Background
Methane is one of the most important greenhouse gases with a Global Warming Potential (GWP) of 34 on a timespan of 100 years, according to IPCC’s 5th Assessment Report. The concentration of methane in the atmosphere has more than doubled in the last 150 years and landfills are the third largest (16%) emitter of anthropogenic methane after fossil fuel production, distribution, combustion (33%) and livestock farming (27%). In the Baltic Sea region, there are up to 100 thousand of landfills including closed or abandoned sites, which pose environmental risks due to greenhouse gas emissions into the atmosphere. According to the Report of National Inventory Submissions to the UNFCCC, 2020, these landfills emit 782 kt in Sweden, 662 kt in Lithuania, 302 kt in Poland, 270 kt in Germany and 21 kt in Denmark of CH₄ emissions. However, only a small number of these are equipped with gas extraction equipment (51 landfills in SE, 267 in PL, 10 in LT). In Denmark there are 10 sites utilizing dual-fuel technology with Diesel as pilot fuel (all operated by Deponigas ApS).
Sixteen EU member states have already applied a landfill ban on organic material, and, as the gas production in landfills declines when no new organic material is landfilled, the methane level decreases and conventional CHP production using an Otto engine is
no longer possible. The current procedure is to cover the landfill and install so-called bio-windows, where microbes oxidize the methane to carbon dioxide. However, the methane content is only reduced, not eliminated, through the use of such bio-windows, and there is no guarantee that all the methane produced inside the landfill will pass a bio-window before entering the atmosphere. In addition, the energy contained within methane is not utilized.

Activities
In this project three different options to use landfill gas and off-gases with low methane (<40%) content will be evaluated and benchmarked. The three options are:

• combustion of low calorific gas in a dual fuel engine using a renewable pilot fuel
• spark ignited engine and oxygen enriched combustion air
• Spinnig Fluids Reactor (SFR) to remove carbon dioxide in order to increase the heating value of the low calorific gas

Aims
The project will result in a decision support tool and recommendations for landfill gas operators and other parties dealing with off-gases containing methane, to minimize methane emissions and produce green power and heat.

Objectives
The objective of this project is twofold; the production of green electricity and heat, which in itself contributes to GHG reduction if the corresponding use of fossil fuels is offset, and reduction of GHG gases by reduction of spontaneous methane emission from landfills and elimination of methane emissions from different types of off-gases. In addition, transforming indigenous low-quality gas streams into power and heat contributes to the security of supply and diversification of energy systems.