Algae fuel, also called algal fuel, algaeoleum or second-generation biofuel, is a biofuel which is derived from algae. During photosynthesis, algae and other photosynthetic organisms capture carbon dioxide and sunlight and convert it into oxygen and biomass. Up to 99% of the carbon dioxide in solution can be converted, which was shown by Weissman and Tillett (1992) in large-scale open-pond systems. As of 2008, such fuels remain too expensive to replace other commercially available fuels, with the cost of various algae species typically between US$5–10 per kilogram. But several companies and government agencies are funding efforts to reduce capital and operating costs and make algae oil production commercially viable. The production of biofuels from algae does not reduce atmospheric carbon dioxide (CO2), because any CO2 taken out of the atmosphere by the algae is returned when the biofuels are burned. They do however eliminate the introduction of new CO2 by displacing fossil hydrocarbon fuels.
High oil prices, competing demands between foods and other biofuel sources, and the world food crisis, have ignited interest in algaculture (farming algae) for making vegetable oil, biodiesel, bioethanol, biogasoline, biomethanol, biobutanol and other biofuels, using land that is not suitable for agriculture. Among algal fuels' attractive characteristics: they do not affect fresh water resources, can be produced using ocean and wastewater, and are biodegradable and relatively harmless to the environment if spilled. Algae cost more per unit mass yet can yield over 30 times more energy per unit area than other, second-generation biofuel crops. One biofuels company has claimed that algae can produce more oil in an area the size of a two car garage than a football field of soybeans, because almost the entire algal organism can use sunlight to produce lipids, or oil. The United States Department of Energy estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (40,000 km2). This is less than 1⁄7 the area of corn harvested in the United States in 2000.
Dry algae factor is the percentage of algae cells in relation with the media where it is cultured, e.g. if the dry algae factor is 50%, one would need 2 kg of wet algae (algae in the media) to get 1 kg of algae cells.
Lipid factor is the percentage of vegoil in relation with the algae cells needed to get it, i.e. if the algae lipid factor is 40%, one would need 2.5 kg of algae cells to get 1 kg of oil.
Currently most research into efficient algal-oil production is being done in the private sector, but predictions from small scale production experiments bear out that using algae to produce biodiesel may be the only viable method by which to produce enough automotive fuel to replace current world diesel usage.
Microalgae have much faster growth-rates than terrestrial crops. The per unit area yield of oil from algae is estimated to be from between 5,000 to 20,000 US gallons per acre per year (4,700 to 18,000 m3/km2·a); this is 7 to 30 times greater than the next best crop, Chinese tallow (700 US gal/acre·a or 650 m3/km2·a).
Studies show that algae can produce up to 60% of their biomass in the form of oil. Because the cells grow in aqueous suspension where they have more efficient access to water, CO2 and dissolved nutrients, microalgae are capable of producing large amounts of biomass and usable oil in either high rate algal ponds or photobioreactors. This oil can then be turned into biodiesel which could be sold for use in automobiles. The more efficient this process becomes the larger the profit that is turned by the company. Regional production of microalgae and processing into biofuels will provide economic benefits to rural communities.
Butanol can be made from algae or diatoms using only a solar powered biorefinery. This fuel has an energy density 10% less than gasoline, and greater than that of either ethanol or methanol. In most gasoline engines, butanol can be used in place of gasoline with no modifications. In several tests, butanol consumption is similar to that of gasoline, and when blended with gasoline, provides better performance and corrosion resistance than that of ethanol or E85.
The green waste left over from the algae oil extraction can be used to produce butanol.
Biogasoline is gasoline produced from biomass such as algae. Like traditionally produced gasoline, it contains between 6 (hexane) and 12 (dodecane) carbon atoms per molecule and can be used in internal-combustion engines.
The algal-oil feedstock that is used to produce biodiesel can also be used for fuel directly as "Straight Vegetable Oil", (SVO). The benefit of using the oil in this manner is that it doesn't require the additional energy needed for transesterification, (processing the oil with an alcohol and a catalyst to produce biodiesel). The drawback is that it does require modifications to a normal diesel engine. Transesterified biodiesel can be run in an unmodified modern diesel engine, provided the engine is designed to use ultra-low sulfur diesel, which, as of 2006, is the new diesel fuel standard in the United States.
Vegetable oil can be used as feedstock for an oil refinery where methods like hydrocracking or hydrogenation can be used to transform the vegetable oil into standard fuels like gasoline and diesel.
