The overall project objective is to make available generic coal information on Chinese and Indian coals with regard to their combustion and emission performance, and to establish correlations between basic properties and this performance. Such information is clearly of value to UK industry in view of the export possibilities in these regions.
This profile contains information on the project's:
Publisher: Department for Environment, Food & Rural Affairs
The principal aim of the project was to produce a verifiable methodology for generating accurate and reliable estimates of methane emissions from abandoned mines in the UK, to be considered for inclusion in the UK greenhouse gas inventory.
The prime drivers for methane emission from abandoned mines are displacement by rising mine waters and the rate of emission of methane from the coal seams in the strata disturbed by mining. Rising mine water also serves to isolate methane reserves by cutting them off by flooding. The UK coalfields have been modelled to obtain estimates of water inflow and methane reserves within the coalfields. Measurements have also been made on methane emissions from mines, either from vents or from more general diffuse emissions from the surface. The general methodology has been to seek a relationship between the measured methane flows and parameters relating to the water and gas in the underlying abandoned workings
No suitable relationship was found between vent methane flow data and the water flow in the underlying abandoned workings. However, vent methane flow data did show an increase with the size of the underlying methane reserve in the abandoned workings. Flux data from the diffuse monitoring was converted into flows by multiplying by the area of underlying workings. These flows also showed an increase with underlying gas reserve. The data was scattered in both sets, but the gradients of regression lines through the flux data was within 11% of the vent flow data. Consequently the two data sets were combined and a regression provided a gradient equivalent to an emission of 0.74% of the underlying gas reserve per year.
This report is divided into the following sections:
Introdution
General Methodology
Sources of Data
Mine Water Recovery
Mine Water Recovery Modelling
Methane in Mines
Monitoring of Methane at Surface Vents
Monitoring of Diffuse Methane Emissions
Methane Reserve Modelling
Methodology for Estimating UK Emissions
Results
Conclusions
Recommendations
Acknowledgements
Appendix A - Report uses as source data for study
Appendix B - Map of coalified areas and zones
Appendix C - List of coal authority monitoring sites and pumping sites
Appendix D - Sites of recorded surface gravity discharges of mine water
Appendix E - Average permeabilities used for modelling coalfields
Appendix F - Direct measurement of methane flux on one day campaign
Appendix G - Background to the reserve modelling method
Appendix H - Reserve estimates by coalfield area and year
Publisher: Department for Environment, Food & Rural Affairs
This document is a report for the project titled 'Emissions from Abandoned Coal Mines in the UK'.
This work to project methane emissions from abandoned coal mines to 2050 has been carried out as an extension to DEFRA Project EPG 1/1/149 "Development of a Methodology for Estimating Methane Emissions from Abandoned Coal Mines in the UK" . The projected emissions are calculated by adding the emissions from mines abandoned before 2004 (as in the full report) and emissions from collieries to be closed after that date.
The modelled closure of collieries has been matched to the losses to production to maintain consistency with Entec's work on the operating mines methane inventory. On average, a reduction of about 1 million tonnes (Mt) production is equivalent to the closure of one colliery. It has been assumed that deep coal mined production will fall by 5Mt in the next 5 years (2005 to 2010), with a final 5Mt production being lost between 2021 and 2025.
The emission of methane from collieries after closure has been derived primarily using a hyperbolic function, which calculates emission over time as a proportion of emission during production. An alternative methane emission calculation method (FPPROG) has been examined and found to correspond in general form with the hyperbolic function. The emission during production has been calculated from colliery production specific emission values calculated for individual collieries, with an allowance for gas utilised during production. Where the emission calculated from the hyperbolic function falls below the emission based on 0.74% of reserve, the latter value is used to bring it into line with the emission calculations for the rest of the coalfields. In addition, emissions from collieries closed in the near future have had allowance made for mitigation of the gas being released beyond the first year following closure.
This report is divided into the following sections:
Introduction
Methane Reserve and Emissions from Mines Abandoned Before 2004
Methane Reserve Calculations for Mines Closed After 2004
Methods of Calculation of Projected Emission from Newly Closed Mines
Calculation of Methane Emissions from Mines Closed After 2004
Projections of Total Methane Emissions from Abandoned Mines
References
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