The Use of Coal Mine Methane as a Natural Gas Motor Fuel for Commercial Motor Transport in Donbass Cities

Introduction . Coal mine methane, a greenhouse gas released during underground coal mining, is considered to be a cause of global climate change. However it is also a valuable energy resource. Currently, the global utilization rate of coal mine methane is low, and the amount of methane released into the atmosphere is increasing every year. To limit greenhouse gas emissions, several legislative initiatives have been implemented, including the Kyoto Protocol, the Paris Agreement, and Federal Law No. 296-FZ “On Limiting Greenhouse Gas Emissions”. In the conditions of Donbass, the task of mine methane utilization is relevant due to the dense location of emission sources and the need to improve the safety of mining operations, as well as to ensure the implementation of the principle of integrated field development. In addition, the ongoing hostilities have led to an increase in fuel prices in the region and an increase in road transport due to the limited availability of rail, sea, and air transportation. The aim of the research is to conduct a calculated assessment of the energy efficiency of using mine methane from Donbass coal deposits as motor fuel for commercial vehicles with internal combustion engines. Materials and Methods . As an example, the studies were conducted on BAZ-2215 vehicles on the GAZelle Business chassis, GAZelle Next Citiline, and PAZ 3203, which were commonly used on urban routes in Makeyevka (DPR). These vehicles were equipped with UMZ, ZMZ, and Cummins spark and diesel engines. The full composition of methane-air mixture samples from several mines (Chaykino Mine, Makeyevka, Komsomolets Donbassa Mine, Kirovskoye), taken from degassing systems, was determined in the laboratories of Makeevka Research Institute for Mining Safety and Donetskavtogaz using a Kristallyuks 4000M gas chromatograph. The energy efficiency of engines operating on various types of fuel, including mine methane, as well as the performance characteristics of selected buses (fuel consumption, distance-to-empty, and carbon dioxide emissions) under urban driving cycles according to GOST R 54810–2011, were determined through a series of calculations using well-established methods. Results . An estimation of the energy efficiency of mine methane as a gas engine fuel has been performed. In the range of concentrations of the studied samples of gas-air mixtures, the calculated maximum loss of effective power for ZMZ and UMZ spark engines was up to 15%. For gas-diesel engines, such as Cummins, power could be increased by up to 29%. These findings did not prevent selected buses from operating under driving cycles in accordance with GOST R 54810–2011. Under these conditions, fuel consumption and range per refueling depended significantly on the component composition of mine methane. For the samples studied, it was 1.8–3.5 times worse than for natural gas used for refueling. Emissions of carbon dioxide were reduced by 62–73% compared to gasoline. Discussion . Due to the specific features of degassing processes and the mining and geological conditions of different mines, the alternative fuel discussed in this article has a variable component composition. In this regard, the transfer of PAZ and GAZ bus rolling stock to a byproduct of coal mining — mine methane — is associated with several challenges. These include the need for more powerful fuel systems (three times or more than the power supply systems of internal combustion engines of comparable power, operating on compressed gas) and deterioration in fuel-economic and traction-speed properties of vehicles, as well as reduced range. A quantitative assessment of these changes has been obtained through research. The positive impact of the proposed measures stems from the reduction in negative environmental impact by using mine methane as a fuel for vehicles, which reduces the carbon footprint of road transport and decreases the consumption of liquid hydrocarbon fuel. Conclusion . As a result of the study, it has been found that the methane from the Donbass coal mines can be used as motor fuel for commercial vehicles such as city buses. The study has determined the corresponding energy efficiency parameters (the effective power generated by internal combustion engines, the specific fuel consumption, the range of vehicles under driving cycles, etc.), as well as the degree of their reduction compared to traditional fuels. It has been established that this does not affect the performance of transportation work (in compliance with GOST R 54810–2011) and is beneficial from the perspective of saving non-renewable resources and improving environmental safety in the region.