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Study Finds Integrated Biorefinery Processes Could Be Highly Competitive With Petroleum Fuels on Efficiency and Costs, While Offering Substantial Reductions in Greenhouse Gas Emissions

Processing efficiencies for biorefinery scenarios (energy out as percent of feedstock lower heating value). Laser et al. (2009) Click to enlarge.

Biomass refining technologies integrating biological and thermochemical processing to produce biofuels and/or power could offer similar, if not lower, efficiencies and costs and very large reductions in greenhouse gas emissions compared to petroleum-derived fuel, according to a comparative analysis of 14 mature technology biomass refining scenarios.

The paper results from the “The Role of Biomass in America’s Energy Future (RBAEF)” project and is published in a special issue of the journal Biofuels, Bioproducts and Biorefining which presents a collection of papers with technology-oriented analysis resulting from the RBAEF project.

The RBAEF project, which was launched in 2003, is the most comprehensive study of the performance and cost of mature technologies for producing energy from biomass to date. It seeks to identify and evaluate paths by which biomass can make a large contribution to energy services in the USA and determine how we can accelerate biomass energy use. In addressing these issues, the study has focused on future, mature technologies rather than today’s technology.

—Professor Lee Lynd, Dartmouth College

The RBAEF involves experts from 12 institutions, and is jointly led by Dartmouth College and the Natural Resources Defense Council and sponsored by the US Department of Energy, the Energy Foundation and the National Commission on Energy Policy.

Professor Lynd, from Dartmouth College’s Thayer School of Engineering, and a co-founder of Mascoma Corp., a company commercializing a cellulosic ethanol production process, is co-author of five of the eight papers in the special issue. Three of these papers are open access, including a paper in which Mark Laser and his colleagues carry out the comparative analysis.

The biomass refining scenarios considered include both biological and thermochemical processing with production of fuels, power, and/or animal feed protein. The emissions analysis does not account for carbon sinks (e.g., soil carbon sequestration) or sources (e.g., forest conversion) resulting from land-use considerations. The scenarios evaluated are:

  1. Ethanol + Rankine power
  2. Ethanol + gas turbine with combined cycle (GTCC) power
  3. Ethanol + F-T fuels + GTCC power
  4. Ethanol + F-T fuels (w/once-through syngas) + CH4
  5. Ethanol + F-T fuels (w/recycle syngas) + CH4
  6. Ethanol + H2
  7. Ethanol + protein + Rankine power
  8. Ethanol + protein + GTCC power
  9. Ethanol + protein + F-T fuels
  10. F-T fuels + GTCC power
  11. Dimethyl ether + GTCC power
  12. H2 + GTCC power
  13. Rankine power
  14. GTCC power

The analysis compares the technologies in their mature context—i.e., a state of advancement such that additional R&D effort would offer only incremental improvement in cost reduction or benefit realization.

...performance parameters were selected consistent with the above operational definition according to a knowledgeable optimist’s most likely estimate. This is neither the optimist’s best-case estimate, nor the average, most likely estimate of experts spanning the optimist–pessimist spectrum. Estimates were made by members of the project team with some consultation with experts not part of the project, but without a systematic survey of such experts.

—Laser et al.

Overall findings include:

  • The thermochemical scenario producing only power achieves a process efficiency of 49% (energy out as power as a percentage of feedstock energy in); 1,359 kg CO2 equivalent avoided GHG emissions per Mg feedstock (current power mix basis); and a cost of $0.0575/kWh ($16/GJ) at a scale of 4,535 dry Mg feedstock/day, 12% internal rate of return, 35% debt fraction, and 7% loan rate.

  • Thermochemical scenarios producing fuels and power realize efficiencies between 55 and 64%, avoided GHG emissions between 1,000 and 1,179 kg/dry Mg, and costs between $0.36 and $0.57 per liter gasoline equivalent ($1.37 – $2.16 per gallon) at the same scale and financial structure.

  • Scenarios involving biological production of ethanol with thermochemical production of fuels and/or power result in efficiencies ranging from 61 to 80%, avoided GHG emissions from 965 to 1,258 kg/dry Mg, and costs from $0.25 to $0.33 per liter gasoline equivalent ($0.96 to $1.24/gallon).

Field-to-wheel CO2 emissions and petroleum use for mature biorefinery scenarios relative to a conventional gasoline base case. Vehicle fuel consumption is 12 L/100km (19.6 miles/gallon); base case emissions are 349 g CO2/km; base case petroleum use is 4.31 MJ/km. Laser et al. (2009) Click to enlarge.

Most of the biofuel scenarios offer comparable, if not lower, costs and much reduced GHG emissions (>90%) compared to petroleum-derived fuels. Scenarios producing biofuels result in GHG displacements that are comparable to those dedicated to power production (e.g., >825 kg CO2 equivalent/dry Mg biomass), especially when a future power mix less dependent upon fossil fuel is assumed.

Scenarios integrating biological and thermochemical processing enable waste heat from the thermochemical process to power the biological process, resulted in higher overall process efficiencies on par with petroleum-based fuels in several cases.

We conclude that mature biomass refining is highly competitive with the fuels currently available, based on all the factors considered. The most promising class of processes we analysed combined the biological fermentation of carbohydrates to fuels with advanced technologies that thermochemically convert process residues to electrical power and, or, additional liquid fuels. One of our important findings, which contradicts conventional wisdom, is that similar greenhouse gas emission reductions on a per ton biomass basis are anticipated for the production of liquid fuels and electricity via mature technology.

—Lee Lynd

The researchers also found that the mature cellulosic biofuel technologies analysed:

  • Have the potential to realize efficiencies on par with petroleum-based fuels.

  • Require modest volumes of process water.

