take the rest of the corn plant too.

    In fact, for best yield/acre, you wouldn’t harvest the corn, you would chop the crop with a forage harvester and then send that to the processing plant.  Cheaper to harvest, more to transport = more localised plants.

    It also means the farmers can grow anything (switchgrass etc) for this, so farmers are winners, its just the ethanol industry that has a competitor.

    We’ll see what Rufus has to say…

  5. By Wendell Mercantile on July 19, 2010 at 3:57 pm

    But it can also take the rest of the corn plant too.

    Paul N,

    That’s certainly true, but it’s also a lot more expensive to plant and cultivate corn than the other crops and plants this process could use. I doubt corn farmers would get near the return on their investment they now get. A plant using MixAlco wouldn’t be likely to pay corn farmers what they thought their crop was worth when there are less expensive feedstocks available.

    As you said, it means corn farmers could switch to other crops, but I don’t know how many are that flexible. Raising corn is what they were raised knowing how to do, and many have made big investments in the specialized ag equipment needed for corn.

    My hunch is that only the most progressive corn farmers would support a move away from conventional corn ethanol to MixAlco.

  6. By paul-n on July 19, 2010 at 4:19 pm

    Wendell, it’s true that farmers (generally) are a conservative lot, and like to keep doing what they have been doing.  Corn farmers are the epitomy of that!  But if you are set up for intensive production of corn (all the equipment, etc) then you can also do intensive production of things like forage sorghum.  Like corn and sugar cane, sorghum is a C4 grass, which means it is the highest class of photo-synthetic efficiency.  

    If  you have the growing conditions for corn, you can grow sorghum, which responds equally well to fertiliser and irrigation.  By cutting for forage, it will re-grow, and you can get several cuts in the same season, for a higher total biomass yield per acre.  And if it’s going to Mix Alco, all they need is more biomass, not the corn itself.  

    It also means the farmer is better off in marginal conditions, – a good early season means early grwoth, but if there is a drought from mid season onwards, you get corn plants but minimal corn – cost more to harvest than is worth. But with forage, you  can cut it at mid season, for full value, and you may or may not get any more if the rest of the summer is dry, but you have already got a crop, and covered your costs – a less risky approach.

    Basically, anything that gives the farmers more options is good, and should be supported by the farm state senators.

    Unfortunately, in this case, that option does not belong to any of the big agribusiness companies, so won’t be supported – a very perverse world!

    That’s why I’m so happy to Valero and Waste Management in here.  If they get it to become viable, then big agri-business has been bypassed!

  7. By Benny BND Cole on July 19, 2010 at 5:36 pm

    Well, this is nostly over my head, but I admire the people who do the real hard work of sceince and engineering–and I equally admire people who explore dead ends as those lucky who few find success.

    BTW, OT, but interesting: Evidently the Congressional Budget Office recently put out a paper on ethanol. Looks bad for Rufus. Ethanol gets subsidies of nearly $2 a gallon.

    See below:

    BY DAVID NICKLAUS • > 314-340-8213 | Posted: Friday, July 16, 2010 5:14 pm | 1 Comment

    A new report from the Congressional Budget Office is providing plenty of fuel for critics of federal ethanol subsidies. The CBO added up the tax subsidies designed to encourage ethanol production, and calculated that they come to $1.78 for each gallon of gasoline replaced by corn-based ethanol. For cellulosic ethanol, an industry that is in its infancy, the subsidy comes to $3 per gallon of gasoline replaced.

    Ouch–can we just mandate PHEVs instead?

  8. By Rufus on July 19, 2010 at 10:48 pm

    Yeah, that was pretty deceptive, I think. They’re saying something like: We’re subsidizing x amount but we would have gotten x – y without the subsidies so they’re applying all of the subsidies to x – y, not to x.

    I wouldn’t get too worked up about it if I were you. The subsidies for corn ethanol are going away fairly rapidly. About all that will be left in a couple of years will be approx $0.10 gal from corn subsidies, and, maybe the small producer credit of $0.10/gal for the smaller refineries. Those might go, also.

