A team of engineers from the University of Virginia's Department of Civil and Environmental Engineering has discovered that wastewater may be the answer to some of the environmental hurdles during the production of algae-based biofuel.
The U.Va. research demonstrates that algae production consumes more energy, has higher greenhouse gas emissions and uses more water than other biofuel sources, such as switchgrass, canola and corn.
"Given what we know about algae production pilot projects over the past 10 to 15 years, we've found that algae's environmental footprint is larger than other terrestrial crops," said Andres Clarens, an assistant professor in U.Va.'s Civil and Environmental Department and lead author on the research paper.
As an environmentally sustainable alternative to current algae production methods, the researchers propose situating algae production ponds behind wastewater treatment facilities to capture phosphorous and nitrogen - essential nutrients for growing algae that would otherwise need to be produced from petroleum.
Those same nutrients are discharged to local waterways, damaging the Chesapeake Bay and other water bodies, and current technology to remove them is prohibitively expensive.
While the researchers found algae production to have a greater environmental impact than other sources, it remains an attractive source for energy.
Algae, which are grown in water, don't compete with food crops grown on land and also tend to have higher energy yields than sources such as corn or switchgrass.
Additionally, algae's high lipid content makes for efficient refinement to liquid fuels that could be used to power vehicles, according to the research.
"Before we make major investments in algae production, we should really know the environmental impact of this technology," Clarens said.
"If we do decide to move forward with algae as a fuel source, it's important we understand the ways we can produce it with the least impact, and that's where combining production with wastewater treatment operations comes in," he added.
The research group's plans include conducting demonstration projects for the wastewater production methods.
They are also pursuing complementary research on the economic lifecycle of algae compared to other bionenergy feedstocks.