## MIT study concludes lifecycle GHG emissions for biofuels should be presented to decision makers and the public as a range

##### 23 April 2011
 LC-GHG emissions for the alternative diesel fuel pathways in the study. Uncertainty bars represent the variability captured by the low emissions, baseline, and high emissions scenarios. Note the different scales for the top and bottom portions of the figure. Credit: ACS, Stratton et al. Click to enlarge.

In a paper published in the ACS journal Environmental Science & Technology, researchers from MIT conclude that it is “paramount” that decision makers and the general public be given the range of LC-GHG emissions that could result from the production and use of a given bio or synthetic fuel, due to high variability within pathways. Among their findings in the study are that subjective choices such as coproduct usage and allocation methodology can be more important sources of variability in the life cycle greenhouse gas (LC-GHG) inventory of a fuel option than the process and energy use of fuel production.

Variability in lifecycle analysis (LCA), Stratton et al. say, must be distinguished from uncertainty. Variability—which is inherent due to both inexact LCA procedures and variation of numerical inputs—is a dispersion of discrete results, each of which has been measured or calculated with an inherent uncertainty in the result. The authors group the sources of variability into three categories: pathway-specific variability; coproduct usage and allocation; and land use change (LUC).

In their paper, they used specific examples from the production of diesel and jet fuels from 14 different feedstocks to demonstrate general trends in the types and magnitudes of variability present in life cycle greenhouse gas (LC-GHG) inventories of middle distillate fuels.

To understand how variability impacts LC-GHG inventories of transportation fuels, a new methodological approach was developed using screening level LCAs. Screening level analyses provide preliminary assessments of technology alternatives with the intent of informing research funding and decision makers.

A requirement of screening level LCAs is to identify the pivotal factors defining the LC-GHG emission profiles of fuel production for each LC step and each feedstock. Optimistic, nominal,and pessimistic sets of these key parameters were developed to formulate corresponding low LC-GHG emissions, baseline or nominal LC-GHG emissions, and high LC-GHG emissions scenarios for each feedstock-to-fuel pathway; hence, results for each feedstock-to-fuel pathway are a range of possible LC-GHG inventories intended to demonstrate variability in fuel production processes.

A requirement of screening level LCAs is to identify the pivotal factors defining the LC-GHG emission profiles of fuel production for each LC step and each feedstock. Optimistic, nominal, and pessimistic sets of these key parameters were developed to formulate corresponding low LC-GHG emissions, baseline or nominal LC-GHG emissions, and high LC-GHG emissions scenarios for each feedstock-to-fuel pathway; hence, results for each feedstock-to-fuel pathway are a range of possible LC-GHG inventories intended to demonstrate variability in fuel production processes.

—Stratton et al.

Transportation fuel pathways often result in coproducts; to allocate emissions among products, a usage must first be defined for the coproduct. In the study, the team examined four allocation methods to assign LC-GHG emissions between the primary fuel product and any coproducts: mass allocation; energy allocation; market-value allocation; and displacement (a.k.a., system expansion).

The choice of coproduct usage and allocation method may significantly affect the final results of the LCA. Several studies in the literature have acknowledged the variability introduced to LCA by different allocation methods. Three examples were chosen herein to demonstrate the variability introduced by coproduct treatment: (1) the oil and biomass coproduct system of soybeans where the biomass has an existing market as an animal feed; (2) the oil and biomass coproduct system of jatropha capsules where the biomass coproducts have a variety of potential uses; and (3) the liquid fuel product slate from a coal and biomass fed F-T facility. All three examples show a general shortcoming in the displacement approach. When the coproduct creation is large relative to the primary product, the LC-GHG inventory of the primary product depends more strongly on the LC-GHG inventory of the displaced product than the processes and energy flows of the product being examined.

—Stratton et al.

 As an example, sensitivity of LC-GHG emissions from jatropha oil HRD to coproduct usage and allocation assumptions are shown. Baseline value indicates the chosen combination to represent HRD production from jatropha oil. Single usage and allocation entries indicate uniform application across all coproducts. Scenario 3 assumes meal is detoxified and used for animal feed with allocation by economic value, while all other coproducts are used for electricity with allocation by displacement of average grid electricity. Credit: ACS, Stratton et al. Click to enlarge.

The team found that all of the biofuel options examined in their study could either potentially be produced with lower LC-GHG emissions than conventional diesel, or with LC-GHG emissions that exceed those of conventional diesel. The difference is due to the LC-GHG intensity of the processes and the emissions resulting from LUC.

For this reason, it is critical to emphasize that the use of renewable resources as feedstock does not guarantee an environmentally beneficial fuel. Knowledge of specific production details is required for any definitive conclusions to be drawn. This constitutes a strong argument for LC-GHG inventories of transportation fuels to be presented as a range.

