We scaled up our novel photobioreactor design and conducted independent functionality tests that confirmed the unit’s robustness. The modular photobioreactors, which are made from off-the-shelf materials, including polyethylene, can withstand category 1 hurricane winds. Because of the materials used and the innovative design, we also have been able to validate low fabrication costs.

—Proterro CEO Kef Kasdin

Kasdin also said that Proterro is in the process of commissioning a pilot plant in Florida and has completed a preliminary design, layout and associated cost estimate for a demonstration-scale plant.

Using CO₂, sunlight and water, Proterro lowers the cost of sugar production to around $0.05/lb through a novel, scalable biosynthetic process that integrates its patented microorganism with its patent-pending photobioreactor. This process yields a fermentation-ready sucrose stream, rather than a mixture of sugars, allowing simple, low-cost downstream processing.

Key features of Proterro’s patent-pending photobioreactor are:

• Collapsible low-cost polyethylene cylinder
• Made from off-the-shelf materials
• Naturally sheds rain and snow
• Favorable aerodynamic shape for wind loading
• Patented cyanobacteria grow on vertical fabric panels
• Water and nutrients drain by gravity on panels
• CO₂-augmented air, or flue gas inflates cylinder
• Natural low point for condensate drain
• Can be UV stabilized

Unlike typical algae cultivation approaches, we grow our high-sugar-producing cyanobacteria on a composite fabric substrate enclosed in our photobioreactor, which optimizes the organisms’ access to light and surrounds them with their carbon-dioxide feedstock. Water and nutrients are trickled into the photobioreactor, creating a controlled cultivation environment.

—Kef Kasdin