CARBON AND ENERGY SAVING
we must expect to see CHP carbon- saving performance fall away as the annual average grid carbon content reduces.
Solutions during ‘Stage 2’ For solutions that fall into Stage 2, we should see much smaller CHP capacities that are ‘heat-led’ rather than electricity- led, such that they modulate downwards in output, and even switch off when there is low heat demand, and may not operate at all in the summer, unless a viable alternative use of the heat can be found, such as for space cooling using heat- powered absorption chillers, or thermal stores that can store the heat for reuse later in the day.
Removal of steam requires replacement equipment in plant rooms, as well as laying new LTHW heat mains. This is a significant investment, and while saving energy and carbon, the payback is not short term, although it often yields large backlog reductions, which can help improve financial viability. Conversely, the cash release savings from CHP are still anticipated to be significant, due to the ongoing spark gap (the difference between electricity and gas costs). This significant cash-saving ability means that CHP remains an interim measure able to help underpin concurrent investment in modernising heat infrastructure, making overall energy project schemes with shorter paybacks than would otherwise be seen, and delivering the foundation that will be compatible with emerging lower carbon technologies.
Considering air quality
It is also important to consider air quality, since all fossil fuel (and biomass) plant is an emitter of NOx, impacting air quality and human health, and thus directly relevant for the NHS. It is possible to limit the NOx impact from modern gas boilers and CHP using ultra-low NOx plant and catalytic reduction, although these measures may impact upon operational costs, so they should be factored into net savings.
Stage 3 – Medium to long term An acute hospital site that has developed an efficient low temperature distribution network with efficient low NOx gas boilers, heat pumps, and/or heat-led CHP, will be well placed to accept future further decarbonising technology as it starts to become more commercially available. This technology is likely to comprise higher temperature heat pumps, electric boilers, and hydrogen fuel cells. Some of these are available now, but their implementation or running cost makes them generally unaffordable. However, this will change in the next few years, as investment costs come down, while energy prices rise.
44 Health Estate Journal June 2020
A switch to hydrogen or bio- methane fuelled plant The shift away from a fossil fuel- dominated heat supply may ultimately see the retirement or conversion/ adaptation of gas boilers and gas CHP installed in Stage 2, in favour of hydrogen or bio-methane fuelled plant, as well as the introduction of more efficient hybrid heat pumps and hydrogen fuel cells in Stage 3. All of these solutions
Stephen Lowndes
Stephen Lowndes BEng (Hons), MSc, CEng, MCIBSE, MEI, has many years’ experience of energy project design, as well as supporting operational management, including carbon and energy management within the public sector that started with NHS projects in the 1980s.
A Chartered Engineer and Certified Measurement and Verification Professional, he leads the Carbon & Energy Fund technical delivery team, working on all aspects of project feasibility, through to construction and operational delivery.
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Any switch from fossil fuel over to low carbon electricity needs to consider the impact to the local electricity supply network and onsite power distribution
Any switch from fossil fuel over to low carbon electricity needs to consider the impact to the local electricity supply network and onsite power distribution, and the risk that local capacity limitations will govern how much electricity can be used to provide heat. For this reason, it is likely that significant levels of solar PV generation will need to be adopted onto sites alongside battery storage. These technologies will assist in reducing the increased power consumption resulting from a move from gas to electricity heating, with battery storage helping to attenuate peak electricity load. To be effective, the amount of solar PV deployed will need to be significant, and the cost of implementing at scale needs to reduce sufficiently – so that solar PV car park canopies, as well as building- mounted arrays, become more affordable. Battery storage technology is also an area seeing rapid growth, and more sustainable models, that utilise recycled electric vehicle batteries to repurpose as power management solutions.
will be feeding heat to buildings utilising the same low temperature energy infrastructure deployed in Stages 1 and 2 described earlier.
Conclusion
It’s clear that a ‘do nothing’ approach is not an option, since there is a mountain to climb to hit 2030 targets, let alone 2050 net zero, and this needs to be tackled in achievable and affordable stages. If the investments made at each stage are strategically planned and delivered in a way that delivers a guarantee of affordability, then getting close to 2030 targets and 2050 net zero become more realistic, and a way forward more believable. From this standpoint can be seen the benefit of strategic investment in the fundamentals of a future-proofed energy infrastructure that can be started now (Stages 1 and 2), that maintains savings throughout its life, and is ultimately adaptable and capable of taking advantage of future technologies as they come on stream during Stage 3 and beyond.
References 1 Committee on Climate Change – UK carbon budgets [
https://tinyurl.com/ y9ej5c7u].
2 The NHS Long Term Plan. NHS UK, January 2019 [
https://tinyurl.com/ y6dzmk2o].
3 Carding N. First region targets 2030 for net zero carbon. Health Service Journal, 10 March 2020 online [
https://tinyurl.com/yb3xv25c].
4 Reducing UK emissions 2018 Progress Report to Parliament. Committee on Climate Change, June 2018 [
https://tinyurl.com/y9v4sddh].
5 Enabling the Gas Markets Plan 2019/2020. National Grid Gas, 2019 [
https://tinyurl.com/y85odx77].
6 Hydrogen in a low-carbon economy. Committee on Climate Change, November 2018 [
https://tinyurl.com/ y88nhr8w].
7 Carbon & Energy Fund project feasibility studies.
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