Dr. Michael Cooney, an associate researcher at the Hawaii Natural Energy Institute at the University of Hawaii at Manoa, is hard at work trying to find a new microbial method to produce fats (lipids) that could both mitigate liquid waste and serve as an alternative source of energy.

Cooney has partnered with Mainland company Community Fuels on the project, which received a DOE Small Business Innovation Research grant to explore the processing of biodiesel from microalgae and yeast. Phase I of the project is now complete and Cooney is hoping the next phase of research will be funded so he can continue this important work.

"The project evaluates the scientific and technical merit of current and novel processes to produce biodiesel from microalgal and/or yeast lipids, with the ultimate goal of developing an energetically feasible method to process biodiesel from the microbes," says Cooney. "Our approach is to grow them heterotrophically on liquid wastes high in sugar and nitrogen."

Cooney is evaluating the degree to which these microorganisms can be heterotrophically cultured to high-cell density and oil content on agricultural waste products such as fruit concentrates and cheese whey, which serve as the source of carbon and nitrogen.

He is also evaluating the efficiency of various solvent extraction methods for their ability to process the lipids into biodiesel. Most traditional techniques require a great deal of energy so the research community is seriously beginning to address the issue of developing new systems, he says.

Biofuels including methane produced from renewable biological resources such as plant biomass and treated municipal and industrial waste are the wave of the future. Some biodiesel sources — alternative fuels formulated exclusively for diesel engines, and typically made from vegetable oil or animal fats — have already been established. However, Cooney’s research is focusing on new processes of heterotrophic production.

"Heterotrophic” refers to organisms that obtain their energy for growth from the ingestion and breakdown of simple and complex sugars. Heterotrophs must obtain carbon from organic compounds; they cannot make their own food from light. All animals are heterotrophic as are many microorganisms including fungi and many bacteria.

So Cooney is growing microalgae and yeast in the dark on sugars where the energy for growth comes from the glucose, much the same way the human body creates energy. The bio-oils cultivated from the microalgae and yeast may later be utilized as an alternative source of biodiesel.

Not all oils or fats, however, will make for a biodiesel that meets strict automotive standards, says Cooney, which is where part of his research comes in. He believes the need for this study is twofold.

"First, the agriculture and food processing industry is under increasing pressure to avoid the discharge of liquid and solid organic waste," he says. "The discharge of waste streams high in carbon or nitrogen encourages the growth of microorganisms that can either upset the local ecology or turn pathogenic."

"Second, many industries are facing decreasing profit margins as energy or waste dumping costs increase."

In this context, any process that helps mitigate a waste stream and produces a little energy along the way can only help these industries remain competitive."