What happens when the wind doesn't blow?

People love to say renewable energy isn't reliable. Fatal flaw or minor hurdle?

One of the most common criticisms of renewable energy is that it's unreliable. If it isn't sunny, solar can't produce power. If there is no wind, wind turbines can't turn. This seems like a fatal flaw, but it's really just a minor hurdle.

There are two ways to get around this snag. The first is to have a diverse energy supply. Sure, if you rely 100% on wind then you're likely to have a problem, but there are plenty of other renewable options. The chances of the tides stopping is pretty low (although we did see a film once where a villain stole the moon), and hydro, geothermal, biogas and biomass can all pick up the slack very easily. Unlike nuclear and coal which need to be kept hot all the time, biomethane and hydro can be turned on and off in a matter of seconds. This makes the National Grid's job of keeping the lights on a lot easier.

That's great you might say, but aren't we wasting a lot of energy when there is TOO MUCH wind and we don't need it? Well, no. Not really actually. On Thursday 9th July 2015 Denmark was producing an impressive 140% of its power needs from wind. Not a problem. Our Danish friends simply sent the excess to Norway and Germany who were able to store the energy in their hydro systems, making them a cool profit in the process. Kudos to them.

This neatly brings us on to the second key way to smooth out renewables: storage. Saving energy for, quite literally, a rainy day. A calm, windless, rainy day. We've already covered hydro storage, and since we've come off as massive fans of Dinorweg hydro plant in other articles we'll just say that it's super impressive.

There are other ways of storing energy too. New York State uses 200 flywheels that each weigh 1.3 tonnes to store 20MW, about 20,000 homes worth of energy. Battery technology is a very exciting field too, with pilot projects demonstrating low energy loss percentages and highlighting their true potential. And products like Tesla's Powerwall let you bring it into your own home too. All in all, Imperial College London has estimated that energy storage could save the UK £10bn a year by 2050. Currently, a lot of coal and nuclear energy is wasted overnight when it isn't needed because they can't easily be wound down. Energy storage lets us be more efficient with the energy we currently have, as well as paving the way for renewables.

Tesla: leading the way in energy storage

So there you have it. There is no reason to think that 100% renewable is a pipe dream. We're not so naive as to think that this will happen overnight, but hopefully this will help convince the naysayers we can rely on clean power. The future is bright, exciting and clean!