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:

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