Pollution-fighting algae: Algae species holds potential for dual role as pollution reducer, biofuel source

A hardy algae species is showing promise in both reducing power plant pollution and making biofuel, based on new research at the University of Delaware.

The microscopic algae Heterosigma akashiwo grows rapidly on a gas mixture that has the same carbon dioxide and nitric oxide content as emissions released from a power plant. "The algae thrive on the gas," said Kathryn Coyne, associate professor of marine biosciences in UD's College of Earth, Ocean, and Environment. "They grow twice as fast and the cells are much larger in size compared to when growing without gas treatment." The algae also make large amounts of carbohydrates, which can be converted into bioethanol to fuel vehicles. The findings could have industrial applications as a cost-effective way to cut greenhouse gas pollution when paired with biofuel production.

Heterosigma akashiwo is found worldwide in the natural environment. Coyne, an expert in algal blooms, discovered that the species may have a special ability to neutralize nitric oxide—a harmful gas that poses threats to environmental and human health. That characteristic prompted Coyne and her team to investigate whether the algae could grow on carbon dioxide without getting killed off by the high nitric oxide content in power plants' flue gas, which had foiled similar attempts by other scientists using different types of algae.

A yearlong laboratory experiment shows that Heterosigma akashiwo not only tolerates flue gas, but flourishes in its presence. The algae also do not need any additional nitrogen sources beyond nitric oxide to grow, which could reduce costs for raising algae for biofuel production.