Hydro electric dams reduce carbon dioxide emissions  Hydroelectric dams burn no fossil fuels so emit no greenhouse gasses at all in producing energy. Suppose we replace all coal fired power stations with hydroelectric power stations. In 2010, over 42% of global electricity production was produced through coal, accounting for over 28% of global carbon dioxide emissions. [1] Since there is more than enough potential capacity for hydropower, [2] we could hypothetically completely replace coal and even other fossil fuels for electricity, thus helping cut down greenhouse gas emissions massively.  [1] IEA, Power generation from coal, 2010  [2] Energy Consumers Edge. Hydropower dams pros and cons.