|Fig. 1: Example of Bioethanol Plant. (Source: Wikimedia Commons)|
The need for an alternative energy source has been critical for the reduction of carbon emissions and for the Earth's future. Biofuels became a promising energy alternative that is both renewable and sustainable. For the effective implementation of biofuel, it is essential to consider whether or not biofuels are technically feasible, economically affordable, and environmentally and socially viable.  This paper will explore the technical, economical, and environmental feasibility of biofuels to analyze the benefits and limits of biofuels.
As of 2010, the total amount of bioenergy accounts for 10% of total global energy supply and is around 5.3 × 1019 joules/ year (53 EJ/yr), a value less than the total amount of non-food energy consumed by civilization, which is 5 × 1020 joules. [2,3] As it is demonstrated in the total amount of bioenergy, bioenergy supplies demonstrate promising prospects in the future, as it is "expected to grow at greater than 3% per year to 2035".  From the perspective of some policymakers, biofuel was considered as a highly beneficial energy alternative, because it can create new income sources for farmers in suburban areas.  With new income sources, the policymakers believed that the production of biofuels may help the local economy to flourish. However, aside from the new income opportunities, some scholars voiced that biofuels were economically inefficient, because the production costs of essentially all first-generation biofuels (conventionally produced from grains, seeds, and sugar crops) in all countries are inherently high due to use of high-cost feedstocks.  The water-intensive nature of the feedstocks requires a great deal of financial investment and therefore leads to high production cost of the biofuels. Because the price of biofuels is relatively high, many concerned that biofuels would not be economically favorable enough to stand as an alternative for nonrenewable energy resources.
However, second-generation biofuels (made from lignocellulose) provides a solution to this economic concern, because second-generation biofuels can be made from lower-cost feedstocks.  Although second-generation biofuels may sound more economically affordable than first-generation biofuels, the technical feasibility of second- generation biofuels is questioned. The biochemical processing of lignocellulose requires advanced technology, which is less likely to be implemented in suburban areas or developing countries.  Fig. 1 shows an example of a bioethanol plant with advanced technology. Also, the use of advanced technology may replace pre-existing jobs, potentially going against the idea of biofuel providing new income sources for farmers.  Also, because the production of biofuels is constrained by the availability of arable land, the competition with food production for land use could drive possible increases in both ethanol and food prices.  With the increases in food prices, the local economy may suffer.
Furthermore, although the use of a nonrenewable energy source may be an eco-friendly approach to respond to the energy crisis, the production process of biofuels raises many concerns about its impact on the environment. Since biofuels are more reliant on the availability of arable land, the biofuel production may encourage more land conversion.  The alteration of the natural landscape for biofuel production may lead to undesirable consequences for the environment. In addition, in scenarios having 25% of transport fuels derived from biomass, the use of fertilizers increases by about 40%.  The increased use of fertilizers following the increased reliance on biofuels may lead to harmful environmental consequences such as eutrophication and reduced land fertility.
Overall, biofuels have many benefits and limitations that have to be taken into consideration for effective implementation. The concerns over high production cost, adoption of biofuel technology in rural areas, availability arable land, competition with food prices, increased fertilizer use, and other environmental externalities should be addressed to encourage the production and use of biofuels in the future. Currently, third generation biofuels are under development to reduce the burdens of economic viability by using cheaper substrates and the burdens of environmental side effects by relying on heterotrophic processes. 
© Hanna Chang. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 T.Gomiero, Are Biofuels an Effective and Viable Energy Strategy for Industrialized Societies? A Reasoned Overview of Potentials and Limits," Sustainability 2015, 8492, (2015).
 S. C. Davis, W. Hay, and J. Pierce, Biomass in the Energy Industry: An Introduction (British Petroleum, 2014).
 "BP Statistical Review of World Energy 2017," British Petroleum, June 2017.
 "Biofuel Production Technologies: Status, Prospects and Implications For Trade and Development," United Nations, 2008.
 "Biofuel Production," International Energy Agency, January 2007.
 J. S. Rokem and C.L. Greenblatt, "Making Biofuels Competitive: The Limitations of Biology For Fuel Production," JSM Microbiol. 3, 2013 (2015).