Across Flanders and other European regions, farmers regularly harvest grass from roadside verges and agricultural buffer strips. While this grass is important for protecting waterways and reducing nutrient runoff, it often has very limited nutritional value and may contain undesirable plants, meaning livestock will not eat it. As a result, it typically ends up being composted, left to rot or removed as waste, offering little or no benefit to the farm.
At the same time, interest in microalgae as a sustainable, high-protein ingredient is growing. Yet the cost of conventional nutrient media remains a barrier for many.
The Grass2Algae process brings these two challenges together. By transforming low-value grass into a nutrient-rich medium for algae cultivation, it creates a valuable product from an underutilised resource.
Why is algae relevant?
Microalgae such as Chlorella and Spirulina are highly nutritious and contain significant amounts of protein. However, they usually require expensive nutrient media, which restricts widespread use and reduces the sustainability of algae production systems.
What is the Grass2Algae concept?
Grass2Algae is an innovative process that converts harvested buffer-strip grass into a nutrient-rich organic medium suitable for microalgae cultivation. Rather than being treated as waste, the grass becomes a valuable input for producing high-protein algae.
How does the Grass2Algae process work?
The process includes several key steps:
- Grass conversion
Up to 40–60 percent of the grass mass can be transformed into grass juice, which forms the basis of the algae medium. - Juice preparation
To prepare the grass juice for algae growth, it undergoes:- sedimentation
- fibre removal
- pH adjustment to 8
This creates a clarified and balanced medium suitable for microalgae.
- Use of remaining fibres
The leftover fibres can be used for bio-based materials or as feedstock for anaerobic digestion, supporting circular resource use on the farm. - Algae cultivation
Once the medium is ready, algae such as Chlorella and Spirulina thrive on it, producing safe, protein-rich biomass containing up to 41 percent protein.
What are the benefits for farmers?
The Grass2Algae process offers several practical advantages:
- Reduces waste by transforming low-value grass into a productive resource.
- Creates new income opportunities through algae production and potential sales of bio-based materials.
- Supports organic markets, as the medium is made from agricultural by-products.
- Provides a sustainable protein source at a time when Europe seeks alternatives to imported protein crops.
Which algae species can be grown with Grass2Algae?
The process supports cultivation of common microalgae such as Chlorella and Spirulina, both of which grow well on the clarified grass-based medium and generate high-protein biomass.
How does Grass2Algae contribute to circular farming?
Grass2Algae closes loops on the farm by converting an underused material into two valuable products:
- a nutrient medium for algae cultivation, and
- fibres that can be used for bio-materials or anaerobic digestion.
This reduces reliance on external inputs, lowers waste and supports circular agricultural systems.
Learn more
Our latest animation below illustrates the process. The NUTRI KNOW project also invites farmers, advisers and local stakeholders to join the Community of Practice. It is a space to share experiences and discover practical solutions for sustainable nutrient management.