Organic waste is increasingly recognised as a resource. Across the Nordics, much of it is collected and directed towards biogas production, supporting renewable energy systems and reducing reliance on fossil fuels. This is an important part of the transition. At the same time, another challenge is becoming more visible: soil health.
When organic waste is treated through anaerobic digestion, energy is extracted in the form of biogas. What remains is digestate, a nutrient-rich material that can be applied to agricultural land. Digestate plays an important role as a fertiliser, returning nutrients such as nitrogen, phosphorus, and potassium back to the soil. However, during the digestion process, a significant share of the easily degradable carbon is converted into biogas during the digestion process, reducing the amount of organic matter that remains available for the soil (European Biogas Association).
This is where the difference with compost becomes relevant. Compost is not primarily about nutrients, it is about structure and stability. It contributes to soil organic matter, water retention, microbial activity, and long-term soil resilience. These are all factors that are increasingly important in maintaining productive and healthy soils (as highlighted in guidance from Zero Waste Europe and the European Compost Network).
In systems where organic waste is primarily directed towards energy recovery, a shift in how organic matter is returned to the soil can occur. Energy is recovered and nutrients are returned, but the organic matter needed to maintain soil quality over time is reduced. Research indicates that while digestate supports plant growth, combining it with compost can improve soil quality more effectively than using digestate alone (Frontiers in Microbiology, 2024).
This is why the conversation should not be framed as a choice between biogas and composting. They are not competing solutions, but different parts of the same system. Biogas contributes to energy and nutrient recovery, while compost supports soil health and long-term fertility. Both play a role, and both are needed.
Ultimately, the value of organic waste is not only determined by how much is collected, but also by what it becomes.
That depends on how it is sorted, how clean the stream is, and how it is processed. Because once contamination is introduced, the ability to return materials safely to soil can be reduced.
Organic waste sits at the intersection of multiple systems: waste management, energy production, and agriculture. Understanding its role requires looking beyond individual outputs and considering the balance between them. In the end, it is not just about recovering value but about where that value goes, and what it supports.
