Assessment of process energy intensity and greenhouse gas emissions from different energy supply scenarios: a case study of future full-scale electrified potash mining and production in Thailand

Demand for materials to support economic and social development has made the mining and materials production industry one of the most energy-intensive sectors and a major contributor to greenhouse gas (GHG) emissions. This study quantified the energy intensity for all potash production processes throughout the mine lifetime and the GHG emissions and intensities of potash production under different energy supply scenarios (purchased grid electricity alone or a combination of grid electricity and self-generated electricity using local biomass as fuel feedstock). A total of 40.4%, 42.5%, and 17.1% of the overall energy demand is distributed to the energy required for ore extraction, potash recovery, and daily project operations, respectively. The overall energy intensities (MJ/ton of potash concentrate produced) are lower during the production phase (1,028 ± 13) than during the mine development (5,003 ± 2,766) and closure (1,759 ± 430) phases because 1.5-2.3 more ore is extracted in the former phase. The assessment of total GHG emissions confirmed lower annual emissions from the project operation solely based on grid electricity (153.18 kt CO2 eq) than those of the operations based on biomass electricity production using only palm kernel shells (283.67-287.42 kt CO2 eq) and a mixture of palm kernel shells and fuel woods (247.23-251.22 kt CO2 eq). Uncertainty analyses indicate 1.6- to 1.7-fold lower or 1.4-fold greater total annual GHG emissions than emissions estimated via a deterministic calculation approach. Over the 20-year project lifetime, up to 5,748.4 kt CO2 eq will be emitted if electricity is generated solely from the combustion of palm kernel shells. The differences in the environmental performance of potash production observed through comparisons of GHG emission intensities between this study and other potash production companies are caused mainly by the mining method, source of energy for project operation, and utilization of renewable energy.