Microalgal bioreactor systems could be built next to industrial chimney flues to take out carbon dioxide (CO2) and heat to produce bio-oils and nutritional products.
Researchers at Swansea University are investigating various ways of harnessing the potential of microalgae, which are culture blooms of photosynthetic single-celled organisms.
‘It’s a tantalising resource in the fact that microalgae grow much faster, and you can get higher yield of things such as oils, compared with terrestrial crops,’ said Dr Adam Powell of Swansea. However, he added: ‘A lot of this technology has previously been oversold to some of the larger oil-refining companies and they started to pull out because the initial claims couldn’t be verified.’
While microalgal do have some key advantages over crops — with some estimates of product yield close to 15 times greater per volume of feedstock — the main problem is the amount of energy and resources required to harvest the cells out of the culture.
‘If you see a very dark culture in a pond it’s probably less than one per cent algal cells, so you need to try and find effective ways of de-watering the culture,’ Powell said.
To avoid some of the pitfalls of past projects, the team is working with different industrial partners to focus on each specific step of the potential algal supply chain. For the initial bioreactor infrastructure it is working with Tata Steel and Strip Products, based in nearby Port Talbot.
‘Tata is taking this seriously — it is looking at a belt-and-braces approach to try and reduce CO2. As well as trying to increase efficiency in-house, it is looking at our low-carbon technology and also things such as geological carbon capture,’ Powell said.
He explained that bioreactors can either be built as raceways (essentially engineered ponds) that are more suitable for warmer climates or alternatively in stacked units that can be built upwards in concert with other infrastructure.
‘If you grow algae adjacent to flue gas you can divert that extra CO2 and heat to drive photosynthesis quicker and that means the carbon is locked up inside the cell as carbohydrate — or, in fact, oil,’ Powell added.
For the purification of the products the Swansea team is working with Axium Process, and for the refining and utilisation of the raw materials it is working with Western Wood Energy Biomass Plant, which is Wales’ first commercial-scale biomass project.
The 30-month project, known as ACCOMPLISH, is being supported with more than £425,000 from EU structural funds, the Welsh government and resources from industrial partners.