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ENERGY EFFICIENCY


(trigeneration) assimilated to renewable sources. A reduction of about 27 per cent in the use of primary energy became the main driver of the project.


A sustainable hospital The new production and distribution system meets the increased needs of the recently constructed buildings, while reducing overall consumption and thereby economic cost and climate altering emissions. Another important innovation is the industrial water network, which is fed by wells, thereby reducing water consumption from the aqueduct. The total duration of the concession (24.5 years) concerns not only the supply of energy vectors (hot water, chilled water, electric energy), but also the management and maintenance of the thermomechanical systems and the maintenance of all buildings. The investment made by private partners is being repaid through management savings. In summary, the project involved:


l the renewal and extension of the distribution networks and related sub- stations and cabins for primary energy, cold water and electricity throughout the hospital


l the renewal of the Malpighi thermal plant for the production of technological steam


l the construction of the new co- generation, thermal and refrigeration plants and the electricity substation.


The most demanding aspect of the work was the construction of the underground thermal power plant. The excavation was adjacent to some historic buildings, which remained in use and the chimney of the old plant was preserved as an urban landmark. Delimited by perimeter walls in reinforced concrete, the thermal power plant is constructed on two levels: the lower one (–10 m depth) houses the boilers, while the upper floor houses fans that provide air for the burners and ducts


ducts for the expulsion of fumes both from the co-generator and the boilers in their vertical tract transit inside the historical tower come out on top. Last in order of completion (January


2017) was the refrigeration plant, which consists of two high efficiency and two absorption electric refrigeration units, which are designed for the production of chilled water using heat recovered from co-generation. Using absorption refrigeration units, the co-generation plant becomes a trigeneration system for the combined production of electric, thermal and refrigeration energy to maximise synergies and contain energy consumption. The refrigeration plant is located in pavilion 19 at the side of the historic tower. The civil works also involved the


Boilers at the power plant.


for the expulsion of combustion fumes. The co-generation plant is located on


three levels of pavilion 19, which is nearby: the ground floor is occupied by co- generators, which are flanked by fans (cooling), while on the upper floors there are ducts for the expulsion of fumes and abatement and energy recovery systems. In the same pavilion is the transformation plant, which elevates the electricity produced by the co-generators to a medium voltage for entry into the hospital’s medium voltage (MV) network. This cabin is equipped with a screening ceiling that is completely plated with diamagnetic alloy metal plates. The upper floors of the pavilion are


mainly occupied by the exhaust ducts for the combustion fumes. The heat recovered from the co-generators is used to pre-heat the water before sending it to the boilers, combined with the contribution of a high efficiency and high temperature heat pump, which permits energy recovery with low enthalpy. The


Azienda Ospedaliera Universitaria Policlinico St Orsola Malpighi (Grantor)


Public contribution 1


Revenues from energy and maintenance


Equity Shareholders


Progetto ISOM SPA Project Company SPV (Concessionaire)


2 EEEF fund Project bond 3


Engineering Procurement and Construction (EPC) ISOM Lavori


Structure of the financial plan. 16 4


Operation and maintenance (O&M) ISOM Gestione


1 Concession contract 2 Project bond contract 3 EPC contract 4 O&M contract


consolidation of the supporting structures and the construction of gardens on the roofs of the St Orsola and Malpighi thermal power plants. The new refrigeration plant (total power 12 MW) is adjacent to the co-generation plant and is connected to the two pre-existing plants, which are located at opposite ends of the hospital, through a distribution network (cooling) designed to minimise losses and interference with other technological services. The trigeneration plant includes two co-generators with alternative engines powered by natural gas (3349 MWe and 2961 MWt each), which produce hot water at 95÷82˚C, coupled with electricity generators (3 KV) connected to transformers/elevators (3/15 kV) for self- production of medium voltage distributed electricity (total efficiency 83.3 per cent). The electricity network is connected to


two new cabins: MV/LV, dedicated to new thermomechanical plants; and MV/LV for co-generators. The other four existing MV substations have been adapted to meet most recent standards and the motorised insertion management system has been completed for all. At the same time, the telecontrol and regulation systems have been implemented. The new thermal power plant (St Orsola) is equipped with four condensing hot water generators (12 MW) with three pass high efficiency flue turns, plus a heat recovery unit on the combustion gases for water pre-heating return from the system (360 kW). The new steam power plant (Malpighi) has four generators, of which two are 2.3 MW (3.3 t/h) and two 5.3 MW (7.6 t/h). They are equipped with modulating burners, inverter on ventilation and recovery systems on the combustion gas side. Each plant is provided with continuous control of all combustion emission parameters. The following equipment was installed


in the new refrigeration plant: l two absorption chillers (each 1951 MW) supplied by the hot water recovered from the co-generators (efficiency 0.731)


IFHE DIGEST 2019


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