Why are there significant emissions from hydroelectric power

This is because large amounts of carbon tied up in trees and other plants are released when the reservoir is initially flooded and the plants rot. Seasonal changes in water depth mean there is a continuous supply of decaying material. In the dry season plants colonise the banks of the reservoir only to be engulfed when the water level rises. In effect man-made reservoirs convert carbon dioxide in the atmosphere into methane. Claiming that hydro projects are net producers of greenhouse gases is not new New Scientist print edition, 3 June but the issue now appears to be climbing up the political agenda.

Methane production will go unchecked because climate scientists cannot agree on how significant this is; it will also vary between dams. The research, which examines recent studies on greenhouse gas emissions from large reservoirs around the world, also calls into question the wisdom of building more hydroelectric dams as countries try to nix their dependence on coal, natural gas and oil. An estimated 3, new dams are proposed or under construction around the globe, the study reports.

It suggests the hydropower industry will need to control its emissions. But industry officials in the US say the study misrepresents the benefit of hydropower in the fight to rein in global warming.

Hydropower is often considered a source of renewable electricity because its fuel, water, is constantly replenished by nature. Others are limited to water storage and flood protection duties, and some of them are good candidates for electricity generation, he adds. As recently as a decade ago, little was known about emissions from water storage reservoirs.

But understanding has evolved rapidly. For instance, researchers initially thought shallow reservoirs in tropical regions were the largest emitters because their stored water was more prone to heating up, which could fuel greenhouse gas production.

But analysis by Deemer and her colleagues shows that the latitude and depth of water are not leading factors. The nutrient runoff can be from natural processes or from farming, logging and land development. Using data from the reservoirs, the authors estimate total emissions from all reservoirs worldwide and conclude that those water storage facilities account for 1.

Another new study published by the journal PLOS One reaches similar conclusions, although it finds carbon dioxide to be a bigger share of emissions than methane. After examining data from more than 1, dams worldwide, it identifies the rate of soil erosion into a reservoir as a leading predictor of carbon dioxide emissions.

It would be a grave mistake to continue to finance those with the impression that they were part of the solution to the climate crisis. Edenhofer, R. Pichs-Madruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P. Eickemeier, G. Hansen, S. We use cookies to improve your experience.

By continuing, you accept our use of cookies. Learn more. Table of Contents. Learn how moving water is converted into electricity in this comprehensive overview, including a discussion of the hydropower resource, its environmental and societal impacts, and the potential for future expansion of hydroelectic energy.

Land use. Renewable energy—wind, solar, geothermal, hydroelectric, and biomass—provides substantial benefits for our climate, our health, and our economy. Land use The size of the reservoir created by a hydroelectric project can vary widely, depending largely on the size of the hydroelectric generators and the topography of the land. Wildlife impacts. Wildlife impacts Dammed reservoirs are used for multiple purposes, such as agricultural irrigation, flood control, and recreation, so not all wildlife impacts associated with dams can be directly attributed to hydroelectric power.

Life-cycle global warming emissions. References: [1] Fearnside, Phillip M.