May
18
The New Miles Per Acre Argument
May 18, 2009 | 10 Comments
A fact is there is always more than one way to look at things. Chris Field, director of the Department of Global Ecology at the Carnegie Institution has a new take on the bio sources for energy that actually makes sense –other than the meat of the argument isn’t on the land, its in how its used.
Asking the question, “How can we maximize our “miles per acre” from biomass?” comes from the presumption biofuels such as ethanol offer an alternative to petroleum for powering our cars, but growing energy crops to produce them can compete with food crops for farmland, and clearing forests to expand farmland will aggravate the climate change problem. That’s a position straddling several politically charged points of view.
But the work answers better than the presumptive question’s position. Better to say is “How much value in energized work can obtained from a unit of land?’ At least that would offer a more common sense sort of starting place.
So Field and his researchers writing in the online edition of the journal Science on May 7 say the best bet is to convert the biomass to electricity, rather than ethanol. In their calculation comparing ethanol used for internal combustion engines with bioelectricity used for battery-powered vehicles would deliver an average of 80% more miles of transportation per acre of crops, while also providing double the greenhouse gas offsets to mitigate climate change.
Field says, “It’s a relatively obvious question once you ask it, but nobody had really asked it before.” It’s a fine idea with much merit, and important for practically everyone. The end value of energy use is the work done; the lower that cost for the tool and the energy it uses decides how much work can be done. That’s the foundation of a high standard of living. Fields goes on, “The kinds of motivations that have driven people to think about developing ethanol as a vehicle fuel have been somewhat different from those that have been motivating people to think about battery electric vehicles, but the overlap is in the area of maximizing efficiency and minimizing adverse impacts on climate.”
While the efficiency issue is paramount and climate change based on human activity nebulous, he is on to something important. I’m almost inclined to sell a little climate change to get more work cheaper. But that would be misleading.
Professors Field Campbell and Lobell
Field is a professor of biology at Stanford University and a senior fellow at Stanford’s Woods Institute for the Environment and is part of the research team that includes lead author Elliott Campbell of the University of California, Merced, and David Lobell of Stanford’s Program on Food Security and the Environment.
The group performed a life-cycle analysis of both bioelectricity and ethanol technologies, taking into account not only the energy produced by each technology, but also the energy consumed in producing the vehicles and fuels. Without seeing the raw data it seems intuitively likely than going directly to electricity from bio matter is going to be more efficient. Yet, for the analysis, they used publicly available data on vehicle efficiencies from the US Environmental Protection Agency and other organizations. Nice to disclose that but the EPA isn’t the Department of Energy and of late has become much more politically oriented instead of the science.
Here are their press release numbers: A small SUV powered by bioelectricity could travel nearly 14,000 highway miles on the net energy produced from an acre of switchgrass, while a comparable internal combustion vehicle could only travel about 9,000 miles on the highway. That is qualified by the average mileage for both city and highway driving would be 15,000 miles for a biolelectric SUV and 8,000 miles for an internal combustion vehicle.
So bioelectricity was the clear winner in the transportation-miles-per-acre comparison, regardless of whether the energy was produced from corn or from switchgrass, the cellulose-based energy crop. “The internal combustion engine just isn’t very efficient, especially when compared to electric vehicles,” says Campbell. “Even the best ethanol-producing technologies with hybrid vehicles aren’t enough to overcome this.”
That comment goes to the point – it isn’t the land that is the consumer’s main point of interest – it’s the choice in energy using tools. The market, agronomy, weather and a wide host of interests will decide what crops are grown – be it for energy or food.
Without meaning to, the good professors make a serious case for humans to be actively involved in the planet’s carbon cycle. The energy from an acre of switchgrass used to power an electric vehicle would prevent or offset the release of up to 10 tons of CO2 per acre, relative to a similar-sized gasoline-powered car. “Some approaches to bioenergy can make climate change worse, but other limited approaches can help fight climate change,” says Campbell. “For these beneficial approaches, we could do more to fight climate change by making electricity than making ethanol.” One might think the war on ethanol is being fought surreptitiously in academia.
