Category The World Around us

Nuclear power plants use radioactive materials such as uranium or plutonium- to power their steam turbines. The atoms of these materials decay, producing heat energy inside a nuclear reactor. Nuclear energy is a “clean” fuel, in that it does not produce the polluting gases that burning fossil fuels do. However, the disposal of used nuclear fuel is hazardous, expensive and poses serious environmental risks.

Nuclear energy is the energy in the nucleus, or core, of an atom. Atoms are tiny units that make up all matter in the universe, and energy is what holds the nucleus together. There is a huge amount of energy in an atom’s dense nucleus. In fact, the power that holds the nucleus together is officially called the “strong force.”

Nuclear energy can be used to create electricity, but it must first be released from the atom. In the process of nuclear fission, atoms are split to release that energy.

A nuclear reactor, or power plant, is a series of machines that can control nuclear fission to produce electricity. The fuel that nuclear reactors use to produce nuclear fission is pellets of the element uranium. In a nuclear reactor, atoms of uranium are forced to break apart. As they split, the atoms release tiny particles called fission products. Fission products cause other uranium atoms to split, starting a chain reaction.

The energy released from this chain reaction creates heat.

The heat created by nuclear fission warms the reactor’s cooling agent. A cooling agent is usually water, but some nuclear reactors use liquid metal or molten salt. The cooling agent, heated by nuclear fission, produces steam. The steam turns turbines, or wheels turned by a flowing current. The turbines drive generators, or engines that create electricity.

Rods of material called nuclear poison can adjust how much electricity is produced. Nuclear poisons are materials, such as a type of the element xenon, that absorb some of the fission products created by nuclear fission. The more rods of nuclear poison that are present during the chain reaction, the slower and more controlled the reaction will be. Removing the rods will allow a stronger chain reaction and create more electricity.

As of 2011, about 15 percent of the world’s electricity is generated by nuclear power plants. The United States has more than 100 reactors, although it creates most of its electricity from fossil fuels and hydroelectric energy. Nations such as Lithuania, France, and Slovakia create almost all of their electricity from nuclear power plants. Nuclear power plants produce renewable, clean energy. They do not pollute the air or release greenhouse gases. They can be built in urban or rural areas, and do not radically alter the environment around them.

The steam powering the turbines and generators is ultimately recycled. It is cooled down in a separate structure called a cooling tower. The steam turns back into water and can be used again to produce more electricity. Excess steam is simply recycled into the atmosphere, where it does little harm as clean water vapor.

However, the byproduct of nuclear energy is radioactive material. Radioactive material is a collection of unstable atomic nuclei. These nuclei lose their energy and can affect many materials around them, including organisms and the environment. Radioactive material can be extremely toxic, causing burns and increasing the risk for cancers, blood diseases, and bone decay.

Radioactive waste is what is left over from the operation of a nuclear reactor. Radioactive waste is mostly protective clothing worn by workers, tools, and any other material that have been in contact with radioactive dust. Radioactive waste is long-lasting. Materials like clothes and tools can stay radioactive for thousands of years. The government regulates how these materials are disposed of so they don’t contaminate anything else.

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Some power stations are able to burn waste products that would otherwise be buried in the ground. Even waste that is already buried can be put to use by harnessing the methane gas that decaying matter gives off. Once purified, the gas can he piped to homes, or used in power stations. However, while it solves the problem of what to do with rubbish, burning waste releases gases into the atmosphere, creating a pollution problem of its own.

Since the industrial revolution, waste has been a major environmental issue worldwide. Wastes are materials we don’t need and thrown as trash. Europe creates over 1.8 billion tonnes of wastes each year. In Australia, 50 million tonnes of waste is generated each year. According to the UK Statistics on Waste, UK generated 202.8 million tonnes of waste in 2014. The total volume of waste is the measure of the overall impact of human activity on the environment. But, we can turn these tonnes of trash into treasure by turning them into energy.

Waste to energy is the process of producing thermal energy from the organic waste. Most wastes to energy processes produce electricity or heat energy directly through combustion.

Waste can be solid or liquid. Both types of waste can be hazardous. Liquid waste can come in non-solid form. Examples of liquid waste include wash water, liquid used to clean in industries. On the other hand, solid waste is any garbage and rubbish we make at our home or any places. Examples of solid waste include car tyres, newspapers, broken glass, broken furniture and even food waste. Hazardous or harmful waste is a threat to human health and environment. This type of waste can easily catch fire, explode and be poisonous to human health. Examples of these types of waste are chemicals, mercury-containing equipment, fluorescent bulbs, battery etc.

