Soil energy is the ideal renewable energy source for hospitals

On Wednesday, Oct. 9, the Soil Energy User Platform organized the workshop "Energy Transition and the Role of Soil Energy in Hospitals. And that role proved to be particularly important. Indeed, according to many attendees and most speakers, soil energy is the ideal sustainable energy source to eventually get hospitals completely off the gas. The workshop took place at the Spaarne Gasthuis in Hoofddorp; a fine example of a hospital where soil energy plays a crucial role.

The Spaarne Gasthuis has had an ATES system at its disposal for many years. But for several years now, the ATES system has been renewed and has therefore become much more effective, resulting in a very sharp reduction in gas consumption. Moreover, there is still a lot of potential that the hospital's technical manager, together with his consultant and technical service provider, Ates Control, want to mine in the coming years. Eventually, it should then be possible to balance the soil resources and completely disconnect the gas-fired boilers and water heaters.

Accordingly, the workshop afternoon began with a presentation by Cor Wegman, the team leader of technical services at the Spaarne Gasthuis, and Sander van der Wilt, employed by Ates Control and active in that role for the hospital in Hoofddorp. The hospital has two doublet systems of 150 m each³/h. Before the renewal, there was one heat pump with 350 kW of heating power and a cooling system through the air handling units based on the ground source totaling 841 kW. There is also a central heating network fed by a steam boiler and a hr boiler. The problem with the old plant was mainly that cold charging did not work sufficiently well. The winters are not cold enough and the heat pump did not perform enough so that on Jan. 1, 2024, there was a heat surplus of 7.1 GWh. A surplus that has grown to this size since 2014.

Since the installation needed to be replaced anyway, this turned out to be a good time to take a close look at the total configuration of the installations. With the help of Ates Control, the system was extensively analyzed. This revealed, among other things, that the heat pump is stopped between an outside temperature of 8 and 16^oC. The objective of the new design had several guiding principles.

Finally, a new system was implemented in which the heat pump provides 3,395 MWh (or 65%) of heat. The flue gas cooler and the central heating boilers now provide more than 30%. In the coming period, the hospital is still looking at implementing a booster heat pump to supply central heating in the summer and tap water supply. If these measures are possible, the hospital could eventually go gas-free.

An important conclusion, Sander van der Wilt of Ates Control told us, is that the knowledge of the hospital's Technical Services Department was indispensable in designing the new, more efficient installation. Good communication and cooperation with the control engineers - in this hospital that is Sauter - is also a must. In addition, you have to analyze very well in advance which customers there are and what requirements they have. Good monitoring is also essential because it gives you insight into the possibilities. Finally, Van der Wilt said, you have to continuously improve such a system in a hospital. For that too, sufficient and proper knowledge in the technical department is indispensable.

After this practical case Stefan van Heumen of TNO was allowed to give an analysis of the level of sustainability at hospitals in the Netherlands in general. For this analysis, the figures from the Care Sustainability Expert Center are important. The Cure portfolio roadmaps have been submitted to that expertise center, and a lot of information can be gleaned from them. For example, a total of 92 portfolio roadmaps were submitted by 8 UMCs, 63 general hospitals and 21 categorical institutions. 80 of those 92 roadmaps have now been finalized, 59 of which have been adopted administratively.

It is noteworthy, for example, that the number of square meters (currently 9.45 million m² gross floor area GFA) to 2030 is decreasing by 6%. The planned new construction until 2030 is now in the picture, but the picture for the years beyond is not yet universally clear. The gas consumption of the 92 institutions that have now submitted the roadmap averages 28 m³ per m² GFA. The projections submitted by the institutions show that gas consumption will decrease to an average of 10 m³ per m² bvo. The CO₂-emissions from all these hospitals will be about 68% lower in 2030 than in the base year.

What will increase in hospitals in the coming years, however, is electricity use. Currently, hospitals use an average of 102 kWh per m² GFA. Power purchases are projected to increase to an average of 136 kWh per m² GFA. Compared to the base year, total electricity use increases by 26% in 2030. However, own electricity generation through PV plants goes up from 19,725,000 kWh now to 51,603,000 kWh in 2030. This is about 9% of all electricity purchased.

Of all 92 hospitals, 33 plan to scale down their CHP systems by 2030. As many as 41 hospitals already have or will commission a CHP system by 2040. 28 hospitals have or will get a connection to a heat network before 2030. The enthusiasm for using aquathermy and geothermal energy is low. Only 4 hospitals have or are investigating one of these technologies. Heat and cold storage is seen by many hospitals as the solution for reducing direct CO₂-emissions.

After these figures, it was time for another practical case, that of the Maxima MC in Veldhoven. Mark Raaijmakers works 3.5 days a week for this hospital as an energy and sustainability specialist. He calls himself a true 'WKO-believer' and is trying to get the hospital's bivalent energy system - currently 70% with WKO and 30% gas-fired - fully monovalent and thus on ground energy. In recent years, the hospital in Veldhoven, neighboring ASML, has grown substantially from 44,000 m² to 97,000 m². Maxima MC's power plant has been operating on soil energy since 2010 but its performance was poor, Raaijmakers said. The capacity was only utilized for 50%. There was a balance in the soil, but the storage of heat and cold was very low. The COP of the heat pumps was only 2, while according to the specs it could be 4.2. In short, the (energy) exploitation was so poor that the investment was not recovered.

