A comprehensive report from IEA Bioenergy Task 37 paints a global picture of manure digestion. The publication, available online since September, concludes that manure can play a significant role in the energy transition and the circular economy, but that its full utilization is hampered by financial and operational barriers. The report examines approaches in six countries, from Canada to China, and emphasizes the need for smart and coordinated policies.
Why manure counts
Anaerobic digestion offers a solution to the environmental problems associated with traditional manure storage. Open manure pits emit methane and ammonia, greenhouse gases that contribute to climate change. By digesting manure, methane is captured and converted into biogas. The residual product, digestate, is a valuable fertilizer that can replace artificial fertilizers and contributes to healthy soil. This technology offers multiple benefits: it reduces emissions, improves water quality, and generates renewable energy. Despite these advantages, the authors state that only a fraction of the available manure worldwide is still digested.
The challenges identified
While the motivations—from replacing fossil fuels to strengthening energy independence—are similar everywhere, the rollout is lagging behind. The biggest hurdles are financial. The investment and operating costs of digesters are high, while revenue from energy sales is often uncertain. This is exacerbated by the low energy content of thin manure streams.
Other barriers mentioned in the report include logistics, such as the distribution of livestock farms across the landscape, and the complex and lengthy permitting procedures. Furthermore, there is often a lack of expertise among farmers and developers, and a lack of standards for emission measurements. Furthermore, revenues from digestate or biogenic CO₂ rarely materialize, meaning a significant portion of the social value of manure digestion remains untapped.
Six countries, different approaches
The report describes the situation in different countries, each with their own approach:
- FranceLeading the way with the fermentation of approximately 19 percent of available manure. New installations are increasingly focusing on the production of biomethane, which is fed into the gas grid.
- FinlandAn estimated 2,6 percent of manure is fermented. Biomethane is considered a key technology for heavy transport. Larger projects, often on a cooperative basis, focus on biomethane production.
- NorwayProcesses approximately 1,3 percent of the manure. Compressed or liquid biomethane is transported by truck to filling stations.
- United Kingdom: Processes approximately 3 percent of manure, with a clear shift from heat and power production to feeding into the gas grid.
- Canada and China: They remain behind at less than 1 percent, although the number of plans is growing and a trend towards larger, centralized projects is also visible here.
Concrete examples, such as the publicly owned project in Vinzier, France, show that manure digestion can offer a wide range of benefits, including protecting water quality.
Success factors and policy recommendations
The report identifies several success factors that are already being implemented in practice. Co-digestion with more energy-rich waste streams is the norm in all six countries. In Canada and Norway, food waste is used, while in Finland, crop residues and potato waste are common. The establishment of centralized facilities, closer to gas networks, and the use of smart logistics for biomethane transport also contribute to a better business case. The shift to cooperative models or the involvement of third parties for construction and management eases the financial burden for individual farmers.
The key message for policymakers is to recognize the full societal value of manure digestion. Policies focused solely on energy yield miss the important benefits of water and air quality, and soil improvement. Explicitly valuing these services, through targeted subsidies and customized solutions for smaller locations not connected to the gas grid, is crucial to fully utilize manure's potential.
Download the full report: “Potential for manure-based anaerobic digestion"
