Chem321:Algal biofuels
This is the 2012 paper by Jonathan Stewart.
Algal Bio fuels
In our post-industrial society, technologies have been developed to attack the issues of global warming, resource depletion, and all sustainability issues in many different ways. Traditional modes of creating heat energy, from the burning of petroleum based fuels, have been found to cause major problems for the environment over the last 40-50 years. Traditional fuels are a finite resource, with its stocks are being exponentially reduced by continued economic growth and population increases. It is now understood that we are using this resource much faster than it could ever replenish itself and alternative fuel will be necessary to continue our society if we are to become a sustainable society. Wind, Hydroelectric, Geothermal, and solar energy systems have all been developed to reduce our use of petroleum-based fossil fuels, and their use has been on the rise for many years.
One of our largest and least environmentally friendly uses of fossil fuels is their use in internal-combustion engines. Predominantly, these engines are found in our everyday automobiles. Many of our personal vehicles run off gasoline, but many large public transportation and freight vehicles utilize diesel fuel. Whether these fuels are used in personal or public transport, there is an ever increasing need to find other sources to derive this utility from. The U.S feedstock of crude oil (the precursor of gasoline and diesel) is of very short supply, and we import millions of barrels of crude oil from around the world every year. Our supply of this oil is 60% imported from other countries, which means that almost half of our energy needs, derived from crude oil, are imported.(USA) When these overseas deposits of crude oil are depleted, more deposits must be found. These new deposits will be more costly to find and extract from the earth as we use the resource. Along with the enviornmental impact that the extraction and use of this oil poses, we need a more reliable, non-foreign source of the energy we derive from this oil. We may not have reached the tipping point yet where there is less oil left than what we have used, but we are more than likely approaching this point and something must be done.
Wind, Geothermal, hydroelectric and solar power systems are not practical for transportation use. Granted, these technologies are able to supply a sustainable form of energy, electricity, that a purely electric car could run on, however this technology is still being developed. Also, Purely electric vehicles only have a specific maximum distance that may be traveled before the car must be recharged, and whether or not it is more or less than a gasoline or diesel engine, the facilities needed to recharge an electric car are few and far between. Until there is a time when one or more of these technologies becomes more practical as a replacement for the internal combustion engine, we must develop more renewable forms of the crude oil we extract.
In the 1920's, the first fuel derived from plant feedstock was created. This fuel, Bioethanol, was designed to be a fuel that could be made from existing stocks or resources during times of shortage, like war. This ushered in the age of biofuels, which has had lasting effects on the fuel industry. Since the first synthesis of bioethanol, many other biofuels have been produced from plant stocks. These fuels are comparable to crude oil in their use, but there is one issue associated with this alternative fuel. The amount of land that must be used to produce usable fuel is large, and also takes away from the available arable land that is available for food production. The amount of land required to reduce our global use of fossil fuels by 5.75% would be comparable to the countries of Germany, Austria and the Czech Republic combined.(Hill) Along with the reduction in arable land available for food production, the plant life used for these fuels, especially corn in the US, can have intense water and fertilizer needs, which can add even more environmental hardship to the surrounding ecosystem.
Biomass that is to be converted to fuel, obtained from food sources like corn or soybean are considered first generation biofuels. Second generation biofuels were developed in response to the issues that first generation biofuels place on food scarcity, and watersheds. By using non-edible, or animal based fats to use in the bio-fuel process, we have overcome some of the issues of the Food Vs. fuel debate. Although the use of tobacco and used cooking oil may help reduce the use of food stocks as fuels, these plants still demand huge amounts of water and land that renders them not economically efficient in many areas of the world. Third generation biofuels have recently been developed to address these issues. Third generation biofuels are created from the biomass created by algal cultures. This third generation of biofuels shows the most promise in becoming a viable, and economically practical route in developing alternative, renewable fuel sources from biomass feedstock that do not reduce available food or land.
