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Renewable and Non-renewable resources, Alternative sources of energy, Nuclear fission and Fusion, Energy crisis
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Alternative Sources of Energy • Alternative energy sources include those that do not consume fossil fuels. These are widely available and do not cause any undesirable consequences to the environment. • Here is the list of major alternative energy sources. • Solar Energy • Wind Energy • Biomass Energy • Geothermal Energy • Tidal Energy • Nuclear energy
Geothermal Energy • Geothermal energy is the thermal energy generated and stored inside the Earth’s crust. • The centre of the Earth is very hot which melts the rocks, increases by 80 C where volcano and earthquake are active • The molten rocks formed in the Earth’s crust are pushed upward where they get trapped in certain regions called ‘hot spots’. When underground water comes in contact with the hot spot, steam is generated. • Sometimes this hot water formed region finds outlets at the surface. When this hot water gushes out of one of these outlets, it is called hot springs. • Heat is evolved out during the volcanic eruption and earthquakes
Geothermal energy • Below Earth’s surface, very high heat melts rock to form magma. This heat is called geothermal energy. • In some places, the magma is close to the surface. Here, underground water boils and forms steam. • Geothermal energy can also be used to generate electricity. Steam turns generators in a power plant to produce electricity.
Geothermal Energy Advantages • Renewable resource: Geothermal energy is free and abundant • Green energy: Geothermal energy is non-polluting and environment-friendly • Can be used directly: for melting of ice on the roads, heating houses in winters, greenhouses, public baths, etc. Disadvantages • High installation • Intensive research required • Limited to particular regions • Impact to the environment: may result in the release of highly toxic gases into the environment
Tidal Energy • The energy obtained from the rise and fall of tides is called the tidal energy. • Tidal barrages or dams are constructed across a narrow opening to the sea. Water rushes into the dam when the sea level rises. This moves the blades of the turbines which are attached at the opening of the dam. This results in the generation of electricity.
Tidal Energy Advantages • Environment-friendly: No pollution • High energy production • Inexhaustible source of energy Limitations • High tidal power plant construction costs • Disrupts in navigation system • Location limits: Not useful for landlocked countries like Nepal • Variable intensity of sea waves
Solar Energy • It is defined as the radiating light and heat from the sun that is harnessed using devices like heater, solar cooker, photovoltaic cell to convert it to other forms of energy such as electrical energy and heat. • Regulates flow of wind and water cycle, provides warmth, used for heating and cooking purposes, provides light energy. • 20 MW per square Km can be harnessed on the earth
Solar energy Advantages • Environmental Sustainability: No pollution • Economically Viable: Operation and maintenance cost of cells are very low. • Accessible: Solar panels are easy to set up and can be made accessible in remote locations. • Renewable: Energy is free and abundant in nature. Limitations • The efficiency of solar panels is low compared to other renewable sources of energy. • Intermittent and unpredictable: can only be harnessed in the presence of sunlight and gets reduced during cloudy weather. • Its storage is problematic.
Wind Energy • Wind power or wind energy is the use of wind to provide the mechanical power through wind turbines to turn electric generators and traditionally to do other work, like milling or pumping. • Used to generate electricity, to move sailing boats, to run a pump to draw water from the ground, etc. Wind turbine blades may be as much as 60 meters long. They turn when the wind blows A gearbox makes the generator spin when the blades turn. The faster the generator spins, the more electricity it makes
Wind Energy Advantages • Do not cause pollution • Wind supply will not run out • Free of cost Limitations • Only work in places where there is enough wind • Wind does not blow all the time
Biomass energy (Bio-fuel) • Biomass energy is a renewable source of energy, derived from burning animal and plant waste (biomass) • The dead parts of plant and tress and the waste materials from animals are called Biomass. • The mixture of methane, hydrogen, hydrogen sulfide gases produced on the degradation of biomass is called biogas. • The physical installation to produce biogas from biomass is called biogas plant. • Used for cooking, lighting, etc
Biomass (Biogas) Advantages • Renewable source of energy. • It reduces the overreliance of fossil fuels. • Less expensive than fossil fuels. • Less garbage in landfills. • Doesn’t pollute the environment Disadvantages • Biomass energy is not as efficient as fossil fuels • It is not entirely clean