    I assume they were doing something similar with the cellulosic.

  9. By Rufus on July 19, 2010 at 11:04 pm

    As for the Mix alco process I wish them well. I’m certainly Not qualified to comment on it. :)

  10. By paul-n on July 20, 2010 at 1:28 am

    Rufus, what I did want you to comment on was whether you think this is a good alternative for the farmers (assuming the process makes it into production), and is effectively competing with cellulosic ethanol.  Seems to me, the more options they have, the better.

  11. By Rufus on July 20, 2010 at 8:02 am

    Paul, I have no idea. I don’t think it’s far enough along to form any good opinions. When hard, and fast “Cost” numbers start emerging we’ll know more. As I said, I’m not “agin’em.” Anything that moves the ball is great with me.

    I wouldn’t, however, count on farmers going in and harvesting the whole plant. They’re not going to do that. They don’t mind selling the, more or less, valueless cobs, and quite a few have said they’d consider selling 1/3 of the “stover;” but that’s about as far as I’d expect they would go. Anyway, I don’t think that’s a major facet of this technology. As I said, We’ll See.

  12. By Wendell Mercantile on July 20, 2010 at 8:58 am

    When hard, and fast “Cost” numbers start emerging we’ll know more.


    Whoa! That’s quite a statement from you. You’re usually so anxious to jump on every cost guess an ethanol company offers in a media release and accept it as gospel.

  13. By Rufus on July 20, 2010 at 9:50 am

    Okay, a Good “Guess,” then.

  14. By Rufus on July 20, 2010 at 11:01 am

    THIS One is “Up and Running.”

    Inbicon opens in Europe…..n-denmark/

    They co-located this one with a coal-fired plant, but in my scenario the plant would be smaller, and fired, primarily, with the lignin from the ethanol process.

    I’m pretty sure this is where we’re going.

  15. By paul-n on July 20, 2010 at 12:07 pm

    Rufus, “up and running” in quotes is quite right, I can see no evidence that it is running.  The news release includes this (emphasis mine);

    The Kalundborg refinery will be integrated with the Asnaes Power Station, Denmark’s largest. A variety of feedstocks can be used: straw, corn stalks and cobs, sugar bagasse, and grasses. Waste steam from the power station will run the biomass refinery, increasing the refinery’s total energy efficiency to 71%.  To produce green electricity, the refinery’s lignin biofuel co-product is so clean it can augment coal-firing in power plant boilers without further purification.

    This entire statement is talking about the future, there is no actual photo of the plant, just a computer image, and Inbicon;s own website says nothing about the opening.  It does talk about the proposed plant, power station etc, also says it will open in 2009 – yet another cellulosic plant that has been delayed.

    I’ve no doubt they will produce something, sometime, but all they have produced here is a press release.

    AS far as the lignin goes, burning it JUST to distill the ethanol is a waste – make electricity from it first, then use the reject heat for  distillation.  An ethanol plant that does this will be self sufficient for both heat AND electricity.  At that point the net energy input for distillation will be zero, maybe even negative (if it exports electricity), and the only external input is the ethanol production.  Then the EROEI for the ethanol will become about 8:1

    Personally, I think this is what POET needs to be aiming for – to do at least one demonstration plant of this type.  I suspect then they could make a successful case for an continued subsidy for energy self sufficient ethanol production.

    Also, saw this on their website – most appropriate name ever for a cellulosic project – project HYPE;…../HYPE.aspx


  16. By paul-n on July 20, 2010 at 12:21 pm

    Now, enough about ethanol – leave that for another thread.

    One thing that is not specifically addressed is the fuel value/characteristics of the MixAlco product.  Has there been any engine testing of the product, either as straight fuel or in gasoline  mixes?  There is no mention of any of this on the Terrabon website.  Presumably they will not go too far down the path of producing this product before they make sure it works they way they think, and that the fuel sellers will accept it – I guess that’s where Valero comes in.

