Visit to New Choren BTL Plant

Figure 1. Choren BTL Production Process. (Source: Choren)

Introduction

I had to dig way back in my Gmail archives to figure out how it was that I first interacted with Choren. I had written several articles on biomass gasification in 2006, and when I announced that I would be moving to Scotland in early 2007, I received an e-mail from Dr. David Henson at Choren. David, at that time in Business Development at Choren and now the President of Choren USA, said he had been reading the blog, and he extended an invitation to visit the biomass-to-liquids (BTL) plant that Choren was building in Freiberg, Germany.

While I tentatively planned to visit several times while I was living in Scotland, it wasn’t until I recently moved to the Netherlands that I was actually able to make the visit. So here is some background information on BTL, followed by the trip report from my visit on April 18th, 2008 (the day after German Chancellor Angela Merkel and Rob Routs from Shell visited for the inauguration of the facility).

BTL Background

I have written a number of articles on biomass gasification. However, let’s review. Biomass gasification takes biomass - ideally some sort of waste (and I understand that the term “waste” can be contentious) plant material - and partially burns the material with a controlled amount of oxygen to produce carbon monoxide and hydrogen (synthesis gas, or syngas). One of the often overlooked benefits of the thermochemical approach over fermentation is that it can be used to produce chemicals, synthetic natural gas, or electricity - and from a wide range of feedstocks. There are many different variations of how the gasification process is done, and I will delve into the specifics of what Choren is doing in the next section.

Once you have produced syngas, you can go a number of different directions. You can burn the syngas to produce combined heat and power (this has some cleanliness and efficiency advantages over directly burning the biomass), produce methanol, ethanol (Range Fuels, Coskata, Syntec), mixed alcohols (Standard Alcohol, Power Ecalene Fuels), or hydrocarbons like diesel via the Fischer-Tropsch process (FT). This latter approach is what Choren is doing. The diesel they are producing is not biodiesel, but “green diesel” as I have described in this essay (scroll down to the “renewable diesel” section).

To my knowledge no other company in the world is as far along as Choren is in producing diesel (and maybe any liquid fuel) from gasifying biomass. Whereas Range Fuels is currently building a plant (and the schedule for that is already slipping), and Coskata is building a much smaller demonstration plant, Choren has been piloting their technology since 1998, and their new plant is mechanically complete. (Yet Choren - funded largely by private investors - has been pretty low-key, issuing a fraction of the press releases of some of the other biofuel companies).

Choren’s Process

The Choren process (incidentally, Choren’s name comes from Carbon, hydrogen, oxygen, and renewable) starts off by feeding biomass into a low-temperature gasifier (about 500 degrees C). The purpose of this step is to remove volatile components that will form tars at higher temperatures. What remains in the gasifier is called char, and is fed into the high temperature gasifier.

Figure 2. Choren Gasification Process. (Source: Choren)

The volatile components are mixed with oxygen and steam and also fed into the high temperature gasifier where temperatures are around 1400 degrees C. Under these conditions, the volatile components are broken down into syngas. The char is first pulverized, and then blown into the bottom of the high-temperature gasifier. The gas that exits the high-temperature gasifier is cooled, generating steam in the process that is used for power generation. The gas is then further treated (filtered and scrubbed), and it is ready for the Fischer-Tropsch process. You can see an animation of the entire process here.

The gasification section of the plant has been in operation since 2004, proving the scale up of the design. Since 2005, the FT section of the plant has been under construction and is now mechanically complete.

I won’t go into detail on the FT process. That technology has been around for almost 100 years, and is best-known as the process by which Germany produced their fuel from coal in World War II. Shell - a world leader in FT technology - provided the FT for the Choren plant. If you are interested in learning more about Shell FT, you can read here about the 15 years of experience they have gained from their gas-to-liquids (GTL) plant in Bintulu, Malaysia. (In addition to providing the FT technology, Shell is also an investor in Choren).

The Plant Tour

It was difficult to find the place, and I got to brush up on my German a couple of times when I had to ask for directions. But finally we (I was with a colleague) found the place and met up with David. He started off with an introductory slide show in which he walked us through the process. One of the more interesting comments he made was that the potential production of their second generation product (dubbed SunDiesel®) is up to 3 times the production of first generation fuels. A third party analysis of various biofuels may be found here, at the Fachagentur fur Nachwachsenden Rohstoffe (FNR). This agency is essentially the German Renewable Energy Department. Detailed information on various BTL platforms can be found here.

