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A new pretreatment process, eliminates expensive toxic acid baths in favor of ammonia. The treatment will help produce cheaper ethanol from plant waste, like these corn stalks shown here.  (Source: 3media.com)

Bruce Dale, University Distinguished Professor of chemical engineering and materials science at Michigan State University invented the cheaper and more efficient AFEX cellulosic ethanol pretreatment process, with the help of his doctoral student Ming Lau.  (Source: MSU)
A new process invented by Michigan State University helps to increase the yields of cellulosic ethanol at a reasonable premium

The world of cellulosic ethanol is a hot business.  GM has already backed two cellulosic ethanol companies, Coskata and Mascoma Corp., and many others are taking a serious look at the new type of fuel.  Essentially with the same advantages and disadvantages from a fuel perspective as normal ethanol, which it shares virtually the same chemical character with, the big bonus is that cellulosic ethanol can be made from plant waste of all times, reducing the price pressure produced by food-crop ethanol.

Using technology to produce cellulosic ethanol, the fruits and vegetables of food crops can ship to the market and the leftovers -- leaves, stalks, stems, and husks -- can be ground up and made into ethanol.  One of the first targets is corn stover, the leftovers from the corn harvest, somewhat of an ironic source as sugarcorn (the food) became one of the two main controversial sources of food-crop ethanol

Unfortunately, the processes to make cellulosic ethanol are still very inefficient.  And while there are acid pretreatments that can improve the performance, freeing up more sugars from the cellulose and hemicellulose in plants to be used in fermentation, these treatments are costly.  Typically the acidic product is toxic, so it must undergo intensive washing and detoxifying, leaching nutrients that could have been used in fermentation and raising the costs.

That's where Michigan State University comes in with a new patented process.  Bruce Dale, University Distinguished Professor of chemical engineering and materials science at the university, has invented a cheap pretreatment process using ammonia, called AFEX (ammonia fiber expansion).

Its 75 percent more efficient than with traditional enzyme treatments says Professor Dale, and is easier and more affordable than acid pretreatments.  The process frees up a lot of sugar to be used in the fermentation to produce more ethanol.

Professor Dale states, "Doctoral student Ming Lau and I have shown that it's possible to use AFEX to pretreat corn stover (cobs, stalks and leaves) and then hydrolyze and ferment it to commercially relevant levels of ethanol without adding nutrients to the stover.  It's always been assumed that agricultural residues such as corn stover didn't have enough nutrients to support fermentation. We have shown this isn't so."

He states, "Washing, detoxifying and adding nutrients back into the pretreated cellulose are three separate steps.  Each step is expensive and adds to the cost of the biofuel. Breaking down cellulose into fermentable sugars cost effectively has been a major issue slowing cellulosic ethanol production. Using AFEX as the pretreatment process can dramatically reduce the cost of making biofuels from cellulose."

Ming Lau, a coauthor of the project who shares the patent with Professor Dale adds, "The research also shows that the chemical compounds created when the stover goes through the AFEX process can improve the overall fermentation process.  This is at odds with the general perception that these compounds are detrimental and should be removed."

The pair is looking to set up a pilot plant at MBI International, a subsidiary of the MSU Foundation.  However, they already are also attracting commercial interest.  States Professor Dale, "There are several companies – including the Mascoma Corp., which plans to open one of the nation's first cellulosic ethanol plants here in Michigan – that may be interested in using this technology.  We are working to make the AFEX technology fit these companies' needs."

The new research is published in the current issue of Proceedings of the National Academy of Sciences (PNAS). 

The work was funded by the GLBRC, the MSU Research Foundation, and the Michigan Agricultural Experiment Station.  



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You hate Ethanol? Please Think Carefully
By Lau on 1/23/2009 12:58:49 AM , Rating: 2
I agree on the fact that ethanol has lower energy content compared to gasoline (about 70%). However, it has higher octane ratio which allows engine to run at a higher compression ratio, and thus higher efficiency. Taking this into consideration, the difference in the "apparent energy content" should be about 85%, not perfect but is good enough.

Putting that issue aside, it is important to distinguish cellulosic ethanol from corn ethanol. Even though, ethanol produced from cellulosic materials is identical in chemical composition, they have substantially different environmental footprints mainly due to much higher yield per hectare of land with little chemical fertilizer required for cellulosic biomass (if appropriate agricultural practice applied).

FURTHERMORE, using cellulosic materials as carbon source enable us to replace foreign oil at a meaningful scale due to abundance of these materials. Hydrogen or battery might be a more elegant approach in certain aspects, however, how are they going to alter transportation fuel profile without excessive alteration of our cars and fuel distribution logistics?!

Moreover, don't forget, cellulosic biomass is the ONLY carbon source that can potentially replace petroleum in other chemicals production. For example, we could use carbon from cellulosic biomass to produce succinic acid and it can be transformed to various useful chemicals and biodegradable plastic.

Using cellulosic materials to produce ethanol is the first step to maturate this young cellulose technology. If/when we are able to efficiently and economically convert plant sugars to fermentable sugars... the potential is enormous both for economy and environment. From the PNAS, the current technology is able to achieve about 65 gal of ethanol/ton of corn stover at more than 5% concentration. These process parameters are not perfect, but have achieved the minimum requirements for commercial production.
Again, ethanol is not perfect, but is a very good starting point.

This is my opinion, I would like to hear others' too. However, please do not take what I said too personal.




By Danger D on 1/23/2009 9:41:57 AM , Rating: 2
Cellulosic ethanol is needed in order to replace gasoline; corn alone can't do it. There are 1 billion tons of biomass in the United States, according to the Department of Energy and Department of Agriculture. That's not counting inaccessible areas, parks, etc. 1 billion tons of retrievable material - if we can develop the infrastructure to harvest, store and transport it - would make 85 billion - 100 billion gallons of ethanol. We use about 140 billion gallons of gasoline annually in the US.

I don't doubt that scientists will figure out how to make cellulosic ethanol commercially viable. Pilot plants are popping up everywhere, and the government is investing heavily in it. The challenge will be getting the public on board. It will take a large number of people willing to essentially become farmers of a wide range of non-traditional crops. We're talking a major expansion and overhaul of agriculture.

It's a challenge, but it's very possible with the right incentives to get it off the ground.


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