  17. By Tim C on July 20, 2010 at 12:58 pm

    Robert – thanks for the info on the MixAlco process. I’m struck by how similar it sounds to ZeaChem’s core process (see…..rview.php). Do you know if there are any IP conflicts between Terrabon and ZeaChem? They don’t seem to be fundamentally different technologies.

  18. By Rufus on July 20, 2010 at 1:00 pm

    Straw, corn stalks and cobs, sugar bagasse, and grasses–it all turns into biofuels at the Inbicon Biomass Refinery, which recently swung into full operation in Kalundborg, Denmark. However, it’s wheat straw that gives this new plant its claim to fame as the world’s largest producer of cellulosic ethanol, known as “The New Ethanol.”

    This power plant operates in conjunction with Denmark’s Asnaes Power Station and uses the waste steam of the station to increase its efficiency by 71%. Even more impressive is the fact that this plant produces not only biofuels but also green electricity, as the refinery’s lignin biofuel co-product is so clean it can augment coal-firing in power plant boilers without further purification.

    Sounds like they’re “open for business,” to me.

    Yes, Paul, the idea is to produce Electricity, and Ethanol.

  19. By David on July 20, 2010 at 1:36 pm

    So assuming that cellulosic ethanol can be made cost effective, do we have any method of ensuring that it won’t lead to soil depletion? Peter Huber had something to say about this:…..print.html

    Now picture a world in which cellulose-splitting enzymes are cheaper than bottled water, and a pint poured into the steel cow behind your hut will quickly turn a hundred pounds of wood chips or grass into a gallon of diesel. However sensibly we Americans might use the enzymes in Kansas, we know where cow-gut chemistry will inevitably lead in rural Burundi, India or China. Sure, a villager will fill the still with waste cellulose first. The enzymes, however, are just as happy to take apart freshly cut wood or grass, and that’s what villagers will use instead when they need or want more energy than waste alone can supply. Just as villagers do today when they cook. The one difference is this: When the villager harvests wood or grass today, he can only bake chapatis, heat his hut or feed his cow. With cheap enzymes at hand, he can also power a generator and a motorbike.

    History has already taught us what a carbohydrate energy economy does to a rich, green landscape–it levels it. The carbon balance goes sharply negative, too, when stove or cow is fueled with anything but waste or crops from existing farmland. It’s pleasant to imagine that humanity might get all its liquid fuels from stable, legacy farms or from debris that would otherwise end up as fungus food. But that just isn’t how humans have historically fed whatever they could feed with cellulose.

    From the perspective of all things green, cellulose-splitting enzymes are much the same as fire or cow, only worse. Fire and cow consume cellulose, but the process is generally messy and inconvenient, which is a big advantage, from the plant’s perspective. To improve on wood-burning fires, or grass-eating cows, perfect the cellulose-splitting enzyme. Then watch what 7 billion people will do to your forests and your grasslands.

  20. By paul-n on July 20, 2010 at 2:01 pm

    Rufus, did you click the link to the statement by the Inbicon CEO?  He says this;

    The Inbicon Biomass Refinery can demonstrate dramatically improved efficiencies when integrated with a coal-fired power station, grain-ethanol plant, or any CHP (combined heat and power) operation.

    “Can” and “when” in this context both refer to the future.  The only reference I can find to production says “limited production” which sounds like trials, that is not “open for business” yet.

    And, of course, this plant (will) make all of 1.4 mgpy, or 380 gallons per day.  It’s a start, but hardly worthy of the hype, IMO.

