Battery energy storage: what it is and how it all works

08 December 2020 | Aimee Tweedale

Every household has some batteries – whether they’re rolling around in the bottom of a drawer somewhere, or powering your remote control. And ever since they were first introduced in the 1990s to power handheld camcorders, rechargeable Lithium-ion batteries have been a familiar household sight. 

But what if we told you that in the near future, you could be using batteries to power your house?

Battery storage is hugely important for the future of clean, green energy. Why? It’s simple: most renewable energy sources depend on the weather, like wind and sunshine – which, as we know in the UK, can be very unpredictable. 

But what happens if everybody’s watching Coronation Street, and goes to make a cup of tea during the adverts, but there’s not enough wind energy to handle the spike in demand? Currently, when this happens, it means the grid has to take energy from fossil fuels instead. But with battery storage, we could make sure that the energy generated during high winds was saved, ready to be used at peak times. 

The same principle can be applied to your home. Home battery storage can save all the energy that’s created during off-peak times, or captured by your home solar panels, and use it to power your appliances during busy times. This wouldn’t just lighten your carbon footprint – it would also save you money.

The idea is simple, but the technology is a bit more complex. Here’s our breakdown of everything you need to know about batteries, and their role in the fight against climate change. 

So, what is battery energy storage?

Battery storage is a way of holding onto energy that has already been generated, so that it’s ready to use when it’s needed. 

In this article, we’ll go through two different types of energy storage:

  • Commercial or utility batteries: these are large-scale batteries designed to hold energy created for the grid.
  • Home or residential batteries: as the name suggests, these are smaller batteries you can install at home, to balance your energy use.

Read more on how smart home tech like batteries can add value to your house

How does battery storage work?

Currently, most commercial and home batteries use Lithium-ion battery technology. This is the same technology that’s used in your laptop and your phone (and in electric cars, too).

In California, the 250mWh Gateway Energy Storage project uses the world’s biggest Lithium-ion battery to balance the grid. (Tesla is already building an even bigger storage project, to be unveiled in 2021.)

Lithium-ion batteries work by causing a chemical reaction, turning chemical energy into electrical energy. You can learn more about the science behind them here.

But when it comes to battery energy storage, scientists are developing lots of other approaches. That’s because Lithium-ion batteries are expensive, and so it’s been difficult to build them big enough to support electricity grids. They’re also not very environmentally-friendly, since lithium is a finite resource. As much as 70% of the stuff could be used by battery technology by 20251.

Here’s a rundown of the main types of commercial and home batteries that are being created right now, and the advantages and disadvantages of each one.

Battery energy storage could power the future of renewable energy

Types of commercial energy storage

Did you know that once we’ve enough commercial batteries to hold around 20% of the electricity generated, we’ll be able to have a 100% renewable system2?

That’s why the race to find a solution that can be scaled up is so important. Here are the main types of battery energy storage solutions scientists are working on right now. 

Electrochemical batteries

These batteries are the most common, and they’re used in everything from watches to cars. They’ve been around since Alessandro Volta created the very first one in 18003. They convert chemical energy into electric energy. 

Lithium-ion batteries are the most popular kind of electrochemical battery. They’re already used to provide back-up power to some homes and hospitals – but it’s mega-expensive to build large enough ones to power cities.

Flow batteries

Flow batteries are another type of electrochemical battery, but they function slightly differently. They work by pumping electrolytes back and forth between two tanks. They can be easily scaled up, by building bigger tanks.

Flow batteries are already being used in some places to support the electricity grid (China is building the world’s biggest) – but there are a few downsides. They’re less efficient than Lithium-ion, and they often depend on the use of vanadium, a rare and expensive metal. Researchers are looking into whether iron can be used instead.

Pumped hydro storage

These storage solutions make use of a force that’s all around us: gravity.

This involves building two huge reservoirs of water, one high above the other. The lower reservoir gets pumped into the higher one, and then the water is released, pushing a turbine. 

It’s a hugely efficient way of storing energy: the size means it does the job really well. The only negative? Because it takes up so much space, it’s only possible to do this in certain locations. 

Thermal energy storage

Energy can also be stored as heat. Innovators like the German start-up Kraftblock are exploring thermal storage options. In this case, super-hot granules are used to capture and transport heat. The Financial Times describes this option as being like a giant “hot water bottle”.

Read more on how thermal energy storage could help you heat the home of your dreams

And more...

Battery storage technology has been a difficult nut for scientists to crack. But recently, exciting developments in energy storage have been making headlines. 

There are proton batteries – an ultra-green alternative to Lithium-ion batteries that scientists at RMIT in Melbourne created in 2018. These run on carbon and water instead of lithium, and could be rolled out commercially in the next decade. 

