Lifecycle Analysis Finds Cellulosic Ethanol Produced by POET’s Project LIBERTY Will Reduce GHG Emissions 111% Over Gasoline
16 June 2010
Cellulosic ethanol produced by grain ethanol producer POET’s Project LIBERTY (earlier post) first commercial cellulosic ethanol plant will reduce greenhouse gas emissions (GHG) by 111% relative to gasoline, an independent lifecycle analysis (LCA) compiled by Air Improvement Resource, Inc., has found. (I.e., the cellulosic ethanol will offset more greenhouse gas emissions than it produces.)
The reduction is somewhat less than the 130% calculated by the Environmental Protection Agency (EPA) in the RFS2 for the production of cellulosic ethanol from corn stover using a biochemical process. Air Improvement’s estimates of emissions from Project LIBERTY’s fuel and feedstock transport and fuel production (the last being the sum of storage, electricity, chemicals, waste disposal, and biogas production) are slightly higher than the corresponding elements in EPA’s analysis.
Project LIBERTY will produce approximately 25 million gallons of ethanol annually using the cobs and upper 25% of the stover as feedstock. Enzymatic hydrolysis will pretreat the biomass for subsequent fermentation. A key co-product from this biochemical ethanol refinery is a biogas that will be used to replace natural gas in POET’s collocated corn-based refinery, which has an annual output of 50 million gallons.
The analysis found that all the inputs into Project LIBERTY will emit 41.8 grams of carbon dioxide equivalent units per megajoule of energy produced (gCO2eq/MJ). The biogas exported as a co-product will offset 49.8 gCO2eq/MJ. EPA estimates for land use and agriculture changes offset an additional 1.7 gCO2eq/MJ, bringing Project LIBERTY’s total emissions to -9.7 gCO2eq/MJ.
EPA’s standard for gasoline emissions is 92.9 gCO2eq/MJ.
| Comparison of LIBERTY to EPA Corn Stover GHG Estimates in RFS2 (g/MJ) | ||||||
|---|---|---|---|---|---|---|
| Profess/activity | Project LIBERTY | EPA-RFS2 Corn Stover Bio-chemical | ||||
| Net Domestic Agriculture | 8.6 | 10 | ||||
| Net International Agriculture (EPA RFS2) | 0 | 0 | ||||
| Domestic Land Use Change (EPA RFS2) | -10 | -10 | ||||
| International Land Use Change | 0 | 0 | ||||
| Fuel production | -12.4 | -31.3 | ||||
| Fuel and Feedstock Transport | 3.1 | 1.9 | ||||
| Tailpipe | 1 | 1 | ||||
| Total GHG Emissions | -9.7 | -28.4 | ||||
| % Reduction of Gasoline | 111% | 130% | ||||
It is important to note, Air Improvement said, that stover removal rates from fields around Project LIBERTY will not be more than 25% of total stover on the fields, so that additional fertilizer will not be necessary for the next corn crop. Consequently, it estimated no increase in agriculture emissions due to the stover removal for the Project LIBERTY facility.
The LCA highlighted a number of characteristics of POET’s process that lead to this large emissions reduction:
Project LIBERTY produces ethanol from agriculture waste. Because it uses a waste product from an existing crop, there are no additional inputs for planting and growing the feedstock.
Indirect Land Use Change, which creates an emissions penalty for grain-based ethanol, does not have any penalty associated with POET’s cellulosic ethanol.
The waste stream from POET’s process is fed into two anaerobic digesters to create biogas. Enough biogas is produced to completely power both Project LIBERTY and the adjacent grain-based ethanol plant. The natural gas that is displaced in this process is credited to the cellulosic ethanol plant.
The Project LIBERTY lifecycle analysis was conducted using the most current design elements available. POET said it will continue to learn from laboratory work and its pilot cellulosic ethanol plant currently operating in Scotland, SD As changes occur, the analysis will be updated.
Resources
Is this a surprise to anyone? And just to get pedantic for a moment, cellulosic alcohol is a key to energy independence. Each gallon of domestic produced ethanol means less $$$ sent to oil cartels holding us hostage to petroleum.
It also means the money is spent paying salaries of domestic employees thus circulating cash. And the less we rely on foreign oil the less (logical) expenditure on defense of those resources.
Posted by: sulleny | 16 June 2010 at 10:05 AM
I imagine someone will come along and say corn cobs are food for animals or sawdust is food for beavers or some other such nonsense. The Mexicans will be pleased that cobs and not corn kernels are used in this process, there will be more corn meals for tortillas. They protested when corn prices doubled caused by hedge funds bidding the price up with rich tax break dollars.
Posted by: SJC | 16 June 2010 at 12:11 PM
There is nothing wrong with debate on the merits, but when it comes down to alternative fuels are not and never will be the way to go, then we have discarded effective options.
Most of us agree that corn ethanol is not the way to go, but it has slowed the growth of imported oil and if it becomes cellulose fuel it can help to reduce the impact of two problems. Those two problems are imported oil and food for fuel.
There seldom is ONE perfect solution where if we all went that way the sun would shine and the clouds would all go away. It would be nice if that were the case, but experience tells me that seldom happens. It is more likely that we pick the best from the options we have and keep trying to improve our options.
Posted by: SJC | 18 June 2010 at 07:22 AM
How can anybody reduce fuel pollution by 111% or 130%? Shouldn't that be 11% and 30% reductions?
Posted by: HarveyD | 18 June 2010 at 05:33 PM
Good question Harvey, I assume that they are counting the methane that runs the two plants from digestion rather than using NG or coal.
That brings up the preprocessing of the cobs, first they digest them and get methane to run the plants and then they break them down and ferment the sugars, clever.
Posted by: SJC | 18 June 2010 at 09:51 PM
Ethanol fermented from any source is a food. The remaining corn stover in the field will release more CO2 and methane into the air as it is digested by microorganisms.
There is not enough crop area and forest area to grow a major part of the energy needed for automobiles alone. Coal and natural gas to liquid fuel conversions are the only way to substantially reduce the cost of importing oil.
Growing large trees instead of corn stover is still a better way of reducing CO2 production. Cows and goats can convert corn stover to human foods other than ethanol. Just use a little more fossil fuel and let the trees collect CO2. Bury the dead wood in salt mines forever.
Almost all fossil fuels are biofuels stored up over millions of years.
Nuclear electricity will free up a lot of natural gas and coal to be made into liquid fuels. Then CO2 and water can use nuclear energy to be made into liquid fuels in unlimited amounts. The Chinese have been too slow in building the more efficient pebble bed reactors to make this process more efficient. ..HG.
Posted by: Henry Gibson | 24 June 2010 at 12:11 AM