Energy is the most important aspect in modern world, as the dependency on energy is inseparable from people’s life. Furthermore, the needs to travel using automobiles create an insatiable need for fossil fuel to power the movements. Unfortunately, fossil fuel is a non-renewable resource that is estimated to be depleted in 2042 (Shafiee and Topal 181). From environmental point of view, fossil fuel combustion from diesel and gasoline vehicles has high contribution to the pollution level in urban areas (Chow and Watson 222). In addition to the pollution level, combustion of fossil fuel releases CO2 a greenhouse gas that contributes to the climate change (Meinshausen, Meinshausen and Hare 1160) . Therefore, a renewable and clean source of energy is needed in order to sustain energy supply and to improve the quality of life.
A solution is available from a new technology that relies on fuel production from microorganisms. This technology is known as microbial fuel cells (MFC) that generates electricity by converting a substrate directly into electricity (Rabaey and Verstraete 291). Various microbial strains that have been utilized for this technology consist of bacterial genera Clostridium, Alcaligenes, and Enterococcus (Rabaey and Verstraete 292), and a high power density for MFC is often derived from mixed bacterial culture found in waste water and sludge containing fermentative and methanogen bacteria that can transport electron extracelluarly (Logan 376). In addition to the abovementioned bacteria genera,
Rhodopseudomonas palustris and Shewanella oneidensis are also known to produce high density power of 2.72 W and 2 W per meter square respectively (Logan 378).
An advantage of microbe-produced energy is the potential of this application to provide solution for wastewater treatment in addition to producing energy. Substance for MFC is primarily wastewater and lignocellulic biomass, so the use of this substance for energy production will also provide a solution for sustainably converting waste into energy (Pant, Bogaert and Diels 1533).
Electricity has been widely accepted as a clean source of energy and it has also been used as energy source to power homes as well as vehicles. Application of electricity in powering electric and hybrid cars has been tested, so microbe-produced electricity for powering vehicles is a promising feat. MFC can also be modified to produce hydrogen instead of electricity (Du, Li and Gu 477), and hydrogen can also be used as a clean source of energy to power vehicles. Another option for microbe-produced fuel is bioethanol. Bioethanol is produced from fermentation process of various raw materials by yeast Saccharomyces cerevisiae strain L1400 (Schell, Riley and Dowe 182), but the best material for bioethanol production is lignocellulose from sugar cane (Sanchez and Cardona 5270). Bioethanol is considered as a renewable source of energy that is competitive with conventional motor gasoline, and its production is appropriate for replication in many countries (Goldemberg 808).
The above examples show that microbe-produced fuel is no longer a science fiction story, as it already has some working applications. The work needed now is simply finding a way of optimizing exisiting technology to obtain the most cost-efficient production of fuel and energy from microbes based on available raw materials. In addition to producing fuel and energy, this technology optimization will yield better and sustainable means for wastewater treatment which will improve existing quality of life. The end result of this feat will be a sustainable process for producing renewable and clean energy that will provide substitute for fossil fuel energy.
Chow, J C and J G Watson. "Review of PM2.5 and PM10 apportionment for fossil fuel combustion and other sources by the chemical mass balance receptor model." Energy & Fuels 2002 16 (2002): 222-260. Print.
Du, Z, H Li and T Gu. "A state of the art review of microbial fuel cells: A promising technology for wastewater treatment and bioenergy." Biotechnology Advances 25 (2007): 464-482. Print.
Goldemberg, J. "Ethanol for a sustainable energy future." Science 315 9 February 2007: 808-810. Print.
Logan, B E. "Exoelectrogenic bacteria that power microbial fuel cells." Nature Reviews Vol 7 May 2009: 375-381. Print.
Meinshausen, M, et al. "Greenhouse-gas emission targets for limiting global warming to 20 C." Nature 30 April 2009: 1158-1163. Print.
Pant, D, et al. "A review of the substrates used in microbial fuel cells (MFCs) for sustainable energy production." Bioresource Technology 101 (2010): 1533–1543. Print.
Rabaey, K and W Verstraete. "Microbial fuel cell: novel biotechnology for energy generation." Trends in Biotechnology 23(6) June 2005: 291-298. Print.
Sanchez, O J and C A Cardona. "Trends in biotechnological production of ethanol from different feedstocks." Bioresource Technology 99(13) (2008): 5270-5295. Print.
Schell, D J, et al. "A bioethanol process development unit: initial operating experiences and results with a corn ﬁber feedstock." Bioresource Technology 91 (2004): 179-188. Print.
Shafiee, S and E Topal. "When will fossil fuel reserves be diminished?" Energy policy (2009): 181-189. Print.