Avoided emissions

There is international consensus that greenhouse gas (GHG) emissions will lead to major climatic changes, and will therefore have consequences on the hydrological system (and thus on water supply and agriculture) as well as on the sea level. Measures accommodating such changes will need to be taken into account when planning the utilisation of the hydropower resource.



The challenge is clear: an inevitable increase in energy consumption in the world, with the risk of a major environmental impact, and climate change, as a result of the combustion of fossil fuels. Hydropower thus has a very important role to play in the future.

Continued international research confirms that the GHG emission factor for hydro plants is substantially less than the factors for fossil fuel generation, taking into account net emissions from reservoirs. Current initiatives involve the validation and standardisation of various measuring techniques, and efforts to obtain greater consensus on the processes determining the river-basin carbon budget (Rosa, 2001).

According to current figures, development of even half of the world’s economically feasible hydropower potential could reduce GHG emissions by about 13% (by avoided fossil fuel-based generation), and the impact on avoided sulphur dioxide (the main cause of acid rain) and nitrous oxide emissions is even greater.

Hydropower also avoids the substantial impact of particulate emissions (fly-ash, for example): the costs to human health in the form of respiratory disease is a very tangible impact of this problem. A recent estimate of the environmental cost of this form of pollution is put at US$ 100-500 per t/year (Oud, 1999).

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