...Three key conclusions can be drawn from the potentially dominating influence of variability due to coproduct usage and allocation and LUC assumptions: 1) minimizing variability across LCA results by maximizing methodological consistency is essential to making useful comparisons between fuel options; 2) the absolute result from attributional LCAs have a diluted physical meaning and are most effectively used as a comparative tool, given the condition from the first key conclusion; and 3) it is paramount that decision makers and the general public be given the range of LC-GHG emissions that could result from the production and use of these fuels.

Such an approach emphasizes the importance of understanding the key aspects that determine the LC-GHG emissions from fuel production and use. Furthermore, it can do so before any production actually occurs. Such knowledge would help to develop technologies and policies that diversify our energy supplies and stimulate economic development while mitigating the LC-GHG emissions from transportation.

—Stratton et al.

Resources

• Russell W. Stratton, Hsin Min Wong, James I. Hileman (2011) Quantifying Variability in Life Cycle Greenhouse Gas Inventories of Alternative Middle Distillate Transportation Fuels. Environmental Science & Technology Article ASAP doi: 10.1021/es102597f

In the U.S. we can turn corn stalks and swithgrass into gasoline, kerosene and diesel and have more CO2 neutral fuels. It takes money to build the plants however. If we took the $100 billion we wasted for one year in Iraq, we could have built 100 fuels plants each producing 1 million gallons per day and we would not need to import ANY middle east oil at all. How many million acres would be required to provide enough switchgrass to produce enough cellulosic ethanol for 240 million gas guzzlers?u Would it leave enough farmland to feed (i.e. overfeed 330 million Americans @ 4000 Kcal/per day/per capita). What would be the impact on local and world food prices? Using coal (CTL) seem to be one of the worse feedstock. You do the math, you can get 12 tons of switchgrass biomass per acre at about 100 gallons of methanol per ton for more than 1000 gallons per acre converted to gasoline, that would be 500 gallons per acre. If each car takes 500 gallons per year then 100 million acres provides 100 million cars with fuel. We grow 100 million acres of corn each year, so we could provide almost half the cars with fuel using marginal farmland planted in switchgrass. Half the cars would be a 25% reduction in oil usage or 5 million barrels per day. 5 million barrels less out of the 11 million barrels we import each day is significant. There are lot of cynics and critics, it is always easier to destroy than create. If we do not make some real moves soon and continue on doing nothing like the last 30 years, we may not have another 30 years that we would really like to experience. SJC has the numbers and a plan. One wonders what oil legislation is under way to stop it. hehe...well, I would not be surprised :) I do not think that we will go with biomass in a big way as a first move. It could be natural gas, then coal, then biomass. The whole synthetic fuels movement was stopped 30 years ago during Carter and we can pretty much guess who was behind it. I would make one further important recommendation which the authors of this study have left out. Namely, that members of the Spinach Party not be given a veto at the decision making table. Not so long ago the Premier of Quebec Province and the Governors of New England came to an agreement that Hydro Quebec would sell renewable electric power to the northeastern states. The deal was ready to be consumated when the Green Party moved in to put the kabosh on the whole thing. As a Bostonian I'd prefer to send money to Quebec for enrgy rather than Algeria. @ SJC: It was Regan that stopped the synthetic fuel initiative not Carter. @ SJC I'm with you on the Iraq war. One of the dumbest mistakes done by "The Decider"; the worst President in US history. Matter of fact he should have been impeached for lying us into that war. "Not so long ago the Premier of Quebec Province and the Governors of New England came to an agreement that Hydro Quebec would sell renewable electric power to the northeastern states. The deal was ready to be consumated when the Green Party moved in to put the kabosh on the whole thing." Something about this statement doesn't ring true. Why would a Green Party be against renewable energy? And how could they put the kabosh on anything if they did? There must be something more to it that you're not saying. I know the purchase of power from Hydro-Québec was an issue during the Massachusetts gubernatorial election of 2010 but given the long history of energy trading between our two countries the only real issues should be: whether the contract is short term or long term, pricing, and expanding/upgrading transmission lines. @ ai vin The Greens were against this plan for a couple of reasons. 1. Environmental damage due to construction of transmission lines. 2. Every hydro project requires a storage reservoir as you know. They were against having to construct this because a few Inuit in northern Quebec would lose the ability to hunt in the designated area. This excuse is rediculous since the size of the reservoir in relation to the number of Inuit who would have been affected is miniscule. The population density is something like 1 person per 10 square miles and the indigenous people are hunter gatherers so they move where the game is. The project was discussed prior to the time when Weld was governor of Massachusetts. The latest proposal is to place the transmission lines under water in Lake Champlain. I can hear it already, "that will disturb the spawning grounds of the yellow toad salamanders" or some such remarkable nonsense. Wind power is also out because it spoils the view. The off shore Cape Cod wind project has dragged on for years because of "environmental concerns". There was also a proposal to import wind enrgy from the Maritime Provinces. That's right it also got thumbs down from the environmentalists. Incidentally the Greens are also against building solar thermal plants in California and the US south west in general for fear that the desert ground squirrel would be disturbed. They managed to convince the gov't to put a 2 year moratorium in place to study the issue. I don't know if that has since been lifted. It is often stated that environmentalist oppose everything, that is the problem, I have seen no real evidence of this. If the arguments brought to court do not carry the day, then the project goes forward. It might delay the project, but I do not think that it will stop it on the merits unless they are valid. All sides should be heard and that is part of the process. History has shown big money interests will try to get their way. The second Yosemite, Hech Hechy valley was turned into a dam because the area was under state and not federal control. There are numerous examples of destructive projects that claim to be for the people but are actually for the profit of a few. If the true factors see the light of day in court, then it is out in the open and no back room deals prevail. Many Greens will oppose ALL energy projects. For them, a return to older ways, without electricity, is the only way to go. How ridiculous can they get? The argument against low cost clean Hydro power doesn't hold scrutiny. How could the North Eastern States Governors fall for that argument? They were offered power as low as$0,05/Kwh, delivered to their border line and refused it. They could have made a huge profit over the next 25 years. Next time around they may have to pay $0.08/Kwh to$0.10+/Kwh because the USD value versus $Can has changed drastically and the new Hydro plants and power lines cost a lot more. Hydro power from the Lower Churchill Falls in Labrador will cost over$0.11/Kwh and at least $0.15/Kwh delivered to Maine and neighboring States. Ok, let's not lump all the greens into the same boat. Those lunatics sound like they are to the environmental movement as the TEA party is to the right wing. OTOH I've heard rumors that some of the most nutty greens are actually secretly funded by big oil so as to discredit the whole movement - nah, that's too much to believe right? Ha ha!! ai_vin climbs aboard the conspiracy bus!! Well, it's reasonable to assume there are ops to discredit both sides of big arguments. I'm with Mannstein - green kooks have spoiled many good projects. The Audubon Society has had to bite their tongue on wind farm bird slaughter - to get past environmental impact reports. Of course much of the controversy could be avoided by focusing on development of distributed energy systems. A real, near-term solution awaits in the installation of NG-fired Combined Heat and Power systems in residences and light industry. Demand for high voltage power transmission lines (and new power plants) would be slashed with rapid growth of distributed energy. Can it be done? Of course. The engineers here know full well off-grid power is viable today. And some are actually going forward building projects with large scale CCHP: http://www.solaripedia.com/13/173/1728/bank_of_america_tower_cogeneration_diagram.html This direction is necessary to avoid the early introduction of disruptive energy technologies. It can be done, but the coal fired power plant companies are so used to milking profits doing it the same old way they will never change, let alone invest in anything different, there is your free market system in action. @ HarveyD As a heads up, I'm paying$.18/Kwh right now in southern New England and the price keeps going up.

