Battery Storage

Posted by PFP Energy

For most people, it would be a challenge to get through a day without using batteries as they’re in everything from TV remotes to smartphones. In recent years, the domestic appeal of larger scale batteries has been flourishing, with tech such as electric vehicles (EVs) and solar panels becoming more affordable, alongside renewable energy becoming a priority for many. In this blog post we look at how batteries work, where they are used and what obstacles still face them on the road ahead. There’s even a handy key word section at the end for those pesky energy terms.

How Batteries Work

Batteries take advantage of electrochemistry – the conversion of chemical energy into electrical energy. They are made up of two electrodes – a cathode (positive) and an anode (negative). Both are conductors that are in contact with the non-metallic part of the battery – the electrolyte solution, which is used to balance charge. The below diagram should help visualise this:

When we connect the electrodes (that’s the anode and cathode) with a wire and create a circuit, a chemical reaction occurs at the anode which breaks it down and produces electrons. Another reaction happens at the cathode which adds materials, requiring electrons. This creates a potential difference, which determines the cell’s voltage. Electrons flow through the wire from the anode to the cathode, giving us a current. If we place a component, such as a light bulb, between the two electrodes, electrical energy can be transferred to that component.

Because the anode is broken down as the battery is running, there is only so long we can power a component – eventually the battery will go flat. We can reverse the process in some types of batteries by connecting the circuit to an external electricity source, allowing us to recharge the battery. This will break down the excess material on the cathode and build the anode back up, allowing us to start again. However, our recharged battery will never be as good as our original and each recharge will degrade the battery even more, meaning even rechargeable batteries must eventually be replaced.

Battery Storage for Home

Two of the most common examples of larger domestic batteries are:

  • Home storage – a home battery that captures the electricity produced from your own source of generation, such as solar panels. When your panels are producing more energy than you are using, the excess will be stored away to be used at a later date, saving you money on your electricity bills. If you are really committed to home generation, these batteries can even allow you to live off-grid so long as your annual generation is higher than your annual consumption. Home batteries can also be used as an emergency backup power source, for peace of mind if nothing else.
  • Electric Vehicles – an increasingly common place to find large batteries at home is in EVs. Although slow to charge, EVs are a great environmental alternative to petrol and diesel vehicles, having a much lower carbon footprint associated with them.

Grid Storage

Renewables have gained a surge of momentum in recent years, but there is still a way to go before our national grid can be fully green. One of the reasons for this is renewables’ weather dependence. During periods of high demand, we can’t just make the sun shine brighter or the wind blow faster, so we have to fire up fossil fuel power plants to fill this energy gap. We need to be able to move away from this at some point if we are to stop polluting our planet.

There are two possible approaches to combat a reliance on fossil fuels. One is to introduce so many renewable sources of electricity that peak demand can be covered at all times, including when weather conditions are unsuitable. However, as renewables are expensive and take time to build, this may not be the best route forward. The other approach is to introduce energy storage to the grid, which will reserve energy that would otherwise be wasted such as at low-demand times. This stored excess energy can then be used to power homes all over the country when demand reaches those tough, peak times.

The Problem(s) with Batteries

To provide a balanced argument about battery storage as a renewable solution we’ve also noted some significant problems associated with using batteries for grid storage. Despite their widespread uses and fundamental necessity to our modern way of life, batteries are far from perfect. Firstly, battery storage is quite expensive now, although investment and growth should bring the cost down somewhat in upcoming years. Secondly, today’s batteries need rare earth elements to make the electrodes. These metals require a highly energy intensive mining process, resulting in about double the energy being needed to produce an EV compared to a petrol or diesel car. Additionally, the metals are difficult to recycle and even when they are recycled, the process is another energy intensive one. Currently, very little battery recycling goes on and with sales of EVs and other battery-using devices projected to skyrocket, something needs to be done about this fast. It is true that most of these environmental problems can be mitigated by using renewable energy for the energy intensive processes, but at the moment this does not happen on a large enough scale.

A deeper problem with battery storage lies in inter-seasonal energy demand from the grid. Today, most grid battery storage only lasts up to two hours, but the big flux in electricity demand is between summer and winter. In other words, to properly store energy over several months, either battery storage technology needs to develop rapidly or an alternative must be found. This is being worked on, with examples including gravitational storage, thermal storage and hydrogen storage.

Alternatives to battery storage

Thus, it is important to find other energy storage solutions. One ongoing project makes use of gravity. All objects on the Earth have gravitational potential energy, i.e., when they move downwards, they can transfer energy in that process. One way to do this is turning a rotor, which can be used to generate electrical energy. This technology is simple and relatively cheap, and may well be the norm for grid storage in the not too distant future.

Another piece of tech that can be used for grid storage is EV batteries. Vehicle to Grid (V2G) storage uses specially manufactured EVs and EV charge points to allow anyone with an EV to use their car as a grid storage device; if your car is plugged into the V2G charge point and demand is high, the charge point will take the stored energy in your car battery and move it to someone’s home, removing the need for those naughty fossil fuels. This is smart technology, which means you can tell the charge point when you need your car battery to be full, i.e., the energy is only fed back into the grid when it is most convenient for you. You may think that EV batteries cannot hold that much electricity, but in fact a single battery can hold enough energy to power a home for two days, and with the number of EVs forecasted to be on the road in upcoming years, the collective storage potential is massive.

Key Words

Electrochemistry – the conversion of chemical energy into electrical energy

Electrode – a conductor through which electricity enters or leaves an object

Cathode – the positive electrode (in the case of batteries)

Anode – the negative electrode (in the case of batteries)

Electrolyte solution – a solution of ions (atoms that have lost or gained electrons) that conducts electricity

Potential difference – the difference in electric potential between two points. The larger the potential difference, the more energy that is transferred between two points in a circuit

Carbon footprint – the amount of carbon dioxide released into the atmosphere as a result of the activities of a particular individual, organization, or community

Gravitational potential energy – the energy an object possesses because of its position in a gravitational field

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