INTRODUCTION
Energy is a concept at the center of every scientific discipline. Students examine the role of energy in our daily lives -- that is, how we produce the energy that we use to power our cities, our homes, and our schools, and at what cost. Students study several forms of energy production. They discuss the advantages and disadvantages of each energy resource, in particular, the controversy surrounding the use of nuclear energy. In the end, students gain insight into the difficult choices that must be made in order to meet the energy demands of a modern society. Renewable energy is energy that can be replenished on a time scale appropriate to human use.
Objectives
BIOMASS SOURCE OF ENERGY
Biomass is solar energy stored in organic matter. As trees and plants grow, the process of photosynthesis uses energy from the sun to convert carbon dioxide into carbohydrates (sugars, starches and cellulose). Carbohydrates are the organic compounds that make up biomass. When plants die, the process of decay releases the energy stored in carbohydrates and discharges carbon dioxide back into the atmosphere.
Biomass is a renewable energy source because the growth of new plants and trees replenishes the supply. The use of biomass for energy causes no net increase in carbon dioxide emissions to the atmosphere. the use of biomass for energy does not increase carbon dioxide emissions and does not contribute to the risk of globalclimate change. In addition, using biomass to produce energy is often a way to dispose of waste materials that otherwise would create environmental risks.
Biomass sources provide about 3 percent of all energy consumed in the United States. In 2002, biomass supplied about 47 percent ofall renewable energy consumed in the United States. Electric generation from biomass (exluding municipal solid waste) represents about 11 percent of all generation from renewable sources in the United States.
Biomass supplied more energy to the nation in 2002 than any other form of renewable energy, including hydroelectric power. Biomass supplied almost six times the energy of geothermal, solar and wind energy sources combined. Globally, biomass meets about 14 percent of the world´s energy needs.
The Department of Energy estimates that the total energy value of biomass fuel consumed in Oregon was 79 trillion Btu in 2003. This is about 10 percent of the total amount of non-transportation energy consumed in the state. Biomass supplies about 9 percent of all industrial energy consumed in the state. Oregon´s biomass resourcesinclude wood, agricultural crop residue and organic waste.
The production of heat for industrial processes and for residential and commercial space heating consumes the largest amount of biomass fuel in Oregon. (1)
Consumption of Renewable Energy in the United States
2002
Oregon Biomass Working Groups
The Oregon Biomass Coordinating Groupprovides support and oversight for theAgriculture, Forest,andUrbanBiomass Working Groups.These three separate working groups focus on specific opportunities, barriers and solutions in the three sector.
Geothermal Electricity Production
Most power plants need steam to generate electricity. The steam rotates a turbine that activates a generator, which produces electricity. Many power plants still use fossil fuels to boil water for steam. Geothermal power plants, however, use steam produced from reservoirs of hot water found a couple of miles or more below the Earth's surface. There are three types of geothermal power plants:dry steam, flash steam,andbinary cycle.
Dry steam power plants
These power plants draw from underground resources of steam. The steam is piped directly from underground wells to the power plant, where it is directed into a turbine/generator unit. There are only two known underground resources of steam in the United States: The Geysers in northern California and Yellowstone National Park in Wyoming, where there's a well-known geyser called Old Faithful. Since Yellowstone is protected from development, the only dry steam plants in the country are at The Geysers.
This geothermal power plant generates electricity for the Imperial Valley in California. Credit: Warren Gretz
Flash steam power plants
Flash steam power plants are the most common. They use geothermal reservoirs of water with temperatures greater than 360°F (182°C). This very hot water flows up through wells in the ground under its own pressure. As it flows upward, the pressure decreases and some of the hot water boils into steam. The steam is then separated from the water and used to power a turbine/generator. Any leftover water and condensed steam are injected back into the reservoir, making this a sustainable resource.
Binary cycle power plants
This type of power plants operate on water at lower temperatures of about 225°-360°F (107°-182°C). These plants use the heat from the hot water to boil aworking fluid,usually an organic compound with a low boiling point. The working fluid is vaporized in aheat exchangerand used to turn a turbine. The water is then injected back into the ground to be reheated. The water and the working fluid are kept separated during the whole process, so there are little or no air emissions.
Small-scale geothermal power plants (under 5 megawatts) have the potential for widespread application in rural areas, possibly even as distributed energy resources. Distributed energy resources refer to a variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system. (2)
GEOTHERMAL ENERGY PRODUCITION AROUND THE WORLD
SOLAR ENERGY
Solar energy for growing plants for food is renewable because light flows continuously from the sun, and plants can be reproduced on a time scale suitable for human needs.
Most use of renewable energy involves the sun. Solar energy is converted to thermal energy for space heating, heating hot water for domestic use and, to some extent, for generating electricity. A photovoltaic cell, which functions like abattery, converts solar energy directly to electric energy. Biomass energy has its origin in plants grown with the help ofsolar radiation. Wind energy is due to unequal heating of Earth's surface by the sun. Ahydroelectricplant converts the gravitational energy of water