The course is devoted to present the main technologies for exploiting renewable Energy sources, the methods to correctly design the main parts of the installation, evaluate the useful energy which may be produced, make a cost-benefit analysis also taking into account environmental impact issues.

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 an installation.

Basic knowledge about Physics, Thermodynamics, renewable energy sources and energy savings are required.

General information about renewable energies.

Importance of renewable energy sources in the frame of environmental problems (Kyoto Protocol). Their role in the Italian and world energy balances. Peak power and yearly productivity. Perspectives for future development.

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 (UNI 8477).

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 characterization of plate, glazed cover, ducts, and insulation.
Installation typologies, components and applications. Production of domestic hot water, ambient heating, swimming pools. The role of thermal storage. Methods for the evaluation of seasonal performance of solar thermal installations. The f-chart method. Cost-benefit analysis.

Some hints on advanced topics:

• seasonal storage systems

• high temperature collectors for thermodynamic electricity generation

• solar cooling through absorption refrigeration and passive solar systems.

Biomass and SUW (Solid Urban Waste).

Characterization of biomass fuel (wood, short rotation forestry, special crops, biogas from animal waste, etc.) as a commercial product, and under the energy, environmental and economic points of view. Main features and components of Heat and CHP (Combined Heat and Power) biomass generation installations. Solid Urban Waste. Emission control. Availability of biomass under its different forms with special attention on Piedmont situation.

Geothermal energy

Low enthalpy geothermal systems will be studied, both for free cooling or preheating techniques, and for ground-coupled heat pumps systems. A brief explanation of the main legal, technical and economic factors will be presented in order to carry on a feasibility analysis of such systems in the Italian climate.

Solar Photovoltaic installations.

Structure of the semiconductors: energy bands; doping; p-n junction and electric field; electron – hole pairs; losses in the energy conversion. Spectral response and efficiency of the main technologies: single, multi-crystalline and amorphous silicon, Cadmium Telluride, Copper-Indium- Diselenide. Surface covering per installed kilowatt. Equivalent circuit of the solar cell, I-V and P-V characteristics at variable irradiance. Datasheets of the commercial PV modules, thermal coefficients of the electrical quantities. DC-AC converters for the grid connection: Maximum Power Point Tracking (MPPT); active/reactive power control; interface protections; protections against over-current and direct/indirect contacts. Optimal coupling PV array/inverter: checking of power/voltage/current limits. Plant schemes; costs of installed power and produced energy. Pros and cons of Photovoltaics. Conventional calculation of energy production: loss sources in the productivity, technical/economic analysis by the Net Present Value (NPV). Automatic Data Acquisition System, experimental results on operating PV plants, typical testing procedure. Focus on an application problem: series/parallel connection of cells; I-V curve mismatch and shading effect; hot spots and breakdown; bypass and blocking diodes.

Wind Energy installations

Characterization of the wind: speed and direction; power density; surface roughness; statistic distributions.
Structure of a wind turbine: blades, hub, gearbox, electric generator, tower. Operating Principle of a wind turbine: lift and drag in a blade; pitch and yaw regulations; adjustment toward stall/feather. Equivalent circuits of induction and synchronous machines and power curve vs. wind speed. A solution for variable speed wind turbines: the doubly-fed induction generator.
Wind farms: interference among wind turbines. Environmental impact of wind turbines: noise. Power size, diffusion of wind installations in the world. Schemes, cost of installation and energy. Advantages and drawbacks.

Visit
Visit to a solar installation

Exercises
Solar radiance calculation for a clear sky (Moon equations).
Solar collector energy balance and temperature distribution (transversal and longitudinal)
Integration of biomass and conventional fuel boiler for heat production

Projects

1. Preliminary design of solar thermal installation for domestic hot water production using different simulation methods. Cost-benefit analysis and calculation of optimal area.

2. Preliminary design of a grid connected decentralized photovoltaic installation (solar roof): analysis of technical data on the basis of commercial catalogues. Software for the simulation of grid connected photovoltaic installation Parameters of the equivalent circuit f the solar cell and inverter losses for grid connection. Load diagrams. Daily simulation, Calculation of energy given and drawn from the grid on a yearly basis. Cost-benefit analysis.

3. Preliminary design of a wind installation.