It is known the use of thermophotovoltaic generators in the state of the art. A thermophotovoltaic generator converts the radiation emitted by a heat source into an electric current with the aid of a photovoltaic junction. The heat source is commonly constituted of a flame produced by fossil fuels. The mechanism for converting radiation into electric current is shown schematically in Figure 1. Air/fuel 1 are introduced in an air/fume exchanger 2 and the energy of the fuel is released in the form of heat inside a combustion chamber 3, inside which there is a burner 4. A portion of this energy is converted into radiation by the emitter 5, which accommodates the combustion chamber 3. Another portion of this energy is instead recovered in order to preheat the combustion air, while the remaining part is released as sensible heat in the exhaust fumes 6. The emitter can be of the type with a broad emission spectrum, such as silicon carbide, or of the selective type, such as rare earth oxides, and in this case it has the characteristic that it emits in a narrow frequency band. Radiant energy, designated by the reference numeral 7, is finally converted by a photovoltaic cell 8 into a direct current. The energy radiation that is lower than the so-called "energy bandgap"of the junction of the photovoltaic 8 cannot be converted into electricity. In order to increase the efficiency of the system and reduce the heating of the photovoltaic cell, an optical filter 9 is introduced which is arranged in front of the photovoltaic cell, between the cell 8 and the emitter 5,

and reflects towards the emitter 5 the radiation that cannot be converted, thus avoiding an unnecessary overheating of the photovoltaic 8. If selective emitters are used, the filter 9 can be eliminated.

Solar radiation can be seen as a black-body emission at 6000 K, which is well- suited for silicon-based junctions (energy bandgap of 1.1 eV), since most of the radiation has an energy which is higher than the energy bandgap.

In thermophotovoltaic applications, the emission temperatures are the combustion temperatures (1000-2000°C) and it is therefore necessary to adopt junctions with a bandgap of less than 0.8 eV. In recent years, various junctions for thermophotovoltaic applications based on GaSb, InGaAs, InGaAsP et cetera have been developed.

In recent years, various thermophotovoltaic systems have been developed, all with relatively low electric power levels (under 1 kW). Most of these applications are designed only for producing electric power, and the only thermophotovoltaic co-generation systems are substantially stoves for heating an enclosed space, in which a small thermophotovoltaic generator for producing a few hundred watts is integrated. As regards currently commercially available small co-generation systems (up to 100 kW), there are systems based on internal-combustion engines or systems based on microturbines. The former have long reached a degree of technological and commercial maturity, while the latter have been marketed only recently. There are also co-generation systems based on fuel cells.

The drawbacks of known types of co-generation systems, using thermophotovoltaic technology, are due to the fact that systems based on thermophotovoltaic technology are small (under 1 kWe) and have an excessively low ratio of electricity to generated heat with respect to the desirable values.

With regard to co-generation systems, which do not use thermophotovoltaic

technology, the following drawbacks may be noticed, according to the type of system. Co-generation systems, which use internal-combustion engines, entail a general complexity of the apparatus, a high level of released pollutants, especially in terms of NOx, a high level of noise pollution, the need for skilled personnel for maintenance, low reliability due to the wear of the moving parts, and the exclusive use of high-cost fuels such as gas and gas oils, with consequent operating expenses. As regards instead conventional co-generation systems based on microturbines, they have the drawback that they must operate at nominal load, on penalty of a loss of efficiency of the system. Furthermore, they too require skilled personnel for maintenance, produce a high level of noise pollution, and use only high-cost fuels such as gas and gas oil. Finally, as regards conventional co-generation systems based on fuel cells, they have the drawback that they have to use a fuel which is even more expensive than gas and gas oils, such as hydrogen, with consequent operating costs.

Therefore, tha aim of the present invention is to provide a system for the integrated generation of electric power, heat and cold which has a high overall energy efficiency, higher than the one obtainable with known types of co- generation system.

Within the scope of this aim, an object of the present invention is to provide a system for the integrated generation of electric power, heat and cold which allows to use low-cost fuels, such as fuel oil and coal.

Another object of the present invention is to provide a system for the integrated generation of electric power, heat and cold which allows to use alternative fuels such as bio-masses, RDF, etcetera.

Another object of the present invention is to provide a system for the integrated generation of power, heat and cold which allows to ensure an extremely low level of noise pollution and chemical pollution and does not require the intervention of skilled personnel for maintenance.

Another object of the present invention is to provide a system for the integrated generation of power, heat and cold which is highly reliable, relatively simple to manufacture and at competitive costs.

Thus, the present invention provides a system for the generation of electric power, heat and cold, characterized in that it comprises at least one thermophotovoltaic generator suitable to generate electricity, at least one heat exchanger suitable to receive in input the exhaust fumes of said thermophotovoltaic generator and to produce heat at high temperature, and at least one absorber connected to said heat exchanger and suitable to generate cold.

