August 10, 2009

The algae solution

Colorado researchers are looking at biofuels as new sources of energy

In their search for new, sustainable sources of clean energy, scientists and engineers are leaving few stones unturned.

Solar and wind have great potential, but neither will replace the gasoline and diesel that we use in our cars, trucks, and airplanes. That's where biofuels come in. The best known are ethanol from cornstarch or sugar cane, and biodiesel from cooking oil.

But there are other options. One of the best sources of biomass for this new generation of biofuels may be surprising: algae. And Colorado is on its way to becoming a world leader in the research and development of algae biofuels.

Some of the most important research on using algae as biofuel was performed at the National Renewable Energy Laboratory in Golden from 1978 to 1996, and has recently been restarted. And key projects are underway within the Colorado Center for Biorefining and Biofuels (Colorado State University, the Colorado School of Mines, and the University of Colorado at Boulder, and NREL) as researchers are working to find the best species of algae, to learn to grow and improve their harvest, and to convert them to fuels more efficiently.

The production of a biofuel begins with a plant or materials derived from plants, such as paper. This biomass is then converted through fermentation or a chemical process to a fuel that can be used in the engines of cars, trucks, ships, and airplanes, as well as in electrical generators. Biofuels hold the promise of reducing greenhouse gas levels since plants grow by removing carbon dioxide from the atmosphere, and biofuels also have the potential to be a renewable, non-extractive, domestic source of energy.

Ethanol and biodiesel have helped the nation make a start toward replacing petroleum-based fuels with renewable alternatives. However, these biofuels represent only a small percentage of the current U.S. consumption of gasoline and diesel. Furthermore, there are concerns about our ability to significantly increase the fraction of our fuel supply that comes from corn grain or oilseed crops, in part because of the amount of water and arable land required.

Like plants, algae are photosynthetic, using sunlight and carbon dioxide to grow. Biofuels research focuses on microalgae — microorganisms that are about one-fiftieth of a millimeter in diameter (about a quarter the diameter of a human hair) and can grow much more rapidly than plants in fresh, brackish, or salt water. Under certain conditions, some species of microalgae can accumulate oils to an astounding degree — levels as high as 75 percent of their dry weight have been reported. The idea for using algae as a source of biofuels is to grow large amounts of algae, harvest the cells, extract the oil, and convert that oil to a diesel-like fuel. Researchers are also evaluating the possibility of fermenting algal biomass to other biofuels or converting it to electricity. Since the algae grow in ponds or in closed containers (photobioreactors), an algae "farm" could be located on land that is not suitable for crops, and linked to combustion power plants and other sources of carbon dioxide.

Solix Biofuels, a Colorado State University spinoff company, is among the leaders in this new industry. Solix has focused on the development of more efficient and economical photobioreactors for the cultivation of algae. The company recently announced the start of operations at an algal biofuel facility on the Southern Ute Indian Reservation near Durango, with the goal of demonstrating its technologies at commercially feasible production levels and costs. Another Colorado company, A2BE Carbon Capture, is focused on the commercialization of algal technologies for the removal of carbon dioxide from stationary industrial sources. Companies like these, supported by the research at Colorado universities and NREL, are examples of the New Energy Economy promoted by Colorado Gov. Bill Ritter and President Barack Obama.

Since the world consumes oil at an astounding rate — more than 1000 barrels of oil every second, or more than 86 million barrels a day — the potential of a biofuels industry based on algae is enormous. More than 100 companies have been started around the world in the past few years. Despite this potential, significant investment in research and development is required to help this technology become commercially viable at the very large scales that are required. Replacing just 10 percent of the U.S. diesel market with algae-derived biodiesel means growing several million tons of algae each year. We can't yet do that cost-effectively, but it's important to remember that there was once a time when the petroleum industry was small and early engines were developed to run on ethanol and turpentine because gasoline was expensive and not readily available. Huge investments and diligent research resulted in the current scope and efficiency of the modern petroleum industry. Since the early 1980s, our country's investment in renewable energy has been minuscule. Considering the potential of algae and other sources of biomass for biofuels, and the need to develop clean energy alternatives, it's time to reverse that trend.

Kenneth F. Reardon directs the Multidisciplinary Approaches to Sustainable Bioenergy Ph.D. training program, funded by the National Science Foundation, and is one of the directors of the Colorado Center for Biorefining and Biofuels.

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