Rob van Haren, lector in Transition Bio Economy at the Hanze University of Applied Sciences Groningen, is currently working on a special semi-industrial biorefinery with supercritical CO2 technologies. The system, according to Van Haren unique in the European research world, consists of several components. ‘During the preparatory treatment in the supercritical extruder, we first extract the fatty components from the biomass. We use CO2 as a carrier instead of water. This way we reduce the biomass flow at the same time so we can go faster from the batch process to a continuous process,’ he explains.
‘The extractor then plays an essential part in extracting the highest-quality components from the biomass, such as components with a pharmaceutical effect. Furthermore, we have two large ten-litre stainless steel reactor vessels connected in series, as well as a four-metre fractionating column. The heat exchangers, the process control systems and the supercritical CO2 spray dryers complete the system.’
The semi-industrial biorefinery was built in the first instance for the European Horizon 2020 project LIBBIO. In this project, Van Haren and other parties are investigating the possibility of getting an entirely new biomass flow going in Europe, based on the Andean Lupin plant. This lupin variety grows excellently on poor soils because it produces its own fertilisers. And since the most fertile soils are already in use, expansion is only possible by using less productive soils. According to Van Haren, lupins are the ideal choice. Moreover, they contain high-quality proteins and high-grade oil. A business case similar to that for the cultivation and processing of soya can be developed with this.
Van Haren is also targeting other biomass flows. ‘For instance, we are also collaborating with Hillebrands Laboratorium and Hoekstra New Food Business on the extraction of lutein from the Tagetes flower, better known as marigold. Lutein is a powerful carotenoid that is used to prevent retinal degeneration, among other things,’ he explains. ‘We are also working on the extraction of genistein from the plant dyer’s broom; this is a phytosterol that is effective against cancer, among other things.’
The most important goal in each project is to first isolate the high-grade components on a semi-industrial scale, and after that extract value from the other material flows, stresses Van Haren. The biorefinery cascading principle is central to this. It means that Van Haren extracts value from all components in the biomass and there is no waste. ‘This approach ties in seamlessly with the plans of the European Commission to create a circular economy in Europe.’
The processing capacity of the system depends on the speed and effect of the extraction process and the composition of the biomass flow, according to Van Haren. ‘In principle we can process hundreds of kilos of biomass per day, but the yield will differ. Take the lupin bean, which contains forty percent protein. If we put one hundred kilos in the system, we get forty kilos of protein out of it.’
Van Haren emphasises that extraction and fractionating are techniques that have long proven themselves in the past thirty years. ‘What is new is that we are building a semi-industrial system here that combines the opening up with extraction. We also have software to calculate the total cost price of the process. This means we are not only able to calculate the technical feasibility of the process, but also its economic feasibility.’
The processes take place under mild process conditions, at temperatures below 70 degrees Celsius, and without the use of solvents (based on fossil raw materials). So it concerns a fully green extraction process in which Van Haren uses only bio-ethanol and water as cosolvents.
He believes that the semi-industrial biorefinery can easily compete with fossil raw material-based systems as far as cost and functionality are concerned. ‘The supercritical CO2 processes are expensive in principle, but you have to compare them with the alternatives. Those are processes based on hexane, often polluting, toxic not only for humans but also for the environment,’ he specifies. ‘What is more important? As a company do you transfer the environmental costs to society, or do you include the environmental costs in your product by putting a premium product on the market?’
In Van Haren’s opinion, consumers increasingly want pure, natural products and are also prepared to pay more for them. ‘From biomass subsidiary flows from the food and process industries we can now extract particularly interesting and valuable components. And in such a way that the original raw material flow remains intact.’
Collaborating with companies in the chain
In the project, Van Haren works together with a number of companies in the chain. Thus Avebe is interested in supercritical CO2 processes for separating in an effective way. This not only increases the yield, but also requires less energy and solvents. In addition, parties such as Syncom and the Ofichem Groep are interested in the industrial production of pharmaceuticals and nutraceuticals. ‘This morning I was in discussion with a party that wants to extract astaxanthin from shrimp shells, a natural pigment that can be used to give salmon a pink colour, for example. In brief: there is more than enough interest from companies in the chain,’ notes Van Haren. He also works closely together with professor Witkamp from the Delft University of Technology, one of the originators of the supercritical CO2 technology in Europe, on the further optimisation of the extraction processes, including deep eutectic solvents (NADES).
Removing mineral oils
Van Haren is also working on the development of a process that uses supercritical CO2 technology to remove residue of mineral oils from used packaging of foodstuffs. The European Commission indicated in early October that more research into this is required. Thus a Euro MP of the Dutch CDA party, Annie Schreijer-Pierik, declared that ‘nobody is keen to ingest ink from old newspapers in their pasta or rice.’ Van Haren’s first attempts on a laboratory scale were successful in removing the residue with supercritical CO2. He is now working on the optimisation of the process.