1) Definition of energy

Energy is an abstract physical quantity, which is linked to dynamic state of a closed system and that remains unchanged over time. You can also define the power of open systems, IE, parts not isolated from each other in a more closed system. A statement of the classical Newtonian physics states that energy is not created or destroyed, only transformed.

Energy is not a real physical state, nor an “intangible substance” but only a scalar number that is assigned to the state of the physical system, IE, energy is a mathematical abstraction or a property of physical systems. For example, one can say that a system with no kinetic energy is at rest.

The magnitude of energy use in practical terms is justified because it is much easier to work with scalar quantities, such as energy, vector magnitude, such as speed and position. So you can fully describe the dynamics of a system according to the kinetic energy, potential and other components. In isolated systems, in addition, the total energy has the property of “conservative”, IE be invariant over time. Mathematically, the conservation of energy for a system is a direct consequence of the evolution equations of this system is independent from the time in question, according to No ether’s theorem.

2) Major sources of energy in nature

Wind Energy

is the energy derived from wind, or the kinetic energy generated by the effect of air currents, and is transformed into other useful forms for human activities.

The wind comes from the Latin word Aeolus, belonging or related to Colo, the god of the winds in Greek mythology. Wind energy has been used since ancient times to move boats propelled by sail or operate machinery mills to move their blades.

At present, wind energy is mainly used for producing electricity through wind turbines. At the end of 2007, worldwide capacity of wind generators was 94.1 megawatts. While wind power generates about 1% of global electricity consumption, representing approximately 19% of electricity production in Denmark, 9% in Spain and Portugal, and 6% in Germany and Ireland (2007 data).

Wind energy is an abundant, renewable, clean and helps reduce emissions of greenhouse gases by replacing thermal fossil fuel, making it a kind of green energy. However, the main drawback is its intermittent.

Solar Energy

Is the energy gained by the abstraction of light and heat emitted by the Sun Solar radiation reaching the Earth could be harnessed through the heat it produces, but also through the absorption of radiation, egg optical devices or otherwise. It is a so-called renewable energy, particularly the non-pollutant, known as clean energy or green energy.

The power of radiation varies according to time of day, weather conditions that soften and latitude. It can be assumed that in a good position to influence the value is approximately 1000 W / m² in the earth’s surface. This power is known as irradiates.

Radiation is usable in direct and diffuse components, or the sum of both. Direct radiation is coming directly from the solar source, without intermediate reflections or refractions. The diffuse is issued by the daytime sky thanks to the many phenomena of reflection and refraction in the solar atmosphere, clouds and other atmospheric and terrestrial elements. Direct radiation can be reflected and concentrated on its use, while it is not possible to concentrate the diffused light coming from all directions.

The direct normal irradiates (or perpendicular to the sun) out of the atmosphere called the solar constant and has an average value of 1354 W / m² (which corresponds to a maximum value at the perihelion of 1395 W / m² and a minimum value at aphelion 1308 W / m²).

Atomic Energy

Used when atoms fission or merge under certain conditions, releases a tremendous amount of energy that is used for generating electricity or producing explosions

Energy Chemistry

Chemical energy is a manifestation of energy. In particular, there is one aspect of the internal energy of a body and, although it is always in the field, we are only displayed when there is an alteration close to it.

In quality, the chemical energy that drives the cars, ships and planes and, in general, millions of machines. The combustion of coal, wood or oil in steam engines as the petroleum products and reduced in the narrow space of the cylinders of an engine explosion, are chemical reactions.

 
Coal and gas are combined aerated with oxygen, reacts with and become soft and slow, in the case of coal, or instant and quickly, in the case of gasoline inside the cylinders of engines. Gaseous mixtures expand considerably swollen and in an instant and quickly communicated to the piston engine to pass his energy, his vital force or movement.

 
If Roseanne coal or firewood, gasoline and oil in an atmosphere of inert gas, egg nitrogen gas, neither the first nor the last arderían exploited in the cylinders. Nitrogen does not react with those bodies and the mixtures of gasoline and nitrogen or burn or explode.

Finally, there are the latest and most spectacular application of the chemical energy to achieve what for many centuries was his dream: the return trip to outer space and the Moon, as well as the placement of different types of artificial satellites certain orbits.

Thermal Power

Is called thermal energy to the energy released as heat. Can be obtained from nature, from the chemical energy through an exothermic reaction, such as the combustion of any fuel for a nuclear reaction of fission or fusion, by electricity or by Joule effect thermoelectric effect, or by friction , as a residue of other mechanical or chemical processes. You can also take energy from nature, which is in the form of heat, such as geothermal or solar energy.

The thermal energy can be transformed using a heat engine, either into electricity in a thermal power station, or into mechanical work, as in a motor car, plane or boat.

Obtaining thermal energy involves an environmental impact. The combustion releases carbon dioxide (CO2) emissions. Current technology in nuclear power leads to radioactive waste that must be controlled. They must also take into account the use of land for power plants and pollution hazards from accidents in the use of the materials involved, such as oil spills or petrochemical derivatives.

Biomass energy

Biomass is defined as organic matter that originates from a biological process and distinguish various types, as plant biomass, which are plants in general and animal biomass, which would be animals.

Is one that encompasses forests, thickets, etc.. Waste wood can be used to produce energy. For example, the logging produced a series of waste or by-products with a high energy, not used for furniture and paper, as are the leaves of branches, and which can be exploited as an energy source. By the same token, can be used as a fuel remnants of processing industries of timber, such as sawmills, carpentry or furniture and other materials.

Radiant Energy

Is the energy possessed by the electromagnetic waves as visible light, radio waves, ultraviolet (UV), infrared (IR), etc. The main feature of this energy that is propagating in a vacuum without any material support. Transmitted by units called photons, these units are also called photons as particles, should be raised as the physicist Albert Einstein in his theory of general relativity.

3) Principle of energy conservation

Indicates that energy is not created or destroyed, only transformed into other shapes. In these transformations, the total energy remains constant, IE the total energy is the same before and after each transformation.