Recently a study named “Should we build more large dams? The actual costs of hydropower megaproject development”, authored by Atif Ansar et al. has been released by the Said business school of the Oxford University. The main conclusion of the report is that large dams projects experienced cost and time overrun, that their benefit cost ratio is very low and that small project are to be preferred. As small dams may only ensure a few percent of the storage and energy provided by large dams, this presentation actually favors not the small dams, but the fossil fuel plants.
This study focuses on cost and time overrun without addressing the true challenges. It is suffering important drawbacks and methodology issues that we will detail.
The existing 50 000 “large dams” supply 15% of the world electricity production and provide irrigation water for feeding 800 million people. But there are extra needs, as can be seen in many countries of Africa where people are cutting the forest for cooking energy, where they live in darkness and are hit by water-related diseases and malnutrition which result in millions of fatalities each year, mainly women and children.