Grass Refinery for Sustainability & Shared value

PROJECT DESCRIPTION

BACKGROUND

Verge grass is one of the most abundant and available biomasses in the Netherlands. Between 300 000 and 450 000 tons of verge grass is produced each year by maintenance activities of the road network, nature reserves and rural areas. The amount of verge grass available in the European region is estimated at 4 400 000 tons. The owners of the grass-sites in the Netherlands include local municipalities, provinces, and water boards. Verge grass is often considered a waste product with high disposal costs, and the aforementioned parties have been looking for alternative ways to process verge grass into high-value products instead of just low-value compost. A study has been performed with the aim of examining greenhouse gas (GHG) emissions from different verge grass processing techniques over a total life cycle of 5 years. The study has shown that mono-fermentation results in the lowest GHG emissions, compared to all other options (co-fermentation, composting, agricultural use as direct fertiliser and soil improvement). Verge grass can thus make a major contribution to the reduction of GHG emissions and the development of a sustainable economy, by focusing not only on biomethane production but also considering the entire cascade of high-value renewable products.

OBJECTIVES

The GR4SS project will develop the Grass Refinery for Sustainability & Shared value (GR4SS), the world’s first commercial grass mono-fermentation demonstration plant.

The project’s main objectives are twofold:

• Develop a mono-fermentation grass refinery to convert verge grass into four high-value products: (i) biomethane; (ii) peat substitute: a high-quality and sustainable growth substrate for the greenhouse horticulture sector; (iii) biogenic CO₂ plant fertiliser for greenhouses; and (iv) organic fertiliser for the agriculture sector.

• Develop a strong and innovative business model, to enable suppliers of the grass to become off-takers of the products. This would facilitate the shift towards a sustainable, circular, renewable energy-based and local economy for grass processing.

To that end, a mono-fermentation Grass Refinery demonstration plant will be constructed, based on a combination of innovative and existing technologies that have not been integrated before.

 

RESULTS

Expected results:

The relevance of the GR4SS project is related to maximising the impact of GHG reductions. This will be achieved by cascading use of biomass, creating new sustainable products and therefore avoiding the utilisation of current fossil-based alternatives.

The demonstration plant will:

1. Process annually 30 000 tons of grass, producing between 75 Nm³ biomethane per ton grass (fresh-weight), resulting in a total production of 2 250 000 cubic metres of biomethane per year. The biomethane will substitute fossil fuel gas and therefore reduce GHG emissions by 3 995 tons CO₂ equivalent per year.
2. Produce 25 000 m³ of high-quality renewable peat substitute per year, resulting in an annual GHG emission reduction of 5 185 tonnes CO₂ equivalent per year.
3. Produce 2 700 000 kg of liquefied biogenic CO₂ per year, resulting in an annual GHG emission reduction of 2 700 tonnes CO₂ equivalent per year.
4. Produce 175 000 kg organic fertiliser per year, resulting in an annual GHG emission reduction of 680 tonnes CO₂ equivalent per year.