How do natural gas power plants really compare with coal-fired power plants? Does it make sense for the environment to switch from coal to natural gas as a bridge to a longer-term transition toward renewable technologies?

New research seeks to answer these questions by comparing the temperature increases caused by different kinds of coal and natural gas power plants. It was conducted by Ken Caldeira and Xiaochun Zhang at the Carnegie Institution for Science, together with Nathan Myhrvold of Intellectual Ventures, and their findings have been published in Environmental Research Letters.

The researchers established that power plant efficiency and, in the case of natural gas plants, methane leakage during the supply process are the key factors behind most of the difference in greenhouse gas emissions between individual gas and coal plants. Based on that knowledge, they came up with a simple model for the climate effects caused by the carbon dioxide and methane released by a particular plant.

This allowed the team to predict how much global warming would be produced by different kinds of power plants during and after their period of operation.

Results confirmed that because natural gas plants are more efficient than coal plants overall, they can cause less warming in the long term. However, a crucial element to consider is the amount of methane leakage that occurs.

The researchers concluded that replacing old coal-fired power plants with new natural gas plants could result in greater climate damage in the coming decades, unless their methane leakage rates are very low and the new power plants are very efficient.