BioProcess Algae Senior Scientist Toby Ahrens notes that while carbon dioxide may not yet be an official liability, any CO2 exiting up the stack of an industrial facility is, at the very least, a missed opportunity. Pointing also to the high cost and difficulty of sequestering carbon, Ahrens and BioProcess Algae seek not to sequester carbon dioxide  but to utilize it to create a biomass stream that can be converted into high-value feed, fuel and specialty coproducts. This month, we catch up with Ahrens and inquire about his history with algae, the advantages of algal cultivation and BioProcess Algae’s progress at its pilot facility in Shenandoah, Iowa.

You grew up on an island in Maine. How did this experience shape your interest in marine science?

I certainly spent a lot of time on the water.  I loved growing up on the coast.  But before we get too romantic about my island life, a bridge connected us to the mainland because Maine’s largest fossil-energy power generation facility is on the island as well.  I also believe it was the last oil-fired generating facility commissioned in the US.  Maybe the CO2-to-algae seeds were planted in my brain earlier than I thought.

Can you recollect the first time you thought about, or studied algae?

Well, macroalgae was hard to miss growing up, especially when my mother made us haul it from the beach up to her garden.  My first introduction to microalgae must have been when my Uncle Bert gave us a microscope―I must have been five or six at the time. That was really cool, but rotifers (essentially miniature buzzsaws with big appetites) were far more popular with me then than they are now! I also spent a few days at the Maine’s Department of Marine Resources in high school learning about monitoring for harmful algal blooms, and that was probably the first time that I really got hooked from a scientific perspective.  I worked in Dr. Peter Siver’s phycology laboratory at Connecticut College and he was my first true mentor in research science. 

During a portion of your education, you studied conventional production agriculture, nutrient usage by wheat, I believe.  In that context, why are algae such a good fit for production agriculture?

Nutrients are an expensive input to any agricultural system, and I always liked the 4R’s concept: the right source, at the right place, at the right time, in the right amount.  In conventional agriculture, logistics (and economics) prevent you from applying every day in small doses as the plants need them.  As a consequence, applications are grouped throughout the season and some nutrients are lost to the atmosphere, in surface runoff or leached through the rooting zone.  Algae is unique in that nutrient delivery can be monitored and maintained in real time as the crop needs it.  Nutrient-use efficiency can be extremely high. 

What does a typical day at work look like for you?

Typical? Not sure I know what that means―I haven’t had one of those in a long time! 
Fair enough. Let me rephrase. What responsibilities at BioProcess Algae take up the lion’s share of your time?

Making sure R&D priorities are aligned with commercialization efforts, but that is a broad umbrella.  I work closely with the biology group to make sure strain selection and bench experiments match product demand.  I also work a lot with downstream partners.  Various animal feeds have taken up the bulk of my time in recent weeks.

BioProcess Algae has been paired with Green Plains Renewable Energy in Shenandoah since its beginning. What makes that corn ethanol facility such a great venue for continued R&D and the company’s continued commercialization efforts?

The ethanol industry understands how to scale biological cultures as well as the importance of coproducts in making biofuels economically viable.  We certainly share that sentiment.  From a commercialization standpoint, it also means that we have access to very high-quality CO2, waste heat in the winter.  Commercializing in the Midwest has also given us access to some of the premier research groups in the country for traditional food crops and oilseeds processing.

At the heart of the BioProcess Algae cultivation technology is a biofilm where the algae grow. What advantages does this approach offer?

The three biggest advantages are light penetration, high-density harvests and efficient gas transfer.  Our substrate has an enormously high surface area on which the algae attach, which lets us maintain much more biomass per unit area in thin biofilms that minimizes shading and translates into higher productivity.  We can then harvest more biomass into less water, so the culture coming out of the reactor are several times more dense than is typical.  This means lower-cost dewatering―smaller systems and lower operating expenses.  The gas transfer is an interesting one.  CO2 can be one of the most expensive nutrients in liquid cultures, but in our system, the CO2 can be added directly to the headspace as a gas. This is a big cost savings by not having to get it into solution. 

Whenever commercialization challenges in the algae industry are discussed, harvest and dewatering seem to come up pretty quickly. What makes those two so difficult and how is BioProcess Algae tackling them?

A typical harvest is more than 99 percent water.  We are harvesting at concentrations two to eight times more dense than typical systems, which means we have to handle two to eight times less water during dewatering.  This translates to lower capital costs for smaller dewatering systems and less energy to run them.  BioProcess Algae grew out of a wastewater treatment company, so we have great in-house experience removing suspended solids from water. 

What has to happen for algal protein to become regularly included in livestock rations?

We have had great early results from poultry trials suggesting that the algae we tested was highly digestible, rich in protein and high in the appropriate amino acids.  Studies on palatability, inclusion rates and any regulatory concerns need to be addressed before the product can be commercialized.  We are working with groups on all of these fronts, as we speak.

You have two offtake products, as I understand it: oil and dried powders. Is it possible to optimize your system and strain selection in order to pursue one more diligently over the other?

One of the nice things about our production system is that it is highly flexible and we can dedicate different reactors to grow up material for different markets at the same time.  The strains themselves can always be improved, and our biology group works closely with downstream partners to make sure we are selecting strains and optimizing for product quality as well as robust culture characteristics for mass production. 

It's been an incredibly hot summer. Climate scientists are reminding the general public that carbon emissions are altering the planet’s climate and the carbon capture and sequestration has never been greater. Is algal cultivation amongst our best chances to begin to tackle carbon emissions and turn the ship around?

From an environmental standpoint, CO2 mitigation is certainly a huge service provided by algae farms, but the farms also score well in terms of resource-use efficiency, including nutrients, energy and, last but not least this year, water.  But even in a resource-constrained future, these benefits are meaningless unless the technology is profitable, socially acceptable and equitable.