# Techno-Economic Analysis of a Solar Thermal Plant for Large-Scale Water Pasteurization

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

^{−3}to ≈25 EUR-cents m

^{−3}.

## 1. Introduction

## 2. Experimental Pasteurization Tests

## 3. Plant Model Design

#### 3.1. Solar Field

#### 3.2. Auxiliary Gas Burner

#### 3.3. Plate Heat Exchanger

#### 3.4. Heating Coils

#### 3.5. Pumping System and Pipe Losses

#### 3.6. Treatment Unit

#### 3.7. Lumped-Component Plant Model

## 4. Cost Estimation Model

#### 4.1. Capital Costs

#### 4.2. Operating Costs

#### 4.3. Insurance and Maintenance Costs

#### 4.4. Total Costs

#### 4.5. Economic Optimization Scenarios

## 5. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## Nomenclature

T | Temperature |

A | Area |

$\eta $ | Efficiency |

$\mathrm{NTU}$ | Number of transport units |

$\mathrm{Nu}$ | Nusselt number |

$\alpha $ | Convective heat transfer coefficient |

$\mu $ | Dynamic viscosity |

$\kappa $ | Thermal diffusivity |

N | Number of ducts |

G | Mass-flow velocity |

${I}_{s}$ | Solar irradiance |

$\dot{m}$ | Mass flow rate |

H | Heating value or Head losses |

C | Heat capacity or Cost |

$\mathrm{Pr}$ | Prandtl number |

$\lambda $ | Thermal conductivity |

$\beta $ | Chevron angle |

s | Thickness or spacing |

f | Friction factor |

$\mathrm{Ra}$ | Rayleigh number |

$\Phi $ | Heat flux |

${c}_{p}$ | Specific heat |

$\u03f5$ | Effectiveness |

$\mathrm{Re}$ | Reynolds number |

${f}_{s}$ | Solar factor |

R | Resistance |

$\rho $ | Density |

L | Length or width |

$\Delta p$ | Pressure drop |

v | Fluid velocity |

## References

- WHO/UNICEF. Progress on Drinking Water, Sanitation, and Hygiene: 2017 Update and SDG Baselines; World Health Organization: Geneva, Switzerland, 2017. [Google Scholar]
- Guidelines for Drinking-Water Quality, 4th ed.; World Health Organization (WHO) Chron.: Geneva, Switzerland, 2011; Volume 38, pp. 104–108.
- Cheremisinoff, N.; Knovel, F. Handbook of Water and Wastewater Treatment Technologies; Chemical Petrochemical & Process; Elsevier Science: Amsterdam, The Netherlands, 2002. [Google Scholar]
- Schwarzenbach, R.P.; Escher, B.I.; Fenner, K.; Hofstetter, T.B.; Johnson, C.A.; Von Gunten, U.; Wehrli, B. The challenge of micropollutants in aquatic systems. Science
**2006**, 313, 1072–1077. [Google Scholar] [CrossRef] - Bergamasco, L.; Alberghini, M.; Fasano, M. Nano-metering of solvated biomolecules or nanoparticles from water self-diffusivity in bio-inspired nanopores. Nanoscale Res. Lett.
**2019**, 14, 336. [Google Scholar] [CrossRef] - Howe, K.J.; Hand, D.W.; Crittenden, J.C.; Trussell, R.R.; Tchobanoglous, G. Principles of Water Treatment; John Wiley & Sons: Hoboken, NJ, USA, 2012. [Google Scholar]
- Woldemariam, D.; Martin, A.; Santarelli, M. Exergy analysis of air-gap membrane distillation systems for water purification applications. Appl. Sci.
**2017**, 7, 301. [Google Scholar] [CrossRef][Green Version] - Saber, O.; Kotb, H.M. Designing Dual-Function Nanostructures for Water Purification in Sunlight. Appl. Sci.
**2020**, 10, 1786. [Google Scholar] [CrossRef][Green Version] - Lau, M.; Monis, P.; Ryan, G.; Salveson, A.; Blackbeard, J.; Gray, S.; Sanciolo, P. Selection of surrogate pathogens and process indicator organisms for pasteurisation of municipal wastewater—A survey of literature data on heat inactivation of pathogens. Process Saf. Environ. Prot.
**2019**, 133, 301–314. [Google Scholar] [CrossRef] - Voukkali, I.; Zorpas, A. Disinfection methods and by-products formation. Desalin. Water Treat.
**2015**, 56, 1150–1161. [Google Scholar] [CrossRef] - Hua, G.; Reckhow, D.A. Comparison of disinfection byproduct formation from chlorine and alternative disinfectants. Water Res.
**2007**, 41, 1667–1678. [Google Scholar] [CrossRef] - Von Gunten, U. Ozonation of drinking water: Part I. Oxidation kinetics and product formation. Water Res.
**2003**, 37, 1443–1467. [Google Scholar] [CrossRef] - Von Gunten, U. Ozonation of drinking water: Part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine. Water Res.
**2003**, 37, 1469–1487. [Google Scholar] [CrossRef] - Hijnen, W.; Beerendonk, E.; Medema, G.J. Inactivation credit of UV radiation for viruses, bacteria and protozoan (oo) cysts in water: A review. Water Res.
**2006**, 40, 3–22. [Google Scholar] [CrossRef] - Gray, N.F. Ultraviolet Disinfection. In Microbiology of Waterborne Diseases; Elsevier: Amsterdam, The Netherlands, 2014; pp. 617–630. [Google Scholar]
- Nguyen, H.T.; Corry, J.E.; Miles, C.A. Heat resistance and mechanism of heat inactivation in thermophilic campylobacters. Appl. Environ. Microbiol.
