Being the poster child of Agnosticism makes sure things somewhat of a luxury. I enjoy knowing that my parents will still be out shopping on Dec 24th (which is the day we celebrate Christmas in Sweden), that I keep extending my gym membership with the naive intention of actually going and that hydroelectric plants don’t emit greenhouse gases (GHGs). Of course, like in the case of the power plants (but never the gym), even our sure things sometimes take us by surprise. The Swedish Society for Nature Conservation had consultant Göran Eklöf analyse the studies claiming that many hydroelectric plants actually emit as much or even more GHGs than your everyday fossil fuel plant would, to produce the same amount of electricity. In his analysis “A wolf in sheep’s clothing? - Water power and greenhouse gases”, Eklöf emphasizes the importance of different biotopes’ relationship to carbon, the base of GHGs carbon dioxide and methane. To put it very crudely, natural habitats can emit carbon, store it or function as a carbon sink. Stagnant waters like lakes or dams naturally emit carbon, whereas for example forests often have a balanced intake and emission. So if a reservoir floods a forest area the vegetation will rot, stored carbon will be released and the net emission of GHGs will rise. Furthermore, should this emission take place in an oxygen-free surrounding (as is often the case in the bottom layers of a dam), the carbon could be released into the atmosphere in the form of methane. Methane is about 20 times more powerful a GHG than the carbon dioxide that is usually emitted.

To get exact calculations on hydroelectric GHG-emissions we need to know the specific area's pre-dam relationship to carbon, and since these theories are fairly young there isn’t an abundance of statistics. But worst case scenario, do these findings constitute the end of water power? No; if executed correctly and under the right circumstances, GHG-emissions from hydroelectric plants are minuscule compared to those from the burning of fossil fuels. Generally, higher emissions seem to come from shallow dams in tropical areas. I on the other hand can splurge on hydroelectric power without giving a thought to global warming. It’s just one of many perks that come with living in a country dominated by complete, subzero darkness six months a year.