New microalgae biorefinery technology using brine water and clever cultivation and harvesting processes paves the way for natural food additives, proteins, colourants and feed stocks, as well as potential treatments for diseases of the skin, eyes, arteries, and even diabetes.
These results, reported by a research team led by the University of Greenwich, are attracting the attention of diverse sectors, from food and feed to consumer and healthcare products in what could develop into billion-euro businesses. But the real story is the ingenuity of the full-scale biorefinery which uses sustainable energy and some clever production and harvesting techniques to grow a sensitive microalga, called Dunaliella salina, under controlled conditions.
“This is tantalising proof of the potential of Europe’s Blue Bioeconomy in market terms, but also in scientific and environmental terms,” says Patricia Harvey, coordinator of D-FACTORY – the EU-backed project behind the pioneering results.
The project’s work goes some of the way to answering a question posed by authors of ‘Food from the oceans’, an EU-backed report by the Scientific Advice Mechanism (SAM), which asks how more food and biomass can be obtained from the oceans in ways that don’t deprive future generations of their benefits.
“Using salty, non-potable water as the growth medium means huge savings in fresh water and it frees up arable land for other purposes. We also use flue-gases to promote rich algal growth which further helps to cut CO2 emissions,” she adds.
Dunaliella salina is a tiny alga that harnesses the sun and absorbs/stores carbon dioxide (CO2) as it merrily grows in briny mixtures of salt and fresh waters worldwide. It produces carotenoids and other commercially valuable compounds, such as emulsifiers, polymers and glycerol. But despite years of effort, scientists have struggled to produce good-quality, industrial-scale quantities of this halotolerant (able to live in salty environments) species with the right properties for different applications.
D-FACTORY has isolated and commercialised new algal strains at its test site in Eilat (Israel), and developed novel processes and models, including using special photobioreactors to double the amount of Dunaliella salina biomass output, demonstrating what Harvey describes as “optimal properties” for extracting and preparing them for different potential uses. Dried powders are then processed for valuable carotenoids and nutrient-rich biomass using certain bioprocessing techniques (including supercritical CO2 and other cheaper extraction methods).
These solutions have now been successfully transferred to a production facility in Monzón (Spain), with good expansion potential (up to 100 hectares), making it the largest algal biorefinery of its kind. Backing is being sought for this development.
“We’ve placed great emphasis on developing sustainable technologies for producing the halotolerant microalgae by cultivating them using waste CO2 from flue-gasses, for example, to reduce carbon emissions in large-scale production systems that can run all year round, even in snow!” Harvey points out.
This meant the team had to spend extra time in studying and creating a full value chain, from low-cost cultivation to high-yield harvest to recycling and up-cycling opportunities, and eventual sale of biomass and other algal-based materials.
“This wasn’t easy because the techniques we’re using are so new and the potential markets for these materials were far from well-known while we were working on this four-year venture,” the coordinator adds.
What is known, however, is that Dunaliella salina is the richest known source of natural orange/yellow/red pigments (carotenoids), which was a good place for D-FACTORY to start while analysing potential markets. These include colourant extracts as well as various compounds suitable for treating diseases like atherosclerosis (plaque build-up in the arteries), diabetes, skin ailments like psoriasis and eye disease.
“One of the biggest challenges we faced was to separate pure carotenoid compounds ready for scaled-up batches, so we had to develop highly concentrated varieties,” reveals Harvey. But the extra effort, now patented, has paid off because the new solution produces superior-grade materials, with better health benefits, and which are easier to extract at lower cost.
“And these superior base materials and colourants can now be more readily incorporated into foods than any other natural carotene preparation currently available on the market,” concludes Harvey.
Image © PJ Harvey. View of Dunaliella salina production facility in Monzón (Spain), with a raceway in the foreground showing pipework delivering flue-gas CO2.