Solar Energy

ISTITUTO COMPRENSIVO SAN VENDEMIANO – Treviso – Italy – «G.Saccon» Lower Secondary School

CLASS 3C Comenius Project 2012/13

Sun vs fossil fuels In 1973 in Italy, after the energy crisis, we began looking carefully on the sun as an alternative source for the production of electricity.

In these last years, global warming is changing the climatic conditions of our planet.

The European Council has begun to provide incentives for renewable and clean forms of energy which do not involve any kind of emissions in the atmosphere.

Renewable energies: forms of energy produced from renewable sources that can regenerate at least at the same speed they are used or aren’t “ exhaustible “ in a “human” time scale. Their use doesn’t affect natural resources for the future generations and are clean energies, not polluting.

Solar energy is the energy associated with solar radiation and it represents the primary source of energy on the Earth and it makes life possible.

The sun irradiates the terrestrial surface with 50 milion GWATT every moment.

Nearly all other other available energy sources derive from this energy, such as: fossil fuels, wind, water, biomass, tides.

SOLAR ENERGY GLOBAL RESOURCES The colours on the map show the average solar power that reaches the Earth, also taking into account cloudiness indicated by weather satellites.

The covered area needed to provide the energy equivalent to the current primary energy demand is indicated by the dark disks.

TW (tera watt ) = 1012 W Twe (tera watt energy)

The scale is in WATT per square metre.

Annual irradiation in Italy

Energy from the sun

Advantages   

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It is renewable.

It is a free, clean and unlimited source.

It does not produce pollution because it does not burn materials which release toxic gases in the atmosphere.

It reduces the consumption of fossil fuels.

It increases the economic value of a house.

It sets in motion an economic sector which is doing well (Green Economy). its systems are strong (25 years warranty).

It has low maintenance costs.

It has a system of modular installation.

Disadvantages • • • • •

Harmful disposal.

Discontinuous production.

Not very high efficiency.

High surfaces occupied.

High initial costs.

Solar energy use Solar energy can be used in many ways, the most used are solar cells and solar panels.

Solar thermal panels can be: -

for domestic use to produce hot water in small home plants.

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for industrial use to produce steam to generate electricity.

Photovoltaic panels are used:

For domestic and industrial use to produce electricity directly.

Domestic use

: it heats a fluid as part of a heating system or to produce hot water. It allows to capture solar energy, store it and use it in various ways, in particular for hot water supply in replacement of boilers fired by natural gas. : it heats a fluid to produce electricity thanks to a turbo- alternator. : it turns solar energy directly into electricity thanks to the photovoltaic effect using the necessary technology and mechanical automatic solar tracking systems. : it is a connection of a solar panel with a photovoltaic solar panel.

Natural circulation thermal solar panels Natural circulation thermal solar systems are so called because they exploit hot liquids properties to rise in a natural way.

(A) Sunbeams heat transfer fluid (water + antifreeze) which rises naturally up to the tank placed horizontally above the panels.

(B) The liquid transfers its heat to the water inside the tank and enters the hydraulic water circuit of the house

Diagram of a solar panel 1) Valve 2) Storage tank 3) Insertion pipe 4) Absorption panels 5) Cold water insertion pipe.

The photovoltaic principle Augusto Righi was an Italian physicist of Bologna and he was the first to recognize this phenomenon in 1888

even if you had to wait the writings of Einstein for a formalization of the physical principle.

Photovoltaic Technology Using semiconductors, solar PV modules create power by converting sunlight into electricity.

The semiconductor material most commonly used for the construction of photovoltaic cells is silicon.

The silicon is found in nature Surely the material most often used is crystalline silicon, one of the most common chemical elements in the earth crust.

Other materials used for the construction of photovoltaic cells are: copper, indium, diselenide, cadmium, telluride To coat and protect the thin layers of semiconductor material, most of the photovoltaic technologies use glass.

Approximately 80% of the weight of a module is made of glass.

The photovoltaic principle The capability of photons to extract electrons from atoms is called photoelectric effect.

A photovoltaic panel is made of some tens of silicon cells connected by conductor joints

Every cell consists of two main layers: one charged positively and the other negatively.

This produces a steady electromagnetic field within the cell which conveys the flux of electrons.

The aluminum and silicon dioxide layers constitute the elements of the circuit itself, allowing the current transition.

A photon which interacts with the atoms of the positive layer arrives (the anti-reflecting layer favours the input) freeing an electron that is conveyed to the circuit:

WE HAVE THE CURRENT.

E

The most common version of a photovoltaic cell is constituted by a lamina of semiconductor material, the most widespread of which is silicon, and it is generally blue or black.

Small amounts of silicon photovoltaic cells are found in calculators, watches etc..

