Biofuels: How "green" are these crops?

The International Herald Tribute has an article titled Studies conclude that biofuels are not so green. This study, along with many other recent criticisms have brought a strong attack against the claim that biofuels are cleaner and will be able to replace a substantial portion of the United States transportation energy needs.

Land-Use
The study by Princeton University includes a factor that is frequently ignored or assumed to be insignificant: land use. The study states:

The clearance of grassland releases 93 times the amount of greenhouse gas that would be saved by the fuel made annually on that land, said Joseph Fargione, the lead author of the other study and a scientist at the Nature Conservancy. "So for the next 93 years, you're making climate change worse, just at the time when we need to be bringing down carbon emissions."

According to this study, land use is an important factor. Once it is taken into account, it is apparent that at least from a greenhouse gas emission perspective biofuels are not better than conventional fuels, but in fact worse.

Life-Cycle Analysis
The problem with any environmental studies is that they have to make assumptions. This is necessary in sciences where it is simply not possible to measure everything. Most scientists or engineers have to make assumptions at some point but the validity of the assumption can often be questionable. Previous studies did not include land use into the study and apparently missed a large portion of the emissions.

My Thoughts
My primary reason for studying Chemical Engineering was alternative and renewable energy such as hydrogen fuel cells and biofuels. However I quickly realized that these will not be able to replace conventional fuel.

When you look at the economics and the engineering behind it there are many reasons why alternative fuels will not be able to quickly (if ever) displace a significant portion of conventional fuels. The most important factor in determining whether or not a fuel is viable, or in the case of transportation critical, is it's energy density. Simply put, it is how much energy per unit mass or unit volume. See the Wikipedia article on Energy Density.

Conventional fuels such as coal or petroleum products have been used because they have a high energy density and can be transported efficiently. If fuel is grown, it is in extremely low density and must be changed into higher quality fuel. Some studies even show that ethanol is a net energy loser, meaning that it needs more energy to produce than energy in the end.

Growing crops for fuel has only been profitable because of the subsidies given to the corn industry and the subsidies for ethanol. Take those away and there is little economic viability. The government needs to stop given subsidies to fuel "sources" that are not viable and start focusing on conservation efforts and investing in infrastructure for lower energy intensity lifestyles.

There isn't one technology that is going to save us for the upcoming energy crisis and we should be skeptical of anyone promising us a miracle fuel. Let's focus on the principals of sustainability and consuming less to get us through peak oil.

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Recommended Books:

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