Genetically modified algae has been shown to have a very high lipid content, chemicals that can be refined to make biofuels almost chemically identical to traditional gasoline and diesel (minus some impurities).  The promising alternative energy solution has many startups racing to become the first to mass produce algae-based biofuel on a commercial scale.  The government has also pitched in a good deal of funding for the promising industry.

However, a recent study by the University of Virginia's Civil and Environmental Engineering department has raised some questions about how green the biofuel really is when stacked up against its competitors.

According to the study, algae production has a larger carbon emissions footprint than traditional biofuels or cellulosic ethanol produced from switchgrass, canola, and corn.  Key challenges with the algae are that they need carbon dioxide, phosphorous, and nitrogen supplies.  Additionally, they also require a lot of water.  According to the U of V engineers, these factors combine to raise the biofuel's carbon footprint.  

Andres Clarens, an assistant professor, was the lead author of the study.  He states, "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."

He suggests that algae biofuel makers couple their plants to wastewater treatment facilities.  That would solve the problem of procuring nitrogen and phosphorous -- and would solve the waste water plant's opposite problem (eliminating these wastes).  It would also give them easy access to a water supply with minimum additional infrastructure.  Describes Clarens, "There are a lot of nutrients that we flush down the toilet."

The study did praise algae for having lower land use and nutrient runoff -- the only areas the technology came out ahead in, according to the study.

Other authors of the paper include Lisa M. Colosi, also an assistant professor in the department; Eleazar P. Resurreccion, a graduate student in the department; and Mark A. White, a professor in U.Va.'s McIntire School of Commerce.

The study was published in the journal Environmental Science & Technology.

Despite the minor praise that the overall critical study offered, it was not met with a warm welcome by many algae-proponents in the biofuels industry.  Mary Rosenthal, the executive director of the Algal Biomass Association writes, "We appreciate and support the interest in algae among the scientific community, and agree that examination of the life cycle impacts of algae for fuel processes is important.  However, we expect such research to be based on current information, valid assumptions and proven facts. Unfortunately, this report falls short of those standards with its use of decades old data and errant assumptions of current production and refining technologies."

Others in the industry have offered similar criticism, saying the study failed to use the latest generation of algae growth equipment and organisms.  Professor Clarens, writing to the New York Times defends the study, while admitting the data he used was 10 years old.  He writes, "Everybody talks about the next generation - what is the next generation?  I’d be happy to model it if somebody produces it."

The good news is that the dialogue opened discussions between the Algal Biomass Association and Professor Clarens, according to the NYT.  The pair plan to conduct a new study with the next generation of the technology.