  21. By Rufus on July 20, 2010 at 7:43 pm

    Paul, I think you dropped a zero. 3,800gpd

  22. By carbonbridge on July 20, 2010 at 11:53 pm

    OFF Topic:  All Systems Go At World’s Largest Cellulosic Ethanol Plant

    Such news, I wish these Denmark folks well.  And I wish their acidic enzyme companies well too.  This is a very small, extra acidic batch fermentation “true-blue” ligno-cellulosic ethanol plant here.  This very tiny ligno-cell ethanol plant (75 bpd) is claiming largest volume output status worldwide with ligno-cellulosic EtOH at barely over 1 mgpy total capacity.  But they are ahead of other true ligno-cell companies (and those other companies who have pirated the ligno-cell label for gov’t grants) and they also indicate they want to directly use their same C2 ethyl alcohol fuel output to go into boilers in the adjoining coal fired power plant.  Now this was indeed news for me!

    Interested folks need to read between the lines here a bit.  What is the next-door coal-fired electrical power plant doing with the ethyl alcohol in their coal-fired boilers?  No answers.  And if you read closely through their website, these Danes are hiding one kind of biofuel which they are also producing.  They list its volumes and yet do not identify it.  Geez, biofuels are all the same, right?  The interesting thing is that they’ve impressed the Japanese (Mitsui) who are licensing these I.P. plant designs and this same Japanese firm is capable of scaling and fabricating this ligno-cell ethanol plant many fold larger throughout Asia.

    This particular news was a replay for me.  Links were forwarded to me last week from a shareholder who was watching news releases.  This Danish firm was operational and active when the Copenhagen global warming talks were held this past winter.  Blink.  Now it is one month past the longest summer light day in the northern hemisphere.  And a well cap is also holding back the Gulf Gusher too. 

    Continue to read between the lines everywhere folks.  Here is a link to some images from this Danish ligno-cell ethanol plant ostensibly doing a 7-day batch fermentation process and focused on one specific agri-biomass feedstock.  Become your own judge and remember that a carbon is a carbon is a carbon as an elemental building block of hydrocabon float-on-water oily fuels or oxycarbon, water soluble, biodegradable alcohol fuels.  Nite.…..plant.aspx


  23. By Jim Takchess on July 21, 2010 at 7:14 am

    David has a good point. Excessive requirements for fuel can lead to strip foresting. That happen to the Northeast US and the demand for Potash in the 1800′s.

    I have an idea : feed cows grass/hay and produce a non petroleum fertilizer . I think I can do it with a half a billion of government subsidy.

  24. By Wendell Mercantile on July 21, 2010 at 9:44 am

    I think I can do it with a half a billion of government subsidy.


    All things are possible with the right government subsidies and mandates. I could make a nice living and bring hundreds of jobs to my community if I could only get the US Government to mandate that everyone buy one of the panametric hydrocoptic turbo-encabulators my company has designed and wants to start producing.

  25. By Optimist on July 22, 2010 at 1:05 pm


    It looks very interesting. One of my favorite parts: “We do NOT have any issues with maintaining sterility…all bugs are welcome to the table…may the best bugs win!!” Now if only someone could explain this principle to the algal fuel people. Back to the topic at hand: I do have a few questions:

    1. Why such a big effort to prevent methane formation? Methane easily separates from the fermentation broth, making the whole MVR step redundant. Surely methane is an even better feedstock for synthesis than acetic acid? If you are concerned about the additional CO2 coming from the methane formation, there are ways to incorporate that CO2 into the subsequent synthesis.

    2. Assuming you have good reason to avoid methane formation, acid phase digestion would allow you to (a)reduce HRT and (b)increase conversion, while using low pH to keep methanogens out. Making acid phase digestion work is a challenge by itself, but it has been done…

    3. Once you have dewatered the fermentation broth, you have a mix of product and unconverted feedstock. Are these easy to separate?

    4. I see they propose an aerated pretreatment step to break down the lignin. Of course, adding air means converting some of the fermentable substrate to CO2, with the energy released as heat. With an unknown substrate (MSW) it would be a fine line between benefitting from lignin degradation and reducing overall efficiency.

    5. The “pile style” fermentor seems labor intensive and according to “Fig 4-18″ would need 120 days to complete the fermentation. How is that going to work? Can you keep recovering carboxylate salts from Pile #1 for 120 days while you wait for Pile #2 to complete its fermentation? And assuming you could, how close to 100% recovery would you be at the end of Day 120?

