Intelligent Management of Distributed Energy Resources for Increased Resilience and Environmental Sustainability of Hospitals

: There is a global trend towards zero-energy or even positive-energy buildings, including healthcare facilities. Energy e ﬃ ciency activities have been investigated and applied successfully for more than 20 years in healthcare facilities in general and hospitals in particular. It is in the last decade that on-site energy production mainly from photovoltaics has been considered mainly as an extra revenue stream for healthcare facilities. Back-up systems are still diesel generator-based in most cases and only recently has there been interest in unifying the energy systems of healthcare facilities in order to integrate the operation of the main systems of the hospital with the on-site renewable energy production and the back-up systems. Hospitals play a very crucial role in our societies. There is a need to achieve the best results in terms of healthcare services but, at the same time, to reduce the cost of these services without a ﬀ ecting the quality level, to enhance resilience and to increase environmental sustainability. As far as energy is concerned, this is feasible and can be accomplished using energy e ﬃ ciency interventions and on-site power generation and storage using renewable energy technologies. An Intelligent Energy Management System (IEMS) has to be in place in order to harvest the beneﬁts of all the related subsystems allowing them to operate e ﬀ ectively and harmoniously, while at the same time ensuring the operation of the hospital under extreme conditions, e.g., after a natural disaster. The research concerning IEMSs for hospitals is at its ﬁrst steps and needs to gain momentum.

Any location where healthcare is provided can be considered as a healthcare facility. This includes everything from a dispensary in a developing country that is just one room with the most basic provisions for minor treatments to the large hospitals of the developed countries that have capacities over 2000 patients providing state-of-the-art health services. At the same time, there is a global trend towards zero-energy or even positive-energy buildings (ZEHB/PEHB), including hospitals [1,2]; in various parts of the world, like the European Union, the regulations drive towards near-zero-energy buildings.
The various departments of a hospital are presented in Table 1 in accordance with [3], along with key aspects related to energy consumption. Energy efficiency activities have been investigated and applied successfully for more than 20 years in healthcare facilities in general and hospitals in particular.
Hospitals need to have a strictly controlled environment and employ energy consuming equipment to provide optimum healthcare services to patients. A problem in the provision of power can lead to the failure of multiple devices and appliances, which can have a significant detrimental effect on the hospital's operation. These problems can be either related to patients monitoring and treatment or Diagnostic, interventional and therapy departments Many special systems and medical equipment are installed in these departments since this is the core departments where the healthcare services are provided.
Notably electrical systems (appliances and lighting), heating ventilation and air conditioning (HVAC) as well as plumbing networks for medical gases, water supply and infectious waste disposal.

Public and administrative departments
Admitting and discharge These departments usually present loads comparable to an office building consisting of appliances and HVAC systems. It is understandable that the backup power system ought to meet all the loads of the hospital. Emergency generators are traditionally the most utilized approach for providing backup power [4]. The provision of energy under these scenarios is concerned with the stored fuel in the hospital and the ability for refueling the storage tanks. If there is a brownout or blackout of the main grid due to some technical fault, most of the time the stored fuel is enough to allow the generators' operation until either a refueling takes place or the main grid fault is fixed. However, in a natural disaster scenario, this process becomes more complicated as refueling might not be possible. Examples from the 2005 Hurricane Katrina in the USA showed fuel running out after 36 h [4] and, in the 2016 Kumamoto Earthquake in Japan, power failures occurred for seven days [5]. Research has taken place in the classification and prioritization of loads for extending the operation of a hospital under extreme emergency conditions [6]. Research for such extreme scenarios goes beyond the provision of power, as is understandable, and includes addressing the structural problems of the buildings, inability of personnel to work at the hospital, damage to plumbing, etc. [6].
With the rise of Distributed Energy Resources (DER) and the economic benefits they brought along with schemes like feed-in tariffs, hospitals around the world invested in such systems [7]. The most common intervention has been the installation of a photovoltaic (PV) array that feeds power to grid either under a feed-in or net metering scheme [8]. Since hospitals also have high cooling and heating needs, there have also been investments in co-generation and tri-generation systems, most often based on natural gas consumption [9], as well as polygeneration systems [10]. Research in this field is also investigating hybrid systems which include photovoltaics, fuel cells, waste energy, batteries etc. [11].
As the onsite generation technologies evolve and as more distributed storage technologies are considered, a microgrid approach integrating them seems the most sensible [12]. Microgrids, at the same time, are by definition able to operate interconnected with the main grid, but also in islanded mode. The use as such of microgrids also as a part of the backup system of the hospital is the next logical step. The existing emergency generators can also be part of the microgrid, as can the co-/tri-generation systems.
Since the existence of emergency generators is usually a legal prerequisite, complex systems need to be investigated which can include renewables, diesel generators, co-/tri-generation systems and storage components. For these systems to operate effectively and also provide increased resilience in natural disasters scenarios, Intelligent Energy Management Systems (IEMSs) are a prerequisite.
The research in IEMSs at the household, tertiary sector level and generally towards the path to smart cities through smart energy management is strong. This reality is currently not reflected in hospital related research with few research publications on the subject. Prudenzi et al. in [13] investigated the improvement of the hospitals' resilience through the development of a supervising platform in the hospital's electricity distribution system to collect and centralize anomalies or malfunctioning or outages. Moreover, they developed a low-cost Internet of Things (IoT)-based solution to implement the above scheme. In further research, Prudenzi et al. [14] developed a low-cost supervising system based on single board computers (Raspberry Pi 3) in order to connect the main components of the various systems in the hospital to a server PC, implementing this way a distributed supervising system. Iza et al. investigated the installation of grid-connected photovoltaics, a fuel cell and a battery under a microgrid topology for a hospital. They developed an energy management system and optimized its operation using Genetic Algorithms. The results showed the viability of such a system for the hospital. Vaziri et al. [15] investigated grid-connected photovoltaics and wind turbine and developed a demand dispatch energy model for using them efficiently. The model resulted in the reduction of the energy costs of the hospital, while at the same time, the specific constraints related to hospitals were satisfied.
Hospitals play a very crucial role in our societies. There is a need to achieve the best results in terms of healthcare services, but at the same time to reduce the cost of these services without affecting the quality level, to enhance resilience and to increase environmental sustainability. As far as energy is concerned, this is feasible and can be accomplished using energy efficiency interventions and on-site power generation using renewable energy technologies. An IEMS has to be in place in order to harvest the benefits of all the related subsystems allowing them to operate effectively and in harmony, while at the same time ensuring the operation of the hospital under extreme conditions, e.g., after a natural disaster. The research concerning IEMSs for hospitals is still at an early stage of development and needs to gain momentum.