A friend and colleague of mine drives around in a cute little VW bug
powered by biodiesel. There's a peace sign on the front of
it, which helps it get better mileage. But peace sign or not,
there has been an ongoing controversy about whether biofuels are worth
In this post, I provide a little amateur analysis of the whole topic of
biofuels, and comment on the most recent study of the potential
The controversy stems from the fact that it takes a lot of energy to
plant, transport, harvest, and process the crops needed to produce
biofuels. Some analyses indicated that there was no net gain.
I wa also skeptical of this, because Brazil has been reported
to be making progress toward energy independence, through the use of
biofuels. If there is no net gain with biofuels, it should
not be possible for them to make progress toward that goal.
Actually, there are five reasons to be interested in biofuels.
The most obvious is the allure of energy independence.
If we did not have to import very much oil, the world would
be a safer place. Similarly, if the production of energy were
more widely distributed, it would be more reliable and less susceptible
to attack. Additionally, biofuels do release carbon dioxide,
but that carbon dioxide is reabsorbed from the atmosphere when the next
batch of crops is grown. Therefore, there is less impact on
global warming. Other pollutants are reduced as well.
Finally, domestic production of biofuels would create jobs
across the country, thereby strengthening and diversifying the economy.
So there are many reasons to work toward the development of biofuels,
but all of them require that we get more energy out that we put in.
There is a study on this topic in the journal, Proceedings of
the National Academy of Sciences.
economic, and energetic costs and benefits of biodiesel and ethanol
Jason Hill, Erik Nelson, David Tilman, Stephen Polasky,
and Douglas Tiffany
Published online before print July 12, 2006
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0604600103
Negative environmental consequences of fossil fuels and concerns about
petroleum supplies have spurred the search for renewable transportation
biofuels. To be a viable alternative, a biofuel should provide a net
energy gain, have environmental benefits, be economically competitive,
and be producible in large quantities without reducing food supplies.
We use these criteria to evaluate, through life-cycle accounting,
ethanol from corn grain and biodiesel from soybeans. Ethanol yields 25%
more energy than the energy invested in its production, whereas
biodiesel yields 93% more. Compared with ethanol, biodiesel releases
just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and
pesticide pollutants, respectively, per net energy gain. Relative to
the fossil fuels they displace, greenhouse gas emissions are reduced
12% by the production and combustion of ethanol and 41% by biodiesel.
Biodiesel also releases less air pollutants per net energy gain than
ethanol. These advantages of biodiesel over ethanol come from lower
agricultural inputs and more efficient conversion of feedstocks to
fuel. Neither biofuel can replace much petroleum without impacting food
supplies. Even dedicating all U.S. corn and soybean production to
biofuels would meet only 12% of gasoline demand and 6% of diesel
demand. Until recent increases in petroleum prices, high production
costs made biofuels unprofitable without subsidies. Biodiesel provides
sufficient environmental advantages to merit subsidy. Transportation
biofuels such as synfuel hydrocarbons or cellulosic ethanol, if
produced from low-input biomass grown on agriculturally marginal land
or from waste biomass, could provide much greater supplies and
environmental benefits than food-based biofuels.
US Department of Energy report released on Friday 7 July said that
biofuels such as cellulosic ethanol could displace 30% of the fuel
consumed in US transportation by 2030, which Tilman thinks is a
long-term viable goal; although it would take significant technological
One of the findings of the study has attracted a lot of attention in
the media. The disappointing finding is that biofuels cannot
replace a large percentage of imported fossil fuel. Even so,
it is encouraging that the largest and best study so far shows a net
My perspective is this: There are many reasons to develop biofuels, and
energy independence is only one of them. The fact that we
will not become energy-independent with biofuels alone should not deter
us for even a moment.
One of the factors that has inhibited the development of alternative
energy has been, in my opinion, the fact that no single alternative
will do the job. What that means is that no single industry
can control the energy market, if many alternatives are developed.
So the incentive is not great, from a corporate point of
view. In fact, the loss of control provides a disincentive.
But from the standpoint of collective good, it is desirable to have a
wide variety of energy sources, and for those sources to be controlled
by different entities.
From a research perspective, it is not possible to know ahead of time
which technologies will turn out to be the best, so it makes sense to
study and develop all of them.
If it turns out that biofuel can only replace 10% of imported oil, that
is not great, but it brings up 10% closer to the goal. If the
cellulosic ethanol works out, and gets us 30% there, that's pretty
good. Also, keep in mind that we do not have to achieve
complete independence in order to improve the world security situation.
But also keep in mind that biofuels will be only one part of
the total solution to the energy problem.
There is additional perspective in this editorial:
...The focus on biofuels as a silver bullet to solve our energy and
climate-change crises is at best misguided. At worst, it is a scheme
that could have disastrous environmental consequences. And it will have
little effect on our fossil-fuel dependence...
I think she is overstating the case against biofuels, but it is
important to keep in mind that there are many specific things we could
be doing today to move us toward energy independence. She
cites several of them in the editorial. I don't know that
many people are realistically thinking of biofuel as a silver bullet,
but I do agree that the media seem to portray it that way, sometimes,
and that they do not give enough attention to the total picture.
It simply is not glamorous enough to warrant their attention,
to talk about things such as mass transit.
One bit that disturbs me about these articles is the repeated meme that the crops used for energy production are lost to human consumption. Byproducts from these fuels -- distillers grain and oilseed meal -- are "protein-enriched" livestock feeds and at one point brought in more money for companies than fuel they produced. Most if not all of the fiber and protein in these crops is retained for livestock feed and since something like 94 percent of corn and soybeans is run through a cow, pig or bird before it comes to the dinner table, the loss of food production is greatly overstated.
In Germany, biodiesel is produced out of canola. Is there a reason that this isn't considered here in the US?
I am not an expert on this, so I am not the best person to answer the questions posed here. I will say that it would make sense to consider adapting a variety of crops and crop byproducts to see how well they can be merged into the energy stream. Some will be more efficient than others, obviously, and some will make more economic sense that others. I think the consensus at this point is that cellulosic ethanol is gong to be the way to go. Cellulose is the most abundant material in most crops, and it is present in all crops. The problem is, we are still in the process of developing the technology for efficient enzymatic degradation of the cellulose. It has to be broken down into sugar first. Figuring out how to do that cheaply and in mass quantities is the trick.
Biodiesel is a different story. That is made from vegetable oil, as opposed to ethanol, which is made from sugar, starch, or cellulose. The trick there is to figure out how to get the maximum amount of vegetable oil for a minimum investment of materials and energy input. I am sure that some crops are inherently more efficient than others, but that is not the only thing that determines which is used. I suspect that early on, we will adapt whatever is currently being grown in a given area. As time goes on, we will figure out what is optimum in a given situation.