BioCycle June 2008, Vol. 49, No. 6, p. 44
THERE are no silver bullet solutions to cheap energy, but algae could come close. Algae has the capacity to remediate carbon dioxide (CO2) emissions, produce energy, generate a source of protein for animal feed and even provide dietary and medicinal supplements for humans. Algae technology developers are racing toward commercial production of algae based on decades of existing research, such as from the Department of Energy (DOE).
In nature, algal blooms and red tides generally indicate unnatural nutrient-laden waters. These unintended eruptions out-compete the steady-state aquatic life and take over. The new cultivated algae take advantage of the rapid growth attributes of “wild, free-range” algae and reduce the human carbon footprint at the same time.
The science of intensive algae production is tied to the basic photosynthesis relationship. Green plants convert CO2 and water into sugar (carbohydrates) and oxygen. In this relationship the three limiting factors are CO2, water and solar energy. The most limiting factor will restrict the yield. As solar energy and the CO2 concentration increase, carbohydrate production also increases.
While nitrogen (N) and phosphorus (P) also can be limiting nutrients in crop production, they fuel algae growth. (This is why algal blooms grow so fast in nature.) Cultivating algae to remediate water quality problems related to N and P, and at the same time remediate CO2 emissions, is a winning proposition. The project only needs a good supply of solar energy and the facilities to extract the oil and protein from the algae.
The most compelling motivator driving commercialization of algae production is as a new source of raw material for biofuels. Algae does not compete with conventional crop production. Various algae strains produce different quantities of vegetable oil with the oil content generally described as 30 to 50 percent by weight. The algae are harvested and extruded much like soybeans into vegetable oil and solids. The solids can be further processed into a source of protein.
AND THE RACE IS ON!
Cultivated algae technologies operate in a variety of ways. Some developers are commercializing surface production of algae grown in ponds. This simple technology does not attempt to increase either the solar energy or the CO2 exposure. Petro Sun, Inc. opted for this approach as it could move more quickly into commercial production rather than waiting for refinements in more sophisticated technologies.
As a result, Petro Sun is the current leader in the race to commercialize algae to biofuels. In April, the company opened a 1,100 acre algae farm in Rio Hondo, Texas. This farm utilizes saltwater ponds to grow a marine algae, producing 4.4 million gallons of oil and 11 million pounds of biomass. Live Fuels, Inc. of California appears to be following a similar business model.
The threat of CO2 emissions to human health has created a compelling market for CO2 remediation. GreenFuel Technology tested algae to remediate CO2 for the Sunflower Electric Power Corporation in Holcomb, Kansas. It was the same electric company that was denied the air permits on its proposed coal-fired power plant expansion based on the perceived threat of CO2.
Valcent is building a large pilot plant in Texas. As reported in the February issue of BioCycle (“Confronting Challenges In Developing Bioenergy and Biofuel”), its Vertigro system grows algae in high-density, closed-loop vertical bioreactors made from plastic sheeting. The sheets are hung within a greenhouse in a vertical orientation to increase the surface area and exposure to sunlight. The three-dimensional, “vertical” nature also permits greater control in pumping CO2 through the system. Another algae vertical system is emerging from the Massachusetts Institute of Technology marketed by Mighty Algae Biofuels.
Technology developers like Solix (Colorado) and XL Renewables (Arizona) are incorporating waste nutrients into intensively managed algal fields. These fields and arrays are an open-air technology. They are managed more intensively than surface ponds, but less than the vertical production technologies. XL Renewables plans to utilize the residual nutrients from a large dairy as part of its nutrient supply. These companies are targeting both the biofuels market, and the environmental remediation benefits.
Other algae developers are combining multiple technologies. Solena (Washington, DC) is cultivating algae to feed into its plasma gasification technology. Blue Marble Energy (Washington) is focusing primarily on wastewater treatment, but is pairing algae production with anaerobic digestion to do so. Algaewheel, Inc. (Indiana) utilizes three-dimensional wheels to maximize algae production from wastewater treatment.
Theoretical potential benefits of algae production begin at a 40 percent reduction in power plant CO2 emissions, 4,000 gallons/acre of vegetable oil for algae-based biofuels, additional protein and biomass production, and complete utilization of waste nutrients. As further evidence that the algae industry is coming of age, in April the National Algae Association was formed to champion the growth of the algae production industry.
Algae production changes the debate from “Food vs. Fuel” to “Food and Fuel.” None of the benefits mentioned here were discussed merely three years ago in the biofuels benchmark 2005, U.S. DOE “Billion Ton” report. While there is no such thing as a silver bullet biofuels technology, I’ll settle for calling algae the Wonder Crop of Tomorrow.
Mark Jenner, PhD, operates Biomass Rules, LLC and has over 25 years of biomass utilization expertise. Burning Bio News is Jenner’s monthly scorecard of bioenergy project adoption, available at www.biomassrules.com.