Article by The French Solid Waste Partnership – an ISWA Platinum Member.
Landfills have bad press. But there are landfills and landfills. There is actually a whole array of installations that are called landfills in common language but that actually are completely different infrastructures. Some are very similar to open dumps, others – the most advanced, are controlled industrial facilities. In this array of solutions, the environmental impact varies greatly from very detrimental to contained risks and managed impacts.
We do want to reduce as much as possible what goes to landfills. That is a founding stone of waste management systems. We need to reduce the waste produced (re-use, repair, neighborhood composting…), then recycle as much as possible from the waste collected (organics, valuable plastics, paper & cardboards, metals). But then, the waste that remains needs to be managed to prevent sanitary risks and pollution, as well as reduce GHG emissions.
Once we have worked on reduction, biowaste separation, and recycling, what should we do with all the rest? With what is too polluted to be valorised, or with the refuse from recycling activities?
A final sink is needed, even if we aim for it to be as small as possible. If we don’t plan for it properly, this waste pollutes soils, water and air. When we plan for it, the pollution will not be zero but can be reduced by many folds.
These final elimination systems are 1/incineration with flue gas treatment to protect air quality, and 2/ engineered landfills with leachate collection and treatment to protect water. Both these sinks are net GHG emitters through fossil CO2 burnt in incinerators or through biogenic CH4 leaking from landfills.
Both solutions offer opportunities to capture energy (heat, electricity or biomethane) when managed under state-of-the-art practices. The initially land-consuming landfills can easily be transformed into solar plants once the cells are closed. Both solutions therefore support our energy transition out of fossil fuels, in different local contexts.
These projects are often controversial because citizens focus on the small amount of pollution that remains, rather than on the huge amount it prevents. The “not in my backyard” often prevails, making it very difficult for authorities in charge to plan and build these infrastructures, even though we all contribute to producing this waste that cannot be valorised. So, until we have managed to reduce and change our waste production to enable 100% valorisation, we need these projects… and the choice between the two solutions depends on the local context: land availability, local capacities, available funding, client affordability, etc…
Trifyl Engineered Landfill
Landfill Tabanan
The Waste Management & Research article “Enhancing Landfill Efficiency to Drive Greenhouse Gas Reduction: A Comprehensive Study on Best Practices and Policy Recommendations” presents the state-of-the-art practices that can enable drastically reducing GHG emissions from landfills. These practices are as follows (without any specific prioritisation):
- An anticipated capture system during the operating phase,
- Prompt installation of the final cover and capture system, with the use of an impermeable cover,
- Operated as a bioreactor, keeping optimal humidity,
- Adequate maintenance and reporting,
- Enhanced recovery of captured gas,
- Treatment of residual methane emissions throughout the waste decomposition process.
Case study evidence led to conclude that 80 to 90% of the biomethane produced in the landfill cells over a 50-year period could be recovered, rather than leaked to the atmosphere. This finding is based on assessing the difference between the IPCC methane generation models and the actual biogas captured and purified into biomethane before injection into the grid. This assessment is validated through a few cases of on-site monitoring of methane leakage. However, there is a recognized standardization gap regarding the way methane emissions from engineered landfills should be measured and reported. These figures therefore still need to be taken with caution.
The article also shares the results of a study based on the French waste mix and the assumption that the EU directive objectives for organic waste diversion are met. Extrapolating these assumptions to the whole of Europe, the upgrade of all landfills to best-in-class engineered landfills would reduce methane emissions by ~21MtCO2eq (-36%) of emissions due to the degradation of waste landfilled between 2024 and 2035, compared to the “business-as-usual scenario”, at an abatement cost of ~20€/ tCO2eq.
Under this latter assumption of all European landfills being upgraded, the potential to recover biogas from European landfills represents 5 to 10% of the repower EU Biogas production targets. In the rest of the world, where landfill diversion is still low and organic content is high, working on a 2-pronged approach to REDUCE waste going to landfills AND drastically improve the landfill infrastructures, presents a huge opportunity to contribute to both climate mitigation and renewable energy goals.
This paper will be presented during the ISWA World Congress in Cape Town. We also hope to hold a discussion on methane emissions from landfills MRV frameworks during the ISWA Landfill Working Group session at the Congress. Come and join us for the discussion!
