Holy floating photobioreactors, Batman! With a little help from the Japanese corporation IHI, Alabama can now lay claim to the world’s first algae biofuel system that also treats municipal wastewater, resulting in a carbon-negative process. IHI’s Algae Systems LLC company has just completed a demo run on a 40,000 gallon-per-day plant that deploys floating photobioreactors in Mobile Bay at Daphne, Alabama.
That’s quite a step up from the test tube-sized algae biofuel experimentation going on at the Daphne Utilities treatment plant last fall. Aside from the carbon-negative angle, the system is particularly interesting because it relies on local, naturally occurring algae rather than those amped-up proprietary algae strains we’ve been fangirling on lately.
Plenty Of Room In The Algae Biofuel Pot
If you’re a little skeptical of the naturally occurring strain thing, consider the parallel with solar power. While ultra-efficient solar cells are coming on the market, the most efficient solar cell does not necessarily lead to the most cost-effective solar installation, or to the broadest range of application.
Think about the contrast between relatively low-efficiency organic solar cells and their high-efficiency silicon cousins, and you’re on the right track.
Crossing that idea over to algae biofuel production, IHI and Algae Systems have taken a holistic, energy-efficient approach to algae biofuel production. While the new algae biofuel system might not boast the most efficient strains for biofuel production, it is a problem-solver that piggybacks on a liability — that would be the municipal wastewater — and extracts value from it.
The Alabama Algae Biofuel Photobioreactors
For those of you new to the topic, floating photobioreactor is algaespeak for plastic bag. What you do is you take long, durable plastic bags, fill them with a nutrient-rich growing medium (wastewater, in this case), throw in some algae, and let sunlight work its magic. The algae grow quickly in the closed environment, and there’s your biofuel crop.
The Daphne Utilities wastewater treatment plant chugs away at three million gallons per day, so there’s plenty of wastewater to spare for the new demo plant. That takes care of the water supply angle, which is something that bedevils conventional algae farming.
The choice of local algae means that up-front costs are nothing compared to developing a proprietary strain. It also provides for lower running costs, since the local algae are already acclimatized and require no special environmental controls. That also translates into lower energy use.
The cost and energy consumption angles also come into play with the choice of floating the photobioreactors out in the bay, rather than building new infrastructure on land. The bay waters help to stabilize the internal temperature, and the waves provide a natural means of keeping the contents mixed for optimal growing conditions.
As the algae grow, they take up the nutrients in the wastewater, which would otherwise require an energy intensive treatment process. That’s the carbon-negative deal in a nutshell. According to IHI, after the algae is harvested the result is clean water than can be discharged into the bay without risk of creating dead zones.
Not for nothing, but NASA is also tinkering around with a similar wastewater/algae photobioreactor system, with an eye toward recycling wastewater in space.
From Algae To Biofuel
As for the conversion of algae to biofuel at the Daphne facility, that’s the proprietary part of the system, so we can’t tell you too much about that.
What we can tell you is that the system is based on a hydrothermal liquefaction process, which was promising enough to win new Energy Department funding to the tune of $3.2 million for further improvement as part of a $6 million advanced biofuel development package announced last month. The other part of the package went to a woody biomass project.
The $3.2 mil for algae biofuel goes to a research consortium led by SRI International and Algae Systems. As far as we can tell, one focus of the project will be to improve the fuel quality by reducing the nitrogen content of the feedstock.
This is where the marriage between IHI and Algae Systems comes in. Algae Systems is a start-up that boasts a five-year history dating back to 2009, but IHI got its start in 1853. The company has taken a deep dive into equipment supply for high tech systems in the thermal energy, nuclear power, and aerospace fields, so its areas of expertise dovetail with the hydrothermal liquefaction process.
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