New ‘game changing’ domestic heat batteries could decarbonise Britain’s rural homes and take pressure off the grid

A novel domestic heat battery could help decarbonise millions of British homes – and act as massive renewable energy stores in the years ahead.

Heating our homes is one of the UK’s biggest sources of CO₂ – accounting for 15 percent of all emissions.

Most homes are heated by mains gas, which is the main CO₂ culprit – but more than a million rural homes are not connected to the gas grid, and instead rely on highly polluting fuel oil or lpg, which is even worse.

Now British tech firm Caldera has invented a new type of large-scale domestic heat battery, which they say is ideally suited to our off-gas grid homes.

Their technology – known as Warmstone – heats up overnight using cheap, green off-peak electricity. It then releases this heat during the day to power a home’s heating and hot water.

And besides delivering zero carbon heat, they believe that widespread rollout could provide gigawatts of intelligent energy storage to soak up night-time wind power and take pressure off the grid.

The firm is currently rolling out their Warmstone units in twelve pilot homes across the south of England and is taking orders for customers who’d like to have one installed next year.

“It’s a simple idea,” explains company founder and CEO James Macnaghten.

“At its heart lies a patented dense, novel compound comprising recycled and natural materials – known as Warmstone – which is supremely good at holding heat, and this is surrounded by super-efficient vacuum insulation,” Macnaghten says.

Weighing 1.7 tonnes and measuring 1.7 metres tall by one metre diameter, the heat battery is intended to be used primarily as a replacement for oil or lpg boilers, which are used in more than a million UK homes which are not connected to the gas grid.

“Each unit is heated by low carbon, low-cost off-peak electricity and is able to store up to 100kWh as heat – more than enough to provide heat and hot water to the average four-bedroom home.

“When needed we transfer this stored heat energy to the water circuit that runs through the home to heat up radiators and provide hot water, just like a traditional gas boiler,” Macnaghten says.

He states the system is easy to connect and is ideally suited to older homes off the gas grid.

“It can be installed by an accredited plumber and electrician in a day and will tie into your existing central heating and hot water system.

“In Britain, gas is cheap and electricity is expensive – and that is why our homes are heated by gas and oil,” says Macnaghten.

“However, in recent years we have seen the advent of innovative new energy companies – such as Octopus – which offer flexible time of day tariffs.   This means that a Warmstone heat battery, connected to a smart meter, enables householders to buy cheap electricity when it plentiful – at rates as low as 5p kWh – to store for use when required.

“At a stroke, this enables householders to move away from oil and gas and embrace a cost-effective, zero carbon alternative.”

In September, Caldera teamed up with greentech innovators myenergi to to develop a customised version of myenergi’s eddi controller, which will intelligently manage the energy supply into the Warmstone battery.

myenergi are experts in eco-smart technology and their controller will allow householders to rest easy, knowing that their Warmstone heat battery is charging at the optimum time.

Intelligent energy storage

Longer term, Macnaghten believes the nationwide rollout of thousands of domestic heat batteries can create gigawatts of intelligent energy storage which can be used to take stress off an increasingly renewable-powered grid.

“Each of our units has intelligent controls which can sense when prices are low and can also be configured to respond to signals from, say, an energy supplier. This means that thousands of heat batteries can be set to charge and soak up cheap electricity when required.

For example – one million heat batteries could provide 20GW of flexible demand for five hours ie 100GWh.

“At present there are many times during the year where wind generators – for example in the north of Scotland – find their output is constrained due to a lack of grid capacity and cannot be exported.

“The rollout of thousands of Warmstone heat batteries in the far north could create local demand to make good use of cheap, green energy which currently goes to waste.

“There is no single to solution to decarbonising all of the UK’s homes, but we believe heat batteries offer a cost-effective and easily-adopted solution for many hard to heat homes,” Macnaghten concludes.