A recently published peer-reviewed paper shows that a combination of renewable sources and electrochemical storage could power a grid 99.9% of the time.  The authors state "Aiming for 90 percent or more renewable energy in 2030, in order to achieve climate change targets of 80 to 90 percent reduction of the greenhouse gas carbon dioxide from the power sector, leads to economic saving". This is a very useful response to the oft repeated statement that renewables are unreliable. Click here to read more.