The study authors are trying to make the case across vehicle types and different crops. The offset averages claim is more than 100% larger for bioelectricity than for the ethanol pathway. Bioelectricity also offers more possibilities for reducing greenhouse gas emissions through measures such as carbon capture and sequestration, which could be implemented at biomass power stations but not with individual internal combustion vehicles. Note they are suggesting that sequestration takes place from an atmospheric CO2 source.
The results of the study clearly favor bioelectricity over ethanol, no big surprise coming from California. The group cautions that the issues facing society in choosing an energy strategy are complex. Lobell says, “”We found that converting biomass to electricity rather than ethanol makes the most sense for two policy-relevant issues: transportation and climate. But we also need to compare these options for other issues like water consumption, air pollution, and economic costs.” There’s that “policy” word.
It would have been more widely influential if the group had just come out to everyone with the reality that going electric would be less costly. That would be honest and put more emphasis of public attention on electron storage.
Campbell said, “There is a big strategic decision our country and others are making: whether to encourage development of vehicles that run on ethanol or electricity. Studies like ours could be used to ensure that the alternative energy pathways we chose will provide the most transportation energy and the least climate change impacts.”
The guys might try a little less hubris, it isn’t that we consumers are determined to use ethanol; we need to make a transition, so making the transition as low cost as possible has more value than “policy” and other such high sounding premises to attack what is for now, the best and only scaled alternative industry around.
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I have a couple of comments.
1) Many of us are waiting for Battery technology that would be cost effective with quick recharge and long range. I am interested in this but not eager to replace an existing car (with no car payments) for an unproven first generation technology. There will be need for liquid fuel equivalents for a while.
2) Khosla has talked about miles per acre in his talks and it is an interesting concept. I wonder if we should think of this as mile per acre over a unit of time. How many miles an acre could produce over a 10 year period of time. Will Switchgrass,Miscanthus, Poplar, Mixed Trees create the best yield at a reasonable price and how quickly can they be replaced. I fear that the wrong biofuel strategy will strip the forests of New England. Although cheap today it won’t be when there are more demand for feedstock and it has to be transported from longer distances(higher costs)
I would like to compliment you on your blog. You have put alot of thought and effort in it. nicely done.
I agree with Jim that your thoughts and efforts here make reading your comments quite worthwhile, Brian.
As to this study, it is not a new finding, but it is somewhat important. Field et als mistake was to overlook the deficiencies of batteries and not to recognise the promise of methanol and ethanol powered fuel cells.
It may be over 20 years or more before all-electric battery cars are ready for prime time, whereas fuel cell cars (and FC hybrids) running on liquid fuels appear to be much closer.
Biomass pyrolysis / gasification to liquid fuels provides a “drop-in” substitute for existing fuels that can utilise the multi-trillion dollar transportation infrastructure that already exists. Field wants to replace it all in one fell swoop.
Why shouldn’t he think that way, as long as the federal government apparently thinks of a trillion dollars as the new penny?
This is just nonsense. The authors of this LCA clearly have an agenda and are not following ISO 14000 methods for performing LCA. Having read many LCA on producing electricity and written one site specific LCA for biomass, I will attest that biomass can be a good environmental and economic choice for making electricity.
However, while biomass is a good source of base load electricity; charging batteries is completely independent of the source of electricity unless except under some rare conditions. In other word, the authors are comparing apples to flying pigs.
Second, LCA should be compare existing technology to existing technology. While it is true that stationary power plants may have a better thermal efficiency than ICE operating under variable speed conditions, I have a ICE in the cheapest PU you could buy and it is still running cleanly 20 years and 250K later. I am skeptical that these researchers can tell thermal efficiency from flying pigs.
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