Further characteristics and advantages of the invention will become apparent from the description of preferred but not exclusive embodiments of the integrated energy generation system according to the present invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a general block diagram of a thermophotovoltaic generator of the known type; Figure 2 is a block diagram of the integrated energy generation system according to the present invention; and Figure 3 is a general block diagram of a thermophotovoltaic generator according to an embodiment of the present invention, suitable for use in the system shown in Figure 2; Figure 4 is a schematic view of an innovative method for generating electricity, heat and cold.

With reference to the above cited figures, the integrated energy generation system according to the invention, generally designated by the reference numeral 100, uses one or more thermophotovoltaic generators 10 for the integrated production of electric power, heat and cold.

In order to improve the combustion system, in the thermophotovoltaic generators there are intercf angeable burners to be used according to the type of fuel to burn. In the particular case of the combustion of gas, so-called "flameless"techniques are used.

In particular, therefore, the system for the integrated generation of electric power, heat and cold 100 comprises at least one thermophotovoltaic generator 10 which is coupled to a device for recovering heat from the spent fumes 6 for producing high-temperature heat, designated by the reference numeral 15. The device for recovering heat from the spent fumes 6 is conveniently constituted by a heat exchanger 16, which is connected to an absorber 17 which is capable of emitting cold 18.

The expression"high-temperature heat"15 is used to reference heat at a temperature between 90 and 120°C.

The photovoltaic cell 8 of the thermophotovoltaic generator 10 therefore allows producing electricity 19 and medium-temperature heat 20 (at a temperature between 45 and 80°C) by means of a device for recovering heat from the cooling of the photovoltaic cell 8. Essentially, the photovoltaic cell 8 is cooled by means of cooling water, and a heat recovery device utilizes the heat contained in said cooling water to generate medium-temperature heat 20. The heat of the fumes 6 that arrives from the combustion chamber 3 of the thermophotovoltaic generator 10 is partly recovered in order to preheat the combustion air, and the remainder is used to produce heat at high temperature by virtue of the heat exchanger 16.

The system according to the invention furthermore has a device for reducing and monitoring emissions (of the fumes 6), not shown in the figures.

Figure 3 is a block diagram, substantially similar to Figure 1, of a thermophotovoltaic generator 10, which has a burner 4. The burner 4 is interchangeable according to the type of fuel used; furthermore, differently

from Figure 1, it also has a radiation concentration device 21, arranged between the photovoltaic cell 8 and the filter 9 and suitable to concentrate the thermal radiation onto a smaller surface. In this manner, it is possible to reduce the sensitive area, required for conversion to electric power and, therefore, the end costs of the generator. Further, it is possible to increase the power density of the radiation, thus increasing the conversion efficiency of the photovoltaic junction of the photovoltaic cell 8.

As mentioned, the photovoltaic cell is provided with a cooling circuit which allows to recover the radiant energy that is not converted into electricity. If photovoltaic cells 8 of the Quantum Well Solar Cell (QWSC) type are used, this entails an operating temperature of approximately 80°C, which is ideal in order to obtain heat recovery with water at medium-high temperature. As regards the burner 4, in the case of gas-fired combustion it is possible to use burners of the regenerative flameless type. These burners have the particularity that they recover up to 85% of energy from the combustion fumes, thus helping to increase the electrical efficiency of the generator. In conventional combustion systems used by thermophotovoltaic generators, thermal recovery from fumes is no more than 70% and since this factor is closely correlated to the conversion efficiency of the photovoltaic cell 8, the ability to increase it means an increase in the overall electrical efficiency of the generator. Furthermore, flameless burners, by having no flame, entail a reduction in NOx emissions of up to 90% and the absence of noise inherently linked to combustion.

Thanks to the system 100, according to the present invention, it is possible to implement an innovative method for the integrated generation of electric power, heat and cold. This method, schematically shown in Figure 4 and designated by the reference numeral 200, comprises the steps of: -generating, by means of one or more photovoltaic generators, electricity (step 201); and

-recovering (step 202) the exhaust fumes generated in step 201; and -performing the generation of cold by means of at least one heat pump of the absorption type, using the residues produced in the step for the conversion of the exhaust fumes of the photovoltaic generator into high-temperature heat (reference 203).

Advantageously, the step 201 can comprise the step 204, which consists in generating medium-temperature heat by using the heat removed from the photovoltaic generator by means of a cooling circuit.

In another embodiment, the step 201 also comprises the step 205 of placing radiation concentrating means inside the photovoltaic generator in order to increase radiation efficiency.

In practice it has been found that the system for the integrated generation of electric power, heat and cold according to the present invention fully achieves the intended aim and objects, since it allows to produce electric power, heat and cold simultaneously and with high efficiency. It furthermore allows to increase the electrical efficiency of the thermophotovoltaic generator, with the possibility to use low-cost or alternative fuels, with low levels of acoustic emissions and reduced maintenance with a long operating life of the system.