Figure 3. Choren BTL Plant in Freiberg, Germany. (Source: Choren)

The new Choren plant, utilizes forest residue and waste wood and will take in 68,000 tons of biomass per year and produce 18 million liters of diesel and 45 MW of power. One thing David mentioned that too many in this business don’t seem to get is “You know, biomass just isn’t very energy dense.” Therein lies the source of a lot of people’s misconceptions about rapidly scaling up biomass to replace petroleum. The energy density is problematic to say that least - and this poses big logistical challenges.

We finally got to walk around the plant, and they have done a really nice job. Everything was brand new, and the design was well-thought out and well-engineered. This was not like a typical dirty, old refinery or ethanol plant I have walked through before: This plant was a Cadillac. Of course it’s a Cadillac yet to be driven, but it sure was a pretty picture. Here are some facts about the plant, courtesy of Choren:

Maximum production: 18 million litres of BTL p.a (= the annual requirement of about 15,000 cars)
Biomass requirement: About 65,000 tonnes of wood (dry matter) p.a.
Raw materials: Forest residue and waste timber
Supply is secure for several years
Investment: About €100 million
Technical details: 31.5 km pipelines, 57 km electrical cables,
5,000 fittings, 5,000 measuring signals,
60 pumps, 181 containers and reactors
45 MWth output
Partners: SHELL, Daimler and Volkwagon
Synthesis/hydrocracking partner: Shell

Of particular interest was the material handling piece, as this is a major cost factor in driving up the capital costs in a BTL plant. We traced out how the material comes into the plant, and how the flows of volatiles and char come off of the low-temperature gasifier. The one piece we didn’t really look at was the FT back end, but then again I have seen those before.

So, where do things stand, and what’s next? From the Choren site:

Over 150 suppliers and around 50 assembly companies, including many from the region, were involved in the building of the Beta plant. CHOREN designed and manufactured 180 main components itself. Over 600 companies had been involved in the development of the Carbo-V® technology. By April 2008 around 800,000 man-hours have been utilized in development and assembly, and the overall number of employees almost doubled.

In the coming months 113 sub-systems in 26 main operating units will be started up individually then in sequence. Around 1,200 steps will be needed for the commissioning of these systems, which in themselves consist of several sub-steps. A highly-complex process, which, not unusually for plants of this complexity, will take 8 to 12 months. CHOREN will receive valuable support for this from Shell.

What’s the Catch?

Capital costs for BTL are still pretty high. On the other hand, Choren’s costs were sunk at a much lower capital cost. Oil at $120/bbl should help them out quite a bit - provided they have a pretty good contract on their biomass. I have no doubt that they will be successful from a technical standpoint. They have a lot of experience on the gasification piece, having piloted it since the 90’s. Shell has many years of experience on the back-end FT piece. No doubt there will be some unexpected bumps as they commission the plant; after all it is a first of its kind and speaking from experience issues will come up. But they have a lot of engineers on staff, and I don’t think they will find any show-stoppers.

There are those who insist that using biomass for fuels can never be sustainable - so there are likely to be critics on that front. However, I disagree with this. There are a number of biomass sources that are true waste, and biomass can be grown sustainably. On the other hand, it can also be used to strip-mine the soil. Like most things, there are right ways and wrong ways to go about it. Biofuels have a part to play. But it would be foolish to try to completely replace petroleum with biofuels. That would require unsustainable practices. Incidentally, Choren has a life-cycle-analysis (LCA) on their process. Highlights can be seen here.

Short-term, I don’t know that this plant will be large enough to be profitable. I don’t think that’s the primary purpose; I think proving the technology for future plants is the purpose. In the longer-term, even though I am a fan of electrifying our transportation options, we will always have a demand for liquid fuel. Choren is trailblazing in an area that I believe will supply our liquid fuel in the future. The only question is, “How far off is that future?”

Additional Reading Material

Brochures and lectures for downloading may be found on Choren’s site here.

Any Biomass into Oil

I have mentioned LS9 here on several occasions, because I think what they are trying to do is pretty cool. They are trying to engineer bacteria that can consume biomass and excrete hydrocarbons. I have said before that I think someone will crack this problem sooner or later.

