The course is devoted to present the main technologies for exploiting renewable energy sources (namely, low, medium and high temperature solar, ground-coupled heat pumps, and wooden biomass), the methods to correctly design the installations for converting them into heat, and estimate their performance.

At the end of the course students should know the main technologies for exploiting renewable sources, and should be able to correctly design the main parts of the installation involved, evaluate the useful energy which may be produced, and make a cost-benefit analysis also taking into account environmental impact issues.

Good knowledge about heat transfer, thermodynamics, and basic information about renewable energy sources.

Calculation of solar radiation.

Position of the Sun in the sky and calculation of incidence angle between the Sun and the collector plane. Atmospheric models for clear and average skies. Data bases of horizontal solar radiation energy (UNI 10349). Calculation of global (direct, diffuse and reflected) irradiance and global solar irradiation on a tilted surface using decomposition and transposition models.

Solar thermal installations.

Solar collectors typologies and definition of efficiency. Thermal balance of a solar collector and analysis of temperature profile of the plate. Hottel equation. Thermal and optical characterization of plate, glazed cover, ducts, and insulation.
The role of thermal storage and sizing criteria. Installation typologies, components and applications. Production of hot water for domestic and space heating uses. Methods for the evaluation of seasonal performance of solar thermal installations. The f-chart method. Software for dynamic simulation of solar thermal installations: Polysun. Cost-benefit analysis.
Some hints on advanced topics:
• seasonal storage systems
• solar cooling through absorption refrigeration
• passive solar systems for air conditioning.

Geothermal energy

Low enthalpy geothermal systems will be studied, both for free cooling or preheating techniques, and for ground-coupled heat pumps (GCHP) systems. Brief explanation of the main legal, technical and economic factors needed in order to carry on a feasibility analysis of such systems in the Italian climate. The geothermal features of ground for GCHP systems. Analysis of the water layer influence.

Introduction to Concentrating Solar Power technologies
Introduction to Concentrating Solar Power (CSP) technologies
In this module a review of the main CSP technologies (Parabolic Trough, Central Receiver, Linear Fresnel, Stirling Dish) will be presented. The state of the art of each technology will be discussed, as well as the main physics principles, features and technical characteristics, together with an analysis of current and future R&D lines and trends. An overview of the commercial experiences worldwide will be given.

• Motivation
• Principles of concentration of Solar Radiation
• Analysis of the most successful technologies so far
- Parabolic Trough
- Central Receiver
• Principles of energy storage in CSP plants
• Modeling & Design tools (Optics, Thermal fluid dynamics, Integration)
• Thesis opportunities

Exercises
Solar radiance calculation for a clear sky (ASHRAE model).
Solar collector energy balance and temperature distribution (transversal and longitudinal)
Analysis of energy balance of heat storage

Projects
Preliminary design of solar thermal installation for domestic hot water production using Polysun software. Sensitivity analysis, cost-benefit analysis and calculation of optimal area.

• Notes from the teachers
• Duffie & Beckman, Solar Engineering of Thermal Processes, John Wiley & sons, 4th edition, New York 2013.
• Tiwari G.N., Solar Energy - Fundamentals, Design, Modelling, and Applications, CRC Press, 2002
• Bent Sorensen, Renewable Energy: Physics, Engineering, Environmental Impacts, Economics, Elsevier Associated Press, London, 2004.
• David Banks, An Introduction to Thermogeology: Ground Source Heating and Cooling, 2nd Edition. ISBN: 978-0-470-67034-7

Before sustaining the final examination students will have the opportunity to discuss an assignment consisting in the design of a solar thermal system using Polysun ® software. This assignment should be discussed before May 31. This will allow them to gain up to 4 points which will be added to the written examination results (28 points), so as to reach 32 points, corresponding to "30 cum laude". For students not able to discuss this assignment before May 31 the maximum mark will be 28/30 points.

The written examination consists of a number of open questions and/or short exercises concerning Solar thermal systems (STS) and Concentrated Solar Power (CSP).
For what concerns Geothermal energy (GTE), a series of questions will be given with closed answers.

The details of the grading of the different parts are: 16 points (including 4 points for the assignment) for STS, and 8 points each for CSP and GTE.