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CleanTech Biofuels and Green Tech America Enter Joint Research Agreement for Waste-to-Ethanol Project

CleanTech Biofuels, Inc. has entered into a Joint Research Agreement with Green Tech America, Inc., a company founded by Dr. Nancy Ho of Purdue University, whereby Green Tech America (GTA) will provide research and testing to CleanTech Biofuels on the fermentation stage of CleanTech’s municipal solid waste (MSW)-to-ethanol project.

CleanTech Biofuels is a development stage company that holds exclusive licenses to a pair of technologies for converting municipal solid waste (MSW) into ethanol. The first, Pressurized Steam Classification (PSC), involves the treatment of MSW at temperature and pressure in order to convert the cellulosic material into a homogeneous cellulosic fuel feedstock, recover other valuable byproducts, and reduce the volume of waste materials that must be sent to landfills. The second, the Brelsford dilute-acid hydrolysis process, converts the recovered cellulosic feedstock into C5 and C6 sugars that are fermentable into ethanol.

Pressurized Steam Classification (PSC). The PSC process separates MSW into organic and inorganic components using a combination of steam, pressure, and agitation in a large rotating pressure vessel (autoclave). Steam in the autoclave sterilizes the material, while the pressure and agitation cause a pulping action, resulting in three outputs, with the mix depending on the composition of the MSW:

  • 55-60 percent cellulosic biomass, which has been decontaminated and homogenized and is available for conversion to ethanol;

  • About 25 percent separated recyclables (steel cans and other ferrous metals, aluminum cans, plastics and glass), which can be sold to recyclers; and

  • 15-20 percent residual waste (rocks, fines, soils, textiles, and non-recyclable fractions), which must be sent to landfills.

The individual autoclave units can process up to 250 tons per day of MSW and can be combined in parallel to handle larger amounts of municipal solid waste. The technology has been used by an operator to generate cellulosic material from garbage on a commercial scale for the production of paper.

Brelsford Process. Brelsford Dilute-Acid Cellulose Hydrolysis (DACH) is a lower-cost acid hydrolysis process that uses low-pressure, high temperature oil to provide energy for the process rather than using more energy-intensive high temperature steam. The process a two-stage plug-flow-reactor system. It further reduces energy requirements by recovering heat and acid used in the first stage of the reaction and reusing them in the second stage.

CleanTech Biofuels cites a review of the technology by the National Institute of Science and Technology (NIST – Final Technical Evaluation Report No. 457) “the Brelsford process has a potential for achieving considerable economic savings in: (1) acid composition, (2) heat-energy supplied for cellulose hydrolysis, and (3) process-energy for fuel ethanol production”.

CleanTech estimates a reduction in total capital and operating costs of roughly 30% compared to other acid hydrolysis processes.

Green Tech America, Inc. is developing and commercializing a yeast-based cellulosic ethanol technology that was pioneered by Dr. Ho, Research Molecular Biologist/Group Leader of the Laboratory of Renewable Resources Engineering (LORRE) at Purdue University. (Earlier post.) During the 1980s and 1990s, researchers at LORRE altered the genetic structure of Saccharomyces yeast to enable the conversion of the two major sugars found in cellulosic materials—glucose and xylose—into ethanol.

The ability to co-ferment glucose and xylose to ethanol was enabled by cloning three highly modified xylose-metabolizing-genes—XR, XD and XK—on a high-copy-number plasmid, followed by transforming the yeast with the plasmid (incorporating the plasmid into the yeast cells). A high-copy-number plasmid is a plasmid capable of self-replicating in the host cells many times—the resulting host cells will contain many copies of the cloned genes via the plasmids.

The initial target was the yeast strain 1400(LNH-ST), which was owned by a company. LORRE began screening for better yeasts with no legal constraints for converting cellulosic sugars to ethanol. Among the yeasts tested and integrated with the XR-XD-XK genes (more than ten yeast strains), 424A (LNH-ST) and 259A (LNH-ST) are effective for industrial production of cellulosic ethanol.

Further genetic engineering of the best yeast, 424A (LNH-ST) improved its xylose fermentation and enabled it to ferment two other minor sugars effectively. The further improved yeast should be able to ferment xylose and other minor sugars 30 to 75% faster.



Nothing is better then using s#it to power the cars and trucks.


My wife wouldn't let me install digesters to milk the Methane from all the free poop available around here.


between the diesel version and this one there will be soon more choice in Audi TT versions than hybrid models for the whole market. When automakers will change this suicidal policy of happy motoring ? and really focus on fuel efficiency and environment friendly vehicule? Audi mileage sucks, they don't have a single hybrid, the reliability is crapy and the confort well below the standard of such pricey vehicle (especially for the rear passenger).



Maybe because some people view driving as an enjoyable experience they like doing, so they buy cars that fit that view? Because if customers don't like what they're driving, they'll go to an automaker that does?

EVs or PHEVs that are fun to drive will sell far better than a box that gets you from Point A to Point B.


250 tons of MSW per day? That is a very positive action. There appear to be a half dozen MSW to ethanol project underway - all of which should be pursued to evaluate which does the job best. If these processing facilities are combined with power generation facilities - we can begin to construct the new grid mosaic. That is a mosaic of small electric generating facilities that use renewable energy resources to generate power. The immediate application is to against the local community with excess sold onto the grid.

Cervus makes a good point. People should be encouraged to purchase new PHEVs as a way of conversion to fuel efficiency. Boxes do not sell. And Restricting movement does not either.


Marketing cars has to be tough. That is one reason why they have concept cars and go to shows. There are so many brands and models and none of them seem to dominate the market. Some sell better than others but after a while people want something else.

Take the Camry as an example. In 1995 Camry and Taurus we about even for sales. Then in 1996 Taurus was restyled with a "bubble " motif and people stopped buying as many. Camry won hands down going away the following years and the rest is history.

People expect the Camry to change styling and features maybe every 5 years in an evolutionary way. Celicas used to change every other year and that grew old in a hurry. No on wants a car that changes too often, the resale value suffers. If they hardly change at all, sales may not grow.

It is up to the marketeers to figure out what people want and they better do it quick and get it right the first time. The U.S. car makers in particular may not get another chance. Surveys, focus groups, test drives...whatever you have to do, but find a profitable chunk of market. You to do have to be the biggest, but being profitable helps.

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