**2006**, 72, 908–913. [Google Scholar] [CrossRef] [PubMed][Green Version] - Lindahl, T. Irreversible heat inactivation of transfer ribonucleic acids. J. Biol. Chem.
**1967**, 242, 1970–1973. [Google Scholar] [PubMed] - Verma, S.K.; Singhal, P.; Chauhan, D.S. A synergistic evaluation on application of solar-thermal energy in water purification: Current scenario and future prospects. Energy Convers. Manag.
**2019**, 180, 372–390. [Google Scholar] [CrossRef] - Chiavazzo, E.; Morciano, M.; Viglino, F.; Fasano, M.; Asinari, P. Passive solar high-yield seawater desalination by modular and low-cost distillation. Nat. Sustain.
**2018**, 1, 763–772. [Google Scholar] [CrossRef][Green Version] - Hohne, P.; Kusakana, K.; Numbi, B. A review of water heating technologies: An application to the South African context. Energy Rep.
**2019**, 5, 1–19. [Google Scholar] [CrossRef] - Zhou, L.; Li, X.; Ni, G.W.; Zhu, S.; Zhu, J. The revival of thermal utilization from the Sun: Interfacial solar vapor generation. Natl. Sci. Rev.
**2019**, 6, 562–578. [Google Scholar] [CrossRef][Green Version] - Signorato, F.; Morciano, M.; Bergamasco, L.; Fasano, M.; Asinari, P. Exergy analysis of solar desalination systems based on passive multi-effect membrane distillation. Energy Rep.
**2020**, 6, 445–454. [Google Scholar] [CrossRef] - Morciano, M.; Fasano, M.; Bergamasco, L.; Albiero, A.; Curzio, M.L.; Asinari, P.; Chiavazzo, E. Sustainable freshwater production using passive membrane distillation and waste heat recovery from portable generator sets. Appl. Energy
**2020**, 258, 114086. [Google Scholar] [CrossRef] - Fasano, M.; Bergamasco, L.; Lombardo, A.; Zanini, M.; Chiavazzo, E.; Asinari, P. Water/Ethanol and 13X Zeolite Pairs for Long-Term Thermal Energy Storage at Ambient Pressure. Front. Energy Res.
**2019**, 7, 148. [Google Scholar] [CrossRef][Green Version] - Verrilli, F.; Srinivasan, S.; Gambino, G.; Canelli, M.; Himanka, M.; Del Vecchio, C.; Sasso, M.; Glielmo, L. Model predictive control-based optimal operations of district heating system with thermal energy storage and flexible loads. IEEE Trans. Autom. Sci. Eng.
**2016**, 14, 547–557. [Google Scholar] [CrossRef] - Pizzolato, A.; Donato, F.; Verda, V.; Santarelli, M.; Sciacovelli, A. CSP plants with thermocline thermal energy storage and integrated steam generator–Techno-economic modeling and design optimization. Energy
**2017**, 139, 231–246. [Google Scholar] [CrossRef] - Feachem, R.G.; Bradley, D.J.; Garelick, H.; Mara, D.D. Sanitation and Disease: Health Aspects of Excreta and Wastewater Management; John Wiley and Sons: Hoboken, NJ, USA, 1983. [Google Scholar]
- Alberghini, M.; Morciano, M.; Bergamasco, L.; Fasano, M.; Lavagna, L.; Humbert, G.; Sani, E.; Pavese, M.; Chiavazzo, E.; Asinari, P. Coffee-based colloids for direct solar absorption. Sci. Rep.
**2019**, 9, 4701. [Google Scholar] [CrossRef] - Alexander, M. Most probable number method for microbial populations. Methods Soil Anal. Part 2 Chem. Microbiol. Prop.
**1983**, 9, 815–820. [Google Scholar] - Lazzarin, R.; Noro, M.; Righetti, G.; Mancin, S. Application of hybrid PCM thermal energy storages with and without al foams in solar heating/cooling and ground source absorption heat pump plant: An energy and economic analysis. Appl. Sci.
**2019**, 9, 1007. [Google Scholar] [CrossRef][Green Version] - Kloben Industries S.r.l. Scheda Tecnica: Collettore Solare Sky Pro Advanced; Kloben Industries S.r.l.: Milano, Italy, 2016. [Google Scholar]
- PVGIS: Photovoltaic Geographical Information System. Available online: http://re.jrc.ec.europa.eu/pvgis/ (accessed on 18 September 2018).
- Marcel, S.; Huld, T.; Dunlop, E. PV-GIS: A web-based solar radiation database for the calculation of PV potential in Europe. Int. J. Sol. Energy
