Methane emission to the atmosphere from landfills in the Canary Islands
- 1Instituto Tecnológico y de Energías Renovables, Granadilla de Abona, Canary Islands, Spain (eleazar@iter.es)
- 2Instituto Volcanológico de Canarias (INVOLCAN), Granadilla de Abona, Canary Islands, Spain
- 3Agencia Insular de la Energía de Tenerife, Granadilla de Abona, Canary Islands, Spain
- 4Dipartimento di Scienze della Terra, Università degli Studi di Firenze (UniFI), Firenze, Italy
- 5Istituto di Geoscienze e Georisorse – CNR, Pisa, Italy
- 6Department of Geological Sciences, Ohio University, Athens, USA
Methane (CH4) is an important greenhouse gas, and is increasing in the atmosphere by 0.6% (10 ppb) each year. Important sources of this gas are landfills; in fact more than 10% of the total anthropogenic emissions of CH4 are originated in them by anaerobic degradation of organic matter. Even after years of being closed, a significant amount of landfill gas can be released to the atmosphere through its surface as diffuse or fugitive degassing.
Many landfills currently report their CH4 emissions to the atmosphere using model-based methods, which are based on the rate of production of CH4, the oxidation rate of CH4 and the amount of CH4 recovered (Bingemer and Crutzen, 1987). This approach often involves large uncertainties due to inaccuracies of input data and many assumptions in the estimation. In fact, the estimated CH4 emissions from landfills in the Canary Islands published by the Spanish National Emission and Pollutant Sources Registration (PRTR-Spain) seem to be overestimated due to the use of protocols and analytical methodologies based on mathematical models. For this reason, direct measurements to estimate CH4 emissions in landfills are essential to reduce this uncertainty.
In order to estimate the CH4 emissions to the atmosphere from landfills in the Canary Islands, 34 surveys have been performed since 1999 to the present. Each survey implies hundreds of CO2 and CH4 efflux measurements covering the landfill surface area. Surface landfill CO2 efflux measurements were carried out at each sampling site by means of a portable non-dispersive infrared spectrophotometer (NDIR) model LICOR Li800 following the accumulation chamber method. Samples of landfill gases were taken in the gas accumulated in the chamber and CO2 and CH4 were analyzed using a double channel VARIAN 4900 micro-GC. The CH4 efflux measurement was computed combining CO2 efflux and CH4/CO2 ratio. To quantify the diffuse or fugitive CO2 and CH4 emission, gas efflux contour maps were constructed using sequential Gaussian simulation (sGs) as interpolation method. Considering that (a) there are 6 controlled landfills in the Canary Islands, (b) the average area of the 34 studied cells is 0.15 km2 and (c) the mean value of the CH4 emission estimated for the studied cells range between 6.2 and 7.2 kt km-2 y-1, the estimated CH4 emission to the atmosphere from landfills in the Canary Islands showed a range of 5.7-6.7 kt y-1 (mean value of 6.2 kt y-1). On the contrary, and for the same period of time, the PRTR-Spain estimates the CH4 emission in the order of 6.4-16.4 kt y-1 (mean value of 9.2 kt y-1), nearly 46% more than our estimated value. This result demonstrates the need to perform direct measurements to estimate the surface fugitive emission of CH4 from landfills.
Bingemer, H. G., and P. J. Crutzen (1987), J. Geophys. Res. 92, 2182-2187.
How to cite: Padrón, E., Asensio-Ramos, M., Pérez, N. M., Di Nardo, D., Albertos-Blanchard, V. T., Alonso, M., Tassi, F., Raco, B., and López, D.: Methane emission to the atmosphere from landfills in the Canary Islands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5651, https://doi.org/10.5194/egusphere-egu2020-5651, 2020.
