Commentary: A case study of cellulosic ethanol
(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).