Britain’s renewable energy network is expanding day by day, with new wind turbines and solar power panels beginning to shift our dependence on burning fossil fuels for electricity. Last month, the National Grid announced their lowest ever predictions for electricity demand this summer – thanks, in large part, to the electricity provided by independent solar panels.
The Problem
However, there is one major problem hampering the energy efficiency of our electricity network. Renewable energy makes use of existing phenomena – which is what makes it so environmentally friendly. Renewable energy generators don’t force chemical reactions, or burn industrial quantities of fossil fuels – they give us wind power when the wind blow, solar power when the sun shines and hydropower when the rivers are flowing. But the problem with this is that we can’t use renewable energy for on-demand electricity. We can’t simply crank up the wind or switch the sun on for a few more hours if we’re failing to meet electricity demand. For that reason, coal and gas plants are left on standby ready to produce on-demand electricity when peak demand is unusually high – ramping up greenhouse gas emissions.
At the same time, days of low demand can see renewable energy systems producing electricity in excess of demand. The turbines turn but the power effectively goes to waste because the electricity produced is not used. This is particularly problematic for renewable sources which are most productive in off-peak periods: for example the electricity produced by wind turbines in a stormy night often goes to waste because most people are asleep and not using electricity!
With wasted energy and too much reliance on fossil fuels for on-demand electricity, we need a new solution.
The Solution
The idea behind electricity storage is simple: to capture and store electrical energy generated at off-peak times to use in periods of peak demand. But the technology to do this is still developing.
So why is energy storage so difficult? Well, that comes down to the dynamic nature of energy. You can’t “store” energy as you would food, books or pieces of furniture; if you want to use it at a time after it’s produced, you have to convert it into another form. Think about it this way: if you kick a football, could you “store” the energy you created to make the football move at a later time? Of course not! Or at least, not easily. If you want to kick now and have the football move later, you have to get clever…
In this metaphor, the “kick” is the electrical energy generated by wind and solar panel and the moving football is the energy received in the home and used to power lighting, heating and appliances. To delay the football’s movement, and to switch the house’s lights on at a later time, we need to find a way to convert the energy into a different form.
How might you do this with a football? There are all sorts of ways, if you’re feeling creative! You could kick the football upwards and catch it in a box on the roof of a building. Now you have converted the kinetic energy of your kick to gravitational potential energy, and at any time you can open the box and let the football fall. Or you could kick the ball into a container slowly filling with water: when the water fills the container it will overflow and push the football out along its course. Or instead of kicking the football, you could kick a block which falls and knocks over another block in domino style, with a chain of blocks looping around the building, until the final block knocks the football along a minute later!
These are all rather silly ideas, perhaps, but they help give you an idea of how scientists and engineers need to think when they tackle the problem of electrical energy storage. Here are four of the most exciting electrical storage ideas currently being developed!
1. Pumped Hydroelectricity Storage – sending water up hills
Currently the most widely-used method of electrical energy storage, this one works on the same principle as the football kicked onto the rooftop. Electricity generated by turbines and solar panels at low-peak times which would otherwise go to waste is used to pump water uphill to a reservoir. When demand increases the water is released to rush down the hill and turn turbines, which create electricity which goes directly to people’s homes. Electrical energy (generated by the turbines) is converted to kinetic energy (to move the water up the hill) where it is converted to gravitational potential energy (ready to fall down the hill when the dams are opened) to be converted into electric energy again (when the water turns the turbines). The low peak electricity is not wasted, and on demand-electricity is ready whenever it’s needed.
2. Air Energy Storage – compressing air into caves
A developing method is to use surplus electricity to pump air into underground caverns, which can later be released at pressure to drive turbines to generate electricity at peak times. This method involves converting electrical energy to pressurised potential energy. This process is limited at present by a lack of suitable geological formations.
3. Heat Storage – molten liquids
Converting electrical energy into heat is another way to store energy so it can later be used to drive turbines and produce on-demand electricity. This is a method currently used in Spain to make better use of solar power: molten salt and other liquids are heated in the daytime and released in the evening to turn turbines. Heat storage is not dissimilar in practice to traditional storage heaters which charge up overnight, store heat in bricks inside the heater and release heat throughout the day. These are not the most efficient heating solutions but they do make good use of off-peak electricity.
4. Cooling Gas Into Liquids – powering turbines when liquids return to gas form
Surplus electrical energy can also be used to cool gases into liquids. They can be stored in their liquid form and then released, driving turbines as they warm and turn back into gases. This is being trialled in a power station in Bury, north Manchester, by using surplus energy to cool air to temperatures below -196 ˚C
So, will they work?
Many of these technologies are still in development, and must prove that the cost of storage does not outweigh the benefit of the energy stored. None of these processes is 100% energy-efficient, with energy lost in the form of heat, motion, sound and sometimes light. It is common sense that converting electrical energy several times before using it again as electrical energy is less efficient than simply using the energy directly; however, as the electricity used in these processes would otherwise go to waste, there remains plenty of scope for these processes to boost the efficacy of our renewable power systems.
Speaking about the potential for electrical energy storage, Phil Taylor, professor of electrical power systems at Newcastle University, described the sector as “a potential game-changer” for energy prices which could also “provide many services to the grid to make the UK’s energy future more efficient, secure and lower in carbon emissions”.
Watch this space for the latest developments in the electrical energy storage sector. We’re confident that one day you’ll be able to run your electric radiators entirely on renewable energy, with none of that energy going to waste. We’re looking forward to learning about the latest ideas and innovations which are pushing us further towards the eco-friendly dream of a carbon-neutral Britain.
—
Eco Stores Direct are here to bring you the very latest energy news, views and opinions from across the UK. They are also suppliers of energy efficient electric heating solutions and are constantly assessing the market for the best products and the latest ground-breaking technology which they think will make a real difference to their customer’s homes. Eco Stores Direct are devoted to helping you reduce your carbon footprint and bring down your energy bills and they work hard to raise awareness of energy efficient products that can make all the difference. If you’re interested in wall mounted electric heaters or infrared panel heaters, call Electric Radiators Direct today on 0330 300 4444 for a free assessment.