By Tanya Silverman
Photo courtesy of Diana House.
It may seem slimy, murky, and messy, but algae offers numerous prospects that could help clean up our planet’s environmental troubles. Researchers are investigating effective ways to grow algae – a diverse group of photosynthetic organisms – at mass scales and apply it to various ecological, commercial, energy, and agrarian purposes.
One researcher, Dr. B. Greg Mitchell, has been involved in promoting algae as biomass for over 20 years. Mitchell is a Research Biologist and Senior Lecturer at the University of California – San Diego Scripps Institution of Oceanography (SIO), as well as Program Chair for the Algae Biomass Summit 2014. He investigates effective methods for farming algae, plus ways the crop can mitigate carbon dioxide, clean wastewater, and apply for fuel production or animal feed.
Working in the laboratory, Mitchell focuses “on optimization of yields of bioenergy molecules in the light-temperature-nutrient matrix that regulate algae growth.”
The rate at which algae develop depends greatly on the way they interact with light, temperature, and nutrients within their environments — fundamental factors that apply to all organisms, regardless of their species, size, or cellular makeup. For humans, Mitchell explains, if you exercise more, your blood pressure decreases, whereas sun exposure can cause your skin to tan.
People that cultivate algae biomass outdoors can regulate the type (and volume) of nutrients supplied to the organisms. The surrounding weather and sunlight, however, are factors beyond their control. Mitchell informs BTR that while constant climactic situations can be arranged in a laboratory, manipulating such settings on a massive algae pond is not realistic – a steady temperature and light level would be incredibly difficult and expensive to maintain.
“So we explore how different strains with different genetics respond to different light, temperature, and nutrient forcing so that we can create models for scale up,” Mitchell tells BTR. “For industry, it is essential to predict outcomes. Our laboratory studies create the basis by which we can predict performance outcomes for different strains of commercial interest by doing relatively high-cost laboratory work at small scale but with realistic forcing [circumstances] as the same strains might experience in scaled up outdoor systems.”
Because algae strains differ greatly – from tiny microorganisms above warm freshwater ponds to towering kelp beneath cold saltwater seas – this California laboratory looks to filter a selection of strains that “thrive at different environmental conditions,” likely between 45-100 degrees Fahrenheit.
Then there’s the greater application. For one, some algae strains hold a high lipid content, oils that can be extracted and converted into biodiesel. Though burning algae biofuel does emit CO2, it is essentially carbon-neutral, as it absorbs the gas as it grows.
“Compared to other biodiesels like ethanol, we don’t need farmland to grow [algae] feedstock for biofuel productions,” Dr. Yebo Li tells BTR, “so we do not compete for land that’s used for food and feed production.”
Li, a University of Ohio bioenergy researcher who focuses largely on algae production, adds that cultivating corn for ethanol requires a certain quality of soil, something that algae does not.
Although algae is more adaptable to thrive throughout non-arable terrains, like any crop, certain environments offer better growing situations than others. For arranging large algae farms, Greg Mitchell says that warm, sunny, coastal places work well, some possible domestic locations being the shores of Florida, Southern California, or Texas.
Potentially, if large-scale algae biomass farms are set up around the United States, harvesting the crop (and extracting its lipids) for biofuel could help alleviate dependence on foreign produced petroleum. Mitchell points to some statistical data, as currently, the American market imports 32 billion gallons of oil annually from the Persian Gulf.
“If we produce oil from algae on 15 million acres at a very low, conservative estimate of 1,000 gallons [per] acre [per] year then we can produce algae oil equal to about 50% of current imports from the Persian Gulf,” he explains, continuing that the United States “can achieve optimistic yields as high as 5,000 gallons of oil per acre per year, then we can produce 2.3 times what we currently import from the Persian Gulf region.”
International trade politics are important, but what about when algae oil is actually used to power a machine?
While taking vehicles to actually test algae biofuel is still just developing, Mitchell alludes to one successful experiment when the military used biofuel on a jet engine. They found, after burning algae biofuel, the jet engine had a lower temperature, meaning longer life for critical parts of the engine, which could save both money and energy.
A number of algae-as-biofuel stories have been spreading lately. However, Mitchell states that algae should not be viewed solely as an energy source, because realistically, it would be very challenging to bring the production costs down to the point where we could actually replace cheaper, plentiful fossil fuels like petroleum and coal. Beyond environmental attractions of biofuel, people should consider algae’s abilities to remediate wastewater and produce animal feed.
“Up to 80 percent of agriculture is in animal feed,” says Mitchell. “Almost all of the biodiversity disasters on earth are related to either terrestrial conversion of land or excess harvesting which destroys the ecosystems.”
While algae crop for livestock is not as mainstream as the soybeans, corn, wheat, and rice that are cultivated, Mitchell states that it “is 3-5 times more efficient in time and space for biomass production than any terrestrial crop.” Like the argument for algae over ethanol, the aforementioned crops require lots of arable land and freshwater, unlike algae, which does not.
A significant concern for all the algae endeavors is that they’re expensive. Yebo Li, who works largely on government grants, tells BTR that while he’s interested in furthering his experiments with algae and wastewater treatment and byproducts of lipid extraction, his overall goal is to reduce the costs of algae production.
Algae biomass offers a number of prospects in avenues like animal feed, biofuel, and pollution alleviation. However, most large-scale effects are still speculative or in need of further development. Ideally, the foreseen environmental advantages will afford the necessary monetary investment for the tentative improvements in laboratory and cultivation fields.