  • Achieve production costs consistent with gasoline when oil prices are at about $30 a barrel.

The RBAEF project has examined many potential biorefinery scenarios, but there are still aspects that we did not examine. For example, a more extensive field-to-wheels life cycle assessment that incorporates the RBAEF process design results—including a comparison of alternative feedstocks—would be useful, as would an evaluation of chemicals co-production. Also, the papers in this special issue do not directly address the issue of gracefully reconciling large-scale biofuel production with competing land use and this clearly needs more study. Finally, it would be of great value to look at how we could find ways to accelerate progress towards the sustainable, large-scale production of cellulosic biofuels.

—Lee Lynd


  • Biofpr Special Issue: The Role of Biomass in America’s Energy Future. Volume 3 Issue 2 (March/April 2009)

  • Lee R. Lynd et al. (2009) The role of biomass in America’s energy future: framing the analysis. Biofuels, Bioprod. Bioref. 3:113–123 doi: 10.1002/bbb.134

  • Mark Laser et al. (2009) Comparative analysis of efficiency, environmental impact, and process economics for mature biomass refining scenarios. Biofuels, Bioprod. Bioref. 3:247–270 doi: 10.1002/bbb.136



I think there is an incredible amount of potential yet with cellulosic ethanol biorefining. Companies have only just begun to develop more productive strains of algae. There is all kinds of genetic modification that could be done to improve yields of Sweet Sorghum and energy cane. Across the sun belt of the USA, electricity from solar panels could be integrated into production processes to drive biorefining costs down further. We have only just begun.


Looks to be so much more Syngas Spin. Figures don't lie, but Herr Doktor Fischer Tropsch wants to slam shut that rapidly closing window of opportunity to do anything about climate catastrophe.


Gasifying those One Billion Tons of farm and forest biomass close to the growing area could prove beneficial. Make the syngas into methane and you can just pipe it to the use point.


I cannot see how this is evidence of some conspiracy to “slam shut that rapidly closing window of opportunity to do anything about climate catastrophe.”

How about February big cars & SUVs (NOT including mid sized SUVs, crossover nor pickups) out sold small cars 275k to 119k.

THAT deserves paranoia.


I knew Herr Fischer and Tropsch personally. I can only say they were hell of a lot nice guys.


I agree with SJC above; the biofuel that should be on the list is methanated syngas produced close to the biomass. That cuts the feedstock transport effort and keeps mineral nutrients in the soil. However extra unbound hydrogen input would help yields greatly.

Carbon neutral synfuel or syngas would be a great way to keep PHEVs on the road when oil is gone.

The Goracle


While Offering Substantial Reductions in Greenhouse Gas Emissions

Efficiency and self reliance are great. Cleaning up pollution (of which CO2 - exhaling - is not) is our duty to future generations. But lets leave the Globalwarmist religion OUT of the discussion. Religion has NO place in science. Fantasy theories (exaggerated models) regarding all coastal cities being underwater in 2020... no, now 2040... no, now 2100... is a pure money (follow the $$$$$) grab, paranoia, and well, silly.



I can't believe I'm agreeing with the Goracle.
Self reliance should be number one because both sides can agree on this, and we all win.
Self reliance, by definition, includes effciency...which we all agree on.
Its the global warming alarmists that start losing some of the crowd. (i include myself among them).


"..thermochemical processing enable waste heat from the thermochemical process to power the biological process, resulted in higher overall process efficiencies on par with petroleum-based fuels in several cases."

This says to me that you can have both thermochemical (gasification) and enzyme production in the same facility with even higher efficiencies. Perhaps, once you have extracted all you can with enzymes, you can process the rest with thermochemical, then return the biochar to the land. There are many possibilities on the way to renewable energy.

Henry Gibson

Sorry folks, there is no renewable energy. It is prohibited by the first law of thermodynamics. Solar energy is not renewable and almost all energy comes from the sun. The sun uses fusion and destroys hydrogen forever when it does. The sun is nuclear energy.

Fission energy is simply using up the energy formed into uranium and other elements by long defunct stars that took fusion to its limits.

Geothermal energy is just the same as fission energy. Atoms in the earth decay and keep the inside hot. Gravity contraction of the earth does some heating. Some hydrogen atoms may actually be involved in iron, nickel or palladium catalysed high temperature cold fusion reactions.

Since there is no renewable energy, now it can be decided which fossil energy to use based on cost and results rather than unproved religeous statements of the truth about the goodness of RENEWABLE energy.

Most creatures and plants that inhabit the earth would be better off if all humans boarded space ships and went to other planets.

It has been long known that cooking can be done with solar heat.

Water heating can be done with solar heat.

Small high efficiency light emitting diodes, LEDs, can provide useful light with low energy use.

Nickel-iron batteries can be made to last for a hundred years to store energy from solar cells for LEDs.

Parabolic mirror solar-electric generators can be made for remote individual use. Larger ones can be made for businesses and factories.

For industry and cities , nuclear reactors will be the cheapest, cleanest form of energy. People can pretend that the nuclear reactor a hundred feet below the city is geothermal energy. Nothing but ordinary buildings needs to be on the surface. Hyperion Power Generation proposes to have unattended buried units in a few years using uranium-hydride moderation and regulation.

Big Nuclear reactors can also be buried. Chernobyl would have not contaminated any land when its steam explosion happened if it had been fifty feet underground. The reactor was safe enough if its safety features had not been intentionally disabled to do a test. And then it was operated very unsafely intentionally by very untrained people who did not understand chain reaction dynamics.

Use nuclear heat for all biofuel and fuel production where possible. It is cheap and CO2 free. Slight, very safe, modifications can be made to steam generators to supply cheap heat to factories nearby an existing nuclear reactor. ..HG..

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