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Enough fossil ahead to the Green

You see things that are and ask yourself: Why? I dream things that never existed and I wonder: why not? (George Bernard Shaw)

For renewable energy refers to the methods of producing energy by sources resulting from natural resources that regenerate at least at the same rate with which they are consumed or not "exhaustible" in the timescale of "geological time". Are therefore alternative forms of energy than conventional fossil fuels (oil, coal, natural gas) and many of them have the distinction of being clean energy, ie not discharged into the air pollutants and responsible of climate such as the CO2 (carbon dioxide).These are the main renewable sources:

Solar power
It is an inexhaustible source of immediate availability and clean. The amount of solar energy that reaches the earth is huge (about 10,000 times greater than the energy used by all mankind) and can be used to generate electricity (photovoltaics) or heat (solar thermal). The photovoltaic has encountered problems of efficiency and high costs: the solar panels that use nanotechnology (with circuits constructed from individual molecules of silicon), they may cost half of the traditional photovoltaic cells. Currently the largest photovoltaic power plant in the world is located in Germany and only in Japan, United States and Germany the integration of buildings (building facades, roofs, photovoltaic shelters) was particularly interesting. The solar thermal for the production of hot sanitary water is now next to the competitiveness in various applications, especially where it is able to replace conventional plants. The solar thermodynamic uses parabolic solar thermal collectors, a fluid system that transfers heat from the collector to the point of use and a tank for the storage of heat for subsequent use. Such systems may be used to heat (the domestic water, the pools and environments), for industrial applications and for cooling.

Wind energy
It is the product of the transformation of the kinetic energy of the wind (the principle is the same as the old windmills). It is mostly converted into electricity by wind turbines that use wind turbines (the most common type is about 50 meters high with 2 or 3 blades 20 meters long and capable of providing a power supply daily to 500/600 kW). However, there are some resistance to the placement of turbines in some areas, for reasons of environmental impact and dangers against some species of birds.

Hydroelectric power
It is a clean and renewable source obtained from the force of the water. The flow of water of a lake, a river or a reservoir, suitably conveyed via appropriate piping, it can turn its power to pressure energy and kinetic. This energy powers a generator that converts it to electricity. This is the first renewable source used on a large scale: the first dam in history was built by ancient Egyptians 6.000 years ago to direct the waters of the Nile and later was used by the water mills. His contribution to world production of electricity is currently 18%. The greatest growth in the sector may be recorded in Asia, particularly in China.

Geothermal energy
It is generated by means of geological sources of heat and can be considered renewable, when evaluated in a short time. It is based on the production of natural heat of the earth (geothermal), he has supplying continuous and independent of climatic influences, but being difficult to transport heat, is used mainly for local use. Geothermal plants -for heating, the cooling of buildings and the production of warm water- may be a vertical probe (with tubes inserted vertically into the soil to a depth of 150m for the removal of heat from the subsoil) and horizontal probe ( with pipes inserted horizontally to 2m deep). However, geothermal energy is available only in limited areas of the world (United States, Central America, Indonesia, East Africa, the Philippines and Italy).

Biomass energy
Under European Community legislation on the promotion of energy from renewable sources, the term "biomass" is understood "the biodegradable fraction of products, waste and residues from biological origin from agriculture, forestry and industries related, including fisheries and aquaculture, as well as the biodegradable fraction of industrial and municipal waste." In Italy (a practice also known as incineration) are also included in the process municipal solid waste, which are not biodegradable. In the exploitation of this resource, they are at the forefront of the countries of Central and Northern Europe, which have installed large co-generation and district heating fueled by biomass.

Marine energy
It is contained in various forms in the seas and oceans. By means of particular techniques, they are exploiting the various potential offered by the sea such as the wave motion, the movement of air above the waves, tides or the temperature difference between the bottom and the surface. The use, however, is still quite complicated and currently very expensive. Portugal, Scotland and Ireland have successfully tested the use of this source, limiting the environmental impact thanks to turbines almost completely submerged and the movement of the rotors at low speed in order not to endanger the wildlife.

Your grandchildren will probably find incredible -or even sinful- you've burned a gallon of gasoline to fetch a pack of cigarettes! (Paul MacCready)

Bioenergy New Technologies: Biofuels and Biogas
The cellulosic ethanol can be obtained from inedible cellulose fibers that form the stems and branches, crop residues (corn stalks, wheat straw and rice), wood waste. France, which has the largest agricultural area in Europe, focusing on the production of biodiesel and ethanol, for use as fuel which has adopted a policy of full tax exemption. Brazil has combined the production of bioethanol from sugar cane and ethanol (already provides 18% of the automotive fuel).Biogas is to reuse the gas from landfills: Britain has developed an efficient recovery of biogas for thermal and electrical.

Future perspectives
The use of renewable sources and the reduction of costs as their objectives necessary for the preservation of the planet, innovation and employment. The elimination of subsidies for fossil fuels and increased incentives and funding for green energy can make a difference! The target energy autonomy without compromising on Environment must be reached and a valid assumption could be the realization of microimplants geographically distributed. They would get so: lower production costs, saving energy during distribution, to facilitate the local management.

Nature provides us with a free lunch, but only if we control our appetites. (William Ruckelshaus)

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