Capturing Carbon: the role of biocatalysts and biofuels

The impact of biocatalytic systems now and later

What’s the capex requirement for a plant? According to the MIT study – it averages 59 percent of the total cost of a carbon capture project, and 65 percent for the Integrated coal Gasification Combined Cycle plants. An 18 percent reduction in capex cost could reduce the overall break-even point of carbon capture of an IGCC plant — if the figures cited held up in actual practice — down to sub-$20 per tonne ranges. Making carbon capture a viable technology in selected cases. The next-gen technology envisioned by Akermin could broaden the field.

The role of biofuels

Biofuels could well be critical to making these technologies economically viable. The main reasons? They are relatively easy to site next to power plants — compare the problems, in term of costs and logistics, of transporting CO2 over long distances for use in enhanced oil recovery, where the oil field location might be far from the power plant site and pipeline or trucking costs come into play.

Most biofuels technologies that directly require CO2 also require just water, a nutrient package including phosphorus and nitrogen, and in most cases also require sunlight. The sunlight intensity can pose some restrictions, but generally these technologies are designed to use water already consumed in power plant cooling operations, or brackish water not otherwise suitable for human or agricultural use.

Prominent among the technology options? Sapphire Energy, BioProcess Algae, Aurora Algae and Cellana just to name four among the algae contenders. There is Joule, which uses CO2, water, sunlight and nutrients to directly generate ethanol, diesel and jet fuel. Proterro uses the same combination of inputs as Joule, with an aim of making low-cost renewable sugars. The class of technologies known as the electrofuels also generally use these inputs to generate alcohol fuels as well as drop-ins such as diesel and jet fuel.

Scale of operations

Coal-fired power plants are big, in the US – generating an average of 667 megawatts each, according to the EPA — and generating, based on 98% uptime, 3.39 million tonnes of CO2 each per year. With a capture rate at 85 percent and using 2.1 pounds of CO2 to make a pound of algae (with a 25 percent oil content), that supports the production of around 120 million gallons of biodiesel per year. With 457 coal-fired plants figuring into this equation — there’s 54 billion gallons of fuel in potential production. That’s without food inputs. But you’d have a lot of land used up in the equation — something on the order of 18 million acres of algae, if production rates reached 3,000 gallons per acre per year.

In today’s Digest, we look at next steps — and ultimately, “feasible or not feasible?” Via the page links below.