General Science: Energy

General Science Energy is the capacity of a system to do work. It causes things to happen around us. During the day, the sun gives out light and heat energy. At night, street lamps use electrical energy to light our way. When a car driven by, it is being powered by gasoline a type of stored energy. The food we eat contains energy. We use that energy to work and play.

Energy exists in many different forms. Examples of these are light energy, heat energy, mechanical energy, gravitational energy, electrical energy, sound energy, chemical energy, nuclear or atomic energy, and so on. These forms of energy can be transferred and transformed between one another. This is of immense benefit to us. For a source of energy to end up as electricity it may undergo many transformations before it can power the light bulb in homes.

Although there are many specific types of energy, the two major forms are Kinetic Energy and Potential Energy.

KINETIC ENERGY

It is a matter of common experience that a fast-moving stone can break a windowpane, falling water can rotate turbines, and moving air can rotate windmills and propel sailboats. In all these examples, the moving body possesses energy. The body does work in motion. This type of energy possessed by moving objects is known as Kinetic energy. Kinetic energy is defined as the energy possessed by an object by its motion.

The magnitude of the kinetic energy depends on both the mass and the object’s velocity according to equation K.E = ½ mv² where m is the mass of the object and v is its velocity.

POTENTIAL ENERGY

Water stored in a reservoir is capable of rotating turbines, which are kept at a lower level i.e. water stored in a reservoir possesses energy. A toy car driven by a winding key. When we turn the key the spring gets wound and if we leave the toy car on the floor, it starts moving due to the unwinding of the spring. This means that the wound spring possesses energy, which in turn moves the toy car. Here the gain in energy is due to its position or condition. Energy by virtue of position or configurations called potential energy. Formula of potential energy is P.E= mgh where m is mass, g is gravitational acceleration and h denotes height.

Energy Sources:

The energy sources have been split into two categories: Non-renewable sources and renewable sources.

Non-renewable sources

Non-renewable energy comes from sources that will run out and cannot be produced on a scale comparable to its consumption. Most non-renewable energy sources are fossil fuels: coal, petroleum, and natural gas. Carbon is the main element in fossil fuels.

Coal:

About 300 million years ago, enormous ferns and other prehistoric plants were common on the swamp-like earth. When those plants died and fell to the ground, they were covered with silt, day and water and they slowly decomposed. As decomposition took place in the absence of oxygen, much of the hydrogen content of the matter was eroded away, leaving a material rich in carob. The material was compressed over the years by sand and dirt, leaving the form of carbon known as coal.

There are various types of coal. The nature of coal is such that the higher the carbon content, the more cleanly and brilliantly the coal burns. The states of coal, from lowest carbon content to highest, are peat, lignite, bituminous coal, and anthracite coal. If the coal is heated and compressed even more, the result is graphite, almost completely pure carbon.

Petroleum:

Petroleum or crude oil is a liquid fuel that is present in various locations throughout the world. It has many uses, from the generation of electricity to the manufacture of medicines, plastics, and other commercial items. Much like coal, petroleum is formed from the remains of biodegraded organic material. When animals that lived in the sea, millions of years ago died the ocean floor. Then, as the years passed, pressure from the layers built up and compressed the organic material, forming the oil.

Natural Gas:

Natural gas is almost always found in deposits of petroleum, when the petroleum is drilled, natural gas is also recovered. Wells with only natural gas also exit. Once the natural gas is recovered other fuels are extracted by processes called condensation or absorption. The remaining gas is piped directly for commercial and residential applications.

The western hemisphere, Europe, and parts of Africa contain the largest natural gas deposits. The gas is usually transported by pipelines. Compared to petroleum and coal, natural gas is relatively clean-burning. Because it contains only trace portions of sulphur and nitrogen, emissions of the harmful by products associated with combustion of other fossil fuels are minimal.

Renewable sources:

Renewable energy is generally defined as energy that is collected from resources which are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat. Let us now discuss renewable energy sources in detail.

