The use of algae as biofuel is a relatively new technology, as compared to other biofuel resources. For production of biofuel, mass cultivation of algae or algaculture is carried out in various regions of the world. Many countries have implemented highly sophisticated techniques for enhancing mass-scale cultivation of algae.
Algae are a large group of primitive, mostly aquatic, photosynthetic chlorophyll-bearing plants, lacking specialized tissues and organs namely roots, stems, leaves, flowers etc. Algae can be broadly categorized into two groups: microalgae and macroalgae. Microalgae are very small (+/- 1 to 50 ìm) while macroalgae can reach sizes up to 60 m in length. Algae are usually found in damp places or bodies of water and thus are common in terrestrial as well as aquatic environments. Like plants, most algae require primarily three components to grow: sunlight, carbon-dioxide and water.
Microalgae, because of their growth rate and yields, are capable of producing a lot more oil than other energy crops. Some estimates suggest that microalgae strains are capable of producing up to 50,000 litres of oil per hectare a year. This could be converted into biodiesel by conventional processes and be used to fuel vehicles from jets to tractors. As per studies conducted on algae, it is observed that about 60 percent of their biomass can be converted into biofuel.
Microalgae, specifically, posses several attractive characteristics:
Impressive productivity: Microalgae can potentially produce 100 times more oil per acre than soybeans or any other terrestrial oil-producing crop.
Non-competitive with agriculture: Algae can be cultivated in large open ponds or in closed photobioreactors located on non-arable land in a variety of climates (including deserts).
Quick growth: Microalgae grow quickly. They commonly double in size every 24 hours. During the peak growth phase, some microalgae can double every three and one-half hours.
Flexible water quality: Marine water as well as wastewater can be used for mass cultivation of algae. Fresh water is not essential to grow algae.
Mitigation of Co2: Algae are capable fixing CO2 in the atmosphere, thus facilitating reduction of CO2 level. During photosynthesis, algae use solar energy to fix carbon dioxide (CO2) into biomass, so the water used to cultivate algae must be enriched with CO2. This requirement offers an opportunity to make productive use of the CO2 from power plants, biofuel facilities, and other sources.
Environment friendly: Algae biofuel is non-toxic, contains no sulfur, and is highly biodegradable, thus reducing the chances of environmental pollution. Moreover, in case there is spillage of algal-based biofuel in water sources, there are no significant adverse effects on the ecosystem.
Broad product portfolio: The lipids produced by algae can be used to produce a wide range of biofuels, and the remaining biomass residue has a variety of useful applications. These are combust to generate heat, use in anaerobic digesters to produce methane, use as a fermentation feedstock in the production of ethanol and use in value-added byproducts, such as animal feed.
One of the key reasons algae are considered as feedstock for oil is their high yields. Algae are the only bio-feedstock that can replace all of our current and future petro-fuel consumption. It will be very difficult for the first generation biodiesel feedstock such as soy or palm to produce enough oil to replace even a small fraction of petro-oil needs without displacing large percentages of arable land meant for food crops.
According to the Department of Energy, USA, the world's use of gasoline and diesel is about 1300 billion gallons per year. Studies revealed that algae have the ability to produce about 5000 gallons of biodiesel/acre. Moreover, about 1.5 billion hectares of non-forested land is available worldwide that is not being used for agriculture. A simple calculation shows that in order for algae biodiesel to completely replace all transportation fuels, it will require about 80 million hectares of land (less than 5%), which sounds achievable. Crops such as palm would require close to a billion hectares for the same result, a daunting and almost impossible task.
The US Navy recently took delivery of 90,000 litres of a new type of biofuel, produced from algae. The successful test flight by a Super Hornet jet fighter using the algae biofuel is a milestone in the US biofuels programme.
In 2008 the British government-backed Carbon Trust launched an £8m Algae Biofuels Challenge, which focused on accelerating the development and commercial production of microalgae biofuels for use in aviation and road transport by 2020. 11 British Universities took up the challenge.
In the USA the Energy Independence and Security Act declared that America should produce 36 billion gallons of biofuels by 2022. President Barack Obama has allocated £530m ($800m) for biofuels research.
Many large companies, such as Aquaflow Bionomic, Cellana, Exxon-Mobil, Solazyme etc are also investing heavily into bio algae research. At present worldwide around 200 companies are conducting the research in wide range of technical sectors to lowering the production cost for commercialising the algal biofuel.
Mary Rosenthal, the Executive Director of the Algal Biomass Organisation said "We're right at the cusp of commercializing and making fuel from algae. There are companies making thousands of gallons of biofuel now, but in several years - maybe by 2015 - we should be at millions of gallons."
The biggest bottleneck today for algae to become a mainstream biofuel feedstock is the higher production cost.
Key challenges: The real challenge facing the algae industry is the high cost of fuel production from algae. The high cost is owing to the following difficulties:
* Difficulty in optimal strain selection
* Contamination management in open cultivation environments and in waste water/sewage
* High capital and operating costs of photobioreactors
* High cost of harvesting
* High cost of biomass gasification
There are two types of challenges to be overcome with respect to processes: (1) Engineering challenges such as making photobioreactors, raceway ponds and centrifuges more efficient and (2) Biological challenges such as increasing oil yields from algae, genetic engineering of algal strains and facilitating specific strains of algae to survive in habitats that are not natural to them. It is expected that many engineering challenges could be solved within the next 2-3 years.
Now it is difficult to predict when the biological challenges will be overcome, though good progress is being made on aspects such as genetic engineering of algae strains. Experts predict that experiments on overcoming the biological challenges could take more than five years (beyond 2015). Then it would be possible to commercialise the algae fuel at competitive cost. If the scientists are able to reduce cost, in near future, algae biofuel may be the alternative fuel that can replace the fossil fuel, which causes global warming by releasing the greenhouse gases that often degrade the environment.
Gd job! :))
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