**2005**, 24, 55–67. [Google Scholar] - Moore, N.; Gibson, N.; Wright, G. Hot water service using high-efficiency gas-fired appliances. Build. Serv. Eng. Res. Technol.
**1992**, 13, 147–153. [Google Scholar] [CrossRef] - Roslyakov, P.; Proskurin, Y.V.; Ionkin, I. Increase of efficiency and reliability of liquid fuel combustion in small-sized boilers. J. Phys. Conf. Ser.
**2017**, 891, 012243. [Google Scholar] [CrossRef] - Bergman, T.L.; Incropera, F.P.; DeWitt, D.P.; Lavine, A.S. Fundamentals of Heat and Mass Transfer; John Wiley & Sons: Hoboken, NJ, USA, 2011. [Google Scholar]
- Khan, T.; Khan, M.; Chyu, M.; Ayub, Z. Experimental investigation of single phase convective heat transfer coefficient in a corrugated plate heat exchanger for multiple plate configurations. Appl. Therm. Eng.
**2010**, 30, 1058–1065. [Google Scholar] [CrossRef] - Neagu, A.; Koncsag, C.; Barbulescu, A.; Botez, E. Estimation of pressure drop in gasket plate heat exchangers. Ovidius Univ. Ann. Chem.
**2016**, 27, 62–72. [Google Scholar] [CrossRef][Green Version] - Kakaç, S.; Liu, H.; Pramuanjaroenkij, A. Heat Exchangers: Selection, Rating, and Thermal Design, 2nd ed.; Taylor & Francis: Abingdon, UK, 2002. [Google Scholar]
- Whitaker, S. Forced convection heat transfer correlations for flow in pipes, past flat plates, single cylinders, single spheres, and for flow in packed beds and tube bundles. AIChE J.
**1972**, 18, 361–371. [Google Scholar] [CrossRef] - Churchill, S.; Chu, H. Correlating equations for laminar and turbulent free convection from a horizontal cylinder. Int. J. Heat Mass Transf.
**1975**, 18, 1049–1053. [Google Scholar] [CrossRef] - Citrini, D.; Noseda, G. Idraulica; Casa Editrice Ambrosiana: Rozzano, Italy, 1987. [Google Scholar]
- Duffie, J.A.; Beckman, W.A. Solar Engineering of Thermal Processes; John Wiley & Sons: Hoboken, NJ, USA, 2013. [Google Scholar]
- Abrams, A.; Farzan, F.; Lahiri, S.; Masiello, R. Optimizing Concentrating Solar Power with Thermal Energy Storage Systems in California; DNV GL: Oslo, Norway, 2014. [Google Scholar]
- González-Portillo, L.; Muñoz-Antón, J.; Martínez-Val, J. An analytical optimization of thermal energy storage for electricity cost reduction in solar thermal electric plants. Appl. Energy
**2017**, 185, 531–546. [Google Scholar] [CrossRef] - Guédez, R.; Spelling, J.; Laumert, B.; Fransson, T. Optimization of Thermal Energy Storage Integration Strategies for Peak Power Production by Concentrating Solar Power Plants. Energy Procedia
**2014**, 49, 1642–1651. [Google Scholar] [CrossRef][Green Version] - Turton, R.; Bailie, R.C.; Whiting, W.B.; Shaeiwitz, J.A. Analysis, Synthesis and Design of Chemical Processes; Pearson Education: London, UK, 2008. [Google Scholar]
- Eurostat Energy Database. Available online: https://ec.europa.eu/eurostat/web/energy/data/database (accessed on 12 November 2018).
- Pitz-Paal, R.; Dersch, J.; Milow, B. European Concentrated Solar Thermal Road-Mapping; The German Aerospace Center (DLR): Stuttgart, Germany, 2005. [Google Scholar]
- Taylor, M. Renewable Energy Technologies Cost Analysis Series: Concentrating Solar Power; IRENA: Abu Dhabi, United Arab Emirates, 2012; Volume 1. [Google Scholar]
- Mellen, C.M.; Evans, F.C. Valuation for M & A: Building Value in Private Companies; John Wiley & Sons: Hoboken, NJ, USA, 2010; Volume 587. [Google Scholar]
- Damodaran, A. Equity Risk Premiums (ERP): Determinants, Estimation and Implications—The 2019 Edition. Soc. Sci. Res. Netw.
**2019**. [Google Scholar] [CrossRef][Green Version] - Fernandez, P.; Pershin, V.; Acin, I. Market Risk Premium and Risk-Free Rate used for 59 Countries in 2018: A Survey. Soc. Sci. Res. Netw.
**2018**. [Google Scholar] [CrossRef] - Izquierdo, S.; Montañés, C.; Dopazo, C.; Fueyo, N. Analysis of CSP plants for the definition of energy policies: The influence on electricity cost of solar multiples, capacity factors and energy storage. Energy Policy
**2010**, 38, 6215–6221. [Google Scholar] [CrossRef] - Morciano, M.; Fasano, M.; Secreto, M.; Jamolov, U.; Chiavazzo, E.; Asinari, P. Installation of a concentrated solar power system for the thermal needs of buildings or industrial processes. Energy Procedia
**2016**, 101, 956–963. [Google Scholar] [CrossRef][Green Version] - Schwantes, R.; Cipollina, A.; Gross, F.; Koschikowski, J.; Pfeifle, D.; Rolletschek, M.; Subiela, V. Membrane distillation: Solar and waste heat driven demonstration plants for desalination. Desalination
**2013**, 323, 93–106. [Google Scholar] [CrossRef][Green Version]

