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Aemetis to use Mitsubishi ZEBREX technology to reduce energy use and lower carbon intensity of ethanol; largest implementation worldwide

Aemetis will be implementing the Mitsubishi Chemical Corporation ZEBREX zeolite membrane dehydration system at the 60 million gallon per year Aemetis fuel ethanol plant in Keyes, California. The Aemetis plant upgrade is the first ZEBREX system installation in North America and is the largest implementation of the ZEBREX system worldwide.

With ZEBREX, ethanol and water are separated by the sharp selectivity of the zeolite, producing 99.5% purity ethanol and recycle water in a single pass.


The upgrade from the traditional Pressure Swing Adsorption (PSA) dehydration process to the ZEBREX system can reduce energy consumption in the production of biofuels by up to 25%, increasing production capacity while reducing the usage of fossil fuel-based energy and lowering the carbon intensity (CI) of ethanol produced at the plant.

The ZEBREx dehydration system does not require regeneration because it is able to continuously separate water and ethanol, whereas the conventional PSA process uses considerable energy. For this reason, ZEBREX is able to reduce steam consumption (utility costs) significantly compared to the PSA process.

The unit will be designed and fabricated for Aemetis by ICM, Inc., headquartered in Colwich, Kansas, a leading ethanol technology provider. The Aemetis plant upgrade is the first ZEBREX installation delivered by MCC’s strategic engineering partner, ICM, in North America.

The ZEBREX system will allow the ethanol produced by Aemetis to use significantly less natural gas; reduce carbon emissions by approximately 16,000 tons per year; and provide increased ethanol production, achieving a lower carbon intensity biofuel that supports the goals of the California Low Carbon Fuel Standard (LCFS) and the US Renewable Fuel Standard (RFS).

—Hiroyuki Kakiuchi, Manager of the ZEBREX product line at Mitsubishi Chemical Company

The ZEBREX system has been installed in approximately 70 alcohol production plants worldwide. The system is a continuous membrane dehydration technology to separate water from ethanol for purification into fuel quality biofuel at lower cost than the energy-intensive PSA units commonly used at ethanol plants.



Sounds good - 25% less energy used to make bioethanol.
What's not to like - (the capital cost ?)
Lets hope it works and scales.


I note that we're not given anything resembling a per-unit energy savings.

Fortunately, we can work it out.  16,000 tpy (16 million kg) divided by 60 million gpy comes to 267 gCO2/gallon.  This is just under 10% of the CO2 produced by burning 1 kg of methane, so based on a 25% reduction we can calculate that the remaining energy consumption is equivalent to about 0.3 kg of methane per gallon.

0.3 kg of methane is about 16.7 MJ of thermal energy (HHV).  The LHV of ethanol is almost exactly 80 MJ/gallon, so the production of ethanol consumes over 20% of its net energy value in natural gas alone.  Adding the inputs for electric consumption and the natural gas used to fix nitrogen for fertilizer, and ethanol looks to be a very inefficient way of turning fossil fuel into a not-very-bio fuel.

Tim Duncan

OK it's not made of unicorn farts. Do you know of a more economical way, a lower carbon way? Many have been trying to put Nat Gas in our fleet for years. This is a way to do that, with minimal impact to distribution and consumer and even less carbon. Economically maintains space, efficiency and power availability of most engines, again much better than NG. And ethanol in general is very large scale. I have been very pleased over 20+ years of watching how carbon and economics of US ethanol have gained impressive ground.

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