Case history of environmental impacts of an Indonesian coal supply chain

Coal will continue to be the most demanded energy source worldwide, which highlights the importance of better understanding current practices and environmental impacts of this industry. Indonesia is the largest coal exporter in the world, but studies evaluating the environmental impacts of the coal industry in this country are missing in the literature. A case study of the Indonesian coal supply is evaluated by using attributional life cycle assessment (LCA) techniques to develop inventory data and to evaluate greenhouse gas (GHG) emissions, depletion of fossil fuels (DFF), and water consumption associated with the production of coal from mining to the consumer's gate. Five scenarios are evaluated to identify opportunities for improvement. Material and energy inputs are inventoried through site visits and surveys, with complementary data added from the literature. Three pits producing sub-bituminous coal are evaluated where the processes of mining, coal transport to local and international markets, administrative operations, and water treatment are analyzed. Results are normalized by the functional unit defined as the energy content in the produced coal (expressed in GJ). Total GHG emissions are 4021 g CO2e/GJ, DFF is 39 MJ/GJ and water consumption is 41.5 L/GJ or 2 L/GJ if recycled water is considered. Mining operations are the largest source of GHG emissions and DFF, with overburden removal and transport responsible for more than one third of these impacts. Fugitive methane release and sea transport to international customers also have a significant impact on GHG emissions and DFF respectively. The energy return on investment (EROI) is 25.9 at the delivery point and 42 at the mine mouth indicating that this is a net energy producing operation. Alternative scenarios show that GHG emissions and DFF could be significantly reduced by increasing biodiesel content in the fuel mix of ground operations and by transporting overburden with a conveyor.