Renewable Resources PDF

Renewable Resources  Solar energy is the sun’s rays (solar radiation) that reach the earth. Can be used to heat water and heat spaces. Conversion to Solar Energy Photovoltaic (PV devices) or “solar cells” – change sunlight directly into electricity. Solar Power Plants - indirectly gene...

Renewable Resources  Solar energy is the sun’s rays (solar radiation) that reach the earth. Can be used to heat water and heat spaces. Conversion to Solar Energy Photovoltaic (PV devices) or “solar cells” – change sunlight directly into electricity. Solar Power Plants - indirectly generates electricity when the heat from solar thermal collectors is used to heat a fluid which produces steam that is used to power a generator. Solar Energy  Solar energy—power from the sun—is a vast and inexhaustible resource. The solar energy may be used directly through passive solar energy systems or active solar energy systems. Passive solar energy system does not need any mechanical power. It is a architectural design of brick wall, stone floor which can absorb heat in day time and pass into the inner wall at night and keep the room warm in winter days. Active solar energy system pumps a heat-absorbing fluid (air/water) through solar collector to heat sink, where the heat is stored until used.  The solar energy is converted into heat or thermal energy through solar collector The solar energy is converted into electrical energy through photovoltaic cell. The devices commonly used for harnessing solar energy are:- Solar cooker Solar water heater Solar water pumps Solar cells Solar power tower Solar cooker- consists of an insulated box with the interior walls coated black. A glass lid or simple plane mirror reflector is attached top box which serves as passive solar collector. These reflect the radiation to the black surface where radiations are trapped. Flat Plate Collector  Solar water heater- is a device used to supply hot water by converting solar energy into heat energy. It consists of a spherical reflector which directs solar rays to a focal point at which water is heated Solar Dish Collector  solar power tower A solar power tower is a system that converts energy from the Sun - in the form of sunlight - into electricity that can be used by people by using a large scale solar setup. The setup includes an array of large, sun-tracking mirrors known as heliostats that focus sunlight on a receiver at the top of a tower. In this receiver, a fluid is heated and used to generate steam. This steam then powers a conventional turbine generator to generate electricity A solar power tower, also known as 'central tower' power plant or ' heliostat' power plant, is a type of solar furnace using a tower to receive focused sunlight. It uses an array of flat, movable mirrors (called heliostats) to focus the sun's rays upon a collector tower (the target). Concentrating Solar Power (CSP) systems are seen as one viable solution for renewable, pollution-free energy Heliostat - an apparatus containing a movable mirror, used to reflect sunlight in a fixed direction. Wind Energy Wind is caused by the uneven heating of the atmosphere by the sun, variations in the earth's surface, and rotation of the earth. Wind energy describes the process by which wind is used to generate electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. A generator can convert mechanical power into electricity. Wind turbines convert the energy in wind to electricity by rotating propeller-like blades around a rotor. The rotor turns the drive shaft, which turns an electric generator. The best locations in terms of wind resource are typically high on mountains, in large open fields, or on the edge of bodies of water.  Geothermal energy Geothermal resource- Below Earth's crust, there is a layer of hot and molten rock, called magma. Heat is continually produced in this layer, mostly from the decay of naturally radioactive materials such as uranium and potassium. The amount of heat within 10,000 meters (about 33,000 feet) of Earth's surface contains 50,000 times more energy than all the oil and natural gas resources in the world. The areas with the highest underground temperatures are in regions with active or geologically young volcanoes. These "hot spots" occur at tectonic plate boundaries or at places where the crust is thin enough to let the heat through. These regions are also seismically active. Earthquakes and magma movement break up the rock covering, allowing water to circulate. As the water rises to the surface, natural hot springs and geysers occur, such as Old Faithful at Yellowstone National Park.  There are three basic designs for geothermal power plants, all of which pull hot water and steam from the ground, use it, and then return it as warm water to prolong the life of the heat source. 1. In the simplest design, known as dry steam, the steam goes directly through the turbine, then into a condenser where the steam is condensed into water. 2. In a second approach, very hot water is depressurized or "flashed" into steam which can then be used to drive the turbine. 3. In the third approach, called a binary cycle system, the hot water is passed through a heat exchanger, where it heats a second liquid—such as isobutane—in a closed loop. Isobutane boils at a lower temperature than water, so it is more easily converted into steam to run the turbine.  