The wastes we are producing every day can be turned into something good. Such as electricity, heat or fuel. The solid wastes can be converted into gas to produce energy. We can generate electricity by burning solid waste found in the landfills. A community must have a waste to energy facility that incinerates garbage and transforms chemical energy into thermal energy.

The following methods are used to turn waste into energy. The most common technology for waste to energy conversion is incineration. In this process, the organics collected from the waste has burnt at a high temperature. This type of treatment is called thermal treatment. The heat generated from this thermal treatment then used to create energy.

This technology uses thermal decomposition in the presence of water. In this process, organic compounds from waste are heated at a high temperature to create thermal energy. In this process, we can generate fossil fuels from the waste. The process of thermal decomposition is also called Hydrous Pyrolysis.

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Solar-power systems convert light energy from the Sun into electricity using photo-voltaic cells. These cells are similar to those used to power pocket calculators, but used on a larger scale they can provide electricity for homes and businesses in areas away from a regular power supply. Most solar-power systems work by charging batteries that store the electricity for later use, act as a back-up system for a conventional power supply. Solar power is also used to heat water.

Solar energy is the most abundant energy resource on Earth. It can be captured and used in several ways, and as a renewable energy source, is an important part of our clean energy future. The sun does more than for our planet than just provide light during the daytime – each particle of sunlight (called a photon) that reaches Earth contains energy that fuels our planet. Solar energy is the ultimate source responsible for all of our weather systems and energy sources on Earth, and enough solar radiation hits the surface of the planet each hour to theoretically fill our global energy needs for nearly an entire year.

Where does all of this energy come from? Our sun, like any star in the galaxy, is like a massive nuclear reactor. Deep in the Sun’s core, nuclear fusion reactions produce massive amounts of energy that radiates outward from the Sun’s surface and into space in the form of light and heat.

Solar power can be harnessed and converted to usable energy using photovoltaics or solar thermal collectors. Although solar energy only accounts for a small amount of overall global energy use, the falling cost of installing solar panels means that more and more people in more places can take advantage of solar energy. Solar is a clean, renewable energy resourcec, and figures to play an important part in the global energy future.

A common way for property owners to take advantage of solar energy is with a photovoltaic (PV) solar system. With a solar PV system, solar panels convert sunlight right into electricity that can be used immediately, stored in a solar battery, or sent to the electric grid for credits on your electric bill.

Solar panels covert solar energy into usable electricity through a process known as the photovoltaic effect. Incoming sunlight strikes a semiconductor material (typically silicon) and knocks electrons loose, setting them in motion and generating an electric current that can be captured with wiring. This current is known as direct current (DC) electricity and must be converted to alternating current (AC) electricity using a solar inverter. This conversion is necessary because the U.S. electric grid operates using AC electricity, as do most household electric appliances.

Solar energy can be captured at many scales using photovoltaics, and installing solar panels is a smart way to save money on your electric bill while reducing your dependence on nonrenewable fossil fuels. Large companies and electric utilities can also benefit from photovoltaic solar energy generation by installing large solar arrays that can power company operations or supply energy to the electric grid.

A second way to use solar energy is to capture the heat from solar radiation directly and use that heat in a variety of ways. Solar thermal energy has a broader range of uses than a photovoltaic system, but using solar thermal energy for electricity generation at small scales is not as practical as using photovoltaics.

There are three general types of solar thermal energy used: low-temperature, used for heating and cooling; mid-temperature, used for heating water; and high-temperature, used for electrical power generation.

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The power of the wind can he used to generate electricity using huge wind turbines. The blades of a wind turbine drive a generator that produces electricity. Large groups of wind turbines, called wind farms, are built in areas where the wind blows fairly constantly. Flat, open areas of land and coastal areas are popular locations for wind farms. The electricity produced by these farms is fed into the electricity grid along with that coming from other sources.

Wind energy (or wind power) refers to the process of creating electricity using the wind, or air flows that occur naturally in the earth’s atmosphere. Modern wind turbines are used to capture kinetic energy from the wind and generate electricity.

When the wind blows past a wind turbine, its blades capture the wind’s kinetic energy and rotate, turning it into mechanical energy. This rotation turns an internal shaft connected to a gearbox, which increases the speed of rotation by a factor of 100. That spins a generator that produces electricity.

Typically standing at least 80 meters (262 feet) tall, tubular steel towers support a hub with three attached blades and a “nacelle,” which houses the shaft, gearbox, generator, and controls. Wind measurements are collected, which direct the turbine to rotate and face the strongest wind, and the angle or “pitch” of its blades is optimized to capture energy.

A typical modern turbine will start to generate electricity when wind speeds reach six to nine miles per hour (mph), known as the cut-in speed. Turbines will shut down if the wind is blowing too hard (roughly 55 miles an hour) to prevent equipment damage.