Researchers at Stanford have also come up with a water-based storage solution: their saltwater battery prototype creates a chemical reaction that stores electrons in the form of hydrogen gas.

Try home energy storage with OVO

We’re trialling home battery storage technology with OVO members in Lincolnshire. Click here to find out more about how we’re bringing the #FutureofEnergy to the here and now.

Battery energy storage in the home

Types of home battery storage

Are you looking for domestic battery storage, to save power at home?

If you’re on an Economy 7 tariff, home battery storage can help you store up electricity during quiet times, so that you can make use of it during surges. This saves you money, and helps to balance the grid.

They’re particularly great if you have solar panels, or another renewable energy system, installed at home. With solar panel battery storage, you can capture and use even more of your clean energy, rather than selling it back to the grid. 

Read on to find out more about the different types of home battery available, or head over to our home energy storage guide. And if you’re interested in going fully green at home, find out more about low-carbon heating solutions that can shrink your impact on the planet.

Lithium-ion batteries

Most home batteries in use right now are powered by Lithium-ion, the same substance that’s been used to make many commercial batteries. 

  • Pros: They’re lighter and more compact than other electrochemical batteries, and will also last longer.
  • Cons: As mentioned above, Lithium-ion is expensive, and it’s also a finite resource – so it’s not the most environmentally-friendly option. 

Lead-acid batteries

These work similarly to Lithium-ion batteries, but there are a couple of key differences. 

  • Pros: These are a slightly cheaper option than Lithium-ion.
  • Cons: They have a shorter lifespan than Lithium-ion batteries, while being less environmentally-friendly than heat and saltwater batteries.

Saltwater batteries

The new kid on the block of home battery tech, saltwater batteries don’t use any heavy metals. Instead, they rely on – you guessed it – saltwater, and its natural electrolytes.

  • Pros: These are very green, and easily recycled (unlike Lithium-ion or lead-acid).
  • Cons: As they’re so new to the market, saltwater batteries are still untested long-term. 

Heat batteries or thermal stores

These are both ways of storing energy as heat. While thermal stores are more like your trusty old hot water tank, heat batteries are their cool younger sibling: they’re sleek, small, and hold on to heat for longer.

Sunamp UniQ heat batteries are perhaps the most compact example out there. Find out more about how you could get one installed in your home as part of our Zero Carbon Heating Trial.

  • Pros: These clever systems can take the place of a regular hot water tank – and in the case of heat batteries, they’ll take up less space, too! They’re super-environmentally-friendly, and won’t lose heat to their surroundings. Oh, and they’re cheaper than electricity batteries, too.
  • Cons: These can get pretty hot to the touch, so you have to be careful. But, all things considered, they’re a great option for your home.

Warming up to the idea? Read our guide to thermal energy storage.

Is battery storage worth it?

Whether a home battery storage system makes sense for your bank balance will depend on how much energy you generate, and how much you use. If you have a small solar panel system that doesn’t create a lot of excess energy, then it might not be right for you.

It’s important to weigh up the costs and benefits. But it’s not just about money – many people might also want to shell out for a home energy storage system because of environmental concerns. 

If you’re someone who wants to take your home off-grid, and reduce your home’s carbon footprint, home batteries are the way forward!

Consider switching to OVO Beyond for greener energy

OVO Beyond is our green upgrade, for OVO members who want to do their bit to lower the carbon footprint of their home. 

Not only do we supply 100% renewable electricity as standard4, we also plant 5 trees every year per OVO Beyond member. Plus: we’ll offset all the carbon emissions that come from the production and use of energy in your home. 

Find out more and switch today.

Sources and references




4. The renewable electricity we sell is backed by renewable certificates (Renewable Energy Guarantee of Origin certificates (REGOs)). See here for details on REGO certificates and how these work.

5. Enjoy even greener energy with OVO Beyond in comparison with our standard OVO plans. In addition to 100% renewable electricity as available with our standard plans, OVO Beyond reduces your yearly carbon emissions from the energy used in your home that is supplied by OVO to net zero by providing 100% carbon-neutral gas (15% green gas and 85% offset) and offsetting all associated lifecycle carbon emissions involved in the production and consumption of your electricity & gas, you will also get 5 trees per year in UK schools and communities and other green benefits. The renewable electricity we sell is backed by renewable certificates (Renewable Energy Guarantee of Origin certificates (REGOs)). See here for details on REGO certificates and how these work. The green gas we sell is backed via renewable certificates (Renewable Gas Guarantees of Origin (RGGOs)). See here for details on Renewable Gas Guarantees of Origin and how these work. We offset the remaining emissions by supporting UN REDD+ carbon reduction projects that are certified to the Verified Carbon Standard or the Gold Standard. See here for more information on how we restore nature and protect rainforests with our offsetting programmes.

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