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The Japanese nuclear disas-ter makes it clear the world is in dire need of clean, safe, reliable (renewable) energy alternatives. Biofuels are a major component of this need; more specifically, algae is feedstock for tomor-row’s fuel, and the high-energy crop far ex-ceeds other biofuel options. However, a mix of biofuels is necessary to bridge tomorrow’s energy demands, and reduce and sequester the ever problematic carbon dioxide (CO2) emis-sions glut.

CO2 is one of the essential components required to grow algae; including sunlight, water and nutrients. The technology is in relatively early stages, used in smaller settings such as breweries, but global power projects

are also interested. It may be a while before it’s brought to full-scale commercialization, however, all components exist—particularly a need for high-energy biofuels. Carbon capture and storage (CCS), or carbon sequestration, is a growing science. This involves geologic se-questration in oil production and coal recovery projects—replacing recovered methane gas with CO2, natural aquifer sinks for CO2—such as those in the North Sea.

Of the gross total CO2 emissions daily on a global basis, China is the highest emitter, followed by the U.S. and the EU. CO2 by far is the greatest greenhouse gas by volume, but others (methane) are much worse. Sequestra-tion means are constantly being evaluated by those major emitters such as chemical and

power generation plants, and oil and ethanol refineries.

Some estimates indicate at least 75 mil-lion metric tons of CO2 are emitted daily from a wide variety of sources. Natural processes such as photosynthesis and natural oceanic ac-tivity are major carbon sinks. The ocean has traditionally absorbed about 25 million metric tons of carbon but it’s becoming more dif-ficult for the oceans to absorb CO2 naturally. Many think the oceans are becoming saturated because atmospheric CO2 is also elevated, and the oceans’ pH is dropping toward an acidic state, where “oceanic acidification” may be-come a major problem. Acidification will damage and kill marine life such as coral reefs, perhaps indefinitely.

Algae produced for biofuels markets will become a major component of the advanced biofuels sector. Algae is an extraordinarily energy-rich crop, exceeding the energy value of soy by 30-fold. A small amount of physical

The claims and statements made in this article belong exclusively to the author(s) and do not necessarily reflect the views of Algae Technology & Business or its advertisers. All questions pertaining to this article should be directed to the author(s).

CONTRIBUTION

CO2 and Algae Projects

An opportunity to sequester and foster algae productionBy Sam a. RuShing

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space is required to produce sufficient algae to replace all domestic petroleum needs.

Requirements Studies suggest two pounds of CO2 on

average is utilized per each pound of algae grown. This can be as low as one pound per pound, and as high as three pounds of CO2 per pounds of algae. Growth settings include raceway configurations, vertical thin sunlit bioreactors, open ponds and coastal sea op-erations. Best suited algae operations for CO2 are a function of strain selection, project size and geography, and the presence of adverse temperatures and other conditions. Should the CO2 be delivered via pipeline, and due the gas’ corrosiveness, the delivery system should be constructed of a high-density polyethyl-ene (HDPE) versus the standard, more costly stainless steel. The CO2 would probably be in-troduced into the pond, bioreactor or raceway as a gas, and the commodity is stored, piped and transported as a liquid. Small operations might start with so-called micro-bulk storage tanks, which can hold from 400 to 600 pounds. Larger operations would use on site, vacuum-insulated liquid storage vessels or refrigeration systems to maintain pressures under 300 psig, and temperatures near zero degrees Fahren-heit. Delivery to the algae system might be a series of diffusers, similar to those used in water treatment applications for CO2; and the piping from the storage to the application site could be composed of stainless steel, or type “K” copper tubing. The systems could be op-erating on timers, with or without a flow meter, however set to inject a given sum of CO2 into the growth medium. The storage, deployment and hardware for CO2 use is rather simple, but CO2 is essential for algae growth.

