Algae are an interesting sustainable alternative to chemicals that are still being extracted from oil today. And to natural products that are cultivated or transported in an unsustainable way. For this to be the case, however, the value chain – from algae cultivation through harvesting and processing to storage and application – would have to be successfully scaled up to an economically viable scale. VITO is taking a wide view and focusing on the entire value chain following algae cultivation.

For years, VITO has been working on (micro)algae with a focus on algae harvesting and further processing and separation of the algal biomass. VITO has even developed its own technology for the harvesting: Membrane Algae Filtration (MAF). This technology forms the core of a continuous harvesting system that is now operational in the Sunbuilt facility, a pilot algae growth and harvesting infrastructure operated by VITO together with Thomas More in Geel. The photobioreactor – the algae grow under the influence of light – has a capacity of three thousand litres. That would seem like a lot, were it not for the fact that it is barely enough for three kilograms of concentrated dry algae. The flip side to that coin is that algae grow particularly quickly: under optimum growing conditions, VITO is able to grow over 1 kg of dry algae each week.

Water recycling and reuse

The MAF technology and the Sunbuilt reactor are pilot installations. In order to be able to upscale the entire installation, the efficiency and reliability of the individual components and functions must be increased. One of these functions is the recycling and reuse of water (which accounts for 95 per cent of the content of the reactor) and of the salts with which the water is enriched. “With our MAF unit, which is based on our own membrane technology, we filter the algae out of the water and purify the algae to a high concentration”, says Leen Bastiaens of VITO. The filtrate (water plus salts) is immediately reusable.” The ability to reuse water quickly is indispensable for preserving the chances of the algae cultivation and value chain succeeding. “If you have to pump all the water out of the soil, this would not even be allowed when it comes to a full-scale installation with such large volumes. At least not in Flanders.”

The advantage of concentrating the algae biomass is that the investment costs for the further processing do not rise too high, precisely because this can be done with smaller machines. A possible profile of a future algae cultivator is that of an ‘algae farmer’ who has an empty greenhouse in which microalgae grow inside transparent tubes. The European IDEA project, which looks for optimal conditions for economically profitable algae cultivation in Northwest Europe (see box), also fits into that picture.

Tough cell walls

After the algal biomass has been concentrated, the processing takes place. Here too, VITO has the required expertise and equipment to break open the tough cell walls of the microalgae and extract the various components and separate them from one other. “Microalgae really are full  of interesting components”, says Bastiaens. “On the one hand, you have molecules that may be able to serve as a sustainable alternative to existing raw materials (such as omega-3 fatty acids, antioxidants, carotenoids, sugars, proteins and fats). On the other hand, there are also substances for which an application is yet to be found. Algae can therefore also give a boost to creative minds in industrial livestock production.”

Broad area of application

Microalgae are very sensitive to changes in the incidence of light and in temperature. If a cultivator is extremely interested in one or more specific components, he can fine tune the environmental conditions so that his algae start to produce those components. A future cultivator could therefore specialise as a raw material supplier with a focus on one or a few specific applications.

The (potential) applications are extremely diverse. From sustainable and natural dyes for cosmetics (e.g. carotenoids) through food supplements (omega 3) to livestock feed (sugars and, in particular, proteins). The choice of application is strongly dependent on whether or not there is an economic success story in algae cultivation. Bastiaens: Not long ago, algae were seen above all as an alternative to biofuel. This did not make much sense, because that application is characterised by a low price per unit of mass and bulk quantities. For the application as a high-quality alternative to raw materials in cosmetics and nutrition (food supplements), it is exactly the other way around, and this creates a much stronger economic incentive. It is in this way that we want to build up the market”.

Algae all year round

VITO is the driving force behind the EU-funded IDEA project (Implementation and Development of Economically Viable Algae-based Value Chains). This project looks for ways of being able to cultivate microalgae all year round, like in South Europe. If farmers know that they can harvest all year round, and not only in the sunny months (algae are very sensitive to light), it will be more advantageous to invest in the expensive harvesting technology. Specifically, IDEA is for example investigating which species of algae are the most suitable for the climate in North-West Europe. In addition, VITO is conducting research within IDEA into methods of stimulating every link in the value chain.

Seaweed farms

VITO’s investigation focuses primarily on microalgae. However, the general public is probably more familiar with macroalgae – or seaweed. These algae are also in the picture in order to play an important role in the transition to a more sustainable economy. In the Netherlands, for example, experiments are already being carried out with real seaweed farms, where algae are cultivated on textile mats or on ropes in the North Sea. Seaweed is particularly rich in carbohydrates and proteins, and the industry is also aware of this (the protein alginate, for example, has already been used in toothpaste for years). VITO is primarily working on the extraction and purification of useful substances from seaweed.