Celluose conversion

The fundamental roadblock that we face in the conversion to an ethanol based fuel economy is the economic conversion of cellulose feed stocks into firstly glucose and then ethanol. We actually understand how this is done - see the link for a quick explanation.

There is no lack of various feed stocks even if once again we lean on corn stalks. Every individual feedstock will present their own individual conversion issues which will obviously impact on the cost. On average though, fifty percent of the feed stock will be separable as cellulose, leaving lignins and other byproducts. This feed stock can then in theory be converted to glucose. After all, a cow does just that.

There exists a great deal of current optimism that this is achievable. I am personally very cautious in this regard. We have not lacked major research on this problem over the past century. It has been a valuable option from the beginning of organic chemistry. And the results have been unsatisfactory.

The difficulty is that we now need to economically solve this problem for a wide range of feed stocks. We can sort of do it at a high cost. Can we bring this cost down?

We already know that half of any feedstock is not cellulose. We can also expect that the recoverable portion after a chemical soak will be perhaps eighty percent of the available cellulose. Thus a first major cost will be the neutralization of the chemical soak, dehydration of the waste and its carbonization. And the volumes exceed that of the produced cellulose. We are looking at a sixty - forty split of waste and product.

Then, with our current knowledge we treat this cellulose with expensive enzymes to produce glucose. At that juncture, we are then able to do classic fermentation and alcohol production. This all promises to be a ghastly technical headache and has been to date.

What we obviously require is a handy microbe that loves dead plant material and does all this for us, including the production of alcohol. It still promises to be an incredibly slow production system. One envisages large vats of wood chips with a sprinkler recycling fluids for months on end. Not an attractive plan and the need for profitability ensures a catastrophic price for the end product.

So yes, we can see how it could work. Right now, the likely cost base means it will be anything but cellulose first.

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