Sample Availability: Specific or different uses of the above reported quantities are detailed in the text. |

**Figure 1.**(

**Left**) Overview of the equipment for the experimental tests: (1) aluminum test tubes and tailor-made 3D-printed holder (detail of the CAD drawing in the inset); (2) thermostatic water bath (CORIO CD-300F, Julabo); (3) industrial furnace for thermostatic applications (TypeM120-VF, MPM Instruments); (4) laptop for data acquisition; (5) digital hot plate stirrer (AREX Digital, VELP Scientifica) for sanitation of the test tubes after each test. (

**Right**) Temperature of the samples during the disinfection tests for the four considered pasteurization protocols, namely 540 s at $70\phantom{\rule{3.33333pt}{0ex}}{\phantom{\rule{3.33333pt}{0ex}}}^{\circ}$C, 114 s at $75\phantom{\rule{3.33333pt}{0ex}}{\phantom{\rule{3.33333pt}{0ex}}}^{\circ}$C, 30 s at $80\phantom{\rule{3.33333pt}{0ex}}{\phantom{\rule{3.33333pt}{0ex}}}^{\circ}$C and 8 s at $85\phantom{\rule{3.33333pt}{0ex}}{\phantom{\rule{3.33333pt}{0ex}}}^{\circ}$C. The solid lines show the mean temperature obtained for each pasteurization protocol (four repetitions each), while the related transparent bands the range between the minimum and maximum values.

**Figure 2.**Overview of the plant layout, which consists of: a solar field for primary solar thermal energy collection; an auxiliary gas burner to overcome the intermittent nature of the solar resource; a central treatment unit for the pasteurization, which also serves as heat storage system; a plate heat exchanger for waste-heat recovery and pre-heating of the water to be treated.

