FUEL FROM ALGAE: The National Academy of Sciences's review of the sustainability of biofuels produced from algae raises concerns about where the water for the process might come from—or go. Image: Flickr/PNNL - Pacific Northwest National Laboratory
The National Academy of Sciences' report on the sustainability of algae biofuels highlights concerns that have already been resolved, industry heads said yesterday.
NAS released a comprehensive report yesterday, identifying potential issues of sustainability in the burgeoning algal biofuels industry. In its report, NAS measured the resources needed to produced 39 billion liters -- or 5 percent of American transportation fuel -- highlighting the low energy output.
Companies are already recycling potentially polluting nutrients and using water that is too salty or too dirty for other uses. Sustainability is a priority, but so are economics, said John Williams, a spokesman for the Algae Biomass Organization.
"Sustainability metrics are inextricably linked with cost-efficient ones," said Williams. "No major algae producer is currently using fresh water."
Water is a major concern, as is the use of nitrogen fertilizers to stimulate growth of cyanobacteria and microalgae -- two microorganisms typically lumped together as algae biofuels. To produce 1 liter of algae biofuel, manufacturers must use 3.15 to 3,650 liters of water -- or up to 123 billion liters for 39 billion liters of algal fuel.
NAS found algae biofuels would need up to 15 million metric tons of nitrogen and up to 2 million metric tons of phosphorus, unless the elements are recycled or included in byproducts. Nitrogen and phosphorus, used in fertilizers, can in excess pollute natural waterways.
Energy output in relation to inputs, or "energy return on investment," remains an issue for algae, says the report. Overall, algae biofuel yields a low energy output for all of the energy needed to produce it. Fossil fuels can produce up to six times more energy than even the most efficient algae fuels, as a ratio of output to the input energy.
The greenhouse gas reduction benefits, which would help contribute to a slowdown of climate change, vary wildly according to study, NAS found, a finding that is related to the poor energy return on investment. As a designated advanced biofuel under the federal renewable fuel standard, it must achieve at least 50 percent reduction compared with fossil fuels.
Using salty and leftover water
While the report does highlight concerns, Williams sees the guidance and framework included in the paper as a "green light" for algae fuels. It encourages companies to keep developing to commercial scale and continue investment in research to improve algae strain selections, mechanisms to grow the algae, and the refining and processing of the algae oil.
"We can run some scenarios today that identify risk factors; none of them are insurmountable through technology," he said.
The issue of water is a "non-starter," said Tim Zenk, vice president of corporate affairs for Sapphire Energy, because no one in the industry uses freshwater resources.
"They rightly point out the issues around freshwater use, but I know of no company using fresh water," he said. Sapphire recycles all its nitrogen and phosphorus leftovers so nothing is released as runoff into the environment.
Sapphire opened in August the first commercial-scale algae facility in Columbus, N.M., a Southwestern desert town that sits atop vast saltwater aquifers. At full capacity, the facility will produce 100 barrels a day of algae crude, culling from 300 acres of ponds.
This weak ratio and other concerns, like the leakage of waste material, remain, said Zenk. The ultimate goal at Sapphire is to create a closed-loop system in which virtually no waste is released. The company isn't there yet, said Zenk. In the meantime, the basic materials for making algae will remain abundant.
The search for a 'drop-in' fuel
"At least for the next several decades, we are not going to be encumbered by the lack of resources: minerals, CO2 and salt water," he said.