Rising jet fuel prices are putting severe pressure on airline companies, creating an incentive for algal jet fuel research. The International Air Transport Association, for example, supports research, development & deployment of algal fuels. IATA’s goal is for its members to be using 10% alternative fuels by 2017.
In February 2010, the Defense Advanced Research Projects Agency announced that the U.S. military was about to begin large-scale production oil from algal ponds into jet fuel. After extraction at a cost of 2$ per gallon, the oil will be refined at less than $3 a gallon. A larger-scale refining operation, producing 50 million gallons a year, is expected to go into production in 2011, with the possibility of lower per gallon costs so that algae-based fuel would be competitive with fossil fuels. The projects, run by the companies SAIC and General Atomics, are expected to produce 1,000 gallons of oil per acre per year from algal ponds.
Algae can produce up to 300 times more oil per acre than conventional crops, such as rapeseed, palms, soybeans, or jatropha. As Algae has a harvesting cycle of 1–10 days, it permits several harvests in a very short time frame, a differing strategy to yearly crops (Chisti 2007). Algae can also be grown on land that is not suitable for other established crops, for instance, arid land, land with excessively saline soil, and drought-stricken land. This minimizes the issue of taking away pieces of land from the cultivation of food crops (Schenk et al. 2008). Algae can grow 20 to 30 times faster than food crops.
Most companies pursuing algae as a source of biofuels are pumping nutrient-laden water through plastic tubes (called "bioreactors" ) that are exposed to sunlight (and so called photobioreactors or PBR).
Running a PBR is more difficult than an open pond, and more costly.
The difficulties in efficient biodiesel production from algae lie in finding an algal strain with a high lipid content and fast growth rate that isn't too difficult to harvest, and a cost-effective cultivation system (i.e., type of photobioreactor) that is best suited to that strain. There is also a need to provide concentrated CO2 to turbocharge the production.
Another obstacle preventing widespread mass production of algae for biofuel production has been the equipment and structures needed to begin growing algae in large quantities. Maximum use of existing agriculture processes and hardware is the goal.
In a closed system (not exposed to open air) there is not the problem of contamination by other organisms blown in by the air. The problem for a closed system is finding a cheap source of sterile CO2. Several experimenters have found the CO2 from a smokestack works well for growing algae. To be economical, some experts think that algae farming for biofuels will have to be done next to power plants, where they can also help soak up the pollution.
Open-pond systems for the most part have been given up for the cultivation of algae with high-oil content. Many believe that a major flaw of the Aquatic Species Program was the decision to focus their efforts exclusively on open-ponds; this makes the entire effort dependent upon the hardiness of the strain chosen, requiring it to be unnecessarily resilient in order to withstand wide swings in temperature and pH, and competition from invasive algae and bacteria. Open systems using a monoculture are also vulnerable to viral infection. The energy that a high-oil strain invests into the production of oil is energy that is not invested into the production of proteins or carbohydrates, usually resulting in the species being less hardy, or having a slower growth rate. Algal species with a lower oil content, not having to divert their energies away from growth, have an easier time in the harsher conditions of an open system.
Research into algae for the mass-production of oil is mainly focused on microalgae; organisms capable of photosynthesis that are less than 0.4 mm in diameter, including the diatoms and cyanobacteria; as opposed to macroalgae, such as seaweed. The preference towards microalgae is due largely to its less complex structure, fast growth rate, and high oil content (for some species). Some commercial interests into large scale algal-cultivation systems are looking to tie in to existing infrastructures, such as coal power plants or sewage treatment facilities. This approach not only provides the raw materials for the system, such as CO2 and nutrients; it changes those wastes into resources. However, some research is being done into using seaweeds for biofuels, probably due to the high availability of this resource.
Aquaflow Bionomic Corporation of New Zealand announced that it has produced its first sample of homegrown bio-diesel fuel with algae sourced from local sewerage ponds. A small quantity of laboratory produced oil was mixed with 95% regular diesel.
Nutrients like nitrogen (N), phosphorus (P), and potassium (K), are important for plant growth and are essential parts of fertilizer. Silica and iron, as well as several trace elements, may also be considered important marine nutrients as the lack of one can limit the growth of, or productivity in, an area.
One company, Green Star Products, announced their development of a micronutrient formula to increase the growth rate of algae. According to the company, its formula can increase the daily growth rate by 34% and can double the amount of algae produced in one growth cycle.
