The answer to cheaper energy bills could be underneath your house

Britain is sitting on a source of cheap energy. No, not coal – though this cheap energy comes from an unexpected consequence of our industrial past.

The coal industry left behind 23,000 or so abandoned mines. Over the decades, many of these mines have naturally flooded with water, which is heated by the ground to between 12°C and 20°C. This geothermal heat can be extracted, boosted, and used to heat homes. And it’s starting to happen. It has been successfully trialled at 350 homes in Gateshead and will be expanded to around 1,500 homes in the next few years.

The system effectively replaces standard household boilers with a giant, communal heat pump by transferring the heat to a “clean loop” of hot water that flows through a home’s pipes and radiators – meaning no dirty mine water enters the home.

And because most of the warmth in the heat pump is transferred rather than generated, they are typically three to five times more efficient than conventional heating technologies like gas boilers, which heat the water from scratch.

As a result, those homes using heat generated in the Gateshead mine project are being given a 5 per cent discount on their heating bills compared with if the heat had been generated by a gas boiler.

Of course, it’s early days at the moment and it could be that mine water heating is only ever a niche source of heat. But the potential is huge, with Ordnance Survey estimating that one in four UK homes is built over an abandoned coal mine. Not all will be suitable – for example, if the mines are too deep. But millions of homes could well be, government research suggests.

And the success of the first large-scale test of mine water heat technology in Gateshead confirms that, for the right sites, it should be able to play a significant role in weaning the UK off gas boilers.

Other developers are now following suit. The first mine water project began in May, in the mining town of Ammanford, just north of Swansea. Another project is being built near the town of Seaham, County Durham, that will heat 750 homes. Meanwhile, the EnergiRaven consultancy found that mine water is among the most viable forms of “waste heat” that could be harnessed in UK households – ahead of datacentres, which produce vast amounts of heat that governments are also starting to utilise.

Geothermal energy is starting to spread across the UK. Heat from the ground is also used in heat pumps, with more than 40,000 “ground source” heat pumps thought to have been installed in the UK so far.

These take the warmth from the ground, boost it and feed it into the home’s central heating system. And, as with the heat pumps that use mine water heat, they are much more efficient than gas boilers because they don’t need to heat from scratch.

As with air source heat pumps (which take heat from the surrounding air rather than the ground and are more common than “ground source” heat pumps), most households are eligible for a £7,500 grant towards the cost. Ground source heat pumps typically cost £14,000 to £20,000 for a standard “horizontal system”, meaning you end up paying £6,500 to £12,500.

You’ll save around £900 to £1,600 a year compared to gas boilers, meaning you can pay it off after around seven years and can then save hundreds of pounds a year over the rest of its 25-year life span. By contrast, air source heat pumps are cheaper, costing around £8,000 to £14,000 for a typical UK home – leaving you to pay between £500 and £6,500 after the £7,500 Boiler Upgrade Scheme grant.

The estimated savings for an average three-person household of this kind of heat pump are typically around £260 a year, meaning it is paid back after around a decade.

As the Iran war continues to focus people’s minds away from oil and gas and towards clean energy and heating, it seems likely that the take-up of ground source heat pumps will accelerate in the coming months. And the Government requirement for most new homes to be fitted with a heat pump will push numbers up further.

Still, the untapped reservoirs of heat under our feet remain a tantalising possibility. The UK has invested heavily in wind and solar power in recent years, and that’s a great start in making us more resilient to shocks to the international energy market.

But given the potential that mine water has to shave valuable pounds off our bills, it’s time we turned the places which smogged up our forebears’ towns and cities into clean energy and warmth for everyone.

المصدر: iNews