The world energy requirements, specifically for electricity, will be increased to a large extent during the 21st century which has already began not only because of demographic pressures but also because of the continuously improved specifications of the existence, the urban and industrial inflation and the increasing expectations. At the same time the increasing price of oil ,and the non renewable sources of oil and lignite are the reasons for other forms of production of energy.The renewable sources of energy that can be used in the stage of home or business include the following technologies : the biomass for heating, the Geothermic for hot water, solar power systems for production of solar electricity, the wind generators from which we have production of electric energy and finally the hydroelectric energy ,where with the force of water we produce electric energy for each use.

Alternative energies

This project is about solar ,wind and hydroelectric energy.

The rational use of energy resources of planet and the use of renewable sources of energy are necessarily in order to prevent the climatic changes.

Renewable sources of energy Soft forms of energy

Renewable sources of energy Soft forms of energy

The soft forms of energy are forms of exploitable energy that emanate from various natural processes, as the wind, the geothermic, the circulation of water and others.

The term “soft” is reported totheir two basic characteristics. Firstly, for their exploitation is not required certain energetic intervention, as excavation, pumping, combustion, as with up to now used sources of energy, but simply the exploitation of already existing flow of energy in the nature.

Second, is “clean” forms of energy, very friendly to the environment, that they do not release hydrocarbons, dioxide of coal or toxic and radioactive waste as the remainder sources of energy that are used in big scale.

Often they are reported also as “renewable sources of energy”.• As “renewable sources” they are considered generally speaking the alternative the traditional sources of energy (e.g.

the oil or the coal), as solar and wind.• The characterization “renewable” is somehow abusive, for certain of these sources, as the geothermal energy that

they are not renewed .

The soft forms of energy are based on the solar radiation, with the exception of the geothermal energy, which is flow of energy from the interior of rind of

ground, and the energy from the tides that exploit the gravity.The based on the solar radiation soft sources of energy are renewable, as they are not to be exhausted as long as the sun exists , that is to say for certain still

billions of years.Solar energy is “packed” in one or other way: the biomass is solar energy

committed in the webs of plants via the photosynthesis, wind energy exploits the winds that are caused by the heating of air and water energy exploits the

circle of evaporation of water and its circulation.The geothermal energy is not renewable, the geothermal fields are at some

time exhausted.The high , however ,up to late price of new energy applications, the technical

problems of application as well as political and economic expediency that they have to make with the maintenance of present status kwo in the energy sector

prevented the exploitation of even this part of potential.Specifically in Greece, that has morphology and climate suitable for new energy applications, the exploitation of this energy potential would help

considerably in the energy autonomy of country.

The interest for the soft forms of energy was brought up the decade 1970, as resulting from mainly the petrol crises of season, but also alteration of environment and quality of life from the use of classic sources of energy.Today however they are taken into consideration in the official plans of developed states for the energy and, even if they constitute very small percentage of energy production, they are prepared steps for their exploitation. The cost of applications of soft forms of energy falls constantly the last twenty years and specifically the Aeolian and hydroelectric energy, but also the biomass, can henceforth rival in the equally traditional sources of energy as coal and the nuclear energy.Indicatively, in the USA a 6% of energy it emanates from renewable sources, while in the European Union of in 2010 the 25% of energy emanate from renewable sources (mainly hydroelectric and biomass).

Types of soft forms of energyTypes of soft forms of energy

Wind energy. Solar energy. Waterfalls. Biomass. Geothermal energy. Energy from tides. Energy from waves. Energy from the oceans.

Aeolian (Wind) energy. It was used in the past for the pumping of water from wells and for mechanic applications. It has begun to be used widely for generation of electricity.

Aeolian (Wind) energy. It was used in the past for the pumping of water from wells and for mechanic applications. It has begun to be used widely for generation of electricity.

Solar energy. It is used more for thermic applications (solar heaters and ovens) .The use for the production of electricity is

at the present moment expensive.

Waterfalls. In the field of soft forms of energy they are specialized more in small hydroelectric power stations. It is the widest spread

form of renewable energy.

Biomass.It uses the carbohydrates of the plants (mainly the waste of industry of timber, foods and forages and industry of sugar) aiming at the disengagement of energy that was committed from the plant with the photosynthesis. Also they urban waste and litter can be used. It can give bioethanol and biogas, that is fuels friendlier to the environment. It is a source of energy with a lot of possibilities and applications that will be used widely in the future.

Geothermal energy. It emanates from the heat that is produced by the radioactive

decomposition of rocks of ground. It is exploitable there ,where this heat goes up in natural way in the surface, for example in geysers or in sources of hot water. It can be

used or directly for thermal applications or for the production of electricity. Iceland covers her 80-90% energy needs with

the help of the geothermal energy.

Energy from tides. It exploits the gravity of Helium and Moon, that causes the elevation of the level of water. The water is stored when it goes up and in order to go down it is forced to pass through a turbine, producing electricity. It has been applied in England, France, Russia and elsewhere.

Energy from waves. It exploits the kinetic energy of waves of sea.

Energy from the oceans. It exploits the difference of temperature between the

layers of ocean, making use of thermic circles. It is found in the stage of research.

Advantages The renewable sources of energy are very friendly to the

environment, having substantially null residues and waste. They are not to be exhausted ever, contrary to mining fuels. They can help the energy self-sufficiency of the small and developing countries, as well as constitute the alternative proposal in combination with the economy of oil. They are flexible applications that can produce energy in relation to the needs of the local population, abolishing the need for enormous units for the production of energy (firstly for the

countryside) but also for transport of energy in big distances. The equipment is simple in the manufacture and the

maintenance and has a long duration of life.

Disadvantages They have enough small factor of output, order the 30% or even lower. Consequently it is

required a big enough initial cost of application in a large surface of ground. For this reason up to now they are used as additional sources of energy. For this reason at the present moment they cannot be used for the cover of needs of big urban areas. The benefit and

output wind, hydroelectric and solar energy depends on the season of the year but also on the geographic width and the climate of the region in which they are installed. For the wind machines exists the opinion that they are not elegant from aesthetic opinion and that they

cause noise and deaths to birds. For the hydroelectric work it is said that they cause emission of methane from the decomposition of plants that is found under the water and thus

contributes to the phenomenon of greenhouse..

• To make sure we have plenty of energy in the future, it's up to all of us to use energy wisely. We must all conserve energy and use it efficiently. It's also up to those who will create the new energy technologies of the future.

• All energy sources have an impact on the environment. Concerns about the greenhouse effect and global warming, air pollution, and energy security have led to increasing interest and more development in renewable energy sources such as solar, wind, geothermal, wave power and hydrogen.

• But we'll need to continue to use fossil fuels and nuclear energy until new, cleaner technologies can replace them. One of you who is reading this might be another Albert Einstein or Marie Curie and find a new source of energy. Until then, it's up to all of us.

• The future is ours, but we need energy to get there.