What’s in store?

BRE’s Steve Pester, looks at the growing importance of energy storage in renewables.

There’s another renewables revolution about to happen. It will initially affect the electrical technologies (PV & wind mostly), but will also catch up with heat technologies at some point. What is this big thing that’s a-coming? A new wonder material? Energy from anti-matter? Methane capture from cows (perish the thought)?

No, I am referring to energy storage technologies. The main objection we tend to hear about renewable energy, aside from initial cost, which, it is now evident to everyone, can fall rapidly, is intermittency. The sun and the wind cannot be switched on and off to order. Hydro power is a little more predictable, but that is also dependent on rainfall. The only way to smooth out the peaks and troughs of renewable generation is by using some sort of energy storage technology.

Why is this so important? Surely the national grid can be used for storage when there’s no wind or sunshine? The grid already has to cope with wide swings in demand on a daily and seasonal cycle. Add to that unusual episodes such as surges due to national events (world cup penalty shoot-outs come to mind – millions of kettles and ovens go on when it’s all over). Then intermittent generators (that’s us in the renewables business) come along and start injecting power onto the grid sporadically – you start to see the problem?

Energy storage has been around for a long time – for example, off-grid battery systems for PV & wind are well-established, albeit not very common in the UK. So what’s new here? Well, there are many possible storage solutions, in various states of development because the financial returns for any successful technologies will be very large. What’s coming along in the short term, thanks largely to electric vehicle manufacturers, are some exciting new battery technologies, designed not to power buildings for days at a time (as is the case for off-grid storage), but to work with the grid, smoothing out the demand peaks and crucially, allowing individual customers to use more of their home-generated energy.

The traditional lead-acid batteries will be around for a while yet because they are relatively cheap and recycling facilities are well-established. These may continue to improve a little, but the rising stars are batteries based on lithium-ion, sodium-sulphur and redox reactions. Domestic scale lithium-ion grid-connected battery solutions are already available for the early adopters – we are just waiting for the initial push (perhaps an extension to the FIT?) to get the market moving and bring down the costs. It will happen – it has to for grid stability, security of supply and because end users have an increasing desire to protect themselves from grid energy price rises.

BRE’s new National Solar Centre will be working to help this happen – details of the centre, which opens in April, can be found at: www.bre.co.uk/nsc .