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Biofuels and land use: a synthetic biology perspective

As CO2 levels in the atmosphere reach alarming levels and the world looks for possible solutions, one of the greatest debates has centered on whether the widespread growth of biomass for biofuels will compete with the land needed to feed our growing world population.

Just like fossil fuels, biofuels or renewable fuels are energy-packed hydrocarbons that can be burned to generate energy and are ultimately released back into the atmosphere as CO2. However, differently from fossil fuels, in which the CO2 was fixed by plant matter millions of years ago, in biofuels the carbon has been recently fixed from the atmosphere into biomass. Therefore, it can argued that the CO2 that results from burning biofuels is neutral, since it was taken from our already polluted atmosphere and will be recycled by the photosynthetic organisms used as biomass as soon as it is released from biofuel burning. So, by not adding CO2 into our atmosphere they are a better alternative than fossil fuels. Other advantages of biofuels are that they emit less toxic pollutants than fossil fuels and could help reduce dependence on foreign oil supplies.

There are two currently available biofuels, also known as first-generation biofuels. One is bioethanol obtained from yeast fermentation of plant-produced sugars, such as sugarcane juice and molasses (Brazil), corn starch (U.S.A.) and beet sugar (Europe). The second biofuel is biodiesel obtained through the transesterification of vegetable oil, such as soy oil, with a short-chain aliphatic alcohol and resulting in esters of fatty acids of varying lengths (biodiesel), with glycerol as the main subproduct.

Bioethanol is being used in gasoline blends for small vehicle engines in several countries. Brazil is the most successful example of bioethanol use. Since the 1970’s and driven by the oil crisis of 1973, the Brazilian government has promoted the large-scale substitution of fossil fuels with bioethanol from sugarcane juice and molasses. Several actions have been taken towards this goal, including the development of ethanol engines, mandatory ethanol content in gasoline ranging from 20% to 30%, and, more recently, the adoption of the “flex fuel engine” developed in the U.S.A., which is able to run on pure ethanol, pure gasoline or any mixture of the two. Since 2004, over 80% of all new cars sold in Brazil run on flex fuel engines and currently produced bioethanol is cheap and not subsidized by government. In the U.S.A. bioethanol is produced from cornstarch and thus requires pre-treatment with amylases in order to release the monossacharides from the starch polymer. The need of pre-treatment results in higher production costs when compared to its Brazilian counterpart, thus requiring government subsidies for cheaper sale price.

Biodiesel can also be used as a sole fuel or in blends with fossil diesel. Both can be used in standard diesel engines with no modifications, although some precautions must be taken to avoid filter clogging and the degradation of gaskets and hoses made of natural rubber. Biodiesel use has been increasing in Brazil, The U.S.A. and Europe. In Europe, the Renewable Transport Fuel Obligation obliges suppliers to include 5% renewable fuel in all transport fuel sold in the EU by 2010, which effectively translates into 5% biodiesel used for road diesel.

Nevertheless, first-generation biofuels suffer from some major drawbacks. Firstly, they are less calorific than fossil fuels and are generally more expensive to produce, thus being less efficient than fossil fuels and usually not economically competitive, requiring government subsidies. Secondly, fuels produced from food sources such as corn, sugar beets and soy beans compete directly with food production. It can also be argued that fuels produced from non-food sources also compete with food production at the level of land use. If rural producers find it more lucrative to sell biomass for biofuels than food crops, this would put a strain on food production and push food prices up. In addition, based on current productivity data for biofuels from biomass crops, serious concerns have been placed on the viability of producing enough biofuels to substitute fossil fuels in large scale without seriously compromising available arable land, which could ultimately lead to the further deforestation of our planet.

In view of these problems, biofuels will only bring the desired benefits to our society when they can be produced in substantial quantities, derived from feedstocks produced with much lower life-cycle greenhouse-gas emissions than traditional fossil fuels, be economically competitive with fossil fuels, and cause little or no competition with food production.

The scientific community seems split on whether or not biofuels will bring these desired benefits. The most pessimistic have looked at current characteristics and productivity data for biofuels and feel that in a world where over half of the population is malnourished, the growth of crops for fuel will squander land, water and energy sources needed for food production, resulting in increased food prices. The most optimistic look beyond the current available data and foresee a bright future where biomass will be a sustainable source for both food and energy, without the need of further deforestation.

However, it is recognized that such a bright future will only be possible through significant innovation and change in the current methods of biomass processing into biofuels. This is where we believe synthetic biology will come to play a large role.

Most of the innovations required in order to reach a sustainable future for biofuels will come from the genetic manipulation of crops for increased biomass production, and of microorganism for increased productivity of current fuels and for the production of more efficient fuels than first-generation biofuels.

In Brazil, the bioethanol industry is thriving. Sugarcane bioethanol is significantly cheaper to obtain than corn ethanol due to not requiring amylase pre-treatment and because sugarcane is a more efficient biomass source than corn. In addition, Brazil’s tropical climate provides not only the abundant sun and water necessary for biomass production, but also a rich microfauna from which very efficient yeast strains for ethanol production have been isolated and are currently used by industry.

In view of this scenario, and as the first Brazilian iGEM team, we decided to apply the concepts of synthetic biology to the bioethanol business. As part of our research we couldn’t fail to notice the biofuels debate.

In order to evaluate the general public’s opinion on this matter and to obtain hints of what the underlying causes for the different opinions could be, we elaborated a survey to be distributed through the internet.


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