Quantifying mining requirement and waste for energy sustainability

Abstract

This study demonstrates the life-cycle assessment of different energy sources-coal, natural gas, solar, wind, nuclear, and hydro-particularly focused on mining activities and waste per given electricity capacity and generation. It also includes carbon dioxide emissions generated during the transportation of raw materials to build and operate electricity generating systems and their environmental impacts in the US from 2023 to 2050. We identify the raw material and metal requirements for the U.S.-based typical systems in each energy type and synthesize datasets on typical ore fraction and material recycling factors, while taking into account the capacity factor of the power plants. We then compute the total mass and volume of material requirements and waste mass and volume for the front-end (i.e., mining, material needed for construction), operation (i.e., fuel, maintenance), and back-end (i.e., decommissioning) activities. The key findings are that (1) the energy transition from fossil fuel to low-carbon energy sources would reduce mining waste as well as the shipping carbon footprint; (2) the difference in capacity and actual electricity generation is significant for the life-cycle assessment due to low capacity factors of solar and wind energy; (3) several key metals with low abundance or high requirements dominate mining waste, which highlights the need for recycling and establishing a circular economy; (4) mining of critical minerals becomes important during the clean energy transition and (5) nuclear energy generates least waste and contributes least to shipping emissions among the low-carbon sources due to the high energy density and capacity factor and the small mass of materials it requires. Although the waste mass may not necessarily be equal to the environmental impact due to different waste isolation technologies, we aim to highlight the importance of considering mining and decommissioning waste, which are often ignored but important for accounting for the environmental impacts and addressing energy justice issues.