Something that almost everybody seems to agree on is that renewable sources like solar and wind are great in many ways, but they do all have one flaw compared to more conventional, fossil fuel burning (or nuclear) power stations: they are not able to generate consistently at all times. The sun may not be shining (whether that’s because it is night time, or because it happens to be a cloudy day). The wind blows stronger some days than others. All of these factors lead to the idea that we might need to include some kind of energy storage mechanism alongside these renewable sources. That storage can be “charged” when there is an excess of renewable energy compared to demand, and then fed back into the system later when demand exceeds the renewable generation capacity.
The most obvious, and one that has already been deployed, is to use batteries. Tesla has its Powerpack solution for utilities to use alongside their solar or wind systems, and even complete solar + battery solutions available for those who don’t have solar already.
There has also been talking of using the excess power to split water, storing the hydrogen for later use in a fuel cell that converts it back to electricity and water. Compressed hydrogen is arguably cleaner than banks of lithium-ion batteries and certainly takes less natural resources.
The most novel idea I’ve seen though, and one that I can see being used in both urban and rural environments quite easily with virtually no downsides, is Gravitricity‘s elegantly simple idea: use gravity.
Don’t panic! This is not some crazy physics research based idea that could destroy the planet. In fact, it is quite the opposite. The idea is simply to wind a weight up high in a shaft using the excess power when it is available. Then, when demand increases and the power is most needed, slowly let the weight drop down the shaft, turning the motor that was used to wind it up and generating electricity to be fed back into the grid.
The images show it in a shaft in the ground, whether purpose built or perhaps over an existing abandoned mine shaft (remember those coal mines we no longer need, well their mine shafts may well come in useful for something like this). I can also see it being embedded in tall buildings in an inner city environment. Imagine if that 100 story skyscraper had, perhaps, one less elevator, and instead that shaft was used to store electricity that the building could draw on when necessary. Overnight when electricity needs in the building are at their lowest, the weight could be wound up to the top of the building using cheap overnight electricity. During the day, as the air conditioning is needed, and lights and computers are all on, the weight can slowly drop offsetting some of the building’s demand on the grid.
Every now and again I see an idea that is a truly elegant solution to a problem. In my opinion, Gravitricity have one of those ideas right here. I am going to follow this company with interest, and I’m hoping to see their idea turned into real installations all over the place.