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ZeaChem Confirms Production of Cellulosic Ethanol at Capacity That Can Scale to Commercial Production; Expanding the Product Portfolio of the Biorefinery

ZeaChem’s process. Click to enlarge.

ZeaChem Inc. announced the successful production of ethanol at a capacity that can be scaled to commercial production. ZeaChem currently uses harvested hybrid poplar trees as the feedstock of choice in its combined biochemical and thermochemical process for the production of ethanol. (Earlier post.)

A recent lifecycle analysis by CH2M HILL calculates that ZeaChem ethanol produced from the farmed hybrid poplar trees offers a 94-98% reduction in greenhouse gas emissions compared to petroleum-derived gasoline. Results are based on a farm yield of 10 bone dry tons (BDT) per acre and 135 gallons of ethanol per BDT.

ZeaChem’s production results have been confirmed by third party vendors who will enable production of ZeaChem biofuels and bio-based chemicals. The company will now demonstrate the integration of its biorefining processes at its 250,000 gallon per year Boardman, Oregon biorefinery. The integrated facility is being partially funded by a $25-million grant from the US Department of Energy (DOE) through the American Recovery and Reinvestment Act of 2009. (Earlier post.)

The company will use the grant to build the chemical fractionation on the front end and the hydrogenation process on the back end for making cellulosic ethanol. The facility will begin to produce cellulosic ethanol in 2011. ZeaChem intends to build commercial biorefineries upon successful operations at the Boardman facility.

The process. After fractionating the biomass, the sugar stream—both xylose (C5) and glucose (C6)—are sent to fermentation where a naturally occuring acetogen ferments the sugars to acetic acid. Acetogens have several advantages to yeast: they convert all xylose (C5) and glucose (C6) sugars and tolerate all breakdown products of biomass; they operate in harsh environments; and they produce no CO2 as a by-product.

In comparison, traditional yeast fermentation creates one molecule of CO2 for every molecule of ethanol. Thus the carbon efficiency of the ZeaChem fermentation process is nearly 100% vs. 67% for yeast.

The acetic acid is converted to an ester which is then hydrogenated to make ethanol. To get the hydrogen necessary to convert the ester to ethanol, ZeaChem takes the lignin residue from the fractionation process and gasifies it to create a hydrogen-rich syngas stream. The hydrogen is separated from the syngas and used for ester hydrogenation and the remainder of the syngas is burned to create steam and power for the process.

The net effect of combining the two processes is that about 2/3 of the energy in the ethanol comes from the sugar stream and 1/3 comes from the lignin steam in the form of hydrogen. At an expected Nth plant yield of 135 gallons per bone dry ton (gal/BDT), the process is nearly balanced with the necessary steam and power generated from the non-hydrogen portion of the syngas stream.

Accounting for yield per acre, ZeaChem calculates, this is five times more than corn-based ethanol and about three times more than other cellulosic processes, either biological or thermochemical. At the Nth plant, says CEO Jim Imbler, the process cost will be less than $1.00 per gallon.

Other products. ZeaChem’s approach can deliver a range of chemicals and fuels within the carbon chain product groups. Imbler says that the company has started work on its C3 organism (which would produce lactic acid, rather than the acetic acid produced by its current C2 organism). The C3 product platform would include propionic acid, propanol and propylene. Moving on to C4 could produce butanol.

Through the successful production of ethanol, we’ve completed ZeaChem’s C2 carbon chain suite of products, which includes acetic acid, ethyl acetate, and ethanol. The next step is to integrate these known processes to achieve the ultimate target of commercial production of economical and sustainable biofuels and bio-based chemicals.

—Jim Imbler

ZeaChem Carbon Chain Product Groups
C2 ChainC3 ChainC4 ChainC6 Chain
Acetic Acid
Ethyl Acetate
Ethylene Glycol
Lactic Acid
Propylene Glycol
Acrylic Acid & Esters
Propionic Acid
Methacrylic Acid & Esters
Butanol Hexanol

Feedstock. Although the ZeaChem process is feedstock agnostic, it is initially concentrating on its farmed hybrid poplar trees. ZeaChem’s analysis has shown the use of short rotation hybrid poplars offers the lowest cost per BDT/acre/year. These short-rotation hybrids can be harvested as often as three years, and require replanting only once every five harvests.

