Mitigation and adaptation strategies for global change via the implementation of underground coal gasification

Abstract

Coal is the most abundant hydrocarbon energy source in the world. It also produces a very high volume of greenhouse gases using the current production technology. It is more difficult to handle and transport than crude oil and natural gas. We face a challenge: how can we access this abundant resource and at the same time mitigate global environmental challenges, in particular, the production of carbon dioxide (CO₂)? The editors of this special edition journal consider the opportunity to increase the utilization of this globally abundant resource and recover it in an environmentally sustainable manner. Underground coal gasification (UCG) is the recovery of energy from coal by gasifying the coal underground. This  process produces a high calorific synthesis gas, which can be applied for electricity generation and/or the production of fuels and chemicals. The carbon dioxide emissions are relatively pure and the surface facilities are limited in their environmental footprint. Unused carbon is readily separated and can be geo-sequester in the resulting cavity. The cavity is also being considered as a potential option to mitigate against change impacts of other sources of carbon dioxide (CO₂) emissions. These outcomes mean there is an opportunity to provide developing and developed countries a source of low-cost clean energy. Further, the burning of coal in situ means that the traditional dangers of underground mining and extraction are reduced, a higher percentage of the coal is actually recovered and the resulting cavern creates the potential for a long-term storage solution of the gasification wastes. The process is not without challenges. Ground subsidence and groundwater pollution are two potential environmental impacts that need to be averted for this process to be acceptable. It is essential to advance the understanding of this practice and this special edition journal seeks to share the progress that scientists are making in this dynamic field. The technical challenges are being addressed by researchers around the world who work to resolve and understand how burning coal underground impacts the geology, the surface land, and ground water both in the short and the long term. This special issue reviews the process of UCG and considers the opportunities, challenges, risks, competitive analysis and synergies, commercial initiatives and a roadmap to solutions via the modelling and simulation of UCG. Building and then disseminating the fundamental knowledge of UCG will enhance policy development, best practices and processes that reflect the global desires for energy production with reduced environmental impact.