NREL’s indoor cultivators mimic conditions in large-scale outdoor algae farms, serving as an efficient testing platform for U.S. Department of Energy (DOE) National Laboratory researchers working to lower the cost of algal biofuels and bioproducts.
In the push for sustainable biofuels and bioproducts, algae have the potential to be a game changer. The photosynthetic organisms excel at transforming nutrients and sunlight into a range of molecules that drive their metabolism and growth, which industries can use to synthesize low-carbon fuels and products.
But to make algae-based products affordable, those industries must master the science of growing algae in large outdoor cultivators. Like a crop on any farm, the algae may be exposed to a range of weather conditions, potentially impacting their growth and productivity.
With funding from DOE’s Bioenergy Technologies Office, a team of scientists at four National Laboratories are putting their heads together to address that challenge: giving algae species the ingredients they need to flourish outside. As part of the DISCOVR consortium—or the Development of Integrated Screening, Cultivar Optimization, and Verification Research consortium—the researchers are refining energy and nutrient balances in algae cultivators to optimize growth, productivity, and quality of the algal biomass.
This is science that takes time and many test cycles. Thanks to researchers at the National Renewable Energy Laboratory (NREL), led by Lieve Laurens, that science just got a lot faster with a custom-built indoor algae cultivator designed and optimized by Nicholas Sweeney, which is already helping DISCOVR push the boundaries of algae productivity.
Mimicking the Outdoors With an Indoor Cultivator
NREL designed a programmable algae cultivator, called a photobioreactor system, that lets the team mimic the conditions outside. To simulate the warm, dry climate of the Arizona Center for Algae Technology and Innovation testbed at Arizona State University, DISCOVR’s outdoor algae research farm, NREL tweaked the cultivator’s lights and temperature, reactor geometry, and carbon dioxide delivery systems.
Having mimicked Arizona’s climate in the lab, NREL was able to test a range of cultivation techniques with various algae species and cultivars. For example, NREL was able to change carbon and nitrogen balances to see how the algae responded in terms of growth rate and biomass composition. That let researchers speed up analysis on two promising algae species to understand their physiological, metabolic, genetic, and biochemical underpinnings.
The next step was to verify their results. Were NREL’s cultivators a reliable stand-in for an outdoor algae farm?
With new data in hand from NREL, and parallel data from partner DOE National Laboratories, the DISCOVR team set out to confirm that the techniques were successful outside the lab, at the testbed in southern Arizona.
After multiple research cycles both indoors and outdoors, the team confirmed it: they had successfully matched increased algae productivity in NREL’s cultivators with data reported outside. In other words, the promising results and techniques NREL demonstrated inside the lab could be reproduced at the farm, too.
The Goal: Overachieving Algae for Cheaper Biofuels or Bioproducts
The success of NREL’s cultivators and growth techniques gives the team confidence to dramatically ramp up their testing cycles in search of the ideal formula to increase the value and productivity of algae. The goal is to engineer algae that not only survive in outdoor farms. They aim for algae that thrive outside, transforming carbon dioxide and sunlight into specialized molecules that industries can use to make the next generation of sustainable fuels and products.
Based on results in 2020, DISCOVR is well on its way to achieving this. Supported by NREL’s indoor cultivators and top-notch compositional analysis, the DISCOVR team demonstrated a 15% improvement in annual algae productivity in 2020, adding to an already significant 36% increase the year before. The algae species Picochlorum celeri—used by NREL on other projects because of its rapid growth rates and attractive light adaptation mechanisms—was particularly successful in summer experiments outside.
Better algae productivity means lower costs down the supply chain, and NREL was able to use sophisticated calculators to estimate the cost of biomass production using the new techniques. NREL researchers, led by Ryan Davis, found that the success translates to a 10% decrease in the minimum cost for a ton of algae biomass, making it an ever more attractive feedstock for companies.
The work does not stop there, of course. As DISCOVR moves forward, the predictive power of NREL’s indoor cultivators will let the team extend these gains in productivity. That’s one more hurdle cleared in lowering the cost for productive, large-scale algae farms, bringing high-performance, algae-based fuels and products closer to the finish line.