University researcher explores microalgae's potential in combating climate change

In the Microbiome and Genomics Lab at the University of Houston at Sugar Land, Venkatesh Balan presents a glass flask containing a putrid green liquid. The contents resemble the aftermath of a clogged sink, but Balan believes it could be a secret weapon in the fight against climate change.

The cloudy mixture contains a culture of microalgae — millions of microscopic phototropic organisms that, like plants, pull carbon dioxide out of the air and release oxygen. In recent years, Balan and other researchers have developed new ways to put these organisms to work on an industrial scale.

“Algae has been doing this for millions of years. So, why don’t we use algae to our advantage and make it much more sustainable?” Balan said.

Balan, an associate professor of biotechnology in UH’s Cullen College of Engineering’s Technology Division, has spent his career researching industrial applications of microbiomes. His research focused on how microbiomes, through biomass conversion and fermentation, can produce ethanol and organic acids used in various chemical products. After arriving at UH in 2017, he decided to shift his attention to environmental issues.

“The biggest threat to the world is global warming, climate change, carbon emissions,” Balan says. “So I started thinking, ‘Why don’t we use our same knowledge on fermentation and biomass conversion in a different area?’ So I started working on algae.”

Unlike carbon capture methods that store captured CO2 underground, algae processes carbon into compounds that can be used to make biofuel and fertilizer.

Researchers and corporations have explored methods to remove carbon dioxide from the atmosphere for years. The most popular mitigation strategies involve direct air capture — industrial-sized plants which can “scrub” carbon dioxide out of the air and pump it into large storage reservoirs underground. However, Balan argues these methods are energy-intensive and expensive and do not adequately account for long-term storage of recaptured CO2.

“We are thinking about the next 50 years,” he says. “But we’re not thinking about beyond 50 years.”

Algae does not require solving for storage of captured carbon. Instead, algae removes carbon by processing it into other compounds — carbohydrates, lipids, and proteins — that can be used to make useful products like biofuel and fertilizer.

“We are working on technologies to capture the CO2 using algae that has 90% efficiency,” Balan says. “The bioproducts produced by processing algae could displace fossil fuel and satisfy growing bioproduct needs.”

Balan highlights how ancient blooms of algae helped oxygenate Earth’s atmosphere hundreds of millions of years ago: “Algae has been doing this for millions of years,” he says. “So why don’t we use algae to our advantage and make it much more sustainable?”

The challenge lies in making algae-driven carbon capture scalable. Scientists have experimented with cultivating algae for biomass conversion and fermentation for several years but found their methods too expensive for commercial viability except in high-value products like biofuels or pharmaceutical ingredients.

Balan's team is focusing on integrating algae cultivation into existing wastewater treatment facilities using Rotating Algal Biofilm (RAB) reactors. These reactors grow algae on a circulating biofilm submerged in water. This method is relatively cheap and simplifies harvesting by scraping the algae from the biofilm. RABs can also be incorporated into systems already processing water, such as wastewater treatment facilities.

Balan conducted a study evaluating potential algae growth if RAB reactors were installed at Texas’ three largest wastewater treatment facilities. The results indicate potential scalability by retrofitting these plants with RABs to reduce overhead costs while cleaning wastewater and sequestering carbon.

Balan is now collaborating with an Iowa-based company on a U.S. Department of Energy-funded project using an RAB system at a wastewater treatment plant to sequester carbon and create biomass fertilizers for Iowa farmers.

Convincing investors and policymakers remains challenging due to significant investments in direct air scrubbing technologies heavily subsidized by federal government support for oil and gas companies. Balan hopes his research will encourage government regulators to invest in greener greenhouse gas emissions capture solutions.

“If the government plays a role,” he asserts, “they can drive it much faster.”