Landfill Methane Capture
Project Drawdown defines landfill methane capture as the process of capturing methane generated from anaerobic digestion of municipal solid waste in landfills and incinerating the captured biogas to generate electricity. This solution replaces conventional electricity-generating technologies such as coal, oil, and natural gas power plants.
Landfill methane capture is most effective in closed and engineered landfills, achieving 85 percent efficiency or more; it is least effective in open dumps, where the collection efficiency is approximately 10 percent and capture is typically not seen as an economically favorable decision. As a waste treatment solution, from a climate perspective, landfill methane capture is generally seen as preferable only to landfilling without methane capture. However, where landfills exist it is an important solution for mitigating greenhouse gases.
This analysis models the impacts of the adoption of landfill methane capture for electricity generation and gas flaring. Landfill methane capture is a mature technology which has been used widely for decades.
Total Addressable Market
Two total addressable markets were developed for this sector solutions, supported on lower and higher climate emissions mitigation targets linked to different levels of electricity demand and renewable energy sources integration. The total addressable market for landfill methane capture is based on projected global electricity generation from 2020 to 2050. Current adoption is considered to be 33.1 terawatt-hours, or 0.13 percent of total electricity generated worldwide. Total adoption estimates vary widely between different future adoption prognostications, due to the fact that different sources place a different value on biomass and waste for energy adoption.
Impacts of increased adoption of landfill methane capture from 2020 to 2050 were generated based on two growth scenarios derived from the evaluation of several global energy system modeling scenarios. These scenarios were assessed in comparison with a Reference Scenario, in which the solution’s market share was fixed at the current levels.
The sources used do not clearly depict landfill methane capture and biogas technologies for electricity generation adoption pathways; instead, their results combine biomass and waste for electricity generation. Therefore, a few assumptions were made to determine future adoption: Biogas represents around 20 percent of total electricity generation from bioenergy worldwide, and biogas from landfills covered within this solution represents 30 percent of total biogas. The remaining 70 percent is covered by methane capture from agriculture, manure, and wastewater.
For landfill methane capture, the two scenarios developed are:
- Scenario 1: Due to landfill methane capture’s low priority in waste management ranking, Scenario 1 is built upon four conservative scenarios from the EU project AMPERE (2014) GEM-E3 Refpol scenario, the 4°C and 6°C Scenarios of the International Energy Agency’s 2016 Energy Technology Perspectives (IEA ETP, 2016), and Greenpeace (2015) Reference Scenario. After integration on the waste cluster integration model to adjust the adoption based on feedstock availability, Scenario 1 foresees landfill methane capture representing only 0.05 percent of the market share in 2050.
- Scenario 2: This scenario follows ambitious adoption projections from the AMPERE (2014) IMAGE Refpol, 550 and 450 scenarios, GEM-E3 model in the 450 and 550 scenarios, and the 2°C Scenario of the International Energy Agency’s 2016 Energy Technology Perspectives (IEA ETP, 2016). After integration on the waste cluster integration model to adjust the adoption based on feedstock availability, Scenario 2 foresees no use of landfill methane capture by 2050.
Landfill methane capture emission rates are estimated using the first-order decay method recommended by the Intergovernmental Panel on Climate Change (IPCC), in order to estimate both total emissions reductions for landfill gas-to-electricity generation and an increase in landfill gas flaring.
The financial inputs used in the RRS model assume installation costs of US$1,921 per kilowatt. Inputs were determined from the variable meta-analysis done, and account for the extra costs of flaring systems. Due to the maturity of landfill methane capture technology, a learning rate of 2 percent was applied. An average capacity factor of 80 percent was used for the solution, compared to 55 percent for conventional technologies. An average fixed operation and maintenance cost of US$237.2 per kilowatt was used in the calculations, compared with US$34.7 per kilowatt for the conventional technologies.
Through the process of integrating landfill methane capture with other solutions, the total addressable market for electricity generation technologies was adjusted to account for reduced demand resulting from the growth of more energy-efficient technologies, as well as increased electrification from other solutions like electric cars and high-speed rail. Grid emissions factors were calculated based on the annual mix of different electricity-generating technologies over time. Emissions factors for each technology were determined through a meta-analysis of multiple sources, accounting for direct and indirect emissions.
The results for the Scenario 1 show that through the advanced adoption of landfill methane capture, installed in over 70 percent of the world’s landfills, the marginal first costs compared to the Reference Scenario would be –US$4.31 billion from 2020 to 2050 and approximately –US$6.89 billion in lifetime savings. The Scenario 1 adoption of landfill methane capture would require an estimated US$34.7 billion in cumulative first costs. Under this scenario, landfill methane capture’s adoption trajectory could reduce 2.2 gigatons of carbon dioxide-equivalent greenhouse gas emissions from 2020 to 2050.
Due to integration and waste feedstock availability, Scenario 2 depicts negative impacts on greenhouse gas emission reductions over 2020 to 2050 of –1.6 gigatons of carbon dioxide-equivalent when compared with a Reference scenario, since the adoption and consequent share of the solution on the total addressable market decrease significantly through the period of analysis.
The landfill methane capture solution is a net benefit for the climate, but depending on the region and technologies being used, it might entail increased costs due to the up-front costs required for landfill gas-to-electricity technologies.
While it is clearly a second-best waste management strategy, as long as landfills are being created it is still a viable and important solution for climate mitigation. Aside from the significant climate benefits and long-term cost savings shown by this study, landfills that capture methane are safer and less of a public health hazard than those that do not. Therefore, as landfills move globally from open dumps or basic landfills to engineered sanitary landfills, the percentage of landfills that use landfill methane capture can and should be expected to increase.