Recent commentary on the New England Clean Energy Connect (NECEC) project has claimed that “hydropower is not clean energy.” This view of hydropower is not supported by the weight of climate science.

Research by the Intergovernmental Panel on Climate Change (IPCC) states that hydropower worldwide has a median greenhouse gas (GHG) emission intensity of 24 gCO²-eq/kWh — this is the grams of carbon dioxide equivalent per kilowatt-hour of electricity generated allocated to hydropower over its life-cycle. To understand that in context, the median for gas is 490 gCO²-eq/kWh.

The low carbon footprint of hydropower was confirmed by a study of almost 500 reservoirs globally by the International Hydropower Association. This study relied on the G-res Tool, which was developed with the University of Quebec at Montreal to accurately estimate the net emissions of a reservoir. This tool takes into account local emissions not just after construction, but also before construction.

To say that hydropower is not clean is to mischaracterize the low carbon, pollution-free benefits that it provides to communities and the environment. Moreover the criticism misses the point that hydropower is an excellent complement to variable renewables like wind and solar, thanks to its grid flexibility services and energy storage. Hydropower can meet demand when these intermittent sources are unavailable.

We need renewables working together if we are to achieve the carbon reduction targets of the Paris Agreement on climate change. As the head of the International Energy Agency said recently, we don’t have the luxury of choosing between these clean technologies.

Eddie Rich

chief executive

International Hydropower Association (IHA)

London