Helping America Understand and Adapt to a New Energy Reality

A Case Study of Cellulosic Ethanol

By on May 9, 2011 in Commentary

(Note: Commentaries do not necessarily represent the ASPO-USA position.)

The March 28, 2011 edition of the ASPO-USA Peak Oil Review had a brief which I found of considerable interest. It stated:

A perspective paper in Journal of Chemical Technology & Biotechnology makes a case that conversion of biomass to cellulosic ethanol is the most efficient and productive use of biomass to create a high-octane, environmentally friendly transportation fuel. (3/23, #17)

I found it to be of considerable interest because there is a proposal to build a commercial cellulosic ethanol biorefinery in the eastern Upper Peninsula of Michigan not far from where I live.

Based upon information provided by the corporation proposing the biorefinery, Frontier Renewable Resources LLC, owned by Mascoma Corporation and J.M. Longyear, I would not consider cellulosic ethanol to be efficient from an energy perspective.

The facility would have 6 boilers rated at 90 million BTU/hour that will operate 24/7 for 347 days per year according to information provided in the U.S. Department of Energy’s (DOE) Environmental Assessment. Converting the BTUs to megajoules, the boilers would generate 4.7 billion megajoules per year of energy that will be used to make ethanol.

The plant is projected to produce 40 million gallons of ethanol/year according to the DOE’s Environmental Assessment and Frontier’s air pollution permit application, which has an energy content of 3.3 billion megajoules of energy. The boiler energy consumed in making ethanol would be 1.43 times more than the energy content of the ethanol that they plan to produce. According to the DOE’s Environmental Assessment, timber harvesting, wood processing and wood transportation would require approximately 3.75 million gallons of diesel fuel per year. When diesel fuel energy use is included in the energy required for the production of the ethanol, the ratio of energy consumed/energy produced increases to 1.59.

There is a question as to what fuel will be used in the boilers. The air pollution permit application indicates that natural gas will be used. It appears that Frontier claimed they would use natural gas so they could easily meet air pollution regulations. In the DOE’s Environmental Assessment, Frontier states they will almost exclusively use lignin and wood in the boilers. I assume Frontier makes that claim so that the project appears “green”.

The “green” idea is that the trees that will be used for boiler fuel, as well as cellulosic ethanol, took CO2 out of the air to grow but the wood, lignin and ethanol will burn to create CO2 that will go back into growing new trees that replace the original trees.

Burning lignin and wood in the boilers would create more particulate matter which would make meeting air pollution regulations more difficult. My impression is that for convenience sake and as a cost advantage, they will use natural gas as long as the price of natural gas is favorable.

From my perspective, Frontier’s biorefinery would not be economically practical without substantial government subsidies and it appears Frontier will receive substantial subsidies.

Frontier will receive, or is likely to receive, nearly $80 million in state and federal grants as well as $60 million in state and local tax waivers over the first 15 years of the facility’s lifetime. Along with that, Frontier wants government assistance for road, water, wastewater, rail and utility construction.

For all the money that governments are providing, the facility will provide employment for approximately 70 workers.

Also of note is the available wood supply for this project. Frontier states that they will use only hardwood trees from inside a specific 150 mile limit. The DOE’s Environmental Assessment states that net hardwood growth in the area of analysis is 4.188 million green tons/year and that present extraction is 2.391 million green tons/year. Frontier would use 1.130 million green tons/year of hardwood. The sum of present extraction and Frontier extraction would be 84% of total net growth, which is not that far removed from 100%.

State and federal lands within the 150 mile limit are at, or close to, their timber cutting limit; so Frontier will have to rely on private landowners who may or may not want to sell their timber. If private landowners don’t want to sell their timber, it could tighten the timber market and drive current wood processors out of business.

Is this really the most efficient and best possible use of our wood resources?

Roger Blanchard teaches chemistry at Lake Superior State University and authored the book “The Future of Global Oil Production: Facts, Figures, Trends and Projections by Region,” McFarland & Company (2005).


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  • Tom Robertson

    My question on this subject is, why is the net energy, or Energy Returned on Energy Invested (ERoEI) an issue today.

