Chevron’s forgotten biofuels wonder-tech gets a second life at Iowa State

September 27, 2016 |

bd-ts-092816-chumbawumba-smYou may recall that The Bloomberg investigative team of Ben Elgin & Peter Waldman in 2013 published an expose on Chevron claiming that the company had developed — then buried — a Catchlight Energy project that could profitably make renewable gasoline at $2.18 per gallon?

Originally the venture was intended to build 17 plants by 2029, making 2 billion gallons of renewable fuel, starting with a $370 million commitment by 2013 and a first commercial plant in 2014. The technology used solvent liquefaction to make bio-oil, which could then be upgraded to fuel-grade at a Chevron refinery.

Catchlight was a JV between Chevron and Weyerhaeuser.

The Bloomberg report pointed to an internal Chevron report, written in 2009, that concluded it would be cheaper to buy renewable energy exemptions than make renewable fuel. And, according to Bloomberg, a few months after the report appeared, Catchlight Energy’s budget to deploy the technology was scaled back.

In the Digest’s reporting, we cautioned that the tech was, at the time it was put on the back burner, at pilot stage. What happened to it?

The Road to Ames

Today, the solvent liquefaction tech is installed and operating at Iowa State’s BioCentury Research Farm in a joint project with Chevron, still at pilot stage, converting biomass such as quarter-inch wood chips into a bio-oil that can be processed into fuels or chemicals and a biochar that can enrich soils.

It doesn’t have a name, so we’ll call it Chumbawumba, after the group behind the 90s hit Tubthumping and its hypnotic “I get knocked down, but I get up again, you’re never going to keep me down” chorus. (Relive the 90s, here.)

The project is supported by a four-year, $3.5 million grant from the U.S. Department of Energy’s Biomass Research and Development Initiative, obtained by Iowa State.

The idea goes back to 2011, not long after Chevron decided not to proceed with development of its Catchlight project, and Iowa State and the DOE popped up and figured out a way, with Chevron, to keep the project alive — via a Biomass Research and Development Initiative Award .

At the time DOE said, “This project is a three-year collaboration to develop an “end-to-end” system to produce bio-gasoline, bio-diesel and associated chemicals from corn stover, forest residuals and intercropped forest-grown switchgrass. Catchlight Energy will collaborate with ISU to relocate their pilot plant to advance the solvent liquefaction technology. This unique solvent system is a nearer-term technology to convert biomass to an advanced bio-crude which can be processed in a conventional refinery.”

The Chevron-Iowa State collaboration actually got underway in 2013 when Chevron moved its $1.4 million Small Continuous Liquefaction Unit from Houston to the research farm just west of Ames. The company was looking for a research partner to develop the plant for continuous production and to build a system for recycling solvent back into the production process. As part of the agreement, Chevron has donated the pilot plant to Iowa State.

What does it look like?

Psst, don’t tell Chevron we showed it to you. Here’s Chumbawumba.


The technology idea

The process begins with a proprietary solvent that’s mixed with wood chips or other solid biomass. The mixture is processed under moderate temperatures and pressures and the resulting slurry is extruded into a reactor.

Now there are solvents and solvents. Water is a typical one, and supercritical water can be a powerful solvent — and that’s the basic technical idea behind Renmatix technology for producing cellulosic sugars from wood.  Ionic liquids have also been used, and JBEI is hard at work bringing that technology forward. In this case, there’s a proprietary solvent that has been kept a little bit mysterious,

After heating in the reactor, production is split into two processing streams: The upper handles gases and vapors, the lower handles liquids and small amounts of solids. A series of filters and separators along both streams recovers bio-oil, small amounts of biochar and solvent for recycling.


What’s solvent liquefaction as opposed to pyrolysis?

“In pyrolysis, the molecules have to be broken down into small enough pieces so they they can volatize” explains Robert Brown, the Anson Marston Distinguished Professor in Engineering at Iowa State University and Director of the Bioeconomy Institute. Of course, that’s only the mild-mannered alias of the Godfatha of the Pyromaniax.

“In solvent liquefaction, they don’t have to break down to that extent, they are in a solvent that moves out of the reactor, so you see a different set of molecular weights. Also, the carbohydrates in solvent liquefaction can be converted in material that is more useful as a starting point for making fuels, than is sometimes the case in pyrolysis, so you can get a better yield.”

So, why isn’t there more activity in solvent liquefaction?

“If you go to technical conferences, there are usually only a small number of papers on solvent liquefaction, and part of the reason is that there are special challenges,” Brown explains. “For one, getting a slurry of water or some organic solvent through the reactor with a relatively viscous material is hard on pumping equipment. Plus you have the challenge of ensuring that you don’t get overly dilute product, and in this case we are operating reactors at high pressure.”

What’s makes this tech different?

“Well, one thing that is interesting in this process,” says Brown, “is that we are trying to produce the solvent that we use. So we have an organic solvent, instead of water. We use some of the product as a solvent, and generate more of it with the process, and then we take some off and we recycle the solvent. In practice, we are studying how to optimize the process of distinguishing the organic compounds we have produced versus the organics that are the solvent.”

Who’s working on it?

There’s this project, of course. And this PNNL project aims at whole algae liquefaction.  Petronas has one, here too. We looked at a whole bunch of cracking technologies here in “2014: Get cracking!

What do you have? What do you get?

You have ontinuous solvent liquefaction, product separation with direct solvent recycle and online solids removal. You get a bio-oil that is low in oxygen and therefore more stable than other bio-oils. Well, sorta on that oxygen content. Back to that in a sec.

The technical goals of the DOE project

The DOE-funded project with Iowa State and Chevron Technology Ventures aims for:

— 8 hours continuous solvent liquefaction operation
— Bio-oil mass yield>30%
— Bio-oil oxygen content<25%
—15 day hydroprocessing operation with production of biocrude with oxygen content < 2%

Things to watch out for

25% oxygen content? Ouch! That’s more than any known hydrotreating technology installed at a refinery can handle.

The rebuilt pilot

“This pilot plant is like a mini commercial system,” said Robert C. Brown, the director of the Bioeconomy Institute and an Anson Marston Distinguished Professor in Engineering. “A good pilot plant has all of the unit operations that take biomass to a product. It’s a big engineering challenge to tie all the steps together and have them operate in concert.”

“Our modular approach to the plant design allowed for a fair amount of prototyping and proof-of-concept experiments along the way,” said Martin Haverly, a doctoral student in mechanical engineering and the lead design engineer for the project. “The system is a blend of commercially available products and custom solutions, all tied together at an industrially relevant scale. All of these efforts helped us end up where we are now, with a safe and functioning pilot plant.”

“This is the culmination of everything we’ve learned about building pilot plants in the past 10 years,” said Lysle Whitmer, senior thermochemical research engineer for Iowa State’s Bioeconomy Institute. “This is really a gem that represents everything we’ve learned thus far.”

Whitmer said the engineers have now demonstrated the viability of every one of the pilot plant’s operations. They’re still working to efficiently and simultaneously run all the operations. The pilot plant operates about once a week, Whitmer added. It can process about a pound of biomass every hour and typically runs for 15 to 18 hours at a time.

Chevron’s take

“Chevron’s internal and university-partnered R&D activities have been very successful in obtaining fundamental knowledge that enabled us to rapidly climb the biofuels learning curve,” said Rick Powell, general manager of Downstream & Chemicals, Fuels and Products Strategy.  “Programs such as the one with Iowa State help Chevron map the competitive landscape, deselect technically or economically unfeasible feedstock and technology options, and identify preferred paths for commercial collaboration.”

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