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Idaho National Lab Developing Highly Carbon-Efficient Biomass-to-Liquids Process Combining High Temperature Steam Electrolysis and Biomass Gasification

9 January 2009

Biosyntrolysis
Overview of the Bio-Syntrolysis process. Source: INL. Click to enlarge.

Researchers at Idaho National Laboratory (INL) are developing a process—Bio-Syntrolysis—that combines high temperature steam electrolysis (HTSE) and biomass gasification to produce syngas for subsequent conversion into synthetic fuels and chemicals. The process results in the highly efficient conversion of biomass carbon to syngas (>90%).

Given the efficiencies of a typical Fischer-Tropsch process, Bio-Syntrolysis would thus convert about 90% of the carbon in biomass to liquid synthetic fuel, INL says. By comparison, INL notes, conventional biomass or coal gasification to liquid fuels converts only ~35% of the carbon to liquid fuel. Likewise, conventional biological routes for ethanol production convert only ~35% of biomass carbon to liquid fuel.

In Bio-Syntrolysis, process heat from the biomass gasifier produces the steam to improve the hydrogen production efficiency of the HTSE process, while the biomass itself is the source of the carbon. Hydrogen from HTSE allows a high utilization of the biomass carbon for syngas production, while the oxygen resulting from water splitting is used to control the gasification process. The new process is an evolution of INL’s earlier work on co-electrolysis (Syntrolysis).

Syntrolysis used high-temperature electrolysis with a solid-oxide electrolysis cell designed to take advantage of electricity from nuclear or renewable energy sources and industrial process heat to simultaneously convert water and carbon dioxide into syngas.

However, splitting pure CO2 is very energy intensive, noted Grant Hawkes, one of the INL team members.

We found that the amount of syngas produced per unit of electricity was a lot higher (~20%) for Bio-Syntrolysis compared to the Syntrolysis process. In the Bio-Syntrolysis process we make very little CO2 and mostly CO in the biomass gasifier. The amount of heat produced by making CO is just a perfect fit for how much heat we need to heat the water to the steam for the High Temperature Steam Electrolysis.

—Grant Hawkes
Biosyntrolysis2
Carbon utilization rates (top group) and syngas production efficiencies (bottom group) for different feedstocks at different gasifier temperatures. Source: INL. Click to enlarge.

In a modeling study, the INL team concluded that carbon utilization in the Bio-Syntrolysis process is only slightly affected by gasifier temperature, and ranges around 94-95% depending upon feedstock and gasifier temperature. Syngas production efficiency is closely tied to the power cycle efficiency. Assuming the thermal efficiency of the power cycle for electricity generation is 50%, (as expected from GEN IV nuclear reactors),the syngas production efficiency ranges around 70% to 73%.

The electrical power needs to be derived from a non-fossil source such as nuclear, hydro, wind or solar to keep the process carbon-neutral.

High-temperature electrolysis. INL researchers hit a milestone in September 2008 with a major scale-up of hydrogen production via high-temperature electrolysis, producing hydrogen at a rate of 5.6 cubic meters per hour—a major scale-up from earlier INL experiments on a smaller scale. (Earlier post.)

High-temperature electrolysis (HTE) adds in some of the energy needed to split water into its components (hydrogen and oxygen) as heat from a source such as high-temperature steam instead of electricity. Because the conversion efficiency of heat to electricity is low compared to using the heat directly, HTE reduces the overall energy required.

The electrolytic cell consists of a solid oxide electrolyte with conducting electrodes deposited on either side of the electrolyte. A high-temperature mixture of steam and hydrogen is supplied to the anode side of the electrolyte.

Regional Bio-Syntrolysis. INL is proposing locating Bio-Syntrolysis plants regionally, close to where the biomass is grown. A 25,000 barrel (1.05 million gallon US, 3.974 million liter) per day plant for full biomass to liquid fuels would entail a capital cost of around $2 billion and an annual operating cost of $1 billion per year.

The plant, according to INL analysis, would have a production cost of around $2.80 per gallon, and use 1,000 MW of electricity. Biomass would be gathered from an area 40-50 miles in diameter.

Widespread implementation of the process would require an enormous increase in non-fossil electrical power production.

INL began modeling and economic analysis of Bio-Syntrolysis in May 2008. That research is expected to continue through FY 2009. A patent for Bio-Syntrolysis is pending at the US Patent Office.

Resources

  • M. G. McKellar, G. L. Hawkes, J. E. O’Brien (2008) The Production of Syngas via High Temperature Electrolysis and Biomass Gasification (IMECE2008 - 68900)

  • Bio-Syntrolysis fact sheet

January 9, 2009 in Biomass-to-Liquids (BTL), Fuels, Gasification, Hydrogen Production | Permalink | Comments (11) | TrackBack (0)

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The plant, according to INL analysis, would have a production cost of around $2.80 per gallon, and use 1,000 MW of electricity.

WTF?? Is this suppose to be a "breakthrough"?

