As the world faces the negative environmental impacts and finite nature of fossil fuels, research is rapidly expanding the field of biofuels. Biofuels, most often derived from living biomass, have the potential to be a renewable fuel alternative, something desperately needed in an age of rising oil prices and growing concerns about the harmful effects of carbon dioxide emissions. So what’s taking so long? As it turns out, biofuel production and use comes with its own suite of issues.
The most commonly used biofuels are liquids, primarily ethanol and biodiesel, used for transportation purposes. Traditional biomass sources of biofuels are food crops; these are known as first-generation biofuels. Bioethanol is produced by yeast- or bacteria-mediated fermentation of sugar and starch crops such as corn, sugarcane, or sweet sorghum. Biodiesel comes from oil crops such as soybeans, rapeseed, coconuts or palms, most often through a process called transesterificaton, in which the oil is chemically reacted with an alcohol to produce the final product.
Though the majority of biofuels currently produced are first-generation biofuels of these two types, this process has important limitations. First, there is a concern that diverting farmland from food production to biofuel production will negatively affect the food supply of a region. This has already been observed in the US, where increasing use of corn crops to make ethanol (from 5% to 25% in the last decade, according to the USDA) has increased the price of corn. Increased demand leads to land in previously undisturbed ecosystems being converted to biofuel or crop production and reduced biodiversity. Production of first-generation biofuels can even have large-scale environmental impacts; growing, fertilizing, transporting, and processing the crops for fuel uses energy (much of it from coal and natural gas) inciting debate over the efficiency and carbon footprint of these types of biofuels.
All is not lost. There are many alternatives being investigated that could wean us of our dependence on fossil fuels with far less detriment to the environment we are trying to protect. Second-generation biofuels are those produced from non-food crops, either cellulosic biomass (dry plant matter), woody crops, or waste biomass. One of the goals of second-generation biofuel production is to use the non-food parts of current crops, nonfood crops, and industry waste such as wood chips and fruit pulp to provide more sustainable biofuel without impacting food production. Breaking down plant matter is more difficult than simply fermenting corn or chemically processing palm oil, however. One possible simplification of the complicated, multi-step process is being researched by a team at the University of Michigan, who are experimenting with a combination of a bacteria and fungus to more efficiently break down woody plant products to cellulosic biofuel.
Another possible alternative biofuel source is algae, which can produce what are called third-generation biofuels. One advantage of using algae is that algaculture (farming algae) does not take up valuable crop land, and has minimal impact on fresh water sources. Currently, production of algal biofuel (sometimes called “oilgae”) is more expensive than production of second-generation biofuels, but supposedly yields much more fuel per unit area.
Despite the drawbacks of production of each type of biofuel, the future is promising. Researchers across the world are working to streamline extraction of precious plant fuel, while maximizing food crops and minimizing carbon emissions. With all the ingenuity of the scientific world, it’s only a matter of time before we shake our dependence on fossil fuels in favor of renewable, responsible biofuels.