Decarbonising our buildings: heat pumps or hydrogen for the future of heating?

In October, the Scottish Government released the Heat in Buildings Strategy: Achieving Net Zero Emissions in Scotland’s Buildings. The strategy presents the approach to achieving the target for net zero emissions from Scotland’s buildings by 2045 and is a key component of the government’s ambitious climate change targets for wider society.

In the same month, the UK Government also unveiled its eagerly awaited Heat and Buildings Strategy. This includes similarly inspired aims, such as the phasing out of all new fossil fuel based heating system installations by 2035.

The coinciding release of the strategies means that the journey to decarbonisation is gradually becoming clearer to the consumer. Both governments have indicated their ambitions to make housing greener.

However, they also recognise that there is no one-size-fits-all to decarbonising the tens of millions of homes with mains gas boilers. This transition will be hugely complex, most likely requiring multiple technologies and approaches.

Industry contest heating up

The major players in the UK’s domestic heating industry – believed to be worth an estimated £17 billion – are already moving to secure their role in line with the new government plans and commitments.

In the future, there will be little place for the out-of-favour gas boiler. Traditional boiler manufacturers are aiming to evolve and align their products for long-term security,  whilst the manufacturers of technologies in their infancy, such as heat pumps, are presented with an opportunity to reform the industry for good.

It’s led to the cottage heat pump industry facing off against the established big gas companies’ development of hydrogen ready gas boilers.

Heat pumps the main contender

Whilst no quick fix technology is currently available to replace boilers, heat pumps are undoubtedly a viable frontrunner. The electric devices are steadily growing in government promotion and consumer popularity, as sales more than doubled in 2021 to give the industry its best ever year.

And, as a key feature of the Heat and Buildings Strategy, homeowners in England and Wales will be offered subsidies of up to £5,000 from April 2022 as an incentive to convert their gas boiler to a heat pump.

Heat pumps extract energy from a lower temperature source such as the ground or air and increase it to an appropriate temperature for a heat source in the home – via a compressor and a circulating structure of liquid or gas refrigerant. This heat can either be directly blown into the property or transferred into the central heating and hot water systems.

The selling point of heat pumps is their potential to greatly reduce carbon emissions if they are powered by low carbon electricity, which much of the UK now is. A new air source heat pump can lower a home’s carbon emissions by over 23 tonnes over 10 years.

Whilst relatively novel, the technology behind air source heat pumps is well established with evident positives. They are typically safer than combustion systems, have a very long lifespan with little maintenance and can double up as an air conditioner during the summer months.

Despite the UK Government and Climate Change Committee (CCC) pushing heat pumps as a blueprint for decarbonising, they are not free of concerns and complications.

Heat pumps are expensive to buy and install upfront and, similarly to boilers, the cost can vary. According to the Energy Saving Trust, an air source heat pump will generally cost around £3,000- £4,000 for an average sized house pre-installation and around £7,000-£13,000 installed – raising concerns about affordability and the average consumer’s willingness to go green.

They are, however, very efficient once installed. With an average efficiency of 250%-350%, a heat pump is likely to save you money, compared to an old gas and oil-fired boiler or electric heating. In well-insulated homes, heating bill savings of as much as 60% can be achieved.

Sufficient insulation is a critical pre-requisite to heat pump success. Commenting on the release of the Heat and Buildings Strategy, the Green Party’s Caroline Lucas described placing heat pumps in Britain’s poorly insulated homes as like “using a teapot full of cracks: its leaky, its inefficient and it’s a waste of money.“

The UK’s housing stock is among the most poorly insulated in Europe and the current insulation of an ageing stock, like Glasgow’s Victorian tenements, poses a real barrier to the mass roll-out of heat pumps. Whilst heat pumps are suitable for older properties, consumers will need to commit to a considerable amount of insulation upgrades and home disruption to realise their benefits.

Hydrogen

An intriguing alternative that is in the developmental stages to replace gas is the use of hydrogen, the most abundant element in the natural world.

Hydrogen is already being heavily researched as a fossil fuel alternative in transport, and support for its role in heating is growing in popularity.

A study by the Institution of Engineers and Technology (IET) found that there is no clear reason as to why hydrogen gas cannot be seriously considered as a clean and safe alternative on the UK grid. Similar to heat pumps, hydrogen has the potential to be entirely renewable with no carbon emissions.

Hydrogen is also attractive as it requires minimal disruption in terms of new appliances and installation in the home. Consumers would use a hydrogen ready boiler that works almost identically to a traditional boiler. Likewise, the UK’s existing gas pipe system is well placed to make the switch due to the ongoing systematic replacement of old, unsuitable iron pipes over the last 20 years.

However, creating a new national network of hydrogen supply to the country’s homes would be a monumental and extremely expensive challenge that has never been done before. Concerns also exist around the extraction of hydrogen at this scale, as it is likely to be extracted from methane.

The extraction process emits carbon emissions which must be contained and stored through carbon capturing. Carbon capture projects of this scale do not currently exist and the idea is still under development, raising concerns around greenhouse gas emissions as a by-product of hydrogen extraction.

Final Thoughts

It is clear that the challenge of reducing building emissions is no longer just about grand intentions and targets. Whilst these are important to commit to, focus must now turn to ironing out the practicalities of how these will be achieved.

