Energy Production

The vision in which the connected sustainable home is a part, involves a residential energy grid setting where independent house units are capable of managing their energy production and consumption intelligently and effectively, based on offer and demand.

The connected sustainable home prototype demonstrates this goal in a feasible, integrated, retrofit-able, market-friendly way.

The energy production system, developed by the Renewable Energies & Environmental Technologies unit (REET) of the Fondazione Bruno Kessler, is a prototype demonstrating clean, renewable energy generation in an autonomous small scale highly efficient ((< 30 kWh/m^2/year) setting. A solar/cogeneration system produces electrical power and heat for the house by combining a solar plant and an energy box. The system may be scaled in cooling/heating capacity, changing the porous material volumes, and in cooling power, changing the air flow through the system itself.The system under optimization will be able to generate a cooling power of about 3.5 – 4 kW. The solar thermal collectors, measuring approximately 1.0 m x 0.70 m per panel, cover a specifically dedicated roof area. For each square meter of solar collector apertures the daily average solar irradiation is 4155 Wh/m^2, which correspond to an annual resource of 1516 kW/m^2. The solar thermal system has been sized on an overall aperture area of about 14 m^2, equivalent to 84 kWh of daily incident radiation in summer, which corresponds to about 60 kWhth on the fluid of the solar system and a stored daily energy of about 50 kWh able to generate 42 kWh of cooling for the indoor environment. The constraints pertaining the proper operation of the solar collectors are: the smooth flow and working temperature of the fluid, which must not exceed 130°C, the energy balance in the whole energy system, and the pressure drop in the solar module. The “energy box” located at the back of the prototype, has:

a) a solid thermal storage component, including a double tank structure coupled with an evaporative module for the production of cool energy;

b) a liquid thermal storage component including a water tank for hot water;

c) a pellet cogeneration boiler, integrated to realize a full plant for the production of thermal energy for heat, cool, hot water and electricity production. The pellet cogeneration boiler is based on the integration between a Stirling engine and a biomass pellet boiler. The model of the engine gives back a rated power output of 1 kWpick at 1500 RPM.
d) a hydraulic component for the distribution of energy and fluids on the components of the energy box and the house interior.

The thermal power is delivered at the house by air, in both cases of cooling and heating. The system may operate exclusively on solar thermal panels, or on pellet boiler, or in hybrid configuration, depending on the external constraints and the interior comfort requirements.

Hot water is mainly produced by solar thermal collectors, or by the pellet boiler, in the case of insufficient solar radiation.

Since the overall system does not currently include electrical energy storage, it is assumed that the produced electrical power is consumed, or sent to the grid, or dissipated into thermal power.

Depending on the energy management strategy, we can define specific operative modes corresponding to the different management premises. In the simpler case, the house system exchanges energy with the grid.

Electrical power can be produced in alternative operation modes, which can be activated on demand. An intelligent system between the end user and the activation of electronic devices is necessary to manage the transition from one mode to the other. This topic is assessed by the higher level autonomous control system of the house.

Crema L, Bozzoli A, Alberti F, Bertaso A, Casalegno F, Scagnetti G, 2012, “Novel Energy Provision System for the Sustainable Connected Home” , Proceedings of the World Renewable Energy Forum 2012 , Denver, Colorado.

Energy Production Diagram_8
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6_Stirling Engine5c copy