the removal of carbon dioxide. At the St. Marys plant, a pipeline has been outfitted to funnel emissions from the cement kiln directly to the algal biorefinery, which is located onsite. The gasses are then released into the photobioreactor – a 25,000-litre box-like structure filled with water and outfitted with LED lights. Algae cultures are then introduced into the water and feed off the C0 2 , other nutrients and bursts of light from the LEDs, causing them to multiply rapidly. Within a few days, the pho-tobioreactor is filled with the dense microalgal biomass. Once established, that biomass can then be harvested and regrown in a continuous around-the-clock process. NRC researchers select which strains of algae to introduce into the photobioreactor according to how well they will grow with the cement kiln’s flue gas emissions. Those emissions are mostly C0 2 , but also contain trace quantities of sulphur oxides and nitrogen oxides. NEXT STEP: BIOFUEL Algae harvested from the St. Marys plant is being used by the NRC to further research the development of biofuels and other bioproducts at NRC labs across Canada. The goal of the project at St. Marys is to recycle C0 2 emissions and eventually produce biofuels onsite for use in the cement-making process. As with many biomass projects, “Scaling up is the next step, but it’s a challenge,” Asselstine says. “There are challenges to ramping it up to industrial volumes and amounts. We currently have a 25,000-litre bioreactor. It’s one thing to fill a little beaker with algae, squeeze it and get a drop of oil and it’s another thing to be producing hundreds of tons of it a day. When you get to those huge amounts of material it’s the same process but the logistics get complicated: you have store, move it, ship it and keep it flowing,” he says. O’Leary says the challenges they face are the same for all research bodies that are studying microalgae for carbon mitiga-tion. The demonstration stage is when researchers can determine how and if the project should scale up. “It’s giving us data that we can use to begin to do a true empir-ical analysis of what this looks like at a commercial scale... what the benefit is to the carbon cycle of a commercial scale tech-nology, and if there is an economic business case to deploy at that scale.” The head researcher says he is optimistic that within 10 years or less the technology for producing microalgal biomass from flue gas will be commercially viable for industry partners. “We’re at the tipping point now,” he says. “Assuming that we’re not hugely disappointed with the data that we collect over the next year and a half, the next iteration of this will be small-scale commercial production within the next two or three years, and then ideally large, full-scale commercial production in five or six years.” Asselstine confirms Votorantim Cimentos’ St Marys Cement business is in the process of evaluating much larger trials for the algal biorefinery, which could see algae produced onsite in a one million-litre photobioreactor. “There is a wealth of opportunities that can be addressed by algae, and if we can grow it using our emissions gases than that’s fantastic, and ultimately our industry, and other industries, may be able to convert a waste product into a valuable resource,” he says. • Canadian BIOMASS 21
Canadian Biomass March-April 2017: Page 21
