Life cycle environmental and economic assessment of coal seam gas-based electricity generation

Abstract

PURPOSE: A large portion of coal seam gas is directly wasted and emitted to the environment, especially China, which is the world’s largest global warming gas emitter and energy consumer. Such emissions place heavy pressure on the Chinese government to achieve its global carbon reduction goals. This study quantified the economic and environmental impacts of coal seam gas-based power generation in China through a cost-combined life cycle assessment to systematically quantify the emission, impact, and mitigation measures caused by coal seam gas release in China. METHODS: Cost-coupled life cycle assessment analysis was conducted with SimaPro 8.4 in accordance with ISO 14040 series standards. Specifically, life cycle assessment was conducted with the IMPACTWorld+ method, and internal (e.g., raw materials, energy, labor, maintenance, infrastructure, and taxes) and external costs (e.g., land eco-remediation cost, human health economic burden, and environmental emission cost) were used to quantify the life cycle cost. RESULTS AND DISCUSSION: Approximately 11.8 kg of CH₄ and 19.8 kg of CO₂ were emitted per ton of coal mining in China in 2015. The direct global warming emission of coal seam gas at the national level accounted for 12% of the national carbon emission in 2015 in China. Coal seam gas-based electricity generation significantly reduced environmental impacts in the key categories of fossil depletion, non-carcinogens, global warming, and respiratory inorganics because of the substitution of coal power. Approximately $ 0.04/kWh of cost benefit was achieved due to the profit from concomitant coal during coal seam gas production. CONCLUSIONS: A win-win situation from economic and environmental perspectives was observed in electricity and freshwater consumption, pollutant emission cost, and human health economic burden. Effective measures to reduce the overall economic and environmental burdens from national coal seam gas-based power generation include alleviation of atmospheric carbon dioxide and dinitrogen oxide emissions, improvement of coal seam gas-based electricity generation and utilization efficiency, intensification of national coal seam gas utilization, and reduction of electricity and freshwater consumption.