Displaying items by tag: Algae

US: Prometheus Materials’ microalgae-based biocement has secured certification for use in concrete masonry unit (CMU) mixes. The cement now holds an ASTM C129 certificate for use in non-loadbearing CMUs and an ASTM C90 certificate for use in loadbearing CMUs. Prometheus Materials’ biocement produces concrete with comparable or superior mechanical, physical and thermal properties to ordinary Portland cement (OPC)-based concrete. It offers little-to-no CO₂ emissions and 95% of water used in production is recycled.

Prometheus Materials CEO Loren Burnett said “We are thrilled to have achieved these two foundational certifications as we proceed in full force with our goal of decarbonising construction. Prometheus Materials’ product is poised to change the future of construction, converting one of the most carbon-polluting industries to a low-carbon – and one day net-zero carbon – reality.”

US: A team from the University of Colorado Boulder (UCB) has developed a carbon-neutral alternative cement from biogenic limestone. The limestone comes from farmed cocolitophores, which capture CO₂ as they grow.

The UCB scientists collaborated with colleagues from the University of Carolina at Wilmington and the National Renewable Energy Laboratory on the project. Their work has received US$3.2m in US Department of Energy funding.

This news story has been corrected to include the correct name of the University of Colorado Boulder

Morocco: Morocco’s second largest cement plant in Safi, HeidelbergCement’s largest in the country, is to receive an adjacent algae pond. Environmental innovator Omega Green has estimated the pond’s rate of carbon dioxide removal at 80-100t/yr. The algae can be sold on to food, cosmetics, and animal feed producers.

An update on the algae bioreactor project at Votorantim's St Marys cement plant in Canada this week provides a good opportunity to review this particular aspect of carbon sequestration. The project, run with Pond Biofuels, went live in 2009. It has now reached its third generation bioreactor at the site.

Little or no performance data has been released generally so we have no way at present of knowing how viable the process is commercially. Cement backers, Brazilian firm Votorantim, are certainly excited by the project even if only for the sustainability kudos it gives them. Director Edvaldo Araújo Rabello presented the project as one of the company's highlights at a keynote presentation at the 6°CBC Congresso do Cimento held in São Paulo, Brazil in May 2014.

One hurdle for the St Marys pilot is the relative lack of light, a required input for algae photosynthesis, even in Canada's most southerly state. Pond Biofuels have reportedly dodged this by using continuously flashing LEDs to simulate artificially short days that encourage growth. On paper or powerpoint a process that could potentially cut even a proportion of CO₂ emissions from a cement plant sounds enticing. Yet if it creates more CO₂ than it saves, through electricity requirements for example, than it isn't worth using.

This is probably what shelved Lafarge's Carbon Capture and Transformation project. It ran a pilot project at its Val d'Azergues plant in France in 2009 with Salata GmbH. The pilot worked but the researchers decided that new advances in processes and biotechnology were required to make the economic and environmental results better. Other companies have also had problems. Holcim started its Aurantia – GreenFuel project in late 2007 at its Jerez cement plant in Spain, backing it with an investment US$92m. This project stalled when GreenFuel shut in 2009 citing lack of funding as the recession hit.

ACC in India also reportedly started its own algae project in 2007, mentioning it in its sustainability report, but nothing more has been reported since. Since this burst of interest InterCement has invested US$2.5m towards algae research in 2013 working with the Federal University of São Carlos, the Federal University of Santa Maria and Algae Biotecnologia.

Algae-based carbon projects for cement plants may remain stuck in the research stage but the market for biofuels continues to grow. For example, this week we report that Ohorongo Cement in Namibia plans to increase its use of blackthorn as a biofuel to use as an alternative fuel in co-processing. The prospects of turning waste CO₂ into a valuable commodity remains uncertain, but the rewards are great. Let's wait and see what St Marys can do.

Canada: Pond Biofuels has set up a bioreactor pilot plant at St Marys cement plant in St Marys, Ontario. The raw smokestack gas from the cement plant is recycled to grow algae in a third-generation 25,000L bioreactor at the on-site pilot plant. The resulting algae can be used for bio-oil, food, fertiliser and sewage treatment.

The algae consume CO₂, NO_X and SO_X from the smokestack gas. Every 1kg of algae produced prevents 2kg of CO₂ from being emitted into the atmosphere. The St Marys Cement Plant produces 720,000t/yr of cement and 540,000t/yr of CO₂. Currently, Pond Biofuels only uses a small portion of the total CO₂ output.

"We consider ourselves a carbon recycling technology," said Steve Martin, founder of Pond Biofuels.

The algae thrive in light filled, CO₂-rich conditions, which are provided in the bioreactor. The light comes from custom-designed red LED lights that flash continuously. The rapid flashing fools the algae into thinking the days are very short, so it grows very fast. "The algae evolve quite quickly; we can get four, five, six generations of algae in a day," said Martin.

Proving the production of algae at commercial scale is important, but the other important part is finding a market for the algae. "Between 10 – 20% of it is oil that be used for producing biodiesel," said Martin. It could also be used a coal replacement, a soil amendment or even animal feed and it can be easily dried using waste heat from the cement plant.