  26. By paul-n on July 23, 2010 at 12:02 pm


    Keep in mind the idea here is to produce (liquid) alcohol fuels.  Any methane that is produced is alcohol not produced, and is of far lesser value than alcohol.  If you let the methane stage begin, then you effectively have an (expensive) anaerobic digestion system.

    Turning gaseous methane into liquids can be done of course, but is a whole different process.

    Good points raised, all of which point to the inescapable conclusion that any biological process is going to have unused material, and inherent inefficiencies.  After all, biological processes are naturally optimised to keep bugs alive and growing, we are trying to steer it towards maximum throughput of food.  

    They all seem  economical if we assume that the feedstock is free, and this is not the case.  We also have to maximise value achieved from the byproducts and this is not always simple either!

    I guess that is why biological processing has only succeeded (unsubsidised) in niche applications

  27. By Optimist on July 23, 2010 at 2:38 pm

    I have to disagree on several points:

    Keep in mind the idea here is to produce (liquid) alcohol fuels.

    Why is the point to produce (liquid) alcohol fuels? Shouldn’t it be to produce (liquid) fuels of any kind? I know the protitutians have distorted the debate, but perhaps its time we took it back, and injected some (common) sense into it.

    Any methane that is produced is alcohol not produced, and is of far lesser value than alcohol.

    Not as fuel is hasn’t. Strip away the subsidies and methane might make a fine fuel. As is. And if you insist on converting it to liquid fuels, I would argue that methane to liquids is easier than carboxylate salts to liquids.

    They all seem economical if we assume that the feedstock is free, and this is not the case.

    Some feedstocks are free and likely to remain that way, for example sewage sludge. Others are free, and may not remain that way, but should still be more profitable that anything else, for example municipal solid waste (MSW).

    We also have to maximise value achieved from the byproducts and this is not always simple either!

    Wrong again! If you rely on by-products to make the economics work, you should admit the process isn’t feasible and go home. See corn ethanol for that spiel.

    I guess that is why biological processing has only succeeded (unsubsidised) in niche applications

    Niche applications? I don’t think so. Anaerobic digestion is used by wastewater treament plants everywhere to reduce the mass of solids going out the gate. The electric power you get from burning the biogas is a nice bonus. Some governments do subsidize things like fuel cells, but even without fuel cells, there are plenty of anaerobic digesters around.

    And the technology is spreading. Dairy farms are getting into the act. CAFOs would likely follow. The food industry is also using AD more and more. Most of these applications are unsubsidized and have good payback due to a combination of power savings and reduced disposal costs.

    I still don’t see why you’d want to stop methane formation. Methane formation (and the ability to go after a wide range of substrates) is why I think AD is the ONLY biological process than has the potential to yield a significant portion of our fuel needs.

  28. By Bill Renfroe on August 9, 2010 at 5:32 pm

    Robert – Thank you for your critical thinking on ethanol. We have a small county in NW California (Del Norte) that is about 70% public lands. Millions of dollars are spent annually for “fuels treatment” in the forests. We were wondering if there is a viable ethanol production technology we might consider. thanks in advance. Bill

  29. By Loren Price on August 13, 2010 at 12:17 pm

    Thanks for the article. I haven’t heard about this process in years. It’s nice to know its moving forward. Are they using any goverment subsidies? There mixed alcohols are straight to tank aren’t they?

  30. By rrapier on August 13, 2010 at 1:04 pm

    Hi Loren,

    The company is eligible for any number of biofuel subsidies, and they are getting some government support. I don’t know exactly what the amount is.

    The finished product should be ready as fuel. I know of a group who has gotten approval for running mixed alcohols as motor fuel. Not sure if the Holtzapple group would have to apply for separate approval – and if so whether they have already gotten it.


  31. By carbonbridge on August 13, 2010 at 3:46 pm

    Robert Rapier said:

    I know of a group who has gotten approval for running mixed alcohols as motor fuel. Not sure if the Holtzapple group would have to apply for separate approval – and if so whether they have already gotten it.




