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| Fig. 1: Algae harvesting Pools (such as above) and photobioreactors produce and harvest algae with little or no environmental impact. (Source: Wikimedia Commons.) |
If human growth and energy consumption continue to increase, alternative sources of energy will need to be developed. Currently, fossil fuels are by far the majority of energy sources across the globe. One alternative energy that currently has some success in today's energy industry is that of bio fuels--fuels generated from living matter, mostly plants. One such source that has great potential and results is algae. The types of energy sources derived from algae (mainly bio fuels) can be used in the ways many fossil fuels are currently used but are cleaner burning and more sustainable. One should note that some difficulties do exist with developing algae fuels.
Currently, algae provides a much higher oil yield per hectare than other present bio-fuels such as switch grass, rapeseed, palm oil, and corn. Lipids, the fat cells and oils, in the algae are harvested to create vegetable oil, biofuels, bio diesel, and jet fuel. While the percentages vary with the species and type of algae, some algae are comprised up to 40% of their overall mass by fatty acids. [1] Algae is robust and can grow in many different conditions. The nutrients required for growing algae are nitrogen, phosphorus, mineral salts, trace elements, and silicon (for diatom). [2] Saline waters or municipal waste waters make suitable growing environments for algae, especially micro-algae. This makes harvesting and production possible in arid lands (not at the expense of harvesting food crops or clean water). There is great potential for widespread use of algae based jet fuels,which are currently only beginning to be used. Even supplying a 15 percent blend of bio-jet fuel (85 percent petroleum/hydrogen based) would require huge amounts of land and agricultural systems. For example, in 2004 the U.S. commercial fleet used about 13.6 billion gallons of jet fuel. A 15 percent blend of bio-jet fuel would require 2.04 billion gallons of pure bio fuel per year. Soybeans yield about 60 gallons of bio fuel per acre. In order to meet this demand, it would require 34 million acres (138,000 square kilometers) of agricultural land, about the land size of the state of Florida. [3] However, algae has a much higher oil content. Algae's potential pure bio fuel output is around 1580 gallons acre-1 year-1. [4] In order to produce 2004 levels of mixed blend jet fuel for the United States, a production harvesting area of roughly 1.3 million acres (5220 square kilometers) would be required. However, at this present time, not all aircraft can utilize bio jet fuel. There are many other advantages when using an algae system for the generation of bio fuels: [5]
A much higher lipid content compared to other plants/bio fuel sources.
Capable of being cultivated without sacrificing other agriculture.
Can be grown in a variety of climates without contamination to the surrounding environments. (Fig. 1)
The use of municipal waste waters, saline water aquifers, or even sea water because these all contain the necessary nutrients for optimal growth (no use of clean water).
Carbon neutrality in growth and production.
Higher combustion efficiencies.
Bio fuels derived from algae are viable sources of alternative energy. However, some disadvantages do exist. Algae fuels often have lower energy content than their petroleum counterparts, are more expensive, and produce less engine power and speed. [5] On the other hand, the advantages identified above make algae fuels a powerful alternative to biofuels, considering that many infrastructures and fossil fuel powered devices would not have to be substantially altered for bio fuel use. More funding, researching, and business ventures for algae harvesting and bio fuel processing should be carried out.
© Sidharth Kumar. 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.
[1] A. Demirbas, "Production of Biodiesel from Algae Oils," Energy Sources A 31, 163, (2008).
[2] Z. Wen, J. Liu and F. Chen, "Biofuel from Microalgae," in Comprehensive Biotechnology, 2nd Ed., ed. by M. Moo-Young et al. (Pergamon, 2011), p. 127.
[3] D. Daggett et al., "Alternative Fuels and Their Potential Impact on Aviation," NASA Glenn Research Center, NASA/TM-2006-214365, October 2006.
[4] P. Pienkos and A. Darzins, "The Promise and Challenges of Microalgal-derived Biofuels," Biofuels, Bioproducts and Biorefining. 4, 433, (2009).
[5] A. Demirbas, "Importance of Biodiesel as Transportation Fuel," Energy Policy. 35, 4661, (2007).