Over the course of a year, modern turbines can generate usable amounts of electricity over 90 percent of the time. For example, if the wind at a turbine reaches the cut-in speed of six to nine mph, the turbine will start generating electricity. As wind speeds increase so does electricity production.

Another common measure of wind energy production is called capacity factor. This measures the amount of electricity a wind turbine produces in a given time period (typically a year) relative to its maximum potential.

For example, suppose the maximum theoretical output of a two megawatt wind turbine in a year is 17,520 megawatt-hours (two times 8,760 hours, the number of hours in a year). However, the turbine may only produce 7,884 megawatt-hours over the course of the year because the wind wasn’t always blowing hard enough to generate the maximum amount of electricity the turbine was capable of producing. In this case, the turbine has a 45 percent (7,884 divided by 17,520) capacity factor. Remember—this does not mean the turbine only generated electricity 45 percent of the time. Modern wind farms often have capacity factors greater than 40 percent, which is close to some types of coal or natural gas power plants.

There are three main types of wind energy:

• Utility-scale wind: Wind turbines that range in size from 100 kilowatts to several megawatts, where the electricity is delivered to the power grid and distributed to the end user by electric utilities or power system operators.
• Distributed or “small” wind:  Single small wind turbines below 100 kilowatts that are used to directly power a home, farm or small business and are not connected to the grid.
• Offshore wind: Wind turbines that are erected in large bodies of water, usually on the continental shelf. Offshore wind turbines are larger than land-based turbines and can generate more power.

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In volcanically active areas of the world, heat energy inside the earth is used for power. Geothermal power-plants use the heat produced by molten rocks to create hot water and steam. The steam powers turbines, while the hot water is piped to homes. Iceland and New Zealand are two countries where geothermal energy is used.

Geothermal energy comes from the heat within the earth. The word “geothermal” comes from the Greek words geo, meaning earth,” and therme, meaning “heat.” People around the world use geothermal energy to produce electricity, to heat buildings and greenhouses, and for other purposes.

The earth’s core lies almost 4,000 miles beneath the earth’s surface. The double-layered core is made up of very hot molten iron surrounding a solid iron center. Estimates of the temperature of the core range from 5,000 to 11,000 degrees Fahrenheit (F). Heat is continuously produced within the earth by the slow decay of radioactive particles that is natural in all rocks.

Surrounding the earth’s core is the mantle, thought to be partly rock and partly magma. The mantle is about 1,800 miles thick. The outermost layer of the earth, the insulating crust, is not one continuous sheet of rock, like the shell of an egg, but is broken into pieces called plates. These slabs of continents and ocean floor drift apart and push against each other at the rate of about one inch per year in a process called continental drift.

Magma (molten rock) may come quite close to the surface where the crust has been thinned, faulted, or fractured by plate tectonics. When this near-surface heat is transferred to water, a usable form of geothermal- energy is created.

Geothermal energy is called a renewable energy source because the water is replenished by rainfall, and the heat is continuously produced by the earth. Geothermal energy is heat derived within the sub-surface of the earth. Water and/or steam carry the geothermal energy to the Earth’s surface. Depending on its characteristics, geothermal energy can be used for heating and cooling purposes or be harnessed to generate clean electricity. However, for electricity, generation high or medium temperature resources are needed, which are usually located close to tectonically active regions.

This key renewable source covers a significant share of electricity demand in countries like Iceland, El Salvador, New Zealand, Kenya, and Philippines and more than 90% of heating demand in Iceland. The main advantages are that it is not depending on weather conditions and has very high capacity factors; for these reasons, geothermal power plants are capable of supplying baseload electricity, as well as providing ancillary services for short and long-term flexibility in some cases.

There are different geothermal technologies with distinct levels of maturity. Technologies for direct uses like district heating, geothermal heat pumps, greenhouses, and for other applications are widely used and can be considered mature. The technology for electricity generation from hydrothermal reservoirs with naturally high permeability is also mature and reliable, and has been operating since 1913. Many of the power plants in operation today are dry steam plants or flash plants (single, double and triple) harnessing temperatures of more than 180°C. However, medium temperature fields are more and more used for electricity generation or for combined heat and power thanks to the development of binary cycle technology, in which geothermal fluid is used via heat exchangers to heat a process fluid in a closed loop. Additionally, new technologies are being developed like Enhanced Geothermal Systems (EGS), which are in the demonstration stage.

To promote wider geothermal energy development, IRENA coordinates and facilitates the work of the Global Geothermal Alliance (GGA) – a platform for enhanced dialogue and knowledge sharing for coordinated action to increase the share of installed geothermal electricity and heat generation worldwide.

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