Algal biomass for CO2 removal at scale

Project duration: July 2023–June 2026

Project lead

Team

Kim Lee Chang

Opportunity

Since the 1950s, cultivation of microalgae has been recognised as a hugely promising technology, with the potential to sustainably produce food, feed and fuel using a much smaller ecological footprint than is possible with plant-based agriculture or fossil fuels.

Recently, there’s also been increased interest in using microalgae cultivation to remove CO₂ from the atmosphere. Unfortunately, neither the carbon-accounting bottom line or cost-benefit analysis have been attractive due to high energy use and costs, primarily for downstream processing of the algal biomass, which results in the emission of more CO₂ than can be stored. Most current microalgae cultivation systems also suffer from an inability to control environmental conditions, particularly at scale. Inefficient water and nutrient recycling, and light utilisation lead to sub-optimal growth conditions and low microalgae productivity. The potential benefits of a microalgae-based system for food, feed, fuel and carbon capture will only be realised when suitable platforms for microalgae cultivation and processing can be identified and scaled-up to demonstrate commercial viability and a negative-carbon balance. What’s required is a new platform design that can overcome current limitations, and contribute to the technology and science required for the biological capture of carbon. Solving this issue would create substantial opportunities in carbon offset markets and position CSIRO as a world leader in biological capture of carbon.

Goal

Our project aims to revolutionise microalgae cultivation by developing a novel production and processing platform that’s economically and commercially viable, and carbon negative.

Using the mutualistic relationship between algae and bacteria, which enhances their growth and resilience, we’ll identify the most suitable microalgae and bacteria species for development of algal-bacterial biofilm platforms that optimise productivity and carbon capture. We’ll begin by creating a laboratory-scale cultivation system to investigate different attachment materials, growth media, lighting, pH and temperature conditions. Following this, we’ll test the biofilm platforms in a field-scale pilot facility to understand the impacts of reduced control of environmental conditions on biomass productivity. We’ll also develop viable but inactive long-term storage methods to ensure resources used for biomass production are optimised.

Barriers

The main technical risks and challenges in the project are with scale-up of the technology, particularly given the substantial differences between laboratory and field environmental conditions. Broad testing of different growth conditions should, however, enable us to identify algal-bacterial biofilms that can adapt more readily to field-scale environmental conditions. There is also a fundamental lack of understanding of the mechanisms of biofilm formation, with research on the attachment and initiation of microalgal biofilm growth particularly poor, but this doesn’t make the goal insurmountable. There are already many suitable substrates, as well as strains of microalgae that are well adapted to biofilm growth and different environmental conditions, and we’ll use these as our starting point.

References

Ozkan, A., Kinney, K., Katz, L., & Berberoglu, H. (2012). Reduction of water and energy requirement of algae cultivation using an algae biofilm photobioreactor. Bioresource technology, 114, 542-548. https://doi.org/10.1016/j.biortech.2012.03.055

Liu, T., Wang, J., Hu, Q., Cheng, P., Ji, B., Liu, J., … & Wang, H. (2013). Attached cultivation technology of microalgae for efficient biomass feedstock production. Bioresource technology, 127, 216-222. https://doi.org/10.1016/j.biortech.2012.03.055