A team of University of Michigan researchers has been awarded a $2 million federal grant to identify and test naturally diverse groups of green algae that can be grown together to create a high-yield, environmentally sustainable and cost-effective system to produce next-generation biofuels.

National Science Foundation funding for the project begins Sept. 1 and will continue for four years. The effort will involve growing various combinations of lake algae in 180 aquariums at a new one-of-a-kind U-M laboratory, then field-testing the most promising candidates inside 80 fiberglass cattle tanks at the university's E.S. George Reserve, a 1,300-acre biological research station near Pinckney, Mich.

The main goal is to test the idea that certain naturally diverse groups of algae have complementary traits that enhance the efficiency and stability of biofuel yield beyond what any single species can do alone. The project involves an unusual collaboration among ecologists, evolutionary biologists and engineers from four labs that will include about 20 researchers and students.

"People have suggested that species diversity might increase the efficiency of algal biofuel systems, but nobody has set up the experiments to test it directly. These will be the first experiments to systematically manipulate the number and types of species in the system to determine how to maximize the yield and stability of algal biofuel," said ecologist and team leader Bradley Cardinale, an associate professor at the U-M School of Natural Resources and Environment.

Researchers have been trying to make affordable transportation fuels, such as biodiesel and jet fuel, from algae for several decades. Most of the work has focused on finding single algal strains that are highly productive, as well as identifying the ideal mix of nutrients and environmental conditions. Genetically engineered "super-species" have even been created in an effort to boost yields so that algae-based biofuels can compete with fossil fuels.

But that dream has not been realized, largely due to multiple problems that arise when you move a single-species, or monoculture, algal system from the laboratory to a pond. In the great outdoors, erratic weather, the invasion of unwanted algae species, and the presence of voracious algae-eating microorganisms can wipe out the "crop."

In addition, growing a single species of algae in a pond requires huge amounts of nitrogen and phosphorus fertilizer, much of which ends up as pollution after the crop is harvested. Add in the pesticides and herbicides needed to control intruders and you have a costly system with significant environmental impacts.

The U-M-led "biodiversity and biofuels" project aims to increase the productivity and stability of algae-based biofuel systems while reducing environmental impacts by recycling wastes and cutting the need for biocides. The end result should be a more sustainable system that is cheaper to operate.

"Rather than engineering a super-species of algae and fighting with nature to maintain it as a pure monoculture through the use of pesticides and herbicides, we propose to cooperate with nature by identifying algal communities that naturally exhibit high biofuel potential and the desired stability through time," said U-M chemical engineer Phillip Savage, one of three project co-leaders. The other two are U-M chemical engineer Nina Lin and evolutionary biologist Todd Oakley of the University of California, Santa Barbara.

In his laboratory in the basement of U-M's Dana Building, Cardinale has established cultures of 55 of the most common species of green algae found in North American lakes.

The focus is on multiple species that naturally co-occur because numerous studies have shown that diverse communities of plants (including green algae) exploit resources more fully and collectively produce more plant tissue than any single species alone. Diverse communities are also more resistant to pests and invaders, can better withstand environmental fluctuations and exhibit more stable yields over time.

Starting around mid-September, Cardinale's lab will begin growing various combinations of eight of the 55 algae species inside 2.4-gallon plastic aquariums called continuous-flow chemostats. The amount of nitrogen, phosphorus, light and carbon dioxide in each tank, as well as the water temperature, will be tightly controlled.

The newly installed chemostats are meant to mimic lakes, and they complement 150 mini-streams, called flumes, installed in the Dana basement two years ago.

Taken together, the 330 chemostats and flumes constitute a state-of-the-art laboratory that is unmatched by any facility in the world, Cardinale said.

"No lab like this exists anywhere else. There's nothing else that even comes close to it," he said.

Using the chemostats, researchers will make multiple measurements of the various algae combinations to assess their efficiency and yield. Stability of the various combinations will be tested by measuring their response to changes in water temperature and the introduction of undesirable algae species.

The highest-scoring algae combinations from the first phase of the project will move on to the next round, the 260-gallon cattle tanks at the E.S. George Reserve, a set-up that mimics real-world, open-pond algal-growth systems known as photosynthetic biorefineries.

U-M chemical engineer Savage's lab will use a technique called hydrothermal liquefaction to measure the quantity and quality of the combustible oils, or biocrude, produced by the various algae combinations—from both the laboratory and field experiments. His team also will compare the ability of single and multispecies systems to reuse and recycle wastes for additional growth.

Lin is a U-M chemical engineer who employs microfluidics and high-throughput screening technologies to "bio-prospect" for microorganisms associated with biochemical or biomedical applications. For the algae project, she is modifying various laboratory techniques so the team can expand the search for multispecies assemblages that exhibit high yields and efficient waste recycling.

By reconfiguring a device her lab originally developed for use with bacteria, Lin should be able to screen more than a million algal species combinations. A $60,000 grant from MCubed, U-M's one-of-a-kind seed grant program, funded a collaboration between Lin and Cardinale that yielded vital preliminary data that was included in the National Science Foundation proposal.

"If, as we propose, it is possible to engineer naturally diverse communities of algae to enhance the efficiency, yield and stability of yields, then the development of multispecies photosynthetic biorefineries would indeed represent a 'win-win' scenario for biodiversity conservation and energy production in the next century," Lin said.

UC-Santa Barbara's Oakley is an evolutionary biologist who analyzes differences in gene expression among species, and the functional differences that result. He will lead the effort to use high-throughput sequencing technologies to quantify every expressed gene in the various algal combinations. That will enable the researchers to determine how the production of biocrude correlates with the expression of any known gene.

The four-year project will culminate in a conceptual design followed by a life-cycle assessment. The conceptual design will examine all aspects of a multispecies algal biorefinery, from algae cultivation to biocrude production. It will determine the size needed for the facility and will estimate the capital and operating costs, which in turn will show the conditions required to make the biorefinery profitable.

The life-cycle assessment will measure the various environmental impacts attributable to all activities related to the construction and operation of a multispecies algal biorefinery—including emissions of heat-trapping carbon dioxide gas largely responsible for human-caused climate change. The results will then be compared to the impacts resulting from the construction and operation of a single-species algal biorefinery. Savage will work with researchers at Argonne National Laboratory on the comparison.

If the four-year project proves fruitful, the researchers hope that future funding could lead to the design and construction of prototypes for a commercially viable multispecies algal biorefinery. But that day is a long way off. For now, Cardinale and his colleagues are focused on 180 aquariums in the basement of the Dana Building.

"Do I feel like we're going to suddenly make algal biofuels economically viable? No, of course not. That will take a decade-long national research program and billions of dollars," Cardinale said. "But I think this project might be an important piece of the puzzle that eventually gets us there."