    The primary energies powering our economies today have ERoEI of more than 10:1–and often much more–with the exception of nuclear, for example, which has an ERoEI of 4.5:1 according to DOE and 2.7:1 according to a nuclear engineer I knew back in the early days of “net energy” analysis (and who quit working in the area.)

    We should accurately (and agreeably) know the ERoEI of every energy source available today, including their variables due to transport, accidents, and all envirionmental costs, etc.

    But we do not, even though the science to have that knowledge is available, but simply not used–for interesting reasons.

  • Don Hirschberg

    Very interesting article Roger. Thank you. Being an ancient refinery designer and refinery starter- upper I could not resist getting the slide rule out and put your numbers in terms more meaningful to an oil refiner. (We didn’t allow any of your sissy little joules in an oil refinery. Our Joule was 778 Ft pounds per BTU.)

    40 million gallons of ethanol per year has the fuel value of about 1,840 B/D of gasoline. (They always use units that make the production of alternates loom large.) If I assume an overall boiler efficiency of 70% I find the boilers alone take 1.40 times as much energy as the calorific value of all the ethanol produced. Your 1.43 is so close it looks as if I fudged.

    There are no refineries today that produce so little gasoline equivalent. To fix ones thinking, back 60 years ago there were about 350 US refineries some as small as 10,000 barrels a day, and a few even smaller. Even a 10,000 B/D refinery would produce about 5,000 B/D gasoline and about 5,000 B/D of LPG, heating oil, diesel, and jet fuel. Such small refineries only employed about 50 very productive and skilled people including the asphalt salesman. Domestic production was soon to peak at 10 million B/D, the rate the Saudis and the Russians can raise today. Foreign oil was about $ 2/ B.

    This article sorta confirms it; I would not invest in Cellulosic ethanol.

  • Lewis C

    Roger – many thanks for this detailed critique of the CE boondoggle.
    I knew the theoretical Eroei was poor, but not that it was demonstrably negative in practice. The favourable approach would of course account yield energy (ethanol) as a percentage of primary input energy (greenwood plus diesel), which I calculate as being ~25%. Assuming a 25% efficient IC engine as the end user, this gives a pitiful overall energy conversion efficiency of around 6.25%.

    Given the defined limits on feedstock supply, the project is surely vulnerable to questions over its actual yield of ethanol if it claims that wood, lignin and ethanol will be used to provide process energy.

    OTOH, providing that process energy from natural gas would both cut the carbon efficiency and make a total nonsense of the project since a greater petrol-equivalent volume of liquid fuel could be gained from refining the gas directly to liquid fuel.

    However, I suggest that the most politically effective critique in terms of halting the proposal will be the provision of a preferable alternative proposal for forest energy processing.
    Drawing on the commercially available ‘village scale’ Biochar & Syngas plants listed on the International Biochar Initiative website, together with the long-proven technologies for converting syngas to methanol, it would seem very likely that an effective counter-proposal could be assembled around which to rally constructive opposition from many stakeholder constituencies. With regard to enviros’ responses, I’d suggest the inclusion of an outline of the exceptional ecological benefits of the highly productive ancient forest sylviculture known as “Coppice & Standards.”

    By my calculation such a proposal could provide both a similar potential scale of petrol-equivalent liquid fuel supply, plus a potential scale of biochar output for around 40,000 acres /year of long-term soil-fertility enhancement. And it could do so with a positive Eroei, outstanding positive carbon efficiency, and many times the employment in numerous small modular local stations. It would also avoid most of the feedstock transport disbenefits, and the monopolizing of nearly all remaining feedstock supply by a single corporation, and the need for massive ongoing state and federal subsidies.

    Most notably it would allow an incremental development of capacity, thereby encouraging ongoing plant design improvements and avoiding the sudden suppression of other forest-dependent industries. It could also make Michigan a unique early centre of excellence in the emerging world market for this crucial bio-energy option.

    Should the assembly of such a counter-proposal for the US conditions appeal to you, even if only as a tactic to block the Frontier CE proposal, I’d hope you would post an account of it here on Energy Bulletin, as many other states both within the US and abroad will no doubt face similar boondoggle CE & Co-firing proposals. If I could be of any assistance I’d be happy to do so – Bart has my address.