Hydroelectricity • According to statistics, hydroelectricity generated around 16.6% of the global energy resources and constituted about 70% of all the renewable electricity. • This energy is another alternative source of energy that is generated by the construction of dams and reservoirs on the flowing water, the kinetic energy from the flowing water is used to run the turbines which generate electricity. • A tidal power which converts the energy of tides and Wave power which captures the energy from the surface of the ocean waves for power generation. • These two forms of hydropower also have huge potential in electric power generation
Hydroelectricity in Nepal • Nepal possesses 6000 rivers including rivulets and tributaries in totaling of about 45,000 km in length and covering an area of 395,000 ha (48%) which offers dimensional uses including hydropower development • Geographically, perennial nature of rivers estimated an annual runoff accounting up to 170 billion m3 that flows from steep gradient and rugged topography and estimated 45,610 MW, feasible for hydropower generation which is equivalent to 50% of the total theoretical potential of 83, 290 MW • Existing production is 650 MW
Hydroelectricity Advantages • Renewable • Pollution Free • Reliable: Unlike when the sun goes down or when the wind dies down, water usually has a constant and steady flow 24/7. • Adjustable: Can produce more energy when it is required or reduce the energy output when it is not needed. Limitations • Energy production varies • Improper construction may affect aquatic organism
Non-renewable source of energy • The non-renewable energy is energy from fossil fuels such as coal, crude oil, natural gas and uranium. Unlike renewable energy, non renewable energy need human intervention to make it suitable for consumption • Natural Gas: The process of decomposition is longer as it is conducted to high amounts of pressure and heat. • Coal: It is formed by the decomposition of trees, plants and ferns which are hardened due to pressure and heat. • Oil: Due to excessive pressure, smaller organisms like zooplankton and algae are decomposed into an oil.
Fossil fuels Advantages • It is easily accessible and more compatible. • The non-renewable source of energy is easy to store. Disadvantages • Non-renewable energy cannot be replaced once their energy source is used up. • The by-products of non-renewable energy cause environmental damages. It also increases greenhouses gases.
Energy crisis in Nepal • The extreme shortage of available fossil fuels to meet the ever increasing demand of energy is called energy crisis. Reasons: • Excess use of non-renewable sources of energy • Growing population requiring more energy consumption • Rapid industrialization • Advanced style of life increases energy consumption
Solutions for energy crisis • Controlling population growth • Use renewable and alternative sources of energy • Wise and efficient use of energy. • Using efficient fuel consuming devices • Create public awareness to save energy.
Nuclear energy (power) • Nuclear power is the use of nuclear reactions that release nuclear energy to generate heat, which most frequently is then used in steam turbines to produce electricity in a nuclear power plant. • Atoms contain huge amounts of energy, and there are two ways in which this energy can be released. • One way is to split atomic nuclei in a process called nuclear fission. • Another way is to join nuclei together in a process called nuclear fusion. • E = mc2 (Einstein’s Theory of relativity) where, E = energy released, m = mass lost, c= velocity of light in vacuum
Nuclear/ Thermonuclear fusion • Nuclear fusion is a reaction in which two or more lighter nuclei/atoms are combined to form a stable heavy nucleus with the release of large amount of heat energy. • The decrease in mass results in release of large amount of energy • Inside the Sun, this process begins with protons (which is simply a lone hydrogen nucleus) and through a series of steps, these protons fuse together and are turned into helium. This fusion process occurs inside the core of the Sun, and the transformation results in a release of energy that keeps the sun hot
Sun • Energy radiation per second = 4 x 1026 J/s • Energy radiation on the earth surface = 1.4 Kw/m2 • Surface temperature = 5700 oC Evidence of nuclear fusion on the sun: • There is huge amount of hydrogen • There is plenty of helium • Enough temperature (106 K) to split the hydrogen atoms into plasma state (required to overcome electrostatic repulsion between lighter nuclei) • Extreme pressure to combine similar charger nuclei
Nuclear fission • Nuclear fission is a reaction in which one heavy radioactive nucleus is split into two or more nuclei with the release of large amount of energy. • Radioactive elements like Uranium (92U235 ), plutonium, thorium are required for this process • The reaction in which the particles that initiates a reaction is also produced in a large number during the course of reaction and the reaction continues on its own till one of the reactant is consumed completely is called chain reaction.
Nuclear energy Advantages • Used to generate electricity • Radioactive elements are used to treat cancer Disadvantages • Emission of radioactive rays cause serious health hazards • Safe disposal of nuclear waste is big problem.
