The Lowdown on Miscanthus

Now that Blogger has determined that I am in fact a real person (see this note for an explanation), I am back in business. I notice the Barack Obama is now in favor of my proposal for allowing drilling and using that to fund alternative energy. Just glad I could help. Call me if you need an energy secretary who detests politics and doesn’t respond to direction very well. More on that proposal in a later post, but first there was some topical alternative energy news from a couple of days ago.

A new report from researchers at the University of Illinois suggests that using Miscanthus as a feedstock for cellulosic ethanol production would be far superior to switchgrass:

Miscanthus can meet U.S. biofuels goal using less land than corn or switchgrass

Using corn or switchgrass to produce enough ethanol to offset 20 percent of gasoline use – a current White House goal – would take 25 percent of current U.S. cropland out of food production, the researchers report. Getting the same amount of ethanol from Miscanthus would require only 9.3 percent of current agricultural acreage.

“What we’ve found with Miscanthus is that the amount of biomass generated each year would allow us to produce about 2 1/2 times the amount of ethanol we can produce per acre of corn,” said crop sciences professor Stephen P. Long, who led the study.

In trials across Illinois, switchgrass, a perennial grass which, like Miscanthus, requires fewer chemical and mechanical inputs than corn, produced only about as much ethanol feedstock per acre as corn, Long said.

One finding that I felt was significant:

“One of the criticisms of using any biomass as a biofuel source is it has been claimed that plants are not very efficient – about 0.1 percent efficiency of conversion of sunlight into biomass,” Long said. “What we show here is on average Miscanthus is in fact about 1 percent efficient, so about 1 percent of sunlight ends up as biomass.”

That’s pretty good solar capture for biomass. It is far short of the efficiency of solar cells, but you have a built in storage mechanism - the primary weakness of solar power.

So what’s the catch? Seems like there is always a catch, doesn’t it? The catch is that it is still highly energy intensive to turn this biomass into ethanol. You have energy inputs in growing and harvesting the biomass, getting it to the ethanol plant, converting the cellulose to sugars, fermenting the sugars to ethanol, and then purifying the highly dilute broth to fuel-grade ethanol. That is of course the conventional cellulosic route, and as I have argued before I do not believe this route will ever be commecially viable. The chemistry and physics are strongly aligned against you, which is why we have spent over 40 years failing to crack this nut. That doesn’t mean that companies won’t try to commercialize. They are trying. I just don’t think they will be commercially viable, any more than I think a company is going to cure the common cold in the next 3 years.

Biomass gasification is another story. While the capital costs are still very high, in the long run you may be able to justify growing something like Miscanthus for a gasification plant to produce ethanol, methanol, or diesel. First, though, there is a lot of available waste biomass that could be utilized. Use the waste that is currently rotting or just being burned, and then let’s debate whether or not to dedicate good cropland to growing fuel.

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.

XTL: Promise and Peril

The following is a slightly modified version of an essay that I posted to The Oil Drum .

Introduction

I have stated on several occasions that I believe global warming is a greater immediate threat than Peak Oil. As long as the demand is there, energy companies will strive to supply fuel to the marketplace. To meet the demand, we will develop tar sands, while consuming enormous quantities of natural gas. We will turn natural gas (or even coal) indirectly (and inefficiently) into ethanol. Finally, we will turn vast quantities of carbon into fuel via what I term “XTL” technologies. XTL technologies consist of a partial oxidation (POX) reaction followed by the Fischer-Tropsch (FT) reaction. When the POX feedstock is natural gas, this is referred to as a gas-to-liquids (GTL) process. If the feedstock is coal or biomass, this is referred to as CTL, or BTL respectively.

I won’t go into a detailed explanation of the POX and FT reactions. What I will give is a quick, layman’s overview. When a hydrocarbon material is burned (e.g. natural gas, coal, biomass, etc.), it can be completely oxidized (combusted) to carbon dioxide and water, or it can be partially oxidized to carbon monoxide and hydrogen. The latter POX reaction is accomplished by restricting the amount of oxygen during the combustion, and it is a potentially deadly reaction should it inadvertently occur inside your home. The resulting mixture of carbon monoxide and hydrogen is called synthesis gas (syngas) and can be used in the manufacture of an abundance of organic compounds.

The FT reaction is a bit more complex than the POX reaction. You can find in-depth information on the FT reaction here. In short, the FT reaction converts syngas generated via the POX reaction into a distribution of long-chain hydrocarbons. Hydrocarbons in the diesel fuel range are very common, making this reaction an ideal way to extend the fossil fuel economy.

