80% of heating in Ireland can be done using heat pumps, with geothermal as a key energy source and store

Figure 1: Heat is the largest energy demand in the island of Ireland.

Both jurisdictions on the island of Ireland, Northern Ireland (NI) and the Republic of Ireland (Ireland or ROI) have big ambitions for their contributions to meeting the climate change challenge.  With respect to final use of energy, it is heating (and cooling) that is the largest component of energy use (Figure 1) and it is this sector that so far is proving hardest to decarbonise. With no or depleting fossil energy supplies on the island, decarbonisation is also now becoming equally important for energy security, energy poverty as well as sustainability.

So, what is the shape and size of the heat decarbonisation challenge?  What are the potential solutions?  What might a zero/low carbon future look like?  Let’s dig in!

Figure 2: The three main sectors of heat demand.

Industrial and Commercial is in both Ireland and Northern Ireland the biggest sector with respect to heat (Figure 2).  Next after that is Domestic or Residential with the Public Sector in third place.  Let’s take the smallest of these first, the Public Sector.

Figure 3: Distribution of energy demand for heating and cooling in the public sector.

Figure 3 shows the energy demand for heat summarized in three buckets, Healthcare, Education and everything else.  All these buildings of whatever size are serviceable by heat pumps instead of the mainly gas and oil fuels that are currently used.  Hospitals sometimes have higher temperature demands for laundry and sterilization of equipment, but this smaller load can now be dealt with industrial heat pumps that are coming on the market or with electric steam boilers.

Causeway Energies completed a geothermal assessment of one of Northern Ireland’s largest hospitals last year.  We found that all the site’s ~8 MWth of heating could be provided by around 4 pairs or doublets of open loop geothermal abstraction and reinjection boreholes.  The hospital intends to heat and cool its newest building with geothermal heat pumps.

Schools are also ripe for geothermal heat pump solutions, from small primary schools in rural settings to large secondary schools in urban settings.  Educational buildings also provide a wonderful opportunity to demonstrate to the pupils and their parents the potential and the benefits of low/zero carbon energy solutions including geothermal which even when deployed is often not known about because of its negligible surface footprint.

Indeed, the public sector in general is currently a substantially missed opportunity to demonstrate climate action and energy policy execution at the same time.

Figure 4: Oil still dominates the Irish residential heating scene.

Domestic heating is an enormous decarbonisation challenge in Ireland.  It is not just a technical and economic challenge, it’s also political since past and recent investment in the natural gas infrastructure is driving the owners of those transmission and distribution pipelines to research and progress possibilities to flow green gas through the system, even in the face of substantial hurdles such as technical risks, scaling problems and concerns of cost escalations.

Hence in both jurisdictions there has been and continues to be much attention paid to biogas, biomethane and green hydrogen for injection into the fossil gas transmission and distribution system.  We consider this focus to be to the detriment of readily available and proven technologies to replace oil and gas in homes, namely heat pumps.  This point is further enhanced by the observation that most homes in both ROI and NI are currently serviced by oil and are not connected to gas.  Hence those homes are natural candidates for heat pumps, rather than being hooked into fossil gas on the hope of some day that being decarbonised.  As further discussed below, we believe green molecular fuels or energy vectors should be conserved for hard-to-abate sectors, typically very high temperature processes, and for long duration energy storage.

Air source heat pumps are often a good solution for homes, but because of the significantly greater efficiencies of their geothermal (or ground source) sisters, we believe that both governments should be promoting heat networks and geothermal or aquathermal sources, particularly for larger demands  The lure of lower capital costs of air source systems compared to geothermal must be balanced with considerations of gross and peak demands of electricity from the regional grid which is already forecasted to be declining in resilience and demand cover over the next few years.

To take advantage of the most efficient energy systems in Irish homes it seems to us very clear that large investments to support demonstrators, pioneers and early adopters in these globally proven but yet sadly locally underutilised technologies are required.  Particular attention will be needed for the development of a capable supply chain with sufficient capacity and oversight to develop a quality, systematic and continuously improving approach to deployment.

Figure 5: Heat energy demand by temperature range and by industry sector in Ireland.

Figure 5 illustrates the SEAI’s findings on heat demand use by industrial sector and by temperature range in Irish industry.  Unfortunately, there isn’t an equivalent dataset for industry in Northern Ireland, but there are a similar range of sectors, perhaps with a bias towards lower temperature manufacturing.  We do know that NI appears to be about two thirds of the ROI for industrial heat (Figure 4).

Current heat pump technologies and those rapidly moving down the path to commercialization can comfortably cover up heat demand up to 150 ºC and higher still sink temperatures are possible. Hence 40% of heat use in Irish industry is within the scope of heat pumps.  We believe that this is an opportunity to focus heat pump technology applications on these demands, as well as the other sectors discussed above, so leaving our renewable heat sources that involve very high temperature combustion (biomass, biogas, biomethane, green hydrogen) or electric arc technology to take care of the rest.  We also support research into using molecular vectors as agents for long term storage of energy to meet the challenges of intermittency and variability in wind and solar.

Figure 6: Transformation od the current fossil fuel dominated system into a Low/Zero Carbon Future for heat in the island of Ireland.

The results of such a systematic approach to decarbonising heat in Ireland are speculatively illustrated in Figure 6.  Again, this is ROI only, as we don’t have the same granularity of data for the current state in NI at present.  But again, the picture will be similar for the whole island.

The projection method here is take all current fossil fuel heat below 150 ºC and convert it to heat pump applications.  In so doing, we assume an average Coefficient of Performance (COP) of 3 for our heat pumps in this transformation.  Therefore, we add on to electricity demand in replacing the fossil fuels, but only one third of the previous use of fossil fuel energy at the point of application and that is without allowing for further end-to-end efficiencies from electrification of heat.  For higher temperatures, we directly substitute fossil fuels for a range of lower carbon sources or in the case of green hydrogen a vector for clean electricity.

So, use of in front of the meter or imported gas, oil or coal is radically reduced, to be replaced with thermal energy from local and indigenous sources – the light green bars in the right-hand side projection in Figure 6.  Depending on the carbon intensity of the electricity used in our future projection, the emissions will be somewhere between zero and 30% of today’s state.  This future is available to us, the technologies proven and their cost-effectiveness assured so the path to this future can be measured in years not decades.

Our Mission at Causeway Energies is focused on the decarbonisation of larger demand heating (and cooling) in the sectors described in this article.  We are building a portfolio of clients in the commercial, industrial, public and heat network sectors.  We are also developing leading edge technologies to improve the bandwidth, efficiency and cost effectiveness of geothermal + heat pump applications.