Climate implications of switching from coal to gas

Switching from coal-fired to gas-fired electricity generation is a way to reduce carbon dioxide emissions, as life cycle emissions of CO2 are less from gas power stations than coal. However, if methane emissions are also considered, the picture becomes less clear-cut, as the literature shows a large variability in upstream fugitive methane emissions. In some cases, there may be more upstream methane emissions from gas-fired electricity generation, however this does not overwhelm the benefits from the lower carbon dioxide emissions. Here, we present an investigation into the climate benefits of switching from coal to gas for electricity production, using a literature survey of upstream and downstream greenhouse gas emissions. We highlight where key uncertainties are in the assumptions required to assess relative emissions from coal or gas. We compare temperature changes from a simple climate model with different emissions metrics for calculating CO2-equivalence: Global Warming Potentials over 100 or 20 years, Global Temperature-change Potentials, and GWP*. We show that GWP* relates CO2e emissions to warming better than other commonly used metrics.