SCOTLAND is sinking cash into an innovative home heating idea borrowed from Germany and Switzerland – to stop cash going down the drain.
For decades, the hot water that disappears into the plughole after we shower or run the washing machine has been an afterthought.
Shower water could save you money on heating.[/caption]
Washing machines could also play a key role in savings.[/caption]
Donald MacBrayne, the business development manager at Scottish Water Horizons.[/caption]
But clever engineers have come up with a way to harness the heat that comes from the waste water and use it to warm up houses, meaning they’re saving the planet and money at the same time.
Donald MacBrayne, Business Development Manager at Scottish Water Horizons, which is pioneering the scheme, says: “The idea is this will be part of the overall mix of solutions for the country moving to net zero.”
Heat accounts for more than 50 per cent of the energy we consume, yet vast amounts are lost every day with warm waste water flowing into the sewer system at temperatures between six to 18°C – essentially pouring away valuable energy.
The green heating tech is being installed in a number of places across Scotland at the moment, with the latest venture in Inverness benefiting homes and offices.
But how does it work? Donald explained: “We use heat pumps at the heart of the process. You might not think you know how a heat pump works but everybody’s got one in their house — on their fridge.
“The fridge is an air source heat pump, that’s why when you go to the back of your fridge it’s hot, it’s rotating the heat because you want your fridge to be cold.
“So the way this works is like that but in reverse. It’s not using air like the fridge but instead uses a water source — wastewater — and we’re primarily using it for heat.
“It takes in warm waste-water and rejects colder wastewater after we’ve extracted the thermal energy from it.”
The energy recovery system involves heat exchangers being connected to the sewer network, with residual heat then captured and amplified using the heat pumps.
The recovered heat is then transferred to a heating network, delivering heating and hot water.
And Donald said it works like a giant radiator. He says: “We have thermal stores which are basically really big tanks of hot water.
“Customers connect up to the district heat network and they take that heat into houses, offices and businesses. If you imagine your domestic heating system, you’ve got your radiators and they are all transferring hot water around in that water loop around your house and then it goes back to the boiler colder than when it went out, because you’ve been using that water for its heating.
“It’s like a massive version of that, so there’s big hot water pipes under the roads that connect up buildings and people take that heat into their buildings and use it and then reject colder water in that loop that goes back around in a circle.”
It’s more efficient than taking water from rivers or the sea, as the water is already warm so it takes less energy to heat it up, making it better for the planet.
The expert said: “These projects are displacing mains gas, which is a fossil fuel, and we’re using something that’s this proper circular economy type thinking so it’s much more carbon friendly than the current situation.”
The big question for consumers is, will it save people money? At the moment there are five of these projects on the go in Scotland, with house builders signing up to the heating networks.
Meanwhile, public service buildings — which are always looking for ways to save money — are also connecting to the low-carbon heating, with a scheme in Stirling seeing a school, leisure centre and football stadium using the waste water heating system.
Donald said: “The key to this is these heat pumps. Their biggest cost to run them is the cost of electricity, so if you start from something warm like wastewater the heat pumps are much more efficient.
“It means you’re using less electricity to get to the same temperature.
“So the benefits to the consumer are that it should be more cost-effective than other sources of heat pumps and what we’re trying to do is target projects to make sure that at the worst case the consumer pays no more but ideally, we want to come up with projects where the consumer’s paying less.”
It’s now hoped more of these types of innovative projects can spring up across Scotland to help in the race towards the country cutting carbon emissions and being net zero — something the government aspires to by 2045.
Donald adds: “We’ve all been having showers, we’ve all been using hot water for things but it just takes someone to think well actually we can use that and we can harness that.”
