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Mohr Davidow Announces Investment in ZeaChem, Developer of Hydrogenolysis Process for Cellulosic Ethanol

ZeaChem’s process combines the output of fermentation and gasification into a third process step, hydrogenolysis. Click to enlarge.

Mohr Davidow Ventures (MDV), a leading Silicon Valley venture capital firm, announced today that it has invested in ZeaChem, the developer of a combined biochemical and thermochemical process for the production of ethanol from cellulosic biomass feedstocks. ZeaChem claims that its technology will produce 50% more ethanol per ton of feed than the current best-in-class technology.

The process combines the outputs of two traditional pathways (fermentation of sugars and gasification of biomass) into a third catalytically-driven step—hydrogenolysis—to produce ethanol. The process results in an energy output that is more than ten times greater than the total non-renewable energy input required to grow and deliver a biomass crop, according to the company.

ZeaChem is now building a biomass-to-ethanol pilot plant with this new process technology. Joining MDV in the $4 million round is Firelake Capital.

The biochemical processing step converts sugars in the cellulosic biomass into acetate via bacterial fermentation. The conversion can be either direct in a one-step fermentation process or via lactic acid to acetic acid in a 2-step process. (The production of lactic acid can provide an additional revenue source.) After fermentation, the acetic acid is extracted from the fermentation broth in an acid recovery stage and esterified.

The thermochemical processing step converts lignin and other non-fermentable materials in the cellulosic biomass into a syngas. The acetate ester from the fermentation pathway and the hydrogen from the syngas combine in a hydrogenolysis reaction to produce the ethanol.

Zeachem uses the thermochemical processing stage also to provide steam and power for the plant.

The Zeachem process thus can use all fractions of the plant—cellulose, hemicellulose, and lignin—producing much higher yield per ton of feedstock.

Because the yield is so much higher and because energy integration is tighter, the ZeaChem process is friendlier to the environment, according to the company. Ethanol produced by corn dry milling in the US has a net energy ratio of less than 1.6, meaning that fewer than 1.6 units of renewable energy are produced for each unit of fossil energy used in the production the crops and conversion of the crops into fuel ethanol. In contrast, ZeaChem claims a net energy ratio of 10-12.

The biochemical processing step can ferment any fermentable sugar, including simple sugars like those found in sugar cane juice, more complex sugars found in corn starch, and the mixed sugars commonly found in cellulosic hydrolyzates. Any material that isn’t readily fermented, such as lignin, can be processed via thermochemical means to produce hydrogen.

The Australian Sugar Research Institute has evaluated the ZeaChem process and confirmed the potential of the process to achieve significantly higher yields of ethanol from a variety of sugar process streams than conventional yeast fermentation process.




So, the gist is that they use pyrolisis to gasify the lignins and use the extra heat what? Distill the fermentation product? They don't say how they recapture the acetic acid from the fermentation broth. Maybe they use the steam to heat the acetic acid for hydrogenolysis. I wonder if they get any other byproducts like char.

50% more ethanol than the best tech today? Does that mean up to 150 gallons per dry ton of biomass?

Could they use the same catalytic process to make biobutanol?

How do they efficiently fractionate the biomass in to high carbs and lignins?

Does anybody know where their pilot project will be physically located?

Is this *THE* answer?


First my ????

"The process results in an energy output that is more than ten times greater than the total non-renewable energy input required to grow and deliver a biomass crop,.."

Measuring the energy (solar excluded) in producing biomass has been a tough question. I avoid that mire.

So how do they quantify 'total non-renewable..'?

Observations: This is small, very small, right now. $4M. But follow on money for later phases may be forthcoming.

They are using a holistic approach and intend to get product of one sort or another from every atom of the biomass. The big picture is well described.

The company bio says little. I did note some positives. The principal officers seem well and appropriately educated. They have been oriented toward industry rather than academia. Some have worked directly on ethanol production at big companies.

I consider the bios positive as is the fact that they have been working on the process since 2002.

Otherwise they are keeping the details secret. As they should, it is their money and sweat.


I think this is pretty crazy. Very very complex, doubtful if economical. First you hydrolize wood, ferment the hydrolizates, separate out acetic acid, I suppose by solvent extraction. Than you need to esterify the acetic acid with ethanol. This means taking the final ethanol product, basically you recycle half of the produced ethanol. This is a catalytic process, you need an acid catalyst. Then you do a catalytic reduction of ethyl acetate over a hydrogenation catalyst. This is only the acetic acid part. All that does not hydrolize has to be separated, dried, and gasified, and shift reaction performed on the syngas, and the hydrogen purified. All these steps need energy and equipment.

Gasification of biomass and subsequent Fischer-Tropsch of the syngas is way way simpler and gives you 30 - 40 % of the energy in the biomass as FT liquids.


Its efficient use of biomass: fermentation can extract energy more efficiently but even cellulosic fermentation can't use all of the plant, what left over can be gasified.

P Schager

One of these days one of these cellulosic processes with its elephant grass feedstock will be so much cheaper than corn that you will not only obviate corn feedstock for ethanol, but it would be cheaper to use ethanol to displace corn calories in the diets of, say, pigs and grow beer belly pork bellies. Bonus is you can tell the animal rightsers that they're feeling no pain. Wouldn't be kosher, though; definitely not halal.

Maybe if we tell the oil companies this is what it's for they'll be less likely to mess with the program.

Paul Dietz

Its efficient use of biomass: fermentation can extract energy more efficiently but even cellulosic fermentation can't use all of the plant, what left over can be gasified.

The point of ZeaChem's process is that less carbon is thrown away (as CO2) in the fermentation of the sugars. This process in effect enables some of the lignin energy to be recycled back into ethanol via the hydrogen from lignin gasification.

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