Everyone is familiar with batteries, most use them every day of their lives. They are present in all sorts of consumer electronics from watches, laptops and mobile phones. When most think of a battery a common AA chemical battery comes to mind, the sort you might put into a torch or a television remote. However this kind of technology is much more widespread than that. Batteries can come in many forms and are used extensively in the power generation and storage industries to manage electrical power within grids. In fact battery technology is likely to be the key factor in the development of renewable energy technology in the coming years.
This is a result of a quirk associated with renewable energy. Unlike other power sources which can be switched on and off as they are needed, renewable energy generation is dependent on the weather, if the weather conditions are poor no electricity is generated. This particularly applies to solar which only generates power during the day and none at night. This leads to a power balancing issue, electricity is used throughout the day and night so needs to be generated by the grid to meet demand.
An entirely renewable system would not meet this requirement as energy generation comes and goes. A system to collect the power generated during the day and distribute it when needed is required. This is where the batteries come in. Large banks of batteries can store the electricity and release it when needed. Systems of this type are already in use today. Large lithium ion battery banks have been constructed as part of the Australian grid to store excess power. The banks are currently in their trial period to test their effectiveness.
Lithium ion batteries are currently the most popular form of batteries in industry, they are the batteries commonly used in mobile phones, consumer electronics as well as electric vehicles. This is because they are, at the moment, the best solution for these applications available. However, they do have some downsides, particularly when you look to apply them to large scale grid electricity storage, as we are looking at today. The materials required to produce the batteries are difficult to source as they are mostly mined in African countries with poor ethical working practices, leading to a great deal of exploitation in the Lithium mining industry.
These material sourcing concerns also result in lithium ion batteries being expensive to produce so the unit of electricity storage per pound spent, in other words cost efficiency, is low. Finally these batteries can have some stability concerns with several batteries causing large scale fires in the Australian battery testing centres when the batteries have overheated. So while these batteries are great for a number of consumer electronic devices, they are not so good for large scale electricity storage.
So what kind of alternatives are out there? There is of course the traditional way of storing electricity… water! Hydroelectric dams are all over the world and a tried and true method of storing and releasing electricity. During peak power generation water is pumped into a reservoir and as electricity is needed, the water is released from the reservoir and passes through a turbine, generating electricity. This system has been used for hundreds of years in one form or another so is a very reliable way of storing large amounts of power. However it does have a large downside, namely the space and investment required to construct such a big project. This kind of project is also limited to a certain geography requiring large elevations and mountainous landscapes.
What battery technology needs is innovation, luckily a number of new battery technology ideas are under development to try and fill this gap in the market. An exciting new Edinburgh based startup has been developing technology in a similar vein to the gravity powered hydroelectric plants we just discussed, lifting a heavy weight in place of the water. Gravitricity has built a test bed for this new technology in Prince Albert Dock, Forth to promising results! The end goal of the company is to retrofit the disused coal mines of the UK as long shafts to raise and lower large weights to store and release electricity.
Now to another kind of energy… Thermal! Researchers at many institutions around the world are investigating the development of thermal batteries. These batteries heat up material when there is excess electricity and convert that same heat into electrical energy for use when there is less energy available. High specification versions of this technology use molten salts, heated to over 1000 degrees celsius as the thermal storage material. Systems like this have seen great promise as an energy storage method but still face issues with moving the molten salts in order to generate electricity from them.
A lower specification version of this technology has been installed in Finland. The system, partnered with a local village, heats regular sand to 500 degrees celsius using renewable energy sources. This stored energy can then be used year round to heat local homes consistently (an especially important factor over cold finnish winters). This pilot plant proof of concept is particularly exciting as it is an extremely cheap way of storing electricity and could easily be integrated into local communities, providing an opportunity to develop local microgrids.
Hopefully you can now see how important battery technology is to the green future of the earth and how different technologies are well under development to ensure renewable energy is more effective and cheaper than ever!