Then today I just ran across this story:

Anything that grows ‘can convert into oil’

Company finds natural solution that turns plants into gasoline

After three years of clandestine development, a Georgia company is now going public with a simple, natural way to convert anything that grows out of the Earth into oil. J.C. Bell, an agricultural researcher and CEO of Bell Bio-Energy, says he’s isolated and modified specific bacteria that will, on a very large scale, naturally change plant material – including the leftovers from food – into hydrocarbons to fuel cars and trucks.

“What we’re doing is taking the trash like corn stalks, corn husks, corn cobs – even grass from the yard that goes to the dump – that’s what we can turn into oil,” Bell told WND. “I’m not going to make asphalt, we’re only going to make the things we need. We’re going to make gasoline for driving, diesel for our big trucks.”

The agricultural researcher made the discovery after standing downwind from his cows at his food-production company, Bell Plantation, in Tifton, Ga.” Cows are like people that eat lots of beans. They’re really, really good at making natural gas,” he said. “It dawned on me that that natural gas was methane.”

Bell says he wondered what digestive process inside a cow enabled it to change food into the hydrocarbon molecules of methane, so he began looking into replicating and speeding up the process.”Through genetic manipulation, we’ve changed the naturally occurring bacteria, so they eat and consume biomass a little more efficiently,” he said. “It works. There’s not even any debate that it works. It really is an all-natural, simple process that cows use on a daily basis.”

Is it for real? Hard to say. The concept is not science fiction. This is not that far removed from what I worked on in graduate school. Cows utilize microbes in their stomachs that break down cellulose into organic acids like acetic, propionic, and butyric acid. It isn’t out of the realm of possibility that the bacteria could be tweaked to produce butane instead of butyric acid.

However, longer chain hydrocarbons are going to be more difficult. It will take more than minor tweaks (IMO) to get rumen microbes to produce something like gasoline or oil. Long chain acids are produced, but in very low concentrations. Even if they got hydrocarbons produced instead of acids, the hydrocarbons in the gasoline range would be of very low concentration. I also find it a bit odd that “it dawned on him that natural gas was methane.” That’s not really a comment I expect to hear from someone on the cutting edge of biofuel research.

The article mentions a patent - presumably pending - but I have spent half an hour searching for it at the USPTO site without any luck. If anyone runs across it, let me know. That will give me a better idea of whether this is more like TDP - in that very big promises were made that never materialized - or whether there is actually something to this.

Cellulosic Ethanol Reality Check

I firmly believe we should be aggressively researching the potential of cellulosic ethanol. This was after all the topic of my graduate school work at Texas A&M. But I think the hype has gotten way out of touch with reality at this point in time. There is a reason that nobody today is making money with cellulosic ethanol. It is quite possible that they never will, and in this essay I will discuss the reasons for that.

I did an interview with a major publication last week on the topic of cellulosic ethanol. I won’t divulge any details, because I don’t want to leak out anything before it is published. But during the course of the interview, I made the point that one of the challenges is in securing a large and steady local supply of biomass to run through the plant. This was one of the points I made in my essay Cellulosic Ethanol vs. Biomass Gasification. Then I was asked about just how much biomass it would take to support a cellulosic ethanol plant. So I decided to do a little calculation.

Iogen, probably the closest to commercializing cellulosic ethanol, has reported that the theoretical yield of biomass to ethanol is 114 gallons of ethanol per ton of biomass. However, what they actually achieve in practice is 70 gallons per ton. Let’s consider a typical mid-sized 50 million gallon per year ethanol plant. Using Iogen’s demonstrated yields, the biomass requirement would be 50 million/70 = 714,286 tons of biomass per year. According to Dr. Bruce Marcot, an ecologist at the USDA Forest Service the average Douglas fir yields about 1660 lbs of pulp (90% of the tree’s weight). So, to run a mid-sized cellulosic ethanol facility would require the equivalent of 714,286 tons * 2000 lbs/ton /(1660) or 860,585 Douglas firs PER YEAR. That’s a lot of biomass, and it puts into perspective the issue of a declining EROEI as biomass must be secured from farther afield.

What does this mean? Even if one achieved the theoretical limit of 114 gal/ton, it is still going to be very difficult to grow enough biomass to keep the plant going. Furthermore, consider the conversion penalty that is being paid when compared to corn ethanol. Let’s presume for a moment that the conversion for corn is the same as for cellulosic ethanol. There are 56 lbs in a bushel of corn. In our example above, it took 714,286 tons to run the 50 million gallon per year facility. This much biomass is equivalent to 714,286 tons * 2000 lbs/ton * 1 bushel/56 lbs = 25.51 million bushels of corn. In a conventional corn ethanol plant, that much corn would produce about 25.51 * 2.8 = 71.43 million gallons, or 43% more than we would get from the same amount of biomass in a cellulosic ethanol plant.

