surface methane emissions measurement

Flux-scan - case studies

  • Landfill Samsun (Turkey)
  • The feasibility study for the landfill in Samsun was completed in order to assess the landfill gas (LFG) emissions in January 2016. The Samsun landfill is divided into three parts (Lots). Lot 1 occupies the area of 5.8 ha, Lot 2 occupies the area of 3.6 ha and Lot 3 has not been developed in the time of the study, yet. The layer of the waste (mainly municipal solid waste) was up to 20 m thick in Lot 1 and about 5-7 m in Lot 2. The daily waste supply to the landfill was around 750 tons.

    Surface emissions of methane were measured using flux-scan sampling device and ECOPROBE 5 portable gas analyser. The outcomes of surface emissions measurement were combined with measurement of LFG quality in the LFG extraction system, composed of a number of sets of horizontal LFG extraction pipes. Surface emissions measurement were used for determination of efficacy of LFG extraction from the landfill and identification of areas with methane leaks and/or inefficient gas extraction.

    The average methane emissions in Lot 1 calculated from all measured spots was 1.93 litres/m2/hour. In Lot 2, two methane emission measurement campaigns were completed in two days with an average emission value of 2.43 litres/m2/hour. The samples were taken on the whole area of both the working parts of the landfill (Figure 1 and 2). The reason for higher emissions from the Lot 2 was likely blocked piping in the southern part with high incidence of high emissions visible on the Figure 2, and just one layer of LFG extraction piping in its southern part. Lot 2 also had been receiving fresh waste several years prior to the study and the methanogenic activity was likely to be at its peak. Lot 1 had several layers of horizontal gas extraction system piping and it contained older waste.

    The LFG extraction rate at the Samsun landfill was reported to be 2250 m3/hour at about 56% of methane. The LFG extraction efficiency was estimated at relatively high value around 82 %. Additionally, areas with weak methane extraction around hubs joining the horizontal LFG extraction piping to the main LFG pipe were identified and improvements for the LFG extraction system were proposed.

    Figure 1: Surface methane emissions measurement in Lot 1 of the Samsun landfill.

    Figure 2: Surface methane emissions measurement in Lot 2 of the Samsun landfill.

    • Landfill Poltava (Ukraine)
    • This feasibility study was focused on identification of technically feasible and economically beneficial options of utilisation of Poltava landfill biogas as a source of energy. The study is especially aimed at contribution to improvement of economic performance of Poltavske KATP-1628 throughout utilisation of the energy resource available to them at the landfill. The landfill is located in an old quarry. Its total territory is about 17 ha. The landfill consists of three parts, the new waste deposit – ca. 6 ha, the leachate pond and other (old waste) territory (Fig. 1). The deposited waste is mostly solid municipal waste and the yearly deposition is around 100 thousand tons.

      Fig. 1: Image showing the new part of the landfill where waste is currently deposited (turquoise area) and three fields where landfill gas emissions were measured on the landfill surface (green areas).

      The landfill gas (LFG) production was estimated using EPA sourced LFG production model based on measured data. Using flux-scan, direct measurement of emissions of LFG components was performed in three fields of the landfill surface on four consecutive days (Fig. 2). As the ambient pressure gradient was relatively stable on the 24th August, the realistic estimate of LFG flow is calculated as the average of the measured and calculated LFG flow values. Data from field 2 and 3 were used only. The total flow of LFG at 55% CH4 from the area of the new waste (6 ha) was estimated at 2.8 million m3 per year. It was calculated that this LFG could replace up to 1.5 million m3 of natural gas (pure methane) or it could produce around 5600 MWh of electric energy per year for the duration of at least 12 years.

      Fig. 2: Methane emission measurements measured using flux-scan in two of the three fields in each image detected on four consecutive days. In each field, 100 measurements were made.

      • Landfill at the city of Kulob (Tajikistan)
      • The landfill located nearby Kulob contains around 120 thousand m3 of waste. The landfill gas emissions were measured in order to assess its possible utilisation. Measurement of methane and CO2 emissions was performed on and under the landfill surface of ca. 3.26 ha, which is covered by a continuous layer of waste. Six sets of surface measurements and three sets of under the surface gas measurements were done within a five day period in September 2015. These data were used to generate the whole year emission estimate, which was found to be 159,923 m3/year. It was evaluated that the landfill gas cannot be utilised for e.g. energy production because of a low methane content as well as difficulties to install the gas extraction system due to thin and irregular layer of waste. Suggestions, such as re-cultivation, were provided in order to improve amount and quality of the produced landfill gas that could be subsequently extracted. However, even upon completion of this measure, the gas production was calculated to be too low to be overall profitable to utilise it for energy generation. Therefore, two alternatives were proposed. First, install a passive landfill gas collection system and simply flare the landfill gas. Hence prevent the gas to escape to the atmosphere and contribute to the greenhouse effect. Second, as there is a space for a new landfill that can be located adjacent to the current landfill, the landfill gas from the current landfill could be collected and utilised in conjunction with the landfill gas from the future waste deposits in the new landfill. The new landfill has a potential to produce sufficient amounts of landfill gas, estimated as 100 m3/t. The most suitable way of utilisation the landfill gas collected from both current and new landfills was suggested to be energy production.

        Visualisation of scope of landfill gas emission measurements on (upper) and 0.6 m under (lower) the landfill surface in the measured area.

        • Radim landfill (Czech Republic)
        • Measurement of methane emissions in two operating states of Radim landfill (about 2 mil. t of waste, most of the surface compacted waste with a thin daily soil cover) was done. In the first case, only one landnfill gas pump ran giving the CHP engine 0,5 MWh electric performance.

          The emissions in this situation were considerably higher, than in the second case, where both landfill gas pumps and CHP engines were on.

          This experiment also allowed to established methane oxidation factor of the landfill cover.

          • Kosova Hora landfill (Czech Republic)
          • Landfill methane emissions were measured on the Kosova Hora landfill with the objective to determine parts of the landfill with low emissions and overall methane production before the landfill closure. The Northern part of the landfill, which is actually the older part, was found being almost without methan emissions. As a result of landfill gas emissions measurements, alterations of gas collection system design were developed with significant cost reduction. Figure 4 shows the optimised design contrasted with the original one. The scope of civil works for trenches installation was approximately halved. The calculation also enabled to design bio-filter with optimum capacity. The capacity of biofilter was set on 12 m3 of methane per hour, that is at the level of maximum emissions.

            Figure 4. Comparison of original (upper) and optimised gas collection system design