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The APR process. Click to enlarge.

Virent Energy Systems, the developers of an Aqueous Phase Reforming (APR) process that converts sugars and glycerin directly into hydrogen and other fuels, has raised a $7.5 million round of private venture financing led by Cargill Ventures.

Honda Strategic Ventures, Venture Investors, and Advantage Capital Partners also participated in this round, which will be used for product development and commercialization of its APR process.

The APR process offers a cost-effective and thermally efficient method for producing hydrogen, fuel gas, some liquid fuels and high value chemicals using renewable biomass. The company has already demonstrated and sold a system that produces SuperNatural Gas, a mixture of hydrogen and alkanes to fuel internal combustion engines. (Earlier post.)

With high efficiency and low equipment costs, this low-temperature, direct conversion process can be used for distributed power systems, fuel stations, centralized fuel production or, longer term, mobile applications. The APR systems can be designed to deliver predominantly hydrogen or alkanes (i.e. methane, ethane, propane and butane), or a customized blend of these fuels.

Virent was founded in 2002 by Dr. Randy Cortright and Dr. Jim Dumesic from the University of Wisconsin and already has received nearly $4.5 million in grants from the Department of Energy and National Institute of Standards and Technology.

Cargill Ventures is the venture capital arm of Cargill, the international provider of food, agricultural and risk management products and services.


Rafael Seidl

Note that glycerin is another word for glycerol, i.e. propane-1,2,3-triol. This compound is a byproduct of the transeesterification phase of regular biodiesel production.

As biodiesel production expands, the market value of glycerol as a feedstock for e.g. the cosmetics industry will fall. The option of using it in a second biofuel process is exciting. The only fly in the ointment is that APR requires sugars as inputs. However, the same pretreatment technologies that are being developed for cellulose ethanol could be applied to the agricultural waste associated with biodiesel production.

Ergo, by combining biodiesel raffination, APR and hemicellulose pre-treatment, you could assemble a biorefinery producing a mix of biodiesel, SuperNatural Gas and hydrogen. The methanol requires for the biodiesel plant could be derived from the methane produced. Unlike existing biorefineries, this setup would allow the whole plant (soybean, rapeseed, jathropha et al.) to be used, rather than just the oil-bearing seeds.

An Engineer

Biodiesel on large scale will soon have its butt kicked by TDP for reasons including:
1. Higher efficiency.
2. Ability to process a dirty oil product (have you seen the pictures of those turkey guts? - see slide #6
3. Superior product, hydrocarbon (TDP) vs methyl ester.

Of course both processes produce glycerine/glycerol as a byproduct, but I am not sure TDP can recover it cost effectively. At Carthage they seem to dump it.

Both processes are utlimately going to limited by feedstock. How much fat/oil/grease can we produce (sustainably)? Probably not that much. Of course, TDP claims to be able to produce oil from any organic waste. That claim remains unproven at this point.

An Engineer

The exciting thing about this process is not the ability to produce hydrogen, but the ability to produce hydrocarbons from biomass at moderate process conditions. This would probably be far more cost effective than cellulosic ethanol, and could potentially yield a superior product. Methane, ethane, propane and buthane are all gaseous, but the same researcher (Dumesic) is behind another process (Four-Phase Dehydration/Hydrogenation, 4-PD/H) that claims to produce higher alkanes (oil) out of carbohydrate (biomass) -

Taking biomass to oil using moderate process conditions - now that is a step in the right direction!

Rafael Seidl

An Engineer -

I'm aware of TDP and quite like the process. With the right process parameters, it can turn almost any organic chemicals into carboxylic acid. However, getting from there to finished products such as #2 diesel requires more sophisticated (read: expensive) petrochemistry than the transesterification of biodiesel. Afaik, there is no glycerol waste in TDP.

TDP's great strength is the ability to render potentially contaminated feedstocks (animal caracasses, medical waste etc.) harmless and produce fuel into the bargain. It remains to be seen if TDP can be cost-effective for agricultural waste feedstocks, e.g. corn stover or sawdust. So far, the only TDP plant in the world is ConAgra's in Carthage while biorefineries are going up left, right and center.

Meanwhile, if the above APR process can be modified to yield liquid alkanes or alcohols, that would indeed be a huge boon. EEI has a competing system for butanol production via fermentation, also a low-temeperature process.

For the US, the important thing is that new biofuels be suitable for spark ignition rather than diesel engines. This is because thanks to EPA/CARB regulations, diesel supply outstrips demand. The surplus is exported to Europe, which in turn ships its excess gasoline to the US. All this shipping to and fro entails risks and increases total consumption.

An Engineer

I am affraid you are misinformed about TDP. That is not surprising. The company (CWT) has not been a well of information. That is also understandable, they are interested in making a profit, not in proving themselves to skeptics, of which there are enough.

If you look at the slide show I referenced above (, slide #9 and #11) that glycerol is indeed a byproduct of TDP.

While we are on slide #11, notice that the plant uses sulfuric acid to aid hydrolysis (aka depolymerizarion) in the first stage. This makes the first stage very similar to Dilute Acid Hydrolysis ( which is, of course, one of the ways to prepare feedstock for cellulosic ethanol.

In effect, the first stage would convert fat to glycerol and fatty acids, carbohydrates to sugars (monomers) and protein to amino acids.

Most importantly, the Carthage TDP plant only sends the fat soluble portion to the second stage. That would be fatty acids and some of the amino acids. The bulk of the amino acids and all the glycerol (with any carbohydrate) goes to the effluent.

CWT neatly markets this effluent as a great fertilizer, see slide #23 to #25. That may be right. However, it also means a lot of BTU in the feedstock leaves the system in the effluent. CWT's claim of 85% efficiency seeems all the more unlikely here.

The carboxylic acids you refer to is a function of the feedstock: fats/oils/grease is hydrolyzed to yield glycerol and fatty acid (carboxylic acids). Proteins yield amino acids, which could also be classified as carboxylic acids, I guess. Carbohydrate would not yield any carboxylic acids.

Notice that the TDP second stage is all about converting the carboxylic acids to hydrocarbons, see slide #15: "Decarboxylation is main reaction; Deamination + some thermal cracking" Not complicated petrochemistry at all.

I know Discover magazine likes to breathlessly report that "anything" can be converted into oil. Perhaps it can. That claim, however, remains unproven. Notice that converting glucose (from cellulose) to a hydrocarbon would be a lot more complicated than decarboxylation. Hence my skepticism.

BTW, another good article on TDP is It was presented before Carthage got to full capacity, so it is a bit dated. Specifically it still claims 85% efficiency. It claims 500 bpd from 210 ton/d of waste. As the Discover article conceded, it is more like 500 bpd from 290 t/d. In other words, rather than getting 2.4 bbl/ton of waste (as claimed in the article), they are getting more like 1.7 bbl/t. That would suggest overall efficiency is not 85%, but rather 62%.

Bottom line: TDP is still a great process for converting waste grease into oil, superior to biodiesel in its ability to handle a dirty feedstock and also its product. Beyond that we have to wait and see...

Rafael Seidl

Thx for the link, quite enlightening.


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