It is logical to evaluate more enriched forms of CO2 from industry, such as etha-nol plants. The power industry is the worst offender by volume of CO2, and the unique nature of hot flue gas from them could apply well to certain blue -green algae that endure heat from the Yellowstone Park geysers. Power plant CO2 is lean in content compared to etha-nol refining effluent or anhydrous ammonia production, with raw gas, water saturated basis of 98 to 99 percent volume or greater. These

“clean sources” generally don’t include sulfur, heavy metals or heavy hydrocarbons. The flue gas from combustion of coal and natural gas can range from 14 percent volume in the raw gas with coal fired plants to 3 percent from a turbine exhaust source. If concentrating CO2, costs become significant but concentration has not yet been considered in the algae project tests and pilot ops within the power sector.

One such power plant algae project is in Southeast Queensland, Australia, owned and operated by MBD Energy and a research co-operative. It is moving forward with an algae synthesis system, whereby the Tarong Power Station flue gas will be injected into wastewater, which contains nutrients, along with sunshine, for production of select algae in a (membrane-based) closed system structured to be a large raceway project. The algae mass is expected to double every 24 hours and be harvested daily and crushed to produce algae oil suitable for biodiesel, meal for cattle feed and clean water. The crude mass for cattle feed contains from 50 to 70 percent crude protein, and feeding trials are being conducted at James Cook Uni-versity. The ultimate operating project is plan-ning an 80-hectare site sequestering more than 70,000 metric tons of CO2 from the flue gas, and producing 11 million liters (2.9 million gal-lons) of oil plus 25,000 metric tons of algae meal. This form of bio-CCS algae sequestra-tion is similar to the earth’s natural carbon cycle, however, it is accelerated exponentially, taking only a day. Other applications for the oil beyond biodiesel include jet fuel production and bioplastic materials. Beyond feed the meal can be used in plastics and fertilizers. The algae product yields 35 percent oil and 65 percent meal. The project has Australian government funding and will lead the way throughout Aus-tralia for similar projects.

U.S. power plant algae endeavors are underway, some are feasibility and pilot stud-ies, many funded by U.S. DOE’s $1.4 billion Clean Coal Power Initiative. Applications for federal and state funding and initiatives for al-gae based sequestration have taken place with Arizona Public Service Company, Duke En-ergy, NRG, Southern Company, and American Electric Power Co; to name a few. The power industry has been the major component of

CO2 emitters to evaluate, test and work on developments toward sequestering CO2 via algae growth. The methodology surrounds a rather methodical selection of the best suited strains of algae, usually capable of enduring SOx , NOx and other compounds, including heavy metals from the power plant flue gas; as well as being tolerant to high temperatures. Other criteria for selection of algae strains are driven by those that yield high amounts of oils and starches. The point of application has been tested in bags, vertical bioreactors, race-ways and ponds. Conceptually, the algae are harvested daily in a large or commercial-scale facility.

the Future’s choiceMany forms of sequestration will be

needed beyond a cap-and-trade system. Some estimates consider at least 50 million metric tons of CO2 are emitted to the atmosphere daily, beyond what the oceans, photosynthesis and other natural means can absorb. This num-ber is likely to grow, with the so-called BRIC countries, growing rapidly. As they grow, so do carbon emissions. Further, the battle against deforestation places added stress on the whole CO2 emissions equation, which removes a sig-nificant natural carbon sink: photosynthesis.

Many strains of algae are being investi-gated to fit niche markets, such as those which retard extreme heat or cold, or grow during the night time with minimal light. Specific algae strains will eventually meet extreme or unique physical conditions for growth. The end result will be extracting the oils for fuels, plastics and other products, and the use of the algae meal for numerous markets. The strains of algae may be derived from far-flung African swamps to frozen, high altitude snowfields in South America. The strains selected to endure the harshest of temperatures and other physi-cal conditions are vast, and commercialization to fit many conditions is one of the most vi-able concepts ever developed to meet tomor-row’s renewable energy needs.

Sam A. RushingAdvanced Cryogenics Ltd.

(305) 852-2597 rushing@terranova.net