What's green, grows practically anyplace that's damp, and can potentially supply all the petroleum the U.S. needs? The humble, ubiquitous algae.
Algae are one-celled plants that contain chlorophyll and have no true roots, stems or leaves. And here's the reason algae are generating excitement as a source of energy: some strains of algae, especially microalgae measuring less than 0.4 millimeters in diameter, produce lipids, or oil.
This algal oil is in a form similar to common vegetable oil. Algae produce the oil through photosynthesis, the process that all plants use to convert sunlight into energy.
Advantages of Algal Oil
As a source of biofuel, algae have many advantages over naturally occurring oil and oil from other plant sources. Some of these are:
- Many strains of algae double their mass two or three times a day. This results in a virtually unlimited stock from which to extract oil.
- Algae provide a high yield of oil compared to other plant sources of biofuels. For example, algae produce 100 times more oil per acre than soybeans, palm or jatropha. Hence, smaller areas need to be cultivated to generate an equivalent amount of energy. The U.S. Department of Energy estimates that if algal fuel replaced all the petroleum in the U.S., it could be cultivated in an area a little larger than Maryland.
- Algal oil can be refined and transported through the existing infrastructure for crude oil. Just like conventional crude, algal oil can be processed into biodiesel, gasoline and jet fuel.
- Since microalgae are not generally used in the human diet, producing algal oil does not deplete food stock. By contrast, when edible plants such as soybeans and corn are used to manufacture fuel, they must be diverted from the food supply.
- Algae are highly efficient sources of energy: Nearly 60% of the plant gets converted to oil.
- Algae can be commercially grown in facilities built on almost any kind of land: arable, non-arable and even deserts.
- Alage grow in seawater, wastewater or fresh water.
- Algae use up carbon dioxide during photosynthesis, helping lower the amount of this greenhouse gas in the atmosphere.
- The biomass residue from the production of algal oil can be used for many purposes, such as animal feed, generation of heat, ethanol production, etc.
Disadvantages of Algal Oil
At present, producing oil from algae is expensive. The cost of making algal biofuel can be more than $8 per gallon, compared to $4 per gallon for soybean oil. However, the benefits of algal oil are so compelling that both public and private sectors are focusing strongly on finding ways to reduce costs and more efficiently manage growing and harvesting algae on a large scale.
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