Generating renewable energy is brilliant and should be something we all aim for. However, there are not easy ways to store excess energy generated from the sun, wind, water etc. To prevent energy going to waste, and with the hope of being able to store it for future use, what is science doing?
Standard fossil-fuel power is distributed as and when it is needed. This is not the case for renewable energy; you can’t tell the sun when to shine, or the wind when to blow. Let’s discuss how we store energy.
Batteries are energy stores. They are self-contained, chemical power packs, which can produce electrical energy when needed. A battery slowly converts the chemicals within it, into electrical energy. Within the battery are numerous cells (i.e. a basic power unit) and there are three parts to each cell: 2 electrodes (i.e. electrical terminals) and an electrolyte (i.e. chemical) between them, all stored within the battery casing. Once the battery is connected to a circuit (e.g. your TV remote), the chemicals begin to react and convert to other substances. These substances react with ions (i.e. an atom with too many or too few electrons) from the electrodes’ material, and electrons now in the system can flow through the circuit and power your device (i.e. create a current). Batteries aren’t just those you buy from Tesco though (these are Primary batteries), they come in all shapes and sizes. Your phone, for example, has a battery which works on the same principle but can be recharged when flat (these are Secondary batteries); recharging effectively runs the chemical reactions in reverse. There are numerous types of battery too: zinc-carbon, lithium, lead-acid, and nickel-cadmium to name a few. If you want to know more about batteries and the various types follow this LINK.
Elon Musk’s Tesla released a new energy storage method which we touched on in the ‘Self Sufficient Homes‘ post back in April. It’s called the Powerwall. This is essentially a large battery integrated into the solar powered system of a home, and is able to store excess energy generated throughout the day, making energy available whenever you need it, minimising reliance on traditional utility companies. Of course there’s an app to go alongside the Powerwall. This enables monitoring of how much power the solar panels generate, how much energy your home uses, and how much energy is then stored for later use. However, over time, batteries begin to not work as well as they did when first bought. Anyone with an iPhone can testify that after a year or so, the battery never quite lasts as long as it once did. This is due to degradation. Every time the battery is recharged, it loses a little bit of its energy storage capacity. Follow this LINK if you want to know more about that. So shouldn’t we be trying to develop other ways of storing energy that won’t use chemicals, or degrade over time?
There may be a very simple solution: converting kinetic energy. This is energy that an object possesses due to its motion. This idea would use ‘old tech to bring in new energy innovations’: the Gravity Train. A Californian company, ARES (Advanced Rail Energy Storage System), has used the gravity train in an attempt to make power grids more efficient. Renewable energy is generated throughout the day, but not needed all the time. In the off-peak times, energy can be lost as there is no way to store it; that’s where the Gravity Train comes in. The Gravity Train is a series of heavy concrete blocks (each block is a ‘car’, and weighs 9,280 tonnes combined) on a railway, and when there is excess energy generated, it is used to push the heavy train up an inclined hillside (2,000 ft, over 8 miles). When energy is needed, and the power grid cannot provide, the train is released back down the track. Upon release, the system uses regenerative braking (i.e. a form of braking where energy is extracted from the parts braked, to be stored and reused) and kinetic energy of the moving train is converted into an electrical current for the main power grid to distribute to homes etc. It is thought each train car can hold 8 hours of power using this method. Here is a great news video showing it in action:
Regenerative braking systems are used in many hybrid cars, by Tesla, and even in F1 to conserve energy for later use, so why not use it on this larger scale? Countries are trying to increase their use of renewable energy drastically over the next 20 years, so we need to devise a way to store the surplus created on a daily basis. Gravity Trains may seem a simple idea, but they could make a huge difference with minimal environmental impact.