On an energy equivalent basis, converting 860,585 Douglas firs to ethanol will displace 0.02% of our annual gasoline supply on a gross basis (not counting the fossil fuel inputs to produce and process the ethanol). If you look at the USDA reports on corn ethanol, they say that to produce 75,000 BTUs of ethanol the fermentation/distillation requirement is 50,000 BTUs on average. That is from actual plant surveys as reported in their 2004 report. However, that is for solutions that are 15-20% ethanol. Cellulosic ethanol produces a crude product that is only 4% alcohol, meaning it will take quite a bit more than 50,000 BTUs to separate it out. I can tell you from experience that once you get down to 3% alcohol, it is classified as a waste stream and sent to wastewater treatment.

Future cellulosic ethanol plants are envisioned as being supplied by something like switchgrass or miscanthus. Will they yield more or less biomass per acre than corn? According to Questions & Answers about Miscanthus:

Over large areas, under typical agricultural practices, an average of about 8t/ha (3t/acre dry weight) may be expected at harvest-time.

That means our 50 million gallon ethanol plant, displacing 0.02% of our annual gasoline demand, would require 714,286/3 = 238,000 acres. To displace 50% of our current gasoline consumption of 140 billion gallons per year would take 70 billion/0.65 (this is for the lower energy content of ethanol) * 238,000/50 million, for a total acreage requirement of 513 million acres. This is about 13% of the land area of the United States; land which is presumably being currently used. This is also about 7 times the land area currently utilized for corn production.

A similar story yesterday came out that echoed this theme:

Study: Up to 100 million acres needed for renewable energy crops

Some excerpts from this story:

As many as 100 million acres of cropland and pastures would have to be dedicated to cultivating biomass fuels like switchgrass to support a national goal of 25 percent renewable energy use by 2025, a University of Tennessee study says.

Of course the reason cellulosic ethanol is so attractive is that the payoff would be huge, as the story explains:

But the rewards could be great. The study projects $700 billion in new economic activity including: a $180 billion growth in net farm income over the next 20 years; creation of 5.1 million jobs to support renewable energy enterprises; and government savings of more than $15 billion in crop subsidies.

The bottom line is that it is going to take enormous swaths of land to supply these cellulosic ethanol plants, and it is questionable whether a farmed source of biomass can be counted on to run the facilities. Better to locate cellulosic ethanol facilities close to a massive source of waste biomass – say a very large municipal dump in which paper is sorted out, a paper mill, or some other consistent source of large volume biomass. If you then use the unconverted waste biomass for process heat, you could end up with a workable process.

I certainly don’t advocate giving up on cellulosic ethanol, but we do need to approach this with a realistic and sober outlook. Men once desired to turn lead into gold. That was ultimately a futile quest (unless you want to try something like a nuclear reaction), but with cellulosic ethanol there is much more at stake. My impression is that many people in our government are basing energy policy decisions on the presumption that cellulosic ethanol is a done deal. My advice would be to have several backup plans.

Cellulosic Ethanol vs. Biomass Gasification

Introduction

I have this neat new cellulose conversion process. I am looking for funding and working on a patent application. The invention is a personal cellulosic biomass reactor. In the first reaction step, the cellulose is partially converted to CO and H2 (syngas). In the second step, one could do many things with the syngas: produce methanol, ethanol, Fischer-Tropsch diesel, or combust it for heat or electricity. I chose the combustion for heat route, which occurs very rapidly following the 1st step. The combustion products are CO2 and water, but the CO2 that is released is equivalent to the CO2 that was taken up by the biomass while it was growing. It is therefore neutral with respect to Greenhouse Gas emissions. I am hoping to get some government subsidies, or possibly Silicon Valley startup money for my invention. You can see a picture of it below.

Personal Cellulose Reactor

And there you have an example of how technical terminology and buzzwords can be used to confuse people. This is currently happening with cellulosic ethanol, so I thought I would write this essay to talk about the differences between cellulosic ethanol and biomass gasification.

What is Cellulosic Ethanol?

