When the UK Government first became sensitive to the importance of curbing greenhouse gas emissions, much of its effort was directed at moving from coal-fired electricity generation to wind farms and gas-fired plants. Gas was still a fossil fuel but it was self-evidently cleaner than coal.

One of the consequences of that early emphasis is that councils in cities with notably poor air quality tend to focus all their efforts on curbing transport emissions.

However, David Pearson, director at the heat pump and district heating specialist Star Renewable Energy, points out that not all of the emissions in cities comes from transport. As much as 50% is down to the gas-fired boilers and gas CHP (combined heat and power) that provide hot water and heating to residential and commercial buildings.

“The Scottish and UK Governments are committed to lowering the country’s carbon footprint. One obvious way of achieving a major step forward in achieving this would be to go for a wide-scale implementation of district heating for as many of the commercial buildings in city centres as is feasible,” Pearson says.

“Take Glasgow city centre. The Scottish Government’s carbon reduction targets are not going to be met unless we stop burning gas in the centre of major cities like Glasgow and Edinburgh within the next 30 years. Schemes that have used engines to deliver heat and power have actually increased the local nitrogen oxide [NOx] emissions and
with wider electricity decarbonisation have seen their carbon dioxide [CO2] emissions for heat rise by around 700% in five years,” he says.

Mr Pearson argues that it is only by managing to reduce dramatically the number of gas-fired boilers in city centres that we will achieve a major reduction in greenhouse gas emissions, while at the same time removing a major source of demand for gas. This in turn will bring about a major improvement in the air quality in city centres.

HeraldScotland: Renewable district heat pump technology nominated twice for top industry awardsRenewable district heat pump technology nominated twice for top industry awards

“Councils and the public all tend to assume that NOx and CO2 come from transport, but burning gas for heating and hot water creates a huge amount of greenhouse gases, probably more than transport,” he says.

The problem in moving forward to fix existing individual buildings with alternatives to gas boilers, such as ground-source heat pumps, is tricky as high-rise office blocks and large hotels have quite a small footprint on the ground by comparison with the number of people that use them. Heat pumps work better if feeding a network of hot water pipes to get the job done.

The owners of large hotels in Glasgow, for example, would find it far easier to join a district heating network than heavily remodel their own systems. “If you are looking to cut the carbon footprint of these kinds of buildings, solutions like better insulation will only drive at best around a 20% improvement, not a 100% improvement. The only way you are going to get to a 100% reduction is through connecting up multiple buildings via a district heating scheme,” says Mr Pearson.

The problem, however, is that no developer or investor is going to start deploying a large-scale district heating system unless they can be sure of getting customers for their heat and hot water.

HeraldScotland: SOURCE: Studies suggest there is more than enough heat in the Clyde to satisfy the needs of the whole of central Glasgow.SOURCE: Studies suggest there is more than enough heat in the Clyde to satisfy the needs of the whole of central Glasgow.

And owners of buildings that currently use gas boilers have absolutely no incentive to switch to district heating – a solution they probably don’t understand and are not even thinking about.

Mr Pearson’s solution for providing the heat for new district heat networks is to take heat from the rivers that run through so many major cities around the world. This is something of a counter-intuitive proposal, since if you dip your hand in the River Clyde it will feel pretty cold to the touch. The average temperature of the Clyde through the
year varies from 5C to 10C.

However, heat pumps work off the same principle as refrigerators. They move heat from the cold area, in this case, taking say 2C out the Clyde and “pumping” it through the heat pump to accumulate heat to the point where the system can heat water to 85C.

Mr Pearson points out that studies show that a river like the Clyde can be a huge source of heat. There is more than enough heat in the Clyde to heat the whole of central Glasgow, and similar figures can probably be derived for many cities that are based on major rivers.

Mr Pearson argues that this approach would be far superior to even the Scandinavian models, a bold claim considering the fact that Scandinavia has been at the forefront of using district heating schemes to heat buildings and provide hot water. “In Scandinavia they are still burning gas in combined heat and power systems, at 1,300C to heat water to 60C. That is not an efficient solution,” he notes.

So how is it going to be possible to get from the present situation to one where Scotland and the UK deploys district heating on a large scale in major city centres?

The problem is finding ways of breaking the chicken-and-egg dilemma, where you can’t have a district heating system if you don’t have customers, and you can’t have customers until you have a joined-up district heating solution.

The solution lies in Government and councils grasping the nettle and issuing compulsory “improvement notices” on building owners. There are already instances of this. In London’s Olympic Park, anyone wanting to build a development in that area has to commit to connecting their development up to a district heating system.


It remains to be seen if there is any political appetite to mandate the use of city centre-wide district heating schemes.

There are some clear steps the UK Government could take. One is to continue the Renewable Heat Incentive. It plans to allow it to finish for heat pumps just as they are being recognised as the only clean solution for cities.

The Scottish Government needs to remove taxes which add 60% to the cost of district heat as the networks and energy centres pay a tax not levied on existing gas boilers.

Planning regulations need to be adjusted to grant district heating the same right of deployment as, say, cold water supplies or broadband.

However the biggest shift, says Mr Pearson, has to be in creating a phasedown on the use of gas. Issuing improvement notices on air quality to gas consumers which could be met by firm agreement to join district heat networks would bring hundreds of millions of investment into this market.

For more information please vist www.star-ref.co.uk

This article appeared in The Herald's annual editorial review of Scotland's Renewable Sector on the 30th April 2019, which you can view online by CLICKING HERE.