A whole series of modifications were then made to the above-ground design of the system. The control and regulation were also greatly simplified and the building installations optimized. This has already led to achieving the theoretical capacity of the ground installation, and the heat pumps are now also operating at their maximum COP of 4.2. This simpler installation also improves operations and management. And the degree to which heat and cold are now stored in the soil is substantially higher. As a result, Maxima MC has reduced its energy consumption by 54% compared to the old situation in 2010. The direct CO₂-emissions was reduced even more, by 64%, even though the Maxima MC has more floor space compared to the baseline year 200%.

To grow even further, the hospital has applied for a permit for a second soil doublet. As early as 2030, the hospital wants to meet the 2050 target set by the Paris Climate Agreement. By 2028, Maxima MC wants to be an all-electric hospital. Thus, 20 to 25% of total annual electricity needs will be generated by the 16,000 m² pv panels. Also, the hospital's entire heating and cooling needs must come from the ground, including heat and water generation. To give attendees a few more tips, Raaijmakers had listed what was initially wrong. For example, half of all valves and pumps in the above-ground system turned out to be redundant. There was also control stacked on control, instead of one main control for the entire plant system. The design did not appear to be matched to the building, so the entire system could have been built for half the investment. "In short, use the KISS principle: Keep it Simple & Stupid," Raaijmakers concluded his presentation.

After a short break and a visit to the technical installation room of the Spaarne Gasthuis, Romy Stijsiger and Niels de Groot of IF Technology were given the floor. Their company is involved in numerous soil energy projects in the Netherlands in many roles. If one component is crucial in all of these activities, it is employee knowledge. Anyone starting a soil energy project must not only acquire the knowledge, Romy and Niels explained, but also know where to start and what to focus on. IF Technology employees mentioned five things you can steer on: Comfort, Sustainability, Effort, Cost and Security of Supply. Next, you need to have a good understanding of what management will look like. Here they distinguish between Energy management, Technical management and Legal management (BRL, environmental permit, etc.). And finally, every owner of a soil energy system has to think about a division of roles at Operational, Tactical and Strategic levels. All these topics make it clear that a lot of knowledge is needed within an organization if you want to secure all this within a hospital independently.

IF Technology helps many organizations provide knowledge and services. To that end, the company has "three flavors" by which it can keep its knowledge level up-to-date: Bronze, Silver or Gold. With a Bronze support package, the company provides light support and periodic checks. The Silver package provides regular support, periodic checks and staff training programs. And the broadest service, Gold, offers comprehensive support, periodic checks, staff training programs and a broad form of relief.

The final speaker during this afternoon was Kevin Kanters of Hydroscope, a company that falls under Brabant Water and is a sister company of Hydreco, operator of CHP systems. Hydroscope focuses on preventing legionella infections. Kanters began his presentation with worrisome figures. In the past decade, the number of reports of pneumonia caused by legionella has risen sharply: from about 300 in 2013 to more than 600 in 2021 and 2022 and even 850 in 2023. The reasons for this increase include the warming of our climate, demographics and better source investigation. Sources are more often wastewater treatment plants, cooling towers and bathing facilities, while drinking water systems are the culprit in only limited cases. At the same time, it is worrisome that healthcare facilities and hospitals are above average in sample results.

Kanters then addressed the need to bring hot water to at least 60^oC to heat up. As we increasingly use heat pumps, and want to use them for domestic hot water heating as well, there are voices calling for that "safe 60^oC' to be allowed to set slightly lower. In any case, that would greatly improve the efficiency of heat pumps. He therefore posited the proposition that 50^oC is safe enough. Many people could go along with that. Others felt that you should still keep the option of raising the temperature to 60^oC to be upgraded.

At the same time, Kanters also advocates designing domestic hot water systems differently or applying other methods of hot water preparation. If we use fewer collective hot water preparation systems, there will also be less need for those 60^oC limit. Administrators should also take a hard look at whether all those hot water taps are so necessary. Cor Wegman of the Spaarne Gasthuis, for example, explained that they have already removed the hot water supply in many places and installed decentralized hot water heaters in others. Various local hot water generators were reviewed: electric instantaneous water heaters, hot water taps, fresh water stations and salt water batteries.

Finally, Kanters discussed a number of legal regulations and intended changes in, for example, the Drinking Water Decree. The question is whether these will offer much additional space in the coming years. Developments with drinking water that may offer more room for sustainability is the utilization of energy in drinking water. Cooling drinking water back lets the knife cut both ways. Colder drinking water is safer and the heat you extract can potentially be used for space heating. There are also already systems that structurally extract heat from drinking water and use that energy as a source for a heat pump or store it in a CHP system. Thus, extraction from drinking water can also be useful to help restore an imbalance in an ATES system.