The Promise

At present, the economics for GTL are far more favorable than for CTL or BTL. There are enormous reserves of natural gas throughout the world. Worldwide reserves of natural gas are estimated to be 6,200 trillion cubic feet, of which 3,000 trillion cubic feet are estimated to be stranded. (Reserves are considered to be stranded if it is uneconomical or impractical to get them to market.) This is enough stranded natural gas to produce 300 billion barrels of fuel, according to Syntroleum (Warning: It’s a 3.4 meg PDF).

GTL is not a pipe dream. The process is technically viable, having been demonstrated on numerous occasions. It is economically viable depending on the price spread between natural gas and oil. Despite the fact that the capital costs for GTL plants are approximately twice those of conventional oil refineries, a number of projects have been announced in Qatar. Plants are being built, and the fuel produced will help supply some of the shortfall that Peak Oil will generate.

The Peril

Of course there is a catch. GTL is not all that efficient. There are efficiency losses during both the POX and the FT processes. It would be far more efficient to run automobiles directly on the natural gas. Due to the fact that the gas is stranded, this is obviously not an option. But the efficiency losses are significant. According to the Syntroleum link, it takes 10,000 cubic feet of gas to make 1 barrel of fuel. 10,000 cubic feet of natural gas contain roughly 10 million BTUs, but a barrel of fuel contains only around 5.5-6 million BTUs. Forty percent of the BTUs are either lost as radiant heat, or turned to steam and consumed in the GTL plant. Unless carbon sequestration is in place (unlikely), all of those BTUs ended up as carbon dioxide in the atmosphere. On top of that, the BTUs from the barrel of fuel are going to end up as carbon dioxide in the atmosphere once the fuel is burned in an engine.

The reason I find this more worrisome than Peak Oil is that I believe this path is inevitable, yet the consequences are unpredictable. We will make and use GTL fuel, as inefficient as it may be. Our carbon dioxide emissions are likely to accelerate in our quest to maintain affordable energy. As stranded gas supplies are consumed and GTL production peaks, there is CTL, with the same efficiency problems, waiting in the wings. From my view, the fossil fuel economy will be with us for a long time to come.

Look at the figure below, and think of the experiment we are conducting. Atmospheric carbon dioxide levels are at their highest levels in human history. The trend in the graph shows a linear increase in atmospheric levels. The trend didn’t deviate at all during the oil shocks of the 70’s.

Source: National Oceanic & Atmospheric Administration

I believe I can see the foresee the consequences of Peak Oil. It certainly won’t be a picnic. But I think I can plan for it, and I believe that we will eventually adjust to a post-oil world. But I can’t foresee the consequences of warming the earth up by 5 or 10 degrees C. Humanity has never had to deal with this problem. The Sahara Desert was once lush with vegetation and teemed with wildlife. Consider the impact if this is the fate of the Corn Belt of the Midwest. Yet I see nothing to indicate that we are going to veer from the course we have set.

Coming Attractions

Just wanted to provide a quick update, since it will be a few more days before I have a new essay up. I am trying to finish up an article on Peak Oil for Omninerd, and need to devote a couple of days toward working on that. I recently finished my first submission for The Oil Drum entitled Big Oil and Alternative Energy . Feel free to comment on it at The Oil Drum, or if you aren’t registered there you can comment on it in this thread. The article addresses the statements from various groups that oil companies should invest their record profits into alternative energy. I explain why this is wishful thinking.

Below is a list of subjects that I will be covering in upcoming essays (not necessarily in this order), along with a brief description. If you have a topic you would like to see addressed, let me know.

The Solar Economy - I have only mentioned solar energy on my blog in passing, but it is far and away my favorite alternative energy choice. There is nothing else that compares to the efficiency of direct solar capture. I can envision a society that is driven largely off of solar power, but electrical applications and many automotive applications would need to be operated via rechargeable batteries.

The Diesel Economy - Even if we had no oil at all left, we can produce diesel from coal, natural gas, or even biomass. The capital costs are pretty high, but the feasibility exists (and in fact, is already taking place).

Fischer-Tropsch - I plan to give a brief, layman’s overview of this very important reaction, which will enable The Diesel Economy. This is also how the Germans produced some of their liquid fuel in WW2.

GTL - Gas to liquids, or diesel production from natural gas. This option is currently well under way in Qatar.

CTL - Coal to liquids. This is Montana Governor Brian Schweitzer’s dream for Montana coal. While it is viable, capital costs will be high, and the environmental costs may be steep. I will have a detailed discussion of the issues.

BTL - Biomass to liquids. This one is the least developed, but has the most potential for producing diesel from a renewable resource. I will discuss potential hurdles to be addressed.

I am open to suggestions on other topics. As always, I will continue to comment on current events, so I expect this list of ideas to take me through the next month or so. But I am always open to suggestions.