    I’ve been waiting to learn anything significant about mixed alcohols via Professor Holtzapple’s “MixAlco process” via this thread.  

    And as a reader, I still cannot fathom much about where higher alcohols or mixed alcohols would actually come from Professor Holtzapple’s batch fermentation process.  

    Having investigated this rather thoroughly for years now, I personally am aware that any higher alcohols which would be produced from this MixAlco fermentation process would be produced at a 3rd or 4th step downstream in this particular batch process.  And I also believe that any higher alcohols (C3+) to be produced via MixAlco would be independently isolated through methods of fractional distillation at the tail-end of this rather complicated fuels fermentation process.  

    The market for these individualized higher alcohols produced via “MixAlco fermentation and distillation” would be very likely limited to the chemical marketplace which would pay $3 per gallon and higher for only limited volume quantities of these stronger BTU alcohols.  I don’t see major oil refiners lining up to purchase smaller quantities of extra-expensive C3+ isolated higher alcohols for gasoline blending purposes.  Yet stranger things have happened.  Valero and Waste Management have both invested in this MixAlco batch fermentation process so they are undoubtedly interested in downstream applicatikons.

    Several times over this past decade I’ve had to explain what I know about MixAlco to people asking questions.  Standard Alcohol Company of America, Inc., (SACA) has been quietly developing a GTL methanization process to synthesize ENVIROLENE® Higher Mixed Alcohols via a traditional world-class Methanol GTL synthesis process.  This is very much like catalytically converting CO & H2 mid-stream synthesis gas into C1 Methanol as has been accomplished through world-scale fixed-bed GTL reactors since 1923.  The difference herein is that some adjustments are made to this very clean-operating, steam-driven Methanol GTL Chemistry Set plus a complete change-over of proprietary fixed-bed catalyst and then C1 Methanol is first formed through catalysis plus a whole series of normal (n) Higher Alcohols are produced as well.  A series of two lower alcohols (MeOH and EtOH) are first formed plus eight Higher Alcohols – thus the name “Higher Mixed Alcohols.”

    In layman’s terms, think of combining two CH3OH (single carbon) Methanol molecules into a (double carbon) synthetic Ethanol molecule described as C2H5OH.  Then hit that C2 Ethanol with another C1 Methanol and grow it into a C3 (n) Propanol.  Hit the C3 Propanol with another C1 Methanol molecule and grow a C4 (n) Butanol molecule via chemical bonding addition in a fixed-bed (KISS) reactor vessel.  This C1 “addition process” continues to form C5 Pentanol, C6 Hexanol, C7 Heptanol and C8 (n) Octanol.  This declining curve can also produce small amounts of C9 Nananol and C10 Decanol in this blend of Higher Mixed Alcohols as well.  The finished Higher Mixed Alcohol fuel product will average about 17% C1 Methanol volumes, 50% C2 Ethanol volumes and 33% volumes of C3 through C10 Higher Alcohols in a declining curve.  This is all accomplished in the same fixed-bed GTL reactor vessel which ordinarily would produce only C1 Methanol – now loaded with a different proprietary catalyst and changes made to reaction kinetic temperatures, pressures and flow-rates of the basic mid-stream CO & H2 syngas through this very common GTL fixed-bed reactor vessel.

    SACA’s blend of synthetically-produced Higher Mixed Alcohols has absolutely NO comparison whatsoever to what higher alcohols Professor Holtzapple intends to produce through “MixAlco batch fermentation” of biomass somehow isolated further downstream through this “batch process via fractional distillation.”  Yet the name “MixAlco” understandably confuses people who are evaluating our firm’s GTL continuous (methanization-type) of Higher Mixed Alcohols GTL fuel synthesis process.  The final “fuel outputs” from these two, distinctively different fuel production processes — would very likely in no way become a similar fuel recipe nor be produced at the same costs.