A popular trend in the media lately – encouraged by various ethanol advocates – is to liberally apply the “cellulosic” label. It has become a buzzword. This is the same thing that has occurred in the field of nanotechnology. Since lots of research funding is available for nanotechnology, things like ultra-fine powders are now being called nanotechnology. This trend is being driven, in my opinion, by a bid for some of the money flowing to the nanotechnology sector.

This brings us to some of the recent claims of a big breakthrough in “cellulosic ethanol” technology. However, one of the “breakthroughs” – biomass gasification - has been around for decades, and the technology is quite different from what is commonly denoted as cellulosic ethanol. It is not completely clear to me why some advocates are so eager to blur the distinction. Perhaps the law is written such that there is a danger of not receiving ethanol subsidies if a combustion process is used. Perhaps they want to be the first to claim commercial success of “cellulosic ethanol.” Perhaps they just want to give the public and the government the impression that great strides are being made in cellulosic ethanol technology, thereby encouraging more money to flow in that direction.

While cellulosic ethanol has only recently gained buzzword status, the term has been around for decades. The historical definition of the term implies certain particular process steps. There is some variance from process to process, but the things that are common are that the cellulose in the plant material is broken down into simple sugars, and then the sugars are fermented into ethanol.

More money than ever before is being poured into cellulosic ethanol, but there are multiple hurdles that have proven difficult to overcome. For a good layperson’s overview of the process, I recommend the recent article in the Chicago Tribune: Beyond corn: Ethanol’s next generation. I think the article paints a balanced picture of the technology. In brief, there are three major hurdles that have proven challenging to resolve.

The first is that plants have evolved defense mechanisms to prevent the cellulose from being easily broken down. Cellulose is actually a polymer – a long chain of connected sugars, and it is intermingled with hemicellulose and lignin. Cellulose provides structural strength to the plant walls. If it was easily broken down, microorganisms could attack the plants and limit their structural stability. What this means is that the cellulose must first be broken down with steam or a strong acid into component sugars that can be fermented, and this adds to the production costs. It is primarily this step that differentiates cellulosic ethanol from grain or sugarcane ethanol.

The second challenge is common to all ethanol fermentation processes, but not to gasification processes. The ethanol that is produced in a fermentation process is highly diluted with water. In fact, the ethanol produced from fermenting grain typically makes up only 15-20% of the solution, with the remainder being mostly water. For cellulosic ethanol, the picture is much worse. The crude ethanol in this case is typically less than 5%, with the remainder being water. Separating water and ethanol is a very energy-intensive process. Even where the EROEI is highly favorable, as is the case with sugarcane ethanol, the distillation step takes up a substantial amount of energy. While the distillation energy in the case of sugarcane is provided by burning the bagasse, separating out that much water is still a major energy sink.

The final challenge for cellulosic ethanol is that it takes a significant amount of biomass to produce the ethanol. As the nearby biomass is consumed, trucks have to travel farther to bring biomass to the refinery. This adds to the energy inputs, and worsens EROEI. According to the previously referenced Chicago Tribune article:

Richard Hamilton, CEO of Ceres Inc., Hamilton termed this “the tyranny of distance,” a major cost issue for would-be producers of cellulosic ethanol. If a refinery needs tons of biomass to produce fuel, he said, “by the end of the year you’re driving your truck a long way to get that wheat or corn stover.”

Some proponents don’t appreciate that there are multiple challenges in bringing cellulosic ethanol to market, and that these challenges won’t be easily solved. When asked about how long it would be before the challenges are resolved, Hamilton added:

“Trying to predict technology trends is a fool’s game,” he said. “I wish I could put my finger on just one bottleneck. But it doesn’t work that way.”

I don’t want to paint too grim a picture of the future for cellulosic ethanol. It is possible that all the hurdles will be overcome. But I also don’t want to present an overly optimistic scenario in which multiple bottlenecks are merely hand-waved away, and successful resolution is presumed. The challenges are well-understood. There just isn’t a clear path at this point to solving them all, and a process with multiple challenges will face a lower probability of success.

What is Biomass Gasification?

