WITH governments and citizens across the globe becoming ever more focused on the need to cut carbon emissions and avert climate disaster, deciding which interventions will work now, in which circumstances, is crucial.
Dave Pearson, Director of Star Renewable Energy and a past Chair of the European Commission’s “Renewable Heating and Cooling Platform” warns that the options chosen will have a major bearing on how successful we are in achieving carbon reduction targets in a timely fashion. “Three things are crucial in considering what we should be doing to de-carbonise heat. Firstly, what segment are we aiming at? Secondly what is available now, and thirdly, what needs to change to make it happen? Wrapped in amongst this, though, are questions around how to deliver these paradigm shifts in consumer practice,” he says.
Pearson points out that today gas is the primary option when it comes to heating. There is a world class skills base around gas, and past attempts at alternative approaches to heating, such as the fad for wood-burning stoves have proved to be dead ends now mired in air quality issues.
The Westminster government, for example, has already announced impending legislation against the sale or use of ‘wet’ wood. The Scottish government is preparing a consultation paper with a view to introducing similar legislation. “We need solutions which are locally clean as well as globally clean,” he warns. Ignoring the gas industry skillset compatibility with “ready now” clean solutions, such as heat pumps, ends up in a slow morass of inactivity. At worst it can lead to wrong turns, dead ends and unacceptable failings. Gas engineers already have the plumbing, controls and electrical hook up skills required for heat pumps,” he says. “Allowing those skills to be deployed in further gas installations just delays progress.”
So what should we do? He identifies five heating ‘segments’ that require a rethink. New build homes; new zones in cities; the stock of existing houses; existing city buildings and industrial processes.
For new build homes, the most obvious solution, he says, is to switch from the present focus on gas boilers to heat pumps of one sort or another, be they air-based or ground-based. Heat pumps installed today, will still be operating well in 2045, providing a cost effective, viable solution to the emissions issue, he argues.
When it comes to deciding which heating option to go for, what the consumer will want, Pearson says, is one that delivers the least maintenance, the longest replacement interval and the lowest running cost, along with the best reliability. He points out that air source heat pumps are subject to the external elements. This can include dirt on heat exchangers or even snow. Ground source pumps require a bore hole, but he argues that the costs of bore holes, given they take approximately 16 hours to dig but spread over three days, are hugely open to efficiency gains when multiple plots are adjacent.
“A well organised builder could arrange a rig at each plot for 16 hours each, moving plot to plot. This means no need to prepare the site for gas. The advantage of ground source is a constant source of heat, night and day, so best suited to buying off peak electr icit y which is now available on half hourly variable tariffs,” he notes.
Overnight this can mean 6p/kWh electricity delivering three units of heat so 2p/ kWh; very similar in base cost to gas. Similarly, existing single-family homes, with modern heat pumps able to reach 60C, would still be converting one unit of electricity to three units of heat, even if the home insulation is sub-optimal. Pearson believes this segment will best be fixed with “heat as a service” contracts where a supplier undertakes all the work in exchange for a fixed monthly fee. Some additional insulation along with good controls to harness the cheapest electricity should produce a solution that is cheaper than gas.
Pearson adds: “Controls are key, a heat pump runs smoothly over several hours rather than in bursts, like a gas boiler.”
Perhaps the biggest challenge to securing progress, in a collective sense, are the existing zones in cities, Pearson says. He points out that this is an area that cannot be fixed by individual consumer initiatives. “It needs a co-operative approach and that needs surety as far as return on investment is concerned,” he warns.
In his view, investment funds would be happy to fund district energy schemes on a massive scale, but only if returns from heat sales were certain. Legislation relating to zoning of cities will pass through the Scottish Parliament this year. Consultations have discussed “obligations” to connect. “However,” he asks, “if you occupied a building in the centre of Glasgow, owned by a commercial landlord and the building was obligated to modify heating systems to connect to district heating but still had access to cheaper gas, would you use gas or district heat? “This shows an obligation alone is insufficient, but equally we aren’t going to see gas banned so we need an imperative to pollute less.”
This situation would still be positive for investors if legislation forced both the owner and the operator to reduce emissions by 10% per year.
It all comes back to government, or perhaps to local councils instituting “clean air” legislation for buildings, much as they now do for transport. Cities have called for Net Zero Carbon in 10 years, so they need to take action to make it happen. In doing so, any new buildings in cities will be better served by agreeing to join the emerging heating networks. Creating “stand alone” gap sites still using gas heating, just makes the job harder. “You need to create a demand for clean heat, deliver networks and supply the networks with the proven solution of river source heat pumps. That will allow a city to trend to zero carbon and zero local NOx.
Industry is going to be another tough nut to crack, Pearson warns, since so much of industry gas usage is to generate high temperatures. “Heat pumps are becoming available that can generate heat between 110 degrees and 150 degrees. Hydrogen won’t help here,” he says. “The idea of taking 1kWh of offshore wind and generating 0.5kWh of hydrogen and heat will never stack up financially when a heat pump solution would have delivered 3 kWh of heat from the renewable wind source.” he notes.
Hydrogen has a role in very high temperature industries. At the same time, storage technologies will be needed to generate electricity in lulls in wind production. The main message for consumers, industry, councils and governments, he warns, is that “business as usual is not an option”. However, a new paradigm represents opportunity and should be embraced, he concludes “but only if based on ‘deliverable now’ solutions before we have dithered any longer”.
For further information about low carbon heat in Scotland join the SDI webinar. Visit: www.sdi.co.uk/ news-features/webinars
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