Energy, Environmental, and Economic Analyses of Geothermal Polygeneration System Using Dynamic Simulations

Francesca Ceglia, Adriano Macaluso, Elisa Marrasso, Carlo Roselli and Laura Vanoli
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Francesca Ceglia: Department of Engineering, University of Sannio, 82100 Benevento, Italy
Adriano Macaluso: Department of Engineering, University of Naples Parthenope, 80143 Naples, Italy
Elisa Marrasso: Department of Engineering, University of Sannio, 82100 Benevento, Italy
Carlo Roselli: Department of Engineering, University of Sannio, 82100 Benevento, Italy
Laura Vanoli: Department of Engineering, University of Naples Parthenope, 80143 Naples, Italy

Energies, 2020, vol. 13, issue 18, 1-34

Abstract: This paper presents a thermodynamic, economic, and environmental analysis of a renewable polygeneration system connected to a district heating and cooling network. The system, fed by geothermal energy, provides thermal energy for heating and cooling, and domestic hot water for a residential district located in the metropolitan city of Naples (South of Italy). The produced electricity is partly used for auxiliaries of the thermal district and partly sold to the power grid. A calibration control strategy was implemented by considering manufacturer data matching the appropriate operating temperature levels in each component. The cooling and thermal demands of the connected users were calculated using suitable building dynamic simulation models. An energy network dedicated to heating and cooling loads was designed and simulated by considering the variable ground temperature throughout the year, as well as the accurate heat transfer coefficients and pressure losses of the network pipes. The results were based on a 1-year dynamic simulation and were analyzed on a daily, monthly, and yearly basis. The performance was evaluated by means of the main economic and environmental aspects. Two parametric analyses were performed by varying geothermal well depth, to consider the uncertainty in the geofluid temperature as a function of the depth, and by varying the time of operation of the district heating and cooling network. Additionally, the economic analysis was performed by considering two different scenarios with and without feed-in tariffs. Based on the assumptions made, the system is economically feasible only if feed-in tariffs are considered: the minimum Simple Pay Back period is 7.00 years, corresponding to a Discounted Pay Back period of 8.84 years, and the maximum Net Present Value is 6.11 M€, corresponding to a Profit Index of 77.9% and a maximum Internal Rate of Return of 13.0%. The system allows avoiding exploitation of 27.2 GWh of primary energy yearly, corresponding to 5.49?10 3 tons of CO 2 avoided emissions. The increase of the time of the operation increases the economic profitability.

Keywords: heating and cooling network; polygeneration system; geothermal energy community; ORC; geothermal energy; energy district (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (8)

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