**Figure 3.**Overview of the Simulink${}^{\circledR}$ lumped- model of the solar pasteurization plant. Solar field, gas burner, heat exchanger and storage tank subsystems are identified with yellow, red, blue and green, respectively.

**Figure 4.**Results of the numerical model: (

**a**) ${f}_{s}$ factor (blue dots) and treatment temperature (red solid line); (

**b**) mean temperature of the water to be treated during its passage throughout the plant. The red and blue sections highlight respectively the pre-heating and post-cooling of the fluid through the plate heat exchanger, which acts as an economizer. The results refer to the 250 L s${}^{-1}$ plant capacity.

**Figure 5.**Components percentage values on the facility cost for various SM values: (

**a**) $SM=0.5$; (

**b**) $SM=1.0$; (

**c**) $SM=2.0$; (

**d**) $SM=3.0$. The duration of the thermal energy storage has been considered equal to 12 h, the capacity of the plant equal to 250 L s${}^{-1}$.

**Figure 6.**Unit cost of water pasteurization (expressed as EUR-cent per cubic meter of treated water) as a function of the solar multiple and thermal energy storage duration for different treatment capacities of the plant: (

**a**) 50 L s${}^{-1}$; (

**b**) 100 L s${}^{-1}$; (

**c**) 250 L s${}^{-1}$; (

**d**) 500 L s${}^{-1}$. Calculations consider 20 years as expected plant lifetime.

**Figure 7.**Unit cost of water pasteurization as a function of the solar multiple for (

**a**) different capacities of the plant (20 years lifetime) and (

**b**) different expected lifetime of the plant (250 L s${}^{-1}$). All these calculations consider 12 h of thermal energy storage duration.

**Table 1.**Coefficients used for the capital cost evaluation of some components of the solar thermal pasteurization plant. Note that, for the tank and gas burner, ${F}_{BM}$ is directly provided [47].

Component | ${\mathit{k}}_{1}$ | ${\mathit{k}}_{2}$ | ${\mathit{k}}_{3}$ | ${\mathit{B}}_{1}$ | ${\mathit{B}}_{2}$ | ${\mathit{F}}_{\mathit{P}}$ | ${\mathit{F}}_{\mathit{M}}$ | ${\mathit{F}}_{\mathbf{BM}}$ |
---|---|---|---|---|---|---|---|---|

Tank | 4.8509 | −0.3973 | 0.1445 | - | - | - | - | 1.10 |

Heating coils | 4.1884 | −0.2503 | 0.1974 | 1.63 | 1.66 | 1.00 | 1.00 | - |

Pumps | 3.3892 | 0.0536 | 0.1538 | 1.89 | 1.35 | 1.00 | 1.00 | - |

Gas burner | 2.0829 | 0.9074 | −0.0243 | - | - | - | - | 2.19 |

Parameter | Range | Units |
---|---|---|

Plant water treatment capacity | 50 ÷ 500 | L s${}^{-1}$ |

Solar Multiple (SM) of the plant | 0 ÷ 3 | - |

Thermal Energy Storage (TES) duration | 0 ÷ 12 | hours |

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Bologna, A.; Fasano, M.; Bergamasco, L.; Morciano, M.; Bersani, F.; Asinari, P.; Meucci, L.; Chiavazzo, E.
Techno-Economic Analysis of a Solar Thermal Plant for Large-Scale Water Pasteurization. *Appl. Sci.* **2020**, *10*, 4771.
https://doi.org/10.3390/app10144771

**AMA Style**

Bologna A, Fasano M, Bergamasco L, Morciano M, Bersani F, Asinari P, Meucci L, Chiavazzo E.
Techno-Economic Analysis of a Solar Thermal Plant for Large-Scale Water Pasteurization. *Applied Sciences*. 2020; 10(14):4771.
https://doi.org/10.3390/app10144771

**Chicago/Turabian Style**

Bologna, Alberto, Matteo Fasano, Luca Bergamasco, Matteo Morciano, Francesca Bersani, Pietro Asinari, Lorenza Meucci, and Eliodoro Chiavazzo.
2020. "Techno-Economic Analysis of a Solar Thermal Plant for Large-Scale Water Pasteurization" *Applied Sciences* 10, no. 14: 4771.
https://doi.org/10.3390/app10144771