If the water comes out of the well as steam, it can be used directly, as in the first design. If it is hot water of a high enough temperature, a flash system can be used; otherwise it must go through a heat exchanger.  Hydroelectric Power Harnessing the power of moving water to generate electricity, known as hydroelectric power. It does not emit air pollution or greenhouse gases but, blocking rivers with dams can degrade water quality, damage aquatic and riparian habitat, block migratory fish passage, and displace local communities. Since hydropower depends on rivers and streams for generation, the potential to use hydropower as a source of electricity varies across the country. To increase the volume of moving water, impoundments or dams are used to collect the water. An opening in the dam uses gravity to drop water down a pipe called a penstock. The moving water causes the turbine to spin, which causes magnets inside a generator to rotate and create electricity.  Hydrokinetic energy Hydrokinetic technologies produce renewable electricity by harnessing the kinetic energy of a body of water, the energy that results from its motion. The tidal cycle occurs every 12 hours due to the gravitational force of the moon. The difference in water height from low tide and high tide is potential energy. Tidal water can be captured in a barrage across an estuary during high tide and forced through a hydro-turbine during low tide. To capture sufficient power from the tidal energy potential, the height of high tide must be at least five meters (16 feet) greater than low tide. There are only approximately 20 locations on earth with tides this high and India is one of them. The largest tides are called ‘spring tides’ and happen when the sun and the moon are lined up in a row. This happens every two weeks during a new moon or a full moon. Small tides are called ‘neap tides’ and they happen when the sun and moon form a right angle to each other. This causes the sun and moon to pull water in two different directions. Neap tides happen during a quarter or three-quarter moon. The Gulf of Cambay and the Gulf of Kutch in Gujarat on the west coast have the maximum tidal range of 11m and 8m with average tidal range of 6.77m and 5.23m respectively. Tidal Barrage Biomass Biomass (plant material and animal waste) is the oldest source of renewable energy. If not managed carefully, biomass for energy can be harvested at unsustainable rates, damage ecosystems, produce harmful air pollution, consume large amounts of water, and produce net greenhouse emissions. Low-carbon biomass can provide a significant fraction of the new renewable energy. Beneficial biomass includes energy crops that don’t compete with food crops for land portions of crop residues such as wheat straw sustainably-harvested wood and forest residues, and clean municipal and industrial wastes  Industrial biomass can be grown from numerous types of plants, including miscanthus, switchgrass, hemp, corn, poplar, willow, sorghum, sugarcane, and a variety of tree species, ranging from eucalyptus to oil palm (palm oil). The process for conversion of biomass into useful biomass fuels are: Thermochemical process- Combustion Gassification Liquification Biological Processes- Enzymatic process Anaerobic digestion Aerobic digestion  Gasification is a technological process that can convert any carbonaceous (carbon-based) raw material such as coal into fuel gas, also known as synthesis gas (syngas for short). Gasification occurs in a gasifier, generally a high temperature/pressure vessel where oxygen (or air) and steam are directly contacted with the coal or other feed material causing a series of chemical reactions to occur that convert the feed to syngas and ash/slag (mineral residues). Anaerobic Digestion (AD) is a natural process where plant and animal materials (biomass) are broken down by micro-organisms in the absence of air. The AD process begins when biomass is put inside a sealed tank or digester. Naturally occurring micro-organisms digest the biomass, which releases a methane-rich gas (biogas) that can be used to generate renewable heat and power; this helps cut fossil fuel use and reduce greenhouse gas emissions. The remaining material (digestate) is rich in nutrients, so it can be used as a fertiliser.  The liquid biofuel in greatest production is ethanol (ethyl alcohol), which is made by fermenting starch or sugar. Brazil and the United States are among the leading producers of ethanol. In the United States ethanol biofuel is made primarily from corn (maize) grain, and it is typically blended with gasoline to produce “gasohol,” a fuel that is 10 percent ethanol. In Brazil, ethanol biofuel is made primarily from sugarcane, and it is commonly used as a 100-percent-ethanol fuel or in gasoline blends containing 85 percent ethanol. The second most common liquid biofuel is biodiesel, which is made primarily from oily plants (such as the soybean or oil palm) and to a lesser extent from other oily sources (such as waste cooking fat from restaurant deep-frying). Biodiesel, which has found greatest acceptance in Europe, is used in diesel engines and usually blended with petroleum diesel fuel in various percentages.