Biomass gasification is different from cellulosic ethanol in at least two major respects. First of all, it is a combustion process, not a fermentation process. As a combustion process, it can be self-sustaining once the combustion is initiated. It does not require continual inputs of energy as is the case with a fermentation process. The products of biomass gasification are syngas and heat, if the reaction is operated in an oxygen-deficient mode, or CO2 and steam (and much more heat) in the case where sufficient oxygen is supplied. In the case of the former, the syngas can be further reacted to make a wide variety of compounds, including methanol, ethanol, or diesel (via the Fischer-Tropsch reaction). A biomass gasification process followed by conversion to a liquid fuel is commonly referred to as a biomass-to-liquids (BTL) process.

However, there is one other major factor that differentiates biomass gasification from cellulosic ethanol. Biomass consists of a number of different components, including cellulose, hemicellulose, and lignin. In the case of cellulosic ethanol, only the cellulose and hemicellulose are partially converted after being broken down to sugars. The lignin and other uncoverted carbon compounds end up as (wet) waste, suitable for burning as process fuel only if thoroughly dried. Conversion is limited to those components which can be broken down into the right kind of sugars and fermented.

Gasification, on the other hand, converts all of the carbon compounds. Lignin, a serious impediment and waste product in the case of cellulosic ethanol, is easily converted to syngas in a gasifier. The conversion of carbon compounds in a gasification process can be driven essentially to completion if desired, and the resulting inorganic mineral wastes can be returned to the soil.

Cellulosic Ethanol vs. Biomass Gasification

Gasification processes are of course not limited to biomass. In fact, biomass is currently the last feedstock of choice for economic reasons. It is much easier to transport natural gas and feed it on a continuous basis to a gasifier. In fact, most syngas in the U.S. today is made from natural gas. Coal is another option for gasification, and coal gasification is currently the dream of Montana Governor Brian Schweitzer.

While natural gas is easier to handle, and coal is cheaper, biomass is the only option capable of producing sustainable energy and mitigating greenhouse gas emissions. It is therefore the option that is most desirable, in my opinion. It is also a better option than most other “renewable” alternatives like corn ethanol or cellulosic ethanol. The conversion is much higher for gasification, and the energy return will undoubtedly be better because the product won’t need to be removed from an aqueous solution.

Compared to cellulosic ethanol, there are few technical challenges to solve with biomass gasification. The problems with biomass gasification aren’t technical, they are economic. According to the EIA’s Annual Energy Outlook 2006, capital costs are $15,000-20,000 per installed barrel for a conventional oil refinery, $20,000-$30,000 for an ethanol plant, around $40,000 for gas-to-liquids (GTL), around $60,000 for coal-to-liquids, and around $120,000-$140,000 for biomass-to-liquids.

Capital Costs of Fuel Facilities
Source: EIA Annual Energy Outlook 2006

The reasons for this should be obvious – it is much more difficult to handle biomass than to handle natural gas, for instance. Until we are willing (or forced) to pay a penalty for using fossil fuels, or are willing to pay a premium for renewable energy, biomass gasification is going to be passed over in favor of lower capital options. In the long-term, though, biomass gasification has staying power as an option for using biomass as a transportation fuel.

Vinod Khosla and Kergy

What actually prompted my interest in writing this essay were the media reports of Vinod Khosla’s latest alternative energy venture. This has been hailed as a breakthrough in cellulosic ethanol. While some may consider this a subtle distinction, I think it is very important that people understand the difference. It may make sense to preferentially fund gasification options over cellulosic ethanol options, but this will be more difficult if the public doesn’t understand the difference.

A recent entry in Venture Beat brought Mr. Khosla’s new venture to my attention. The company is called Kergy, and details were discussed in a recent story in Wired written by Vinod Khosla. Mr. Khosla explains:

In the corner of an unmarked warehouse tucked away in an industrial neighborhood north of Denver, a new company called Kergy has what is, to my knowledge, the first anaerobic thermal conversion machine (which explains why Khosla Ventures is a seed investor). It’s a 6- by 4-foot contraption that stands about 8 feet high. It looks vaguely like a souped-up potbellied stove. But it runs cleanly enough to operate indoors.

Kergy’s machine is special because it makes cellulosic ethanol through anaerobic thermal conversion rather than through fermentation or acid hydrolysis. It does not need organisms or enzymes to do its work. Biomass is heated in an oxygen-free environment to produce carbon monoxide and hydrogen. Once that happens, “the world is your oyster,” says Bud Klepper, the engineer who invented this device. The carbon monoxide and hydrogen are then reconstituted into various alcohols – like ethanol. Better still, fermentation and acid hydrol¬ysis can take days to occur, but thermal conversion breaks down organic matter and converts it to ethanol in minutes.