Biofuels created from algal sources are much more efficient than traditional first and second generation bio fuel feedstock. This is due to the algae's ability to quickly create the biomass that is needed to make bioethanol, or any number of other biofuels. This ability comes from the photosynthesis process that occurs in the algae, a type of plant life, and the by-products this process produces The most important products produced by algal cultures for the biofuel industry, including lipids, carbohydrates, proteins, and other chemicals, are the precursors of biofuels. When these natural chemicals are sent to biorefineries, they are transformed into usable fuels. These chemicals are produced by the algal cultures by harnessing the power of the sun to convert atmospheric carbon dioxide(CO2) into usable molecules for the plant. A major advantage of using biofuels over crude oil is that no new CO2 is released into the atmosphere when they are burned. The carbon that is stored in fossil fuels has been there for millions of years and would never have reached the earths' surface if it was not for our extracting it. This means that as fossil fuels burn, extra CO2 is added to the atmosphere. The benefit of biofuels is that, although burning them still releases CO2, this CO2 has been already been fixed from the atmosphere when the plant was growing. All plants engage in fixing CO2 from the atmosphere through the process of photosynthesis. The advantage of using biomass for fuel is that in the process of burning them, we do not add any more CO2 to the atmosphere than was already there.
Algal biofuels also have other environmentally friendly characteristics that make them the best choice for biofuels. Firstly, the amount of arable land that is needed to house an algal colony is much smaller than the land needed for first and second generation biofuels. For one, the algae live in liquid water, which allows us to harvest the species of algae in closed lakes, ponds and other natural water systems which we can not use for the growth of traditional plant life. The efficiency of algal cultures in creating the lipids, carbohydrates, proteins and other chemicals used in the biorefinement process also greatly overshadows current first and second generation biomass feedstocks. It is estimated that the soy bean plant, a first generation bio fuel feedstock, produces 48 gallons of fuel per acre per year, while Jatropha, a second generation bio fuel feedstock produces 202 gallons of fuel per acre per year. The figure for algae is astounding; somewhere between 1000-6500 gallons per acre per year.(USA) Also, the colonies can be started in large fermentation tanks, man-made open ponds, and devices called photobioreactors. This means that algae can be essentially grown anywhere with enough sunlight and warmth, giving areas that would not have been able to sustain first or second generation bio fuel feedstock a chance to produce bio fuels.
Another benefit that algal biofuels have above the rest of the biofuel feedstocks is its carbon fixation rate. For every 1kg of dried biomass that is produced by algal cultures, 1.83kg of CO2 is fixed from the atmosphere, which allows algae to be very productive compared to other biofuel feedstocks(Najafi et.all). This is a large number but there are some preventative limits on algae's ability to perform this task. Algae can not consume atmospheric CO2 because its concentration is much too low, but the amount of CO2 that is removed from the water during the growth of algal cultures leaves the water that the specimens were grown in CO2 depleted. Smokestack gases, released as waste by many factories, can be used as a “fertilizer” of sorts for certain species, boosting their biomass yields.(Menetrez) Also, the CO2 depleted water that is left after the algal strains have run their course can be used as an effective scrubber for these factory emissions. By bubbling the CO2 gas through the water, CO2 is left in the water at higher amounts than naturally would occur, benefiting the algal growth.(Shilton) An added benefit of this “de-carbonization” of water is that algae also inject oxygen into water, allowing for higher consumers to begin establishing a foothold in the environment.
Along with algae's wonderful performance as a biomass feedstock, and its ability to allow natural scrubbing of factory emissions, algal strains have a strong ability to clean waste water. Studies have shown that algae strains have a strong ability to assimilate free floating nitrogen, phosphorus, and sulfur compounds from waste water.(Menetrez) This technology has been in use for a long time, and is not a new discovery. In 2002, HydroMentia, Inc., of Ocala, Florida, began building 18-million to 20-million liter per day sewage treatment facilities using algal technologies(Adey). As we can see, the benefits of using algae to clean waste water are huge.