    Opposite of MixAlco, the primary function herein is to produce SACA’s synthetic blend of 8 or 10 Higher Mixed Alcohols at 2x the efficiencies of which C1 Methanol itself has been synthesized for the chemical markets during the past 90 years.  The output of this patented blend of synthetically produced E4™ Higher Mixed Alcohols features 90,400 BTU’s/gallon in comparison to Methanol at 56,000 BTU’s or fermented Ethanol at 75,500 BTU’s.  This same mixture of E4™ Higher Alcohols features a very favorable mid-range RVP rating and about 30 more octane points than either Methanol or Ethanol exhibit by themselves.  And yes, this synthetic blend of Higher Mixed Alcohols was approved by the EPA for registration and commercialization authority to be used as a seamless, “drop-in” blendstock to American supplies of gasoline or diesel. 

    SACA’s blend of synthesized GTL Higher Mixed Alcohols (ENVIROLENE® or abbreviated as E4™) can also stand alone as a neat or substitute fuel for use in FFV equipped autos.  As I’ve already indicated in other discussions on RR’s blog that this same blend of Higher Mixed Alcohols would perform even better if FFV chips had a basic adjustment switch which the motorist could trigger.  Ie:  A FFV chip calibrated for C1 neat Methanol or M-85, C2 neat Ethanol or E-85, or neat C1-C10 ENVIROLENE® Mixed Alcohols or E4™–95.  This “adjustable FFV chip” would then compensate as the BTU content and oxygen content of these three alcohol fuels are different.  If the FFV chip interprets which fuel alcohol blend is being fed into the engine, then air/fuel ratios and spark advance timing can all be made automatically to locate the optimum ‘sweet spot’ for the best combustion characteristics leading to highest mileage gains and the lowest tailpipe exhaust emissions as well.

    In conclusion:  The best review of Prof. Holtzapple’s “MixAlco” process which I’ve previously read was written a little over three years ago by two college students from the University of Oklahoma.  This 31-pg. pdf report can be downloaded from this URL below and may supercede any education that readers of this thread may have acquired thus far.…..ixalcs.pdf

    Therein all of the rationale for combusting Higher Mixed Alcohols in this pdf report was gleaned from reading just one of Standard Alcohol’s formula-usage patents and three of us as inventors were footnoted four times within this document.  I note that we should have been footnoted about 20x as any data listed in this report having to do with any sort of combustion improvements via Higher Mixed Alcohols blended into the petroleum fuel equation was gleaned specifically from our firm’s second U.S. formula-usage patent.  However, the footnote in this college report on “MixAlco” only takes the reader to and not specifically to the Patent reference itself outlining combustion improvements produced by ENVIROLENE® Higher Mixed Alcohols which can be located at:…..ks-rights/

    After all of the combustion rationale for E4™ Higher Mixed Alcohols has been first highlighted – then this college report shifts immediately into a whole different process entitled “MixAlco” fermentation from biomass.  Therein the reader will actually start to learn something about MixAlco batch fermentation which has been pioneered at Texas A&M University. 

    In SACA’s GTL version of Higher Mixed Alcohol fuel synthesis, this same sorghum biomass feedstock grown specifically to feed into a MixAlco batch fermentation process (plus beetle-killed pine, garbage, sewer sludge, ground tires, coal of any rank and petroleum coke wastes) would be cleanly and efficiently gasified instead to extract ALL of its carbon building blocks, not inefficiently batch fermented and extracting only a portion of the available carbon content.  As I’ve previously stated on your blogs, “why grow anything via agriculture as a dedicated biofuel crop when so much carbonaceous waste materials are abundantly availble for recycling via gasification?”  SACA’s E4™ GTL fuels synthesis process mimics Methanol synthesis (utilizing superheated-steam as the process driver, not enzymes or biobugs) and operates on a continous, non-stop 24×7 basis for 335 days per calendar year. 

    Mark C. Radosevich

    SACA Co-Founder, Chief Scientist & Inventor

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