The photovoltaic cell efficiency is obtained by evaluating the ratio between the electrical power produced by the cell and the energy of the solar radiation that invests the entire surface .

PHOTOVOLTAIC CELL

SOLAR POWER INSTALLATION fotone

Elements of a photovoltaic plant:

PANELS PANNELLO

When photons (particles of Sun energy) strike a photovoltaic cell, a part of energy is absorbed by the material and some electrons flow through the semiconductor material (suitably treated) producing direct current

STRINGA

CAMPO FIELD

STRINGS

MODULO MODULE

CELLA CELL

SOLAR TRACKING PHOTOVOLTAIC PLANT Solar tracking is a technology able to increase considerably the production of electric power from photovoltaic panels.

Efficiency can increase by 45% The tracking of the sun can be made with a single axle (in this case rotation takes plase only on the horizontal, or vertical, axle) or with a double axle, that is rotation takes place both horizontally and vertically at the same time.

In this second way the panels are always head-on the Sun.

The process to extract and work silicon is very expensive.

We need to limit the costs of production and sales and develop new technologies in the future

Strategies for the future: Expand silicon.

Researchers at Stanford University ,in California, have developed a silicon-based chip which can be mechanically expanded ("stretchare" in U.S. slang, means stretching the chip in every direction) in order to cover a wider area. This chip can be up to hundreds of times the original size.

Use nanotechnologies.

“Nanosolar “produces third generation photovoltaic cells obtained by pressing nanoparticles made of copper, indium, gallium and selenium alloy on flexible material (CIGS: their efficiency is quite the same to the one of silicon, but their cost is approximately about a fifth, which is lower even than the exploitation of coal) with a new "ink energy" able to transform solar radiation into electrical energy .

Concentrate sunlight (CPV tecnhology).

“Emcore Corp”, from Canada, a provider of solar stations and space communications systems, has launched the application of advanced technologies on the Earth. These were tested only out of the atmosphere before. In this type of cells the concentrator has the size of 1 square centimeter, able to generate the same energy of 500 square cm of conventional solar cells. The materials used for the construction of the concentrator are cheap.

Recycling panels Most of a solar module components can be reused.

Thanks to technological innovations occurred in recent years , up to 95 % of some semiconductor materials or glass, as well as vast quantities of ferrous and non-ferrous metals used in photovoltaic modules can be recycled.

However, the percentage of photovoltaic material which is unused or disposed in landfills not suitable for this purpose is still very high.

Furthermore, during the disposal process, with the only exception of certain materials which do not contain toxic substances in their composition, heavily polluting substances from the constituent materials are released into the atmosphere.

From 1 July 2012 photovoltaic panels producers must have the membership certificate of an authority that ensures the recycling of photovoltaic modules.

In the absence of such membership, proved by its certificate to be presented at the time of sale, the manufacturer cannot allow his customers to take advantage of state incentives THE MAIN OBJECTIVE OF PV CYCLE is to recycle 80% (in weight) of a solar module by 2015 and 85% by 2020

Concentration Photovoltaic Installations in California The largest active installation is located in California, near Los Angeles.

It has 118 large panels that exploit the desert sun producing 250 MW power.

This solar power installation is going to reach its maximum power in 2014.

It will increase by 50% the total flow of solar power plants installated in the U.S.A. using the “linear parabolic mirror� concentration technology.

It will be able to cover the consumpition of 54,000 homes.

The mirrors are concave and at least 10 metres long.

The Sun radiation which reaches them is concentred on a pipe put on their focus.

In Europe, the main photovoltaic power installation is located near Gargano in the south of Italy and extends over an area of 4000 square meters.

A photovoltaic installation in Cremona: in 2011 it produced 5789,257 kwh electricity for the National Electric system, net of its own use.

An orbital solar power station is a hypothetical electric power plant It is made of one or more satellites which convert sunlight into electricity through photovoltaic cells.

Then they transmit the energy thus obtained in the form of microwaves or laser through an antenna.

The advantage consists in the constancy of lighting and in the lack of weather conditions (clouds, rain, etc.) which can reduce the flow of energy.

An orbital solar power station is made of three parts: • a big solar energy collector with photovoltaic cells. • an aerial to transmit microwawes towards the earth. • a high dimension aerial on the Earth that receives microwawes and changes them into electric energy.

With a solar power station in space we would receive direct, constant lighting with 99% efficiency.

A big problem will be sending materials into orbit. Taking into account the current cost of space shuttle, the transport is beetwen 8.000 and 11.000 U.S. dollars per kg.

The exact price will dipend on the number of launches necessary to send materials into orbit.

This way to acquire energy is just at the experimental stage at present.

For the future, scientists are looking for new systems to transmit lasers to the Earth, able to overcome technical and economical obstacles.

