A breakthrough in algae harvesting

One of the more perplexing problems of the advanced bioeconomy is getting algae out of the water or the water out of the algae. It simply isn’t a problem in traditional, land-based agriculture and most of the nutraceutical applications of algae that were developed early on featured such high price points that it almost didn’t matter what technique was used. A $20,000 price per ton can be forgiving for a lot of crude harvest and extraction ideas.

For algae to become a viable technology for producing foods, feed, chemicals or fuels, where price points drop below $2000 per ton and on down to the $500 per ton levels of fuels today — the attractive aspect of algae is that it grows so darn fast, and the pesky aspect is the harvest cost. Centrifuges work fine but if algae concentrations are 1-2% then they have to move 50-100 tons of water to produce a ton of harvested algae. The energy costs are murderous.

Reducing energy needs by 99%

So it comes with a “Big News” sign hung around it’s neck when open-pond algae developer Global Algae Innovations began offering for sale a membrane system that, at scale, could use just 1% of the energy needed to run a centrifuge. GAI is Dave Hazlebeck’s company — not long ago, he ran General Atomics’ algae projects and, if you’ll recall, some of the biggest DOE algae grants were going General Atomics’ way.

“It has 100% harvest efficiency,” Hazlebeck told The Digest,”and brings the algae solids concentration up to 15-20%.”

What about fouling? we asked. That’s been a problem for most membrane-based ideas that have come along.

“And no fouling,” Hazlebeck confirmed.

NREL commented on GAI’s algae harvesting system. In part they wrote:

The membrane dewatering performance furnished by GAI and incorporated in the base case, specifically power demand, is significantly better than values found elsewhere in peer-reviewed literature 

After primary settling, the partially concentrated material is sent to central dewatering for further concentration. The second concentration step takes place using hollow fiber membrane technology, which was selected primarily in light of favorable performance and cost results attributed to a commercial-scale membrane system currently installed and operating at the GAI facility. Beyond favorable operational data furnished to NREL by GAI, in general, membrane technology offers several advantages over competing dewatering strategies, including high reliability, direct scalability, and simple thermal, mechanical, and chemical management demands. Additionally, membrane technology produces a filtrate product suitable for recycle, and does not add chemicals to the algal biomass that must be removed later or may negatively impact the value of coproducts. Historical arguments against the use of membrane systems for algal dewatering primarily have been based on fouling and maintenance/reliability issues that have been observed for other membrane types; however, GAI indicated that maintenance and fouling are not typically problematic or costly issues for their process, based on a daily cleaning protocol for the membrane modules. Still, such issues could be both strain- and location/media-dependent and could pose challenges depending on factors such as membrane material, organic (biological) contaminants growing on the membrane surface, or inorganic (silica/ash) contaminants depositing on the surface and blocking pores. 

Although GAI is more of an algae owner/operator, they now have the system for sale. It helps the company with cash flow, helps with potential investors who see a “quick win” profitable product, and expands the circle of GAI’s contacts as they have heard from companies from algae remediation to algae producers and wastewater treatment operations.

“Wastewater treatment applications for smaller communities come generally from service providers, and this could work well for them and we’re hearing from them. It gets out bacteria too, and can help pull out nutrition elements, so that these can be re-supplied to the pond and reduce the cost of refertilzing and re-seeding.”

GAI’s focus in its own operations? Animal nutrition.

“We’re not projecting our models on getting the full fish meal price that you see today. It’s really high now, and at $1600-$2000 ton there are a lot of fish meal customers out looking for alternatives. But there are other options besides algae that are going to be thought of to bring that price down. For example, you can take soy concentrate and use technology to remove things that make it indigestible to fish, and that would cost $1200-$1400.

“So, we feel that a a rush of applications will eventually bring the market price down, and our target for aquaculture is $800-$1200. We feel that algae has a long-term sustainable advantage over soy at that price. But there needs to be some work done in convincing the marketplace to fully value the advantages that algae has, which can include a superior protein profile to other feeds, and that it is more digestible than soy.

“We’ll be focused on aquaculture first, but we see opportunities for algae in the broader animal feed market, even though the straight up returns in aquaculture are higher.”

The focus for now? “Getting to scale,” said Hazlebeck. “As with everything in the [bioeconomy] sector, it’s not enough to be environmentally advantaged, more sustainable. It has to be economic.”

The Global Algae Innovations system

Right now the company is working at an 8-acre scale in its operating module, and Hazlebeck sees an intermediate scale-up opportunity at 20X that size, around 160 acres. What in land agriculture is known as a quarter section — and of which size there are a lot of available land parcels, we night add, because that was the traditional land grant in the old days of the Homestead Act.

But the full commercial size, Hazlebeck speculates, will be in the low thousands of acres.

CO2? That is expected to come from waste sources, and GAI picked up a $1 million Department of Energy grant last summer “to increase algal biomass yield by deploying an innovative system to absorb carbon dioxide from the flue gas of a nearby power plant.”

The partners?

GAI also was a big winner this summer when the DOE’s algae program announced up to $15 million for three projects announced up to $15 million for three projects that take highly productive algal cultivation systems and couple them with effective, energy-efficient, and low-cost harvest and processing technologies.

Global Algae Innovations partnered with the University of California-San Diego, TSD Management Associates, Texas A&M University, General Electric, Pacific Northwest National Laboratory, and the National Renewable Energy Laboratory.

The economics and designs

Bottom line on the economics: GAI’s system is one of the most cost-efficient yet seen in the world of algae for a scaled-up system. Overall, NREL estimated that the complete scale-up cost for a 5,000 acre system would be $146 million. And an annual operating cost of $144 per ton of algae.

Which led NREL to consider an all-in minimum biomass selling price of as low as $490 per ton. Excellent news for chasing the nutrition market, and possibly more.

There’s an excellent paper which NREL’s awesome paper on the topic is available here. It’s essentially the public bible on algae economics at the moment, and which includes a whole bunch of useful detail on GAI’s economics and designs.

NREL observed:

The GAI facility consists of open ponds of varying sizes up to a maximum of 3.2 acres, configured as a “hybrid” between raceway ponds (each pond consists of two channels separated by a center divider) and serpentine gravity-flow ponds (the channels are continuously sloped to induce circulation by gravity). Starting at one end of the pond, channels are continuously sloped over a gradual grade of roughly 0.1%, turning back at the far end and continuing down over a similar graded slope in the second channel. Culture movement is imparted by gravity flow following the graded channel slope. Rather than paddlewheel stations on one end of the pond, circulation is provided by pumping from the lower to the upper channel.

At the time NREL projected two scenarios for GAI designs. One, that it would cost $2.9 million to develop a 10-acre GAI system. In another design, NREL projected an astonishingly low capex of $1.72 million for 50-acre systems.

There’s also a presentation given at the Algae Biomass Summit two years ago, which we highlighted here, with detail on the systems and progress to that date.

The Bottom Line

GAI’s commercial plans will depend to a great extent on the known-unknowns such as finance. For the time present, there’s ample evidence that it has made a substantial breakthrough on harvesting and dewatering. And that’s been a bottleneck for algae development, and the calls into GAI headquarters to look at or purchase the system — that’s  good news for algae’s many fans.