A successful, low-cost feedstock strategy requires three things, Imbler says. The feedstock needs to be

  • Sustainable;
  • Dedicated; and
  • Have “term”

The latter refers to long-term supply agreements. ZeaChem has a contract with GreenWood Resources (GWR) for its feedstock.


Herm Perez

so 1350 gallons of ethanol per acre, every 3 years?.. how hard is it to grow poplar trees?


How hard is it to grow poplar trees?

"the use of short rotation hybrid poplars offers the lowest cost per BDT/acre/year" but they are still TREES: They don't just pop out of the ground overnight you know. In fact, that these hybrids can be harvested as often as three years is quite an achievement.

Chris Jensen

$1.00 per gallon is terrific. To bad we will never be able to buy it because the EPA will not allow more than 10% of our nations gasoline supply to be ethanol. So much for environmental protection.


They could supply E85 pumps and all new cars could be FFV at very low cost. We can reduce oil imports without changing everything and costing a lot. HEV/PHEV/EV batteries will come along with better designs at lower cost, but we need to reduce oil imports now.


Interesting approach for USA and others to reduce crude oil imports and GHG. Could cellulosic butanol be produced at the same price?

Of course, land availability could become a problem or a limiting factor.


With some web searching, I think that the 10 tons should be annual instead of triennial (per the "Approximately 10 tons of poplar could be grown per acre annually" in http://news.uns.purdue.edu/html4ever/2006/060823.Chapple.poplar.html). If this is correct then it's 1350 gallons per acre per year in average, as GWR typically harvests poplar triennually.

In an interesting old article (http://gas2.org/2009/07/24/2000-gallons-of-ethanol-per-acre-for-15-cents-per-gallon-%E2%80%94-made-from-wood/) there are some interesting calculations and comparisons regarding ZeaChem/poplar, corn and algae although they are assuming that the 2000 gallons yield (based on the optimistic 15 tons annual yeild) is triennual.

Yet I believe that the key to biorefinery they revealed is how many BDTs you can get at a profitable price per year, continously. A better conversion process can increase the gross margin, but it won't generate more feedstock.


With 1000 gallons per acre that would be 100 million acres for 100 million cars. That seems like a lot, but that is about how many acres are planted in corn right now.


production of trees is much cheaper than classical agriculture.
Many trees, you only have to plant once, don't need insecticides, don't need herbicides and don't have to be replanted after each harvest. you can just 'mow' them after some years, and let the roots in the ground, new trees will pop-up very fast and grow very fast (because they have already full-grown roots to start with). You also don't have to plow the ground every year, so you don't need big expensive machines except the mower every few year (only one machine can serve an enormous area because you can mow almost at any season, while harvesters for corn obviously are standing idle in winter and spring).
The ecological value of such 'tree farms' can be much better than classical crops. Also soil erosion is almost eliminated since you don't need to plow anymore. Moreover, on top of the 'green' fuel, you have substantial amounts of carbon stored in the rootsystems.

This has great potential.



That sounds cool. I think that I gotta study more regarding tree farming. Previously I am looking at close-loop algae system and apparently it is too fragile to keep a constant high productivity, no matter heterotrophic or autotrophic approach is used.

There is a report saying that switchgrass can reach 20tons per acre per year in Taiwan (where I am located in) although the productivity will drop as the root system aged and a re-plant is needed about every five years.

Should the poplar root system be almost never aged, then we do be able to have a constant and profitable supply of feedstock.


Quick growth tree farming is new. Better species can certainly be produced with enough R & D. Not all unused farm land can be used. If those trees are to be machine harvested, people will plant them on good food production land. This would have similar (but reduced) effects as corn cellulosic ethanol.

It is doubtful if many countries have enough farm land to feed both their ICE gas guzzlers and their human fast growing population. Electrification + the production of cleaner Nuke, Wind and Solar e-energy is a better more sustainable long term solution.


Cellulosic alcohols are a part of the energy transition. With the introduction of Extended Range EVs ala Volt, we have an opportunity to operate wholly renewable energy vehicles. A Volt charging on nuclear or wind powered electricity and burning only cellulosic ethanol would lower the carbon footprint and never use any liquid fossil fuel. Cellulosic ethanol is a vital part of our sustainable energy program for electrification of transport.

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