Storage - the key to our renewable energy future
Scottish Renewables Policy Officer Hannah Smith argues in favour of batteries, pumped storage, supercapacitors and more as SR publishes Energy Storage: The Basics and launches an Energy Storage network to bring members into this evolving debate.
Renewable energy technologies like solar, wind and hydro are Scotland’s largest source of electricity.
They provide more of our electricity that coal, gas and nuclear, and displace the equivalent of the emissions from every car, van, bus and train in our country every year.
But renewables, just like gas, coal and nuclear, have limitations.
Our demand for energy has always fluctuated throughout the day, month and year, and meeting those demands while using clean energy technologies to help tackle climate change – and against that backdrop of changing generation patterns – means asking more and more of an energy system with its roots in the 1930s.
Some critics argue that renewables, despite their tangible benefits, cannot make a significant contribution to our energy mix because the energy they supply doesn’t necessarily correlate with demand.
Sometimes it's very windy, or very sunny, so we can generate huge amounts of energy – but it may be at a time when there isn’t any need for it. For example, wind turbines generating electricity in the middle of the night.
Energy supply and demand, though, aren’t static, so our energy system needs to evolve. Already, National Grid have said the idea of ‘baseload’ power, whereby power stations must run 24-7, is ‘outdated’, But there’s an ace in the hole which could see renewables’ share of our energy mix increasing dramatically: Energy storage.
Storage can take the energy created by renewables at times when it's not needed, or when bottlenecks on the grid mean it can’t get to consumers, and save it for later.
Neither storage nor renewables are perfect on their own, but both can work together to produce a result far more powerful than the sum of their parts.
At a local level, household batteries like Tesla’s Powerwall can provide energy solutions for homes and businesses – for example storing daytime energy from solar panels to be used during dark winter evenings, when demand is highest, saving money on electricity which has to be bought in from the grid. Not only does this mean renewables are used to their full potential; it also gives consumers better control and flexibility over how they manage their energy.
But storage isn’t all about electricity. Thermal stores can absorb and release heat on demand. That heat can be generated from various sources including solar energy and then stored in water, molten minerals, clay or banks of earth.
Sainsbury’s supermarket in East Kilbride installed a system to take heat from in-store freezers, push it into rocks deep underground, then recover it later to warm the store in colder seasons. Increased use of technology like this could give a value to excess heat created by supermarkets, data centres and shopping malls, rather than using electrical refrigeration to transfer it uselessly into the atmosphere.
Storage can also mean creating hydrogen gas from electricity. In Methil, Fife, a five year project to run vehicles on hydrogen produced using wind and solar power is underway, with backers including electronics giant Toshiba, which is using the site as its first hydrogen research project outside Japan.
Hydrogen and wind fit perfectly together, and teaming hydrogen fuel cells with wind power creates portable energy when we can’t immediately use the electricity the wind power provides. Hydrogen can be supplied through underground pipes like conventional gas, and used in its place for cooking and heating, as well as to power a fuel cell to create electricity, as in Fife.
While renewables and storage are complementary, there are other benefits too: reducing the need to invest in power transmission infrastructure and increasing the security and certainty of our energy supply, for example.
The advent of storage technologies will only increase the speed at which our energy system is changing. A real 21st century system will integrate different energy sectors (electricity, heat and transport), while increased household energy control will put people right at the centre of how we create and use power.
Underneath all this lies an imperative. We need to reduce carbon emissions. We must generate clean, secure energy in a way that responds to this changing system, and in a way that makes sense for consumers.
Storage technologies are central to that. They will help us get the most out of our renewable energy sources, and combined storage and renewables are the key to our energy future.