At the moment, the only established technology able to deliver clean heating is the heat pump. Yet, the UK has the worst heat pump sales and second worst installation record in Europe for a country its size. Technology such as hydrogen has potential but is still in the very early stages with many unknowns.

The UK must speed up investment in these industries to meet ambitious targets, with more detail, support and incentives for consumers.


Further reading: more on energy efficiency and decarbonisation from The Knowledge Exchange blog:

Plugging into the future: can electric vehicles clear the air?

“Electric Car2Go”by mikecogh is licensed under CC BY-SA 2.0

Science tells us that improvements to our air quality bring real health benefits – fewer heart attacks, strokes and premature births, less cancer, dementia and asthma, and lower incidences of premature deaths.

Better health because of cleaner air has been a strong driving force behind efforts by local and national government to keep highly polluting vehicles away from city centres, where air quality can be especially poor.

Earlier this year, we blogged about initiatives to improve the air quality of cities by banning the most polluting vehicles that emit dangerous levels of nitrogen dioxide and poisonous particulate matter.

Driving out diesel

There have also been important policy announcements to underline how seriously national and local authorities are taking the issue of air pollution. In July 2017, the UK government announced plans to phase out the sale of new diesel and petrol cars by 2040, with all fuel-powered vehicles to be banned from the roads entirely by 2050. Shortly afterwards, the Scottish Government unveiled plans to ban new petrol and diesel vehicles by 2032 – eight years ahead of the proposed deadline set out by the London government. These moves replicate measures introduced by France and cities such as Amsterdam, and Hamburg.

Electric currents

As diesel and petrol cars are phased out, alternatives, such as battery electric, plug-in hybrid electric and hydrogen-powered vehicles are moving in. These have a lower environmental impact and could also help the UK to meet its target of net zero carbon dioxide emissions by 2050.

At present, electric-powered vehicles make up a small part of the UK car market – just 0.9% of new cars are electric. But sales of electric cars have been rising – in June 2019 there was a 61.7% increase in battery electric vehicles registered in the UK, and in July electric car sales continued to accelerate (meanwhile, diesel registrations fell for the 28th consecutive month). This trend is set to continue as car manufacturers in the UK and overseas invest more in electric vehicle production.

Diesel and petrol cars could be phased out much more quickly if more drivers could be persuaded to go electric. But many are still reluctant to make the switch due to concerns about the distances that electric cars can travel between charges (the electric Volkswagen Golf, for example, needs recharging every 120 miles) and the availability of a robust charging infrastructure. But for most drivers, the leap in costs of switching to electric has proved the major stumbling block.

In the UK, the government has cut subsidies and grants for some hybrid and electric vehicles, leading to a slump in hybrid sales. By contrast, Norway’s government is leaving no doubt that they want drivers to turn away from diesel and petrol cars. The Norwegian government has backed up its ambitious goal to stop selling new gas and diesel passenger cars and vans by 2025 (15 years ahead of the UK government’s target) with incentives to go electric. These include tax breaks for electric cars, access for electric vehicles to fast-track bus lanes, plus discounts on parking and charging. Drivers are getting the message: in April 2019, almost 59% of all cars sold in Norway were electric.

Other countries are also joining the electric vehicle bandwagon, including France, the Netherlands, Germany and the world leader in electric mobility, China.

Meanwhile, in 2018, the House of Commons Business Select Committee said the UK government’s plans to ban diesel and petrol emitting vehicles were “vague and unambitious”. The committee was also critical of the subsidy cuts and the lack of charging points.

Putting the brakes on: the downside of electric vehicles

Electric vehicles have the potential to bring significant benefits to the UK economy, and many believe that Britain could become a world leader in electric car production. But this would require large-scale lithium-ion battery cell plants facilities. There are currently no plans for these in the UK, while China and Germany are setting the pace on battery production.

Although electric vehicles have been heralded as an environmental good news story, manufacturing their batteries requires raw materials such as cobalt, the mining of which has considerable environmental and human costs. At the same time, the electricity used to charge the vehicles is largely generated from fossil fuels. And, just like petrol and diesel vehicles, electric cars produce large amounts of pollution from brake and tyre dust.

Green for go?

Despite the drawbacks, electric vehicles are on the move. Manufacturers are launching new ranges to meet increasing demand and to comply with EU rules on carbon dioxide emissions limits. The International Energy Agency predicts there will be 125 million electric vehicles in use worldwide by 2030.

In Britain, the charging infrastructure is already growing, and  set to improve, further. The UK government is also proposing that all new-build homes should be fitted with charging points for electric vehicles. The Scottish Government has announced plans to make the A9 Scotland’s first fully electric-enabled road, and the city of Dundee is already making progress on zero-carbon transport. Meanwhile, in London Mayor Sadiq Khan has pledged that all London’s taxis and minicabs will be electric by 2033.

But, as a July 2019 report from the Centre for Research into Energy Demand Solutions (CREDS) warns, electric vehicles will not address the problems of congestion, urban sprawl and inactive lifestyles. The authors recommend that governments should be doing more to discourage people from driving, and shifting the focus of travel to more sustainable modes, such as walking and cycling.

Electric cars may help clear the air and bring subsequent health benefits. But they won’t drive away all of the challenges facing our motor-centric cities.


If you’d like to read more on this subject, take a look at our previous blog posts…