Cross-sector Integration in dialysis
How can 100 % of photovoltaic electricity be consumed by the dialysis centre itself through Cross- sector Integration?
Christian Rohde, Partner at GreenTec Dialysis GmbH, started his presentation on Cross-sector Integration in dialysis at the 31st Erfurt Dialysis Conference with this question. To explore the answer to this question, he first explained an impressive correlation:
The electricity demand in a dialysis centre is high. An average centre with around 15,000 dialysis treatments per year has an electricity bill of over € 700,000 over a period of 10 years when supplied with conventional grid energy.
Solar power - times with a surplus and times when the sun is not shining
Reason enough to think about alternative power sources. Photovoltaics (PV) is a promising candidate, as the energy-hungry dialysis treatments take place during the day while the sun provides the necessary energy. Now there are rainy days when not enough solar power is produced and the demand still has to be covered by expensive grid electricity. On the other hand, there are times when the sun shines but there is no consumption, for example on Sundays or short dialysis days, and there is a surplus of renewable solar energy.
The solution could be the temporary storage of electrical energy, which is currently rather unprofitable due to the still very high prices for battery storage. The other option, feeding surplus energy into the public grid, is also not very lucrative due to the low feed-in tariff. Furthermore, the feed-in tariff can lead to a "tax infection of the business purpose" of dialysis, which entails considerable tax disadvantages.
At this point at the latest, the relevance of the initial question became clear to everyone listening in Erfurt: how can we manage to use as much of the photovoltaic power as possible in the dialysis centre itself?
60-65% of the energy requirement in the dialysis centre is needed to heat dialysis water.
To get one step closer to the answer, it is worth taking a closer look at the current collectors in the dialysis centre.
There is water treatment, above all reverse osmosis, which produces the permeate. In the dialysis machines, the permeate is mixed with concentrate to produce the actual dialysis fluid. This fluid is then heated to body temperature by the dialysis machines before it comes into contact with the patient's blood. Did you know that this heating process accounts for 60-65% of the total power requirement in the dialysis centre?
This is because around 320 litres of drinking water have to be heated from an average inlet temperature of 15°C by more than 20 Kelvin to a body temperature of 36°C for each dialysis treatment. The electricity consumption in a centre that carries out 15,000 treatments a year, for example, is a considerable 150,000 kWh.
This is where GreenTec Dialysis comes in, as electricity consumption can be drastically reduced by using renewable energy in the form of a heat pump (HP). From a conservative point of view, the heat pump is able to generate three kilowatt hours of thermal energy from one kilowatt hour of electricity. The energy required and therefore the costs incurred for heating the permeate are already reduced to a third. This process is not magic, but utilises the laws of thermodynamics in a clever way.
Fig.1 Savings potential and self-consumption without vs. with Cross-sector Integration in a dialysis centre
Figure 1 shows the process schematically. The energy generated by the heat pump is stored in a hot water tank. This means that the energy generated during the dialysis-free period is still available to the centre. In a heat exchanger system (HE.RO) specially developed for the dialysis process, the energy is transferred from the hot water circuit to the drinking water, which is heated from an average inlet temperature of 15°C to just under 30°C. This water is then fed into the circulation system. This water then enters the reverse osmosis system. This is where the pure water (permeate) is produced, which is channelled to the dialysis machines via the ring mains. The preheating of the drinking water is only active during the actual dialysis operation, not during the rinsing processes or downtimes, in order to prevent microbiological growth in the ring main.
Once the preheated permeate has reached the dialysis machine, the last few Kelvin required to reach body temperature are introduced via an electric current or the integrated heat exchanger. At this point, however, only a delta of a few degrees is required instead of the usual 20 degrees per litre of heat to be generated.
The investment in the sustainable and innovative HE.RO technology is subsidised by the state. Dialysis centres that fall under the SME regulation (small and medium-sized enterprises) receive a non-repayable subsidy of 55% on the package of heat pump, buffer storage tank, HE.RO and measurement technology. Larger dialysis centres that are no longer classified as SMEs are reimbursed 45% of the costs.
Cross-sector Integration - interaction between photovoltaics, heat pumps and medical technology
The installation of the HE.RO system with heat pump is already a gain for the energy balance in the dialysis centre when viewed in isolation, as the heat pump principle saves at least two thirds of the electricity costs for water heating. If the HE.RO is now intelligently networked with the photovoltaic system, the result is what we call the "booster" effect. (Fig. 1)
The surplus solar power, which would normally be fed into the public grid with the disadvantages mentioned above, can now be used to operate the heat pump. Every kilowatt hour generated - multiplied by the annual coefficient of performance of the heat pump - is thus stored as thermal energy and is available the next morning to heat the drinking water. It is not only important that the total electricity saving increases from 40% (PV alone) to 75% (PV & HE.RO together). It is also important that, returning to the question posed at the beginning, 90% of the total photovoltaic energy can now be utilised in self-consumption instead of 60TP3T. Although the 100% own use of solar power is ambitious, it can be realised through additional consumers, such as e-cars of employees, which can ideally be switched on flexibly over time.
The SMART DIALYSIS® system is a key component in successful Cross-sector Integration. This is the central control element that is used for both the digital recording of operating data and the optimisation of operating states. SMART DIALYSIS® analyses the load profiles between the individual sectors and detects deviations from trends. In this way, the photovoltaic, heat pump and medical technology sectors can interact synergistically, anomalies can be detected and the dialysis centre can benefit fully from the advantages of the installed components.
Fig.2 4 - "Green dialysis" step-by-step plan from recording the status quo to implementation and ongoing operation
Steps to green dialysis
We accompany you on the way to a sustainable and future-orientated "green dialysis". The 4-stage plan is shown in Figure 2. The first step is always a so-called potential analysis. This involves looking at the conditions on site, such as the size of the roof, its orientation, whether there is space for heat storage and whether it can withstand a static test.
The aim is to find the optimum between maximum size of the PV system and 100 % self-consumption.
With the measures identified, the second step is project planning. This includes specialised technical planning, such as the optimal design of the photovoltaic system and heat pump, or structural and static checks for the installation of the technologies. The necessary investments are determined taking into account the various financing options such as contracting and state subsidies. We also submit the subsidy applications to the Federal Office of Economics and Export Control (BAFA) for you at this stage.
The dialysis-experienced technical project managers from GreenTec Dialysis are available to you as your contact partners from day one during the realisation of the project. The services are provided as a general contractor from a single source. For us, the project does not end with the final invoice. We see ourselves as your partner on the road to green dialysis, because optimum savings potential can only be achieved through continuous evaluation and optimisation of the installed systems.
Fig.3 Forecast of operating costs based on the following assumption: 15,000 dialyses p.a. over 10 years / increase in electricity costs of 3 % p.a. / figures for 2022
Is Cross-sector Integration in dialysis worthwhile?
Definitely YES! The dialysis centre calculated as an example in Figure 3 with 15,000 treatments per year will save around half a million euros in electricity costs over the next 10 years with GreenTec Cross-sector Integration. The amortisation of the investment is less than 5 years, even without taking depreciation into account.
The basis for the potential savings of over 40 % of energy costs is the intelligent GreenTec Cross-sector Integration, which combines medical technology with tried and tested technologies such as photovoltaics and heat pumps. The "booster" is that solar surpluses are fed into the dialysis process as heat, significantly increasing the proportion of self-consumption of solar power. This not only benefits the wallet, but ultimately also our climate.