SJC, it's not just coal - it's all fossil fuel industry that has a stranglehold on energy in the USA. But that IS changing - much to the chagrin of oilcos and coalcos.

The time is NOW to start moving away from old fashioned central resources to DISTRIBUTED resources. The evolution path is not difficult - use the abundance of NG to fuel stand alone CCHP systems in residences and new buildings. Eliminate the need for new coal-fired plants, add wind, solar, geotherm and tidal where effective.

In 50 years (or a lot less;) NG can be replaced with another gas found throughout the universe. Energy is abundant and ubiquitous. Human beings will no longer be held captive by those whose agenda is to secrete this fact.

Nothing will change until those with the grip of power decide to grab something else. They will never let go until we pry it from their hands.

And that is being done. Non-violently, with the power and authority of generations of ancestors. Through the powerful court of public opinion. We can thank, ahemmm... Al Gore for the internet, right?

http://www.snopes.com/quotes/internet.asp

Thanks ai_

"During my service in the United States Congress, I took the initiative in creating the internet."

Al Gore, CNN, March 9, 1999

What does the internet have to do with the power of big oil? We are locked into our addiction by pushers and enablers like Bush and Cheney.

I was being sarc with the remark about AlGore... The internet HAS given the world a way to get information not filtered by mainstream agendas. Thus we know a lot more about alternative resources, and alternatives to alternatives. Energy IS abundant - and we KNOW this.

"The internet HAS given the world a way to get information not filtered by mainstream agendas."

And given us a way to get information filtered by alt-stream agendas.
The best thing about the internet is that anybody can go on it and write anything they want.
What's the worst thing? Dido.

Case in point: Orly Taitz

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