Compared to any other form of bio fuel feedstock, algal produced biomass is the most environmentally friendly, and economically viable. Algal yields for biofuels are anywhere from 20 to 40 times larger than oilseed crops, such as soybean or corn.(Woertz) However, the correct conditions, in terms of sunlight and warmth, and the most viable strains for biomass production, are not always available, which renders algal biomass not economically viable everywhere. The added benefits that algal growth has, aside from its biomass and biofuel yields, are where algae will help most in our fight to bring in a new environmentally sustainable society. Algae's ability to fix carbon is huge, decarbonizing water sources in the 6 days it takes for algal growth to reach its peak. This strong ability to fix carbon also depletes CO2 within the water itself, leaving a viable resource for scrubbing CO2 from factory flue's. Along with its amazing CO2 abilities, Algal growth is able to assimilate other potentially harmful elements(Nitrogen, Phosphorus and Sulfur) from waste water sources.
Although this technology is not economically viable in every location around the world, algal growth has potential to be one of the larger sources of environmentally sustainable technology in the future. The combination of algal growth properties are what make it such a strong contender in today's world. By engineering systems that use algal growth, we can reduce our use of traditional fossil fuel use immensely. More than any other source of bio mass, algae have the most positive effects on our fossil fuel use. Although biomass is heavy, if refineries are constructed nearby algal growth centers, bio fuel can be created at little monetary cost, and with little additional transportation fuel needed. As we have discussed however, algal cultures have many more benefits associated with them than just being used as bio fuel The combination of fuel, CO2 remover from air and mineral remover from water will help us overcome many of the wastes we have created already through heavy manufacturing. Although biofuels themselves are a sort of end-means solution, meaning that we are still not addressing our overabundance of waste created, and overabundance of inputs used, algal technologies, and other future biofuel technologies will be able to at least ward off some of the impending dooms that are associated with atmospheric CO2 increases and contaminated waste water.
Algal growth is some of the most promising technology that has arisen to date in our continuing battle to become a more sustainable society. Paul Anastas, a leader within the EPA described our current situation as a environmental game of whack-a-mole. With each new technology introduced, we have discovered that in some way, the new technology is also a burden. Will algal colonies be able to supply local areas with enough bio fuel to meet their current needs? Possibly. Will algal colonies escape containment and pollute local ecosystems irrevocably? Also possible. Algae can help us clean up our air and our water systems if done correctly but are we truly addressing the real issue by investing in algal biofuel technology? Many technologies that have emerged in the last half century have aimed at cleaning up processes and making them more environmentally friendly, including algal biomass, but will we find in the near future that algae, and some of the chemicals and infrastructure utilized in its production are harmful to the environment? The real solution to our problems is not by pushing back the inevitable, like bio fuel technologies are essentially doing, but in redefining the way we conduct production, transportation, and basic services in a way that is sustainable.
Works Cited
Adey, Walter H., Patrick C. Kangas, and Walter Mulbry. "Algal Turf Scrubbing: Cleaning Surface Waters with Solar Energy While Producing a Biofuel." BioScience 61.6 (2011): 434-41. Print.
Hill, Callum A. S. An Introduction to Sustainable Resource Use. London, UK: Earthscan, 2011. Print.
Menetrez, Marc Y. "An Overview of Algae Biofuel Production and Potential Environmental Impact." Environmental Science & Technology 46.13 (2012): 7073-085. Print.
Najafi, Gholamhassan, Barat Ghobadian, and Talal F. Yusaf. "Algae as a Sustainable Energy Source for Biofuel Production in Iran: A Case Study." Renewable and Sustainable Energy Reviews 15.8 (2011): 3870-876. Print.
Shilton, A. N., D. D. Mara, R. Craggs, and N. Powell. "Solar-powered Aeration and Disinfection, Anaerobic Co-digestion, Biological CO2 Scrubbing and Biofuel Production: The Energy and Carbon Management Opportunities of Waste Stabilisation Ponds." Water Science & Technology 58.1 (2008): 253-58. Print.
USA. Department of Energy. Energy Efficiency and Renewable Energy. National Algal Biofuels Technology Roadmap. Print.
Woertz, I., A. Feffer, T. Lundquist, and Y. Nelson. "Algae Grown on Dairy and Municipal Wastewater for Simultaneous Nutrient Removal and Lipid Production for Biofuel Feedstock." Journal of Environmental Engineering 135.11 (2009): 1115. Print.
