In a context where the COP29 held at the end of November 2024 reaffirmed theobjective of the Paris Agreement to limit global warming to +1.5°C [1] compared to pre-industrial levels, the reduction of methane emissions is essential as a fundamental lever. Thanks to its short lifespan in the atmosphere (around 12 years), a rapid reduction of this gas could have beneficial effects on the climate visible in the coming decades. However, waste management in France reveals numerous paradoxes and challenges that urgently need to be resolved.
What is the impact of landfills on the environment?
Methane is the second largest greenhouse gas contributor to climate change after CO2 (carbon dioxide). In landfills, also called landfills, storage centers or ISDND (non-hazardous waste storage facility), the anaerobic (oxygen-free) decomposition of biowaste, i.e. organic waste such as leftovers of meals, peelings, etc., massively produces methane which strongly contributes to climate change, particularly when it escapes into the atmosphere due to inefficient or non-existent capture systems.
Furthermore, another major environmental problem arises due to the formation of leachate in landfills. The latter are extremely polluting liquids produced under the combined action of rainwater and the fermentation of biowaste in landfills (the latter being composed of more than 75% water). When they pass through biowaste, rich in organic matter, these juices are loaded with decomposing elements, chemical substances, heavy metals, and microorganisms contained in the waste sent to landfill. If their management is not rigorous, they can infiltrate the soil and contaminate groundwater or neighboring watercourses. The pollution thus generated affects the quality of drinking water and aquatic ecosystems, representing a threat to biodiversity and human health.
Reducing the share of bio-waste in residual household waste (OMR) is therefore a priority. to limit the double environmental burden represented by methane emissions and leachate production.
Landfill: can France still catch up?
In France, despite the commitments set by the energy transition law for green growth (LTECV) aiming to reduce landfill waste by 50% by 2025 compared to 2010, 2023 figures show that 14 million tonnes of waste were still landfilled. This situation highlights that the target of the LTECV, set at 9.73 million tonnes by 2025, seems out of reach without the implementation of restrictive measures. Furthermore, there are still 178 discharges – or landfill centers, or ISDND (…) – on French territory at the end of 2024. It is important to remember that landfill constitutes the last link in the hierarchy of waste treatment methodsprioritizing prevention and reuse first, then recycling and finally incineration and landfilling.
The limits of current capture systems
In theory, in a landfill, each bin receiving biowaste must be equipped with a biogas collection device in order to limit methane emissions into the atmosphere. However, in practice, these devices are often insufficient, with capture rates varying between 80% and 90%, which allows a significant amount of methane to escape. In addition, many old sites, unequipped or poorly maintained, completely escape any regulation.
The National Low Carbon Strategy (SNBC), which sets objectives to achieve carbon neutrality by 2050, focuses on the capture and recovery of methane from landfills. However, these scenarios have been criticized by scientists for grossly underestimating the true impact of methane on global warming. According to some experts, if these emissions are not better taken into account, France's contribution to global warming could be 51% higher than official forecasts by 2050. [2]
Taking bio-waste out of our trash cans: a solution within reach
In 2021, according to the ADEME collection survey, 24% of residual household waste (OMR) was sent directly to a landfill center without any prior treatment or sorting, despite the hierarchy of waste treatment methods. This situation illustrates a major energy and environmental paradox: biowaste, which represents nearly a third of the waste in our household trash cans according to ADEME's MODECOM characterization campaign, continues to be massively buried, where it produces methane and leachate. This linear model, “produce-consume-dispose”, wastes a precious resource and worsens greenhouse gas emissions.
However, all is not lost. Despite the delay in achieving the objective of reducing landfill waste by 50% by 2025, provided for by the LTECV, an essential solution remains: remove bio-waste from our trash cans.
The AGEC law, which came into force on December 31, 2023, now requires communities to provide their administrators with a solution for sorting biowaste at the source. This effective generalization of sorting at source represents a key lever for limiting landfilling and recovering this waste in a productive manner:
- By compostingto generate natural fertilizers which enrich agricultural soils.
- By methanizationto produce biogas which replaces fossil fuels.
Despite everything, in July 2024, only 40% of the French population had access to a sorting solution at source. By recovering biowaste through methanization or composting, it would be possible to significantly reduce the quantity of waste sent to landfills while promoting the ecological and energy transition.
Solutions to reduce methane emissions from landfills
To limit methane emissions from landfills, several solutions are available to us. Here are some key measures that exist to significantly reduce the quantity of buried bio-waste and promote their recovery, while minimizing the environmental impact of landfills:
Generalize sorting at the source of bio-waste in the territory
Since January 1, 2024, the AGEC law has required all communities to offer a sorting solution at the source of biowaste, but only 40% of the population [3] currently benefits from such a service. For this measure to be effective, it is necessary to:
- Deploy sorting solutions at the source of bio-waste throughout the territory (separate collection and/or local management).
- Massively raise awareness among residents to encourage them to participate in sorting bio-waste at the source.
- Set progressive numerical reduction targets. Zero Waste France recommends reducing biowaste in residual household waste to 39 kg per inhabitant in 2026, then to 15 kg by 2035.
Fight against food waste
In 2023, according to ADEME, 10 million tonnes of food loss and waste were observed in France, the equivalent of 150 kg per inhabitant each year. Among this waste, production and processing alone represent 80 kg, or more than half. It is therefore essential to reduce waste at each stage of the value chain – from production to consumption – and not only at household level, in order to reduce the quantity of bio-waste generated and sent to landfill.
Strengthen regulations on landfills
The current regulatory ceilings on monitoring and reducing emissions from landfills, which allow up to 30% of buried bio-wasteare too high. Reducing this threshold and imposing stricter controls in landfills on the composition of buried waste is essential to limit greenhouse gas emissions.
Optimizing methane capture systems
Although capture in storage facilities is not a miracle solution, it remains essential for existing and older sites. The methane captured can be transformed into energy, thereby reducing dependence on fossil fuels.
In short, reducing methane emissions remains a crucial issue in the waste treatment sector. To achieve this, it is imperative to provide communities with the necessary human and financial resources so that they can finally remove biowaste from the gray trash, thus avoiding their incineration or landfilling, two practices with major environmental impacts. However, the budgetary choices of successive governments give rise to serious concerns. The drastic reduction in the Green Fund, although essential for financing source sorting of bio-waste, seriously compromises the expected progress in this area and jeopardizes the achievement of the objectives provided for by law.
Sources
[1] United Nations Climate Change, “COP29: UN climate conference agrees to triple funding to developing countries to protect lives and livelihoods”, November 2024
[2] Global Chance, “Methane, an important blind spot in the French national low carbon strategy”, March 2019
[3] Ouest-France, “Approximately 40% of French people now have access to a bio-waste sorting solution”, October 2024
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