Wind power:

Airflows can be used to run wind turbines. Modern utility-scale, wind turbines range from around 600 kW to 5 MW of rated power, although turbines with rated output of 1.5-3 MW have become the most common for commercial use; the power available from the wind is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically up to the maximum output for the particular turbine. Areas where winds are stronger and more constant, such as offshore and high altitude sites are preferred locations for wind farms. Globally, the long-term technical potential of wind energy is believed to be 40 times current electricity demand. This could require wind turbines to be installed over large areas, particularly in areas of higher wind resources.

Hydropower:

Energy in water can be harnessed and used. Since water is about 800 times denser than air, even a slow flowing stream of water, or moderate sea swell, can yiel considerable amounts of energy.There are many forms of Hydel energy.

• Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams. Examples are Terbela dam and Magla dam
• Micro hydro systems are hydroelectric power installations that typically produce up to 100 kW of power. They are often used in water rich areas as remote-area power supply.
• Run-of-the-river hydroelectricity systems derive kinetic energy from rivers and oceans without the creation of a large reservoir.
• Tidal power, also called tidal energy, is a form of hydropower that converts the energy of tides into useful forms of power -mainly electricity. Although not yet widely used, tidal power has potential for future electricity generation.

Solar Energy:

Solar energy applies energy applies energy from the sun in the form of solar radiation for heat or to generate electricity. Solar-powered electricity generation uses either photovoltaics or heat engines (concentrated solar power). A partial list of other solar applications includes space high temperature process heat for industrial purposes.

Solar technologies are broad characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties and designing spaces that naturally circulate air.

Biomass and Biofuels:

Biomass is biological material derived from living, or recently living organisms. In the context of biomass for energy this is often used to mean plant based material but biomass can equally apply to both animal and vegetable derived material.

There are a number of technological options available to make use of a wide variety of biomass types as a renewable energy source. Conversion technologies may release the energy directly, in the form of heat or electricity, or may convert it to another form, such as liquid biofuel or combustible biogas. Today, new ways of using biomass are still being discovered.

Geothermal Energy:

Hot water and steam from deep underground can be used to drive turbines: this is called geothermal energy. Several types of rock contain radioactive substances such as uranium. Radioactive decay of these substances releases heat energy, which warms up the rocks. In volcanic areas, the rocks may heat water so that it rises to the surface naturally as hot water and steam. Here the steam can be used to drive turbines and electricity generators,

In some places, the rocks are hot, but not hot water or steam rises to the surface. In this situation, deep wells can be drilled down to the hot rocks and cold water pumped down. The water runs through fractures in the rocks and is heated up. It returns to the surface as hot water and steam, where its energy can be used to drive turbines and electricity generators.

Importance of Renewable Energy:

There are several important reasons that make reasons that make renewable energy extremely important for the future of our society. Renewable energy still has long way to go in order to replace fossil fuel and become primary source of energy consumption by thing have been latterly definitely moving in the right direction. But let us focus here about the future impact of renewable energy on our society.

Positive environmental impact is certainly one to the most important reasons. Fossil fuels when burn, create harmful greenhouse gas emissions and our planet is already feeling the impact of climate change. By using renewable energy instead of fossil fuels we would significantly decrease the current levels of greenhouse gas emissions, and this would have positive environmental impact for our entire planet.

Renewable energy can improve our energy security by reducing the need for foreign oil import. The global oil market has been characterized by extremely volatile prices and or dependence on oil continues to grow. By switching to renewable energy and using more domestic renewable energy sources instead of importing foreign oil we would drastically improve our energy security and energy independence.

Alternative Energy

Alternative energy source is any source of energy that does not belong to traditional energy sources. Traditional energy sources are fossil fuels (coal, oil and natural gas). Some dictionaries, like for instance, Oxford dictionary puts alternative energy sources in correlation to environment by stating that term “alternative energy sources” refers to energy derived from sources that do not use up natural resources or harm the environment. The most common alternative energy sources are: Solar energy, wind energy and geothermal energy. Other alternative energy sources include bio-fuels, tidal, wave power, and hydrogen.

 

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