The most sustainable city..

In 2010 the Economist Intelligence Unit (EIU) designated Copenhagen as the most ecologically sustainable European city.

The British Unit has measured the commitment of 30 cities in 30 countries in riducing the environmental impact, analyzing 7 sustainability aspects: • • • • • • •

level of carbon dioxide emissions energy consumed sustainability of buildings system of transport use of water disposal of rubbish use of territory

SMART CITY: re-think today’s towns Technologies have a more and more important role in our cities and will become an element of daily and spontaneous use for citizens.

The aim is to improve cities with sustainable technologies that enable: • An intelligent managment of car traffic; • The development of Smart grids (they conduct the electric system) which can develop the use of renewable energies; • The development of Smart buildings (with reduction of energy and emission of CO2); From now to 2020 Italian cities that want to become “Smart” will get state incentives. A percentage of these incentives is intended for young people aged under 30 who want to present social innovation projects.

Low2No is a project which involves several economic sectors with "smart services�.

Low2No has been developing and growing for three years: a 100% sustainable area (zero impact) built near Helsinki.

Finland is, despite the small number of its inhabitants, slightly more than 5 million, the third nation in the world for Co2 emissions. It is surpassed only by the United States of America and United Arab Emirates.

A company from Turin won the call for bids in September 2009. It will exclusively use solutions made in Italy.

Low2No wants to promote a more sustainable lifestyle.

The amount of CO2 produced during daily activities by a family has been kept under control like a diet.

The Webster family,who lives in Espoo (Finland) was the protagonist of an experiment lasted one year and documented in the film "Recipes for disaster" (http://www.youtube.com/watch?featur e=player_embedded&v=qlm6GvxdlRE) The documentary showed how it is possible to adopt a low-footprint lifestyle without giving up our habits and nice things life can offer.

Giving up plastic products or cars is undoubtedly a difficult choice to be taken, but absolutely possible, especially if adopted by a group of people.

We can see how two children are able to cope with the new plastic-free life with energy and enthusiasm.

The choice to adopt the metaphor of "Detox Diet" worked.

John Webster and his family, after a year characterized by challenges, difficulties, doubts but also satisfactions and small everyday joys, can effectively reduce drastically the “home production� of Co2.

Primary and secondary school of San Vendemiano

Photovoltaic Plants THE TOWN OF S.VENDEMIANO HAS INSTALLED PHOTOVOLTAIC PANELS WITH POWER UP TO 20Kwp ON OUR SCHOOLS

THEY HAVE BEEN INSTALLED

LAYING ON A TERRACE: one plant on S. Francesco PRIMARY SCHOOL

LAYING RETROFIT: two plants One on G. Saccon

LOWER SECONDARY SCHOOL

One on S. Francesco PRIMARY SCHOOL

PRIMARY SCHOOL

laying on a terrace

LOWER SECONDARY SCHOOL

“Retrofit” laying on the roof

THE PANELS CAN ONLY BE GLIMPSED FROM BELOW

PHOTOVOLTAIC PLANT DIAGRAM INVERTER

PHOTOVOLTAIC MODULES ELECTRIC LINE

NATIONAL ELECTRIC SYSTEM DISTRIBUTION

it turns the direct current delivered by the sisystem into alternate current to put it in the electric system

METER

DIRECTION OF PHOTOVOLTAIC ENERGY FLOW

EXCHANGE/SALE METERS

DIRECTIN OF ENERGY FLOW FROM THE ELECTRIC SYSTEM

USERS

INDICATOR DISPLAY INSTALLED IN THE HALLS OF SCHOOLS

KWH of ENERGY PRODUCED AT THE MOMENT KWH of ENERGY PRODUCED UNTIL THAT TIME

CO2 NOT PRODUCED AND NOT RELEASED IN THE ATMOSPHERE

GRID_CONNECTED: connection to the national electric system. The energy produced is transferred into the national electric system and calculated by the operator. This one can purchase the energy produced or allow us to use it when necessary. In this case, there are state incentives which allow us to amortize the cost of the plant.

Students                   

BAGHIU DIANA BARRO DANIELE BASEI NICOLE BOLDRIN ELENA BONETTO PATRICK BOLZAN ALESSANDRO CASAGRANDE MARCO CARIA IVAN DAL PONTE ELISABETTA DA RIN FIORETTO STEFANO DE ZAN TOBIA ESPOSITO SAMUELE FLAVIANI DEBORA GIACOMIN GIOIA HU ANGELO ISEPPI ANASTASIA TRENTIN OSCAR SCUDELLER GIOIA ZORZINI LORENZO

Teachers: Silvana Sorce Gabriella De Pizzol

Class 3C