There are honnest enough to mention that it won't be a cheap process...the good think is that it requires less land and less biomass to carry from field to processing plant. The bad thing is that it requires massive H2 production. it can be done during low load of the electric grid at night when electricity is cheap. but I always have a problem when it comes to convert electricity to H2 then convert H2 to Ethanol. I mean it converty twice a clean energy into a final less clean energy, can't be very efficient and cheap. But it is true that converting biomass to biofuel is very inefficient as well without addition of H2.

"I always have a problem when ..."
Exactly! The problem is the 2nd Law of Thermo. Whenever there's an intermediary between source & end use there will be a loss. If you got carbon-less electricity, then use it directly to displace carbon producing energy. The Pickens Plan makes more sense than this.
Gasoline is $1.50 in the US and $9 in Europe. I say Market forces will fix the issue of liquid transportation fuel in the US.

The actual price of H2 is not so essential.
There will probably be many ways of producing cheap H2 in the future.
Though, it is a huge advantage to convert almost every carbon atom to fuel. If nuclear elektricity is used, the parameter 'efficiency' has only financial meaning, since the amount of waste produced per ton of fuel is minimal. If solar-thermal stations are used to produce H2, the amount of energy produced per acre is huge compared to even algae. Water is boiled to produce pressure for electricity and (part of) the 'waste'-steam is converted to H2. The overall efficiency will be very high since the heat for steam production is free. (you already have steam). In most actual powerstations, there is also abundant waste-steam.

What gets me is this line; "biomass gasification to produce syngas for subsequent conversion into synthetic fuels"

Syngas IS a fuel. Adding in an extra costly [in energy and dollars] step just to make a fuel in liquid form would not be needed if we were to convert some of our cars to run on gasious fuels. The Pickens Plan would be a good place to start, it would give us time - time to either electrify the transport sector or build up our biomass convertion capacity.

The Picken plan is interesting but it has a flaw, natural gaz production in US will be a problem moving forward, thet have already extracted the easy part and they started to extract the less easy part using horizontal drilling and shale gaz which are more expensive. The Picken plan only makes sense if you invest in setting biogas production from biomass which is still much more efficient than trying to make cellulosic ethanol from biomass.

Correct me if I'm wrong since I certainly am not going to dig deeply into this.

1) Isn't this nuclear reactor boosting output from biomass. Sort of like putting a supercharger on an ICE.

2) It may be a good idea. Superchargers have merits but they also have costs.

3) We need liquid fuels, domestically production is better, and I have long advocated nuclear power as the prime source of electricity.

3)Details: Do they say what liquid fuel they end with?

4) Gripes: They write this stuff as if it were sent from heaven engraved on tablets. So far this is mostly on paper although the engineers probably have it right.

If, politically, we can't build 4th generation nukes for city power then do we build them for this scheme? If we can use them for city power would that make more sense initially?

We don't have, AFAIK, any 4th generation plants in commercial use.

How much water is needed? That is a serious concern in most areas.

In this setup, they wanted to convert virtualy all biomass-carbon to fuel with using minimal 'external' energy for H2 production.
They proved it is feasible, but the price of the fuel depends greatly on the price of the 'external' H2.

If the aim would change to produce as much fuel-energy per biomass-carbon, they would need to add as much hydrogen as chemically possible. The result would be hytane (a maximal reduction of the carbon to only CH4 + some persentage of pure H2). Of course, then you have the (temporal ?) disadvantage of not having a liquid fuel.
Changing the catalists to produce maximal CH4 instead of liquid fuels is relatively easy.
For the moment this is a great achievement.
Also important is that every cent paid for this 'home made' fuel would go to the own economy, instead of OPEC. So even if it is more expensive than imported fuel, macro-economically it is probably much better. It's not so bad if fuel is somewhat expensive, but it is detremental if a trade-deficit kills the economy.

Re stopping at the syngas step and omitting conversion to liquid. Since syngas is mainly carbon monoxide and hydrogen it would be preferable to catalytically convert it to a mainly methane mixture. However I understand syngas doesn't have enough hydrogen (ie the stoichiometic ratio) and an external source is needed. The resulting mainly-methane gas should be compatible with CNG.

Re Pickens plan I think the current fad for building natural gas fired electrical generation is short sighted. Sure it produces less CO2 per kwh than coal but that electricity could also be produced by wind and nuclear, freeing up the gas for transport.

First off, let's clarify a few misconceptions: (1) the syngas is used to run through the Fischer-Tropsch process and create diesel fuel. The purpose of this process is not to make ethanol. (2) Please realize that this biomass is recyclable such as corn stover, wheat and barley straw, and wood chips.

The electrical supply for this needs to be non-fossil. Wind energy might be attractive in the midwest where there is a lot of biomass produced. The Idaho National Laboratory is the lead DOE lab for nuclear research, hence the proposal for using a nuclear plant. This process can use a Gen III nuclear plant or Gen IV, all it needs is electricity, not any process heat from the nuclear plant.

The H2 - CO ratio of the syngas obtained from biomass does not necessarilly have to be unfavorable. In fact, it can be made exactly 2 to 1 (suitable for FT), or the excess of H2 can be even higher. However, this way a considerable proportion of biomass carbon will end up as CO2 because of water gas shift. But so what, this is "recyclable" carbon dioxide anyway. Building expensive H2 production units will not outweigh the increase in fuel yield per ton of biomass.

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