Flemish Farmers have access to an abundance of roadside grass or low quality grass that cannot be used as animal feed. At the moment, not much is done with this biomass and it is usually treated as waste. The Grass2Algae project therefore looked for a way to valorise this bio-stream through the possibilities of microalgae cultivation based on grass juices.

Roadside clippings are a residual flow that is released in large quantities during the maintenance of green zones and the edges of agricultural fields. For the valorisation of clippings, a first refining step is necessary to separate the liquid from the fiber fraction. This liquid fraction is rich in nutrients and can be used by farmers to cultivate algae. In other words, this can become a new source of income for Flemish farmers.

In addition, we see less and less animal proteins in the Western diet. Alternatively, we import vegetable proteins such as soy from South America, which is detrimental to our own agriculture. Algae can offer an alternative to those imported proteins.

Grass2Algae therefore investigated the technical and economic feasibility of algae cultivation based on the amount of grass available on 3 partner farms. The grass processing data were collected by the Grassification project (led by Ghent University) and the microalgae cultivation data were collected by Thomas More, AnKo Projects and Ghent University. Figures from the Grassification project also examined how the fiber fraction can be used to improve the economic feasibility of the process.

Some interesting results emerge from the study. For example, several algae were tested and Chlorella sorokiniana in particular appears to be a very promising micro-algae that can be grown with grass juice. More research is needed to ensure that the cultivated algae achieve the required quality, such as the presence of fungi, yeasts and bacteria in the end product. Upscaling will also be necessary to discover the true potential of the grass juice!

From fermentation to algae cultivation

A farmer who’s already started working with algae cultivation is project leader Kris Heirbaut from Temse. He has been using a bio-digester for some time to power the farm with the manure from his own cows. In this way, he already reduced his farm’s methane emissions. Kris now wants to go one step further and capture the CO2 from the biogas installation to grow algae. The carbon is a food source for the algae, while the oxygen goes back into the air: “With the support of VLIF and the Innovation Support Center, a German manufacturer has designed an algae installation for us with which we can capture between 30 and 36 tons of CO2 and process it into proteins for human consumption, which means we can already halve the CO2 emissions of our biogas installation.” In time, Kris wants to produce protein bars and healthy cakes based on the algae.

What is already happening in Temse is the future. By being innovative, agriculture can play an important role in combating climate change!

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