Techno-economic and environmental assessment of methane oxidation layer measures through small-scale clean development mechanism - The case of the Seychelles

Environmental assessment of landfill gas mitigation using biocover and gas collection with energy utilisation at aging landfills

A life cycle-based environmental assessment was conducted on the mitigation of landfill gas emissions, by implementing biocover and gas collection along with energy utilisation at aging landfills. Based on recent studies about gas generation at Danish landfills, the efficiency of the mitigation technologies involved and the composition of substituted energy production, 15 scenarios were modelled using the EASETECH life cycle assessment model, through which potential environmental impacts in the category "Climate change" were calculated. In all scenarios, biocover and gas collection systems with energy utilisation led to significant environmental improvements compared to the baseline scenario with no emission mitigation action. Scenarios representing biocovers with methane oxidation efficiencies between 70 and 90 % were environmentally superior in terms of climate change impact - in comparison to scenarios with 20-30 years of gas collection and energy utilisation (collection efficiencies between 40 and 80 %). Combining gas collection with energy utilisation and the subsequent installation of a biocover saw major improvements in comparison to where only gas collection and energy utilisation were in effect. Overall, it can be concluded that a biocover under the given assumptions is environmentally more appropriate than gas collection and utilisation at aging landfills, mainly due to methane emissions escaping through the landfill cover during and after the gas collection period playing a crucial role in the latter situation. Maintaining high methane oxidation efficiency for a biocover throughout the lifetime of a landfill is vital for reducing environmental impacts.

Climate change mitigation potential of transitioning from open dumpsters in Peru: Evaluation of mitigation strategies in critical dumpsites

Waste management is a critical policy towards the reduction of environmental impacts to air, soil and water. Many Latin American countries, however, lack a correct waste management system in many cities and rural areas, leading to the accumulation of unmanaged waste in illegal or unregulated dumpsites. The case of Peru is of interest, as it hosts 5 of the 50 largest dumpsites in the world. An erratic waste management compromises climate actions for Peru to commit with the Paris Agreement, as no correct closure systems are established for these dumpsites. Therefore, the main objective of this study is to assess the contribution of the past and present biodegradable waste produced and disposed of in the most critical open dumpsters to the overall annual greenhouse gas (GHG) emissions of Peru using the IPCC model. Thereafter, the climate change mitigation potential of possible dumpsite closure strategies based on a selection of technologies, including economic feasibility, were estimated. Results show that cumulative GHG emissions in 2018 for the 24 critical dumpsites evaluated added up to 704 kt CO₂ eq. and a cumulative value of 4.4 Mt CO₂ eq. in the period 2019-2028, representing over 40 % of solid waste emissions expected by 2030. Mitigation potentials for these emissions tanged from 91 to 970 kt CO₂ eq. in the ten-year period depending on the mitigation strategies adopted. The costs of these strategies are also discussed and are expected to be of utility to complement Peru's waste management commitments in the frame of the Paris Agreement.