Algae-Based Energy Burns With Potential

Signal, Apr 2007 by Kenyon, Henry S

Common aquatic plants offer economies of scale without affecting competition for food, land resources.

Scientists are turning humble pond scum into fuel. A research effort seeks to develop techniques to grow algae economically and to convert the oils produced by the tiny plants into biodiesel on an industrial scale. This program is one of several alternative energy projects under way at Sandia National Laboratories' Livermore, California, facilities. One of the promises with algae is that more oil potentially can be extracted on a per-pound basis than from any other type of vegetable-based fuel, says Blake Simmons, the manager of Sandia's energy systems department.

Sandia's California laboratory has operated a combustion research facility for some 25 years to investigate, evaluate and optimize engine performance. Simmons explains that since the center was established, it has conducted research into a variety of fuels. "Alternative energy research at Sandia has been going on for quite a long time," he states.

The combustion research facility recently began studying the flame and ignition characteristics of biodiesel derived from vegetable oil. Simmons notes that in the past two years, Sandia has seen a surge in biofuels research. This work is funded by several million dollars from internal investment efforts such as the Laboratory Directed Research and Development Program that spends discretionary funds on selected technology proposals.

"The primary motive is to help balance the nation's transportation fuels supply by putting a renewable element in it," he says. Of these internal research programs, five or six now are fully established and investigating the creation of alternative fuels such as biodiesel, ethanol and butanol. One of these efforts, which has been underway for the past 15 months, is genetically engineering the metabolism of certain algae to enhance oil production for conversion into biodiesel.

Algae typically build up oils in their bodies when limited nutrients are available in their environment. The challenge is in optimizing the growth environment-the water they are grown in-for nutrient-limited conditions, temperature and the desired rate of oil production and storage. Algae create oil in the form of triglycerides in their cell vacuoles.

But finding the right growth medium is only a small part of the project. To produce oil in industrial quantities, Sandia researchers must genetically alter the algae. And once the algae can be made to produce enough oil, Simmons notes that the last challenge is to extract and process the oil into biodiesel.

Simmons explains that various species of algae have different metabolic functions to survive in specific environments. For example, scientists use green algae to produce hydrogen. Other types of algae are not good hydrogen producers but are adept at producing oil. He adds that up to 60 percent of the weight of some algae is in triglycerides that can be converted into biodiesel products. The challenge is that while algae produce more oil with less nutrients, algae do not grow and reproduce as quickly when fewer nutrients are available. Researchers hope to overcome this impediment by modifying the algae's genetic structure to maximize both oil production and growth.

Sandia's research is built on groundbreaking work conducted by the National Renewable Energy Laboratory (NREL), Denver, in the late 1980s and early 1990s. The NREL's Aquatic Species Program studied algae to determine the best means to produce fuel stock. The program examined how algae made and stored oil and searched for the species that were most suitable for industrial use. Simmons maintains that the knowledge generated by the initiative was essential to all further research. However, the NREL program was unsuccessful because researchers did not have the genetic tools to make viable quantities of algae-derived biodiesel. "The [NREL's] final report is depressing in the historical sense because they were cut off right as the genomics explosion occurred around the world," he says.

Sandia scientists now have the genetic sequences of several species of algae that can be engineered to enhance oil production. "That is the power of the genomics age. We have the genomic tool box," Simmons states. "We can hopefully manipulate these organisms so that we don't have to achieve such a delicate balance," he continues, explaining that without this manipulation, scaling up is an unwieldy problem. "This has to be a scalable solution if we're going to make any kind of a dent on diesel use in the United States. It has to be a massive operation if it is to achieve its promise," he emphasizes.

Simmons notes that most small commercial biodiesel operations buy feedstock oils from supermarkets or fried fats from restaurants. He explains that this oil already is processed and ready for conversion into fuel. But to make fuel from algae, a completely different system of harvesting, extraction and conversion is needed. And an algae-based fuel system requires a large-scale operation to be efficient. "That is why you need to develop an algae to get the most oil for your buck," he says.