And here’s the really exciting part: Because all organic matter contains carbon, Klepper can make ethanol out of cellulose or any form of organic matter. This means the usual suspects such as corn, switchgrass, sugarcane, and miscanthus but also any waste product such as wood chips, paper pulp, cow manure, and even human waste. Municipal sewage has been tested already, as has hog manure. “We could double the ethanol output of the Mead facility,” Klepper says. It’s a big leap forward on the biohol trajectory, and it is right in front of us.

In back of Kergy’s warehouse, workers are busy putting the finishing touches on a beautified and expanded version of his original thermal convertor. The new one is made out of lustrous red I-beams, shiny metal tanks and coils, bright blue metallic joints, and a porous metal-grating floor. The whole thing is 14 feet high, 40 feet long, and 25 feet wide and is capable of producing 15,000 gallons of ethanol a day. And the machine can be scaled for far more capacity.

I knew this technology has been around for a while, so I looked up Klepper’s patents. After reading through the claims, it wasn’t at all clear to me what differentiated Klepper’s version from the patents that came before. Sometimes it boils down to very subtle differences in the claims, so I wrote to Mr. Khosla asking for some information:

Hi Vinod,

Just finished reading the Wired essay. Of course I disagree with several of the things you wrote, but that isn’t the purpose of this e-mail. What I am particularly interested in are the claims on “anaerobic thermal conversion.” Some people have been calling this cellulosic ethanol, but that’s really a misnomer because it is a completely different process. It is actually biomass gasification to produce syngas, a technology that has been around for at least 30 years. So it certainly isn’t “the first anaerobic thermal conversion machine.” Lots of people have done this, just not commercially. The technology for turning the resulting syngas into methanol, ethanol, or even diesel (via the Fischer-Tropsch reaction) has also been around for many years.

As I am sure you know, the reason this hasn’t been done commercially before is the high capital costs per barrel of product. But I just did a patent search, and saw that Klepper has been issued a patent on the process. It just isn’t clear to me what distinguishes his patent from those that came before. Do you know? I am not trying to downplay the invention; differences in patents are often very subtle. But I am trying to determine how his patent differs from all of the other biomass gasification patents.

I will say that I believe you are on the right track with biomass gasification. I have never had any concerns about this technology, and I believe that this is clearly the future. I just don’t know if it will be commercially viable without subsidies or mandates, because it is much easier (and far less costly) to do the same process with natural gas (GTL). But it is certainly more efficient to gasify biomass than it is to ferment it. I think you will find that it would be far more efficient to turn the syngas into diesel, but you might lose out on the subsidies. I guess if the government accepts this process as cellulosic ethanol, then maybe they would accept that product as biodiesel (which would qualify for the subsidies).

Sincerely,

Robert Rapier

He responded, but on the topic of Kergy he wrote “I am not interested in public disclosure of what we are doing at Kergy at this stage. Hope you understand.” Of course I wasn’t asking for proprietary information; I just wanted to know what distinguished this patent from previous gasification patents.

Again, my purpose here is certainly not to denigrate those involved with Kergy. In fact, if an opportunity hadn’t come up recently at work (see the note at the end), I would seriously consider working for them. Mr. Khosla and I have discussed this, and I was contacted over the weekend by one of their Senior VPs. I think what they are doing is definitely a step in the right direction, and I think it would be fun to be a part of it.

I just want people to understand that this is not brand new technology, so they shouldn’t think that the cellulosic ethanol problem has suddenly been resolved with a breakthrough. Biomass gasification certainly works, but it worked 20 years ago. It is just a capital-intensive process that has the problem of competing against lower cost (but unsustainable) gasification options.

Personal Note

I recently accepted an offer to take up a management position within my company in Aberdeen, Scotland. I will be responsible for 10-15 engineers in our Europe and Africa business unit. Most of the work will involve exploration and production projects in the North Sea, but the best draw of all is that my family and I love Scotland.

My report date is February 1, 2007, and I will be pressed for time between now and then. Therefore, my posting will be sporadic over the next few months. Hopefully, after I get settled in over there, I can start contributing again on a regular basis. I have lived in Europe before, and I am slowly archiving the essays on our previous trips at Traveling in Europe. I plan to keep this updated as we travel around Europe. I will continue to maintain the same Gmail address, so feel free to contact me there with questions or comments.