Consequence Analysis of Scarcity using Impacts from Resource Substitution

Published data from Australian and international sources are used to compile inputs and outputs for the combined system of fuel extraction and processing and electricity generation, for the cases of conventional natural gas, coal seam gas, and black coal fuels. A new method is being developed to assess the consequences of resource scarcity using mid-point impact indicators derived from established life cycle assessment methodology. When one particular resource such as natural gas is substituted by another resource such as coal, then the difference between the indicators corresponds to the environmental impact associated with this substitution. In this study, these differences are compared for the substitution of conventional gas with either black coal or coal seam gas to generate electricity. The results indicate lower cradle to gate impacts in global warming, acidification, particulates and solid waste generation as well as water consumption when substituting natural gas with coal seam gas. Conversely, substitution of conventional gas with black coal will result in overall higher impacts in these categories. However, coal seam gas involves greater withdrawal of underground water than in the case of the other fuels; this water requires treatment, involving production of a potentially damaging saline effluent. Potential risks may also exist arising from the large number of on-shore coal seam gas wells required per megajoule of fuel.