First of all, power plants operating on renewable resources are not as green as one might think. Hydroelectric and tidal power can harm water ecosystems, wind turbines can harm wildlife and solar plants need a large space to be built on and are only really efficient in deserts. Nuclear power stations are relatively green since they do not primary produce any “dirty gases.” The only problem is mining uranium and the nuclear waste, which is increasingly able to be recycled and potentially reused as fuel for more modern nuclear plants.  Furthermore, gas stations are operating with non-renewable source of energy – natural gas. Therefore, when speaking about efficiency -nuclear power stations are generally more effective than gas power stations [1] [2] – it is better for environment to operate on few nuclear power stations rather than on many of gas power stations. Nuclear power stations are not flexible, but they can represent the base of needed energy, which does not fluctuate, and the rest of needed energy which varies in time may be supplied with power plants operating on renewable sources and few power plants operating on other non-renewable sources.  [1] ‘Cooling power plants’, World Nuclear Association, September 2012,   [2] Kirk T. 2007 Physics IB Study Guide, Oxford University Press, p.68