Hydroelectric dams provide cheap access to renewable energy  In 2010, about 1.4 billion people had no access to electricity. [1] Hydropower provides a source of energy that is cheaper even than conventional coal. [2] Large dams can last for over a hundred years [3] and are easy to switch on and off according to demand, making them very cost-effective. Given that having no access to electricity makes work and study nearly impossible, alleviating global poverty by giving access to electricity is an important step to take.  [1] IEA, Access to Electricity, 2010  [2] Wikipedia. Cost of electricity by source.  [3] WWF, Dam Right!, 2003