Michelle’s core expertise is in air pollution, greenhouse gases and climate science. She has worked on the greenhouse gas methane and its sources particularly in the UK and in the Arctic. She has taken part in field campaigns to measure methane in the atmosphere, using computer models to link these measurements back to sources such as remote wetlands. Her current work in on the warming impact of short lived climate pollutants like methane, and how emissions metrics can be improved in the context of mitigating emissions to achieve the Paris Agreement.
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.