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Green heat: not all going to plan

By Dave Elliott

A new report ‘Policy for Heat: Transforming the System’, from Carbon Connect, follows a cross-party inquiry chaired by Shadow Energy Minister, Jonathan Reynolds MP, and Conservative MP Rebecca Pow. It argues for the better development and greater integration of policy on low carbon heat, energy efficiency and new-build homes. It notes some big problems with current programmes, not helped by the scrapping of the Green Deal and the Zero Carbon Homes policy.

The situation certainly looks fraught: ‘the UK has a relatively low installation rate of retrofit energy efficiency measures and struggles at assessing the efficacy of its policies. Partly as a result of this, an estimated 4 million households in the UK in 2011 were unable to afford to heat their homes’.

The Renewable Heat Incentive (RHI) still survives, but the report says it ‘has not realised the uptake figures originally projected. At current levels, the RHI is not effectively driving low carbon heat. The recent scrapping of the zero carbon homes standard and the Green Deal energy efficiency scheme has created even greater pressure for the RHI to deliver. However, as currently constituted, the RHI is not designed to encourage a widespread deployment of low carbon heat technologies but rather is designed to foster more practical experiences of renewable heat options’. Sounds like it would prefer district heating. It says that the development of district heat networks ‘has been too slow in the UK, with a lack of an overarching strategy from the Government. Decision makers are still reinventing procedures and trying to overcome obstacles, when it should have been possible for networks to have been developed earlier and faster’.

Nevertheless it sees electric heating as still the key, although it has problems. The report notes that, ‘with many future energy pathways in the UK relying heavily on the electrification of heat, there is a need to re-inforce the electricity networks. Local energy plans will need to take into account information regarding the costs and feasibility of upgrading electricity networks, requiring coordination between local authorities and network operators. Smart-grid technologies will help manage impacts on electricity networks as well as unlock other benefits such as demand side response and distributed energy storage’.

However, it does also mention what some see as a better approach – the use of low carbon gas rather than grid power, although it stresses ‘the significant uncertainties regarding the availability and costs of the different low carbon gas energy solutions in the future, as well as their best uses in the energy system’. But green gas/SNG options are expanding. And in system terms, heat demand exhibits huge daily and seasonal swings, much larger than those for electricity demand, which would be hard for electricity grid-based systems to meet. The gas grid handles 3-4 times more energy than the power grid, and also provides major storage and balancing services. But then lurking in the background, maybe Small Modular Reactors might provide nuclear-derived urban heat!

Actually though, the report mentions a different ‘SMR’ option – Steam Methane Reformers – for hydrogen production. That seems a bit old hat, given the rise of power-to-gas electrolysis, but it does briefly mention newer ideas like this for hydrogen and syngas production, although it seems to link the prospects for that to the success or otherwise of Carbon Capture and Storage, which would provide the CO2 feedstock for converting hydrogen, produced perhaps using surplus wind-derived power, to synthetic methane. It’s not clear if hydrogen or synthetic methane is the best option – maybe a mix, added to fossil gas in the gas grid. The report says ‘there are opportunities for innovative approaches to the mix of gas used in the system’, but says there are implications for pipelines and end-use devices, although these are being studied. Certainly there have been examples of mixes with high hydrogen content, including the UK’s old town gas. But the report says more research is needed and that ‘the requirements of hydrogen, along with other low carbon gas sources, need to be considered and integrated into current planning on gas networks’.

Overall, the report outlines a range of possible new and revived technical directions: e.g. although it doesn’t see much merit in solar heating (given its high carbon abatement cost), it sees potential gains if Combined Heat and Power (CHP) was ‘relaunched with greater emphasis on decarbonisation’. And, politically, it says Local Authorities need to be more involved with energy planning. Well, even just judging by this report, they could hardy do worse than central government!

Some similar points on green heating were also raised in a broader study of UK energy policy by the ICEPT team at Imperial College London. In particular it called for ‘a long term, effectively targeted investment programme in residential and commercial buildings to reduce energy demand for space heating and hot water’, and ‘plans at a local level for the potential use of heat pumps and district heating’. It was, however, more forthright on the potential role ‘for ‘decarbonised’ gas to allow continued use of valuable gas network infrastructure and storage’. It stressed that it was important to properly consider the inherent value of the gas networks that today provide an almost uniquely flexible part of the energy system – not only delivering the energy needed, but also the ability to transport and store the fuel to meet the un-paralleled extremes of daily and seasonal heat consumption patterns, at the same time capable of bridging use across the three main sectors of heat, transport and electricity’. And it noted that ‘research has started under Ofgem’s Low Carbon Network Fund (LCNF) and Network Innovation Competition (NIC) to examine the potential to re-purpose the gas networks for gasses other than natural gas, e.g. biomethane from anaerobic digestion, hydrogen and synthetic natural gas (SNG), as well as on ‘power to gas’ where excess electricity from renewable sources could be used to produce hydrogen at low cost rather than being constrained off the system at times of high output and low demand’.

However, it said if these options were not taken up, and ‘if there is a more limited future for the gas network’, then ‘serious consideration must be given to the costs and implications of replacing these intrinsic properties in some other way’. Heat pumps were one of the main proposed approaches at present, replacing gas boilers, but ICEPT worried that, quite apart from the extra electricity demand aspect, at peaks especially, and the need for costly power grid upgrades, heat pumps were ‘currently more expensive than equivalent gas boilers and, despite their efficiency, heat pumps will only perform effectively and economically in well-insulated buildings and may require a change to the internal radiator system, the costs of which must also be considered’. In addition, there were operational issues: ‘the performance of air-source heat pumps is particularly dependent on the ambient temperature and falls off rapidly at lower temperatures’.

It was more sanguine about district heating: ‘Shared heat systems, due to economies of scale, can be much more efficient in the production of heat, can significantly lower electricity system peak loading’ and ‘may also more readily incorporate options for storage which can reduce peak demands’. They could be fed using a variety of heat sources, including green gas, with changes in source involving ‘no disruption to individual users fed by the heat networks.’  There were also system integration benefits: ‘the amalgamation of district heating with Combined Heat and Power (CHP) and renewable electricity generation can prove a valuable means of balancing supply and demand across the heat and power sectors’.

However, it was all still in flux: ‘there is no consensus on the exact proportions of the differing heat supply solutions’, and ‘no clear consensus amongst scenarios on gas and gas network use for heating in the 2020s nor what will happen beyond 2030’. But some favourites seem to have emerged. And, given studies like this, the options for green heat may be a little clearer.


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