A possible nutrient source is waste water from the treatment of sewage, agricultural, or flood plain run-off, all currently major pollutants and health risks. However, this waste water cannot feed algae directly and must first be processed by bacteria, through anaerobic digestion. If waste water is not processed before it reaches the algae, it will contaminate the algae in the reactor, and at the very least, kill much of the desired algae strain. In biogas facilities, organic waste is often converted to a mixture of carbon dioxide, methane, and organic fertilizer. Organic fertilizer that comes out of the digester is liquid, and nearly suitable for algae growth, but it must first be cleaned and sterilized.
The utilization of wastewater and ocean water instead of freshwater is strongly advocated due to the continuing depletion of freshwater resources. However, heavy metals, trace metals, and other contaminants in wastewater can decrease the ability of cells to produce lipids biosynthetically and also impact various other workings in the machinery of cells. The same is true for ocean water, but the contaminants are found in different concentrations. Thus, agricultural-grade fertilizer is the preferred source of nutrients, but heavy metals are again a problem, especially for strains of algae that are susceptible to these metals. In open pond systems the use of strains of algae that can deal with high concentrations of heavy metals could prevent other organisms from infesting these systems (Schenk et al. 2008).
There is always uncertainty about the success of new products and investors have to consider carefully the proper energy sources in which to invest. A drop in fossil fuel oil prices might make consumers and therefore investors lose interest in renewable energy. Algal fuel companies are learning that investors have different expectations about returns and length of investments. AlgaePro Systems found in its talks with investors that while one wants at least 5 times the returns on their investment, others would only be willing to invest in a profitable operation over the long term. Every investor has its own unique stipulations that are obstacles to further algae fuel development. Additional concerns consider the potential environmental impact of Algal fuel development, as well as secondary impacts on wildlife such as bears and fish.
Whereas technical problems, such as harvesting, are being addressed successfully by the industry, the high up-front investment of algae-to-biofuels facilities is seen by many as a major obstacle to the success of this technology. Only few studies on the economic viability are publicly available, and must often rely on the little data (often only engineering estimates) available in the public domain. Dmitrov examined the GreenFuels photobioreactor and estimated that algae oil would only be competitive at an oil price of $800 per barrel. A study by Alabi at al. examined raceways, photobioreactors and anaerobic fermenters to make biofuels from algae and found that photobioreactors are too expensive to make biofuels. Raceways might be cost-effective in warm climates with very low labor costs, and fermenters may become cost-effective subsequent to significant process improvements. The group found that capital cost, labor cost and operational costs (fertilizer, electricity, etc.) by themselves are too high for algae biofuels to be cost-competitive with conventional fuels. Similar results were found by others, suggesting that unless new, cheaper ways of harnessing algae for biofuels production are found, their great technical potential may never become economically accessible.
Universities in the United Kingdom which are working on producing oil from algae include:University of Glasgow, University of Brighton, Cambridge University, University College London, Imperial College London, Cranfield University.
The Aquatic Species Program, launched in 1978, was a research program funded by the United States Department of Energy (DoE) which was tasked with investigating the use of algae for the production of energy. The program initially focused efforts on the production of hydrogen, shifting primary research to studying oil production in 1982. From 1982 until its end in 1996, the majority of the program research was focused on the production of transportation fuels, notably biodiesel, from algae. In 1995, as part of overall efforts to lower budget demands, the DoE decided to end the program. Research stopped in 1996 and staff began compiling their research for publication.
At the Woods Hole Oceanographic Institution and the Harbor Branch Oceanographic Institution the wastewater from domestic and industrial sources contain rich organic compounds that are being used to accelerate the growth of algae. The Department of Biological and Agricultural Engineering at University of Georgia is exploring microalgal biomass production using industrial wastewater. Algaewheel, based in Indianapolis, Indiana, presented a proposal to build a facility in Cedar Lake, Indiana that uses algae to treat municipal wastewater, using the sludge byproduct to produce biofuel.
The Algal Biomass Organization (ABO) is formed by Boeing Commercial Airplanes, A2BE Carbon Capture Corporation, National Renewable Energy Labs, Scripps Institution of Oceanography, Benemann Associates, Mont Vista Capital and Montana State University.
Global air carriers Air New Zealand, Continental, Virgin Atlantic Airways, and biofuel technology developer UOP, a Honeywell company, will be the first wave of aviation-related members, together with Boeing, to join Algal Biomass Organization.
The National Algae Association (NAA) is a non-profit organization of algae researchers, algae production companies and the investment community who share the goal of commercializing algae oil as an alternative feedstock for the biofuels markets. The NAA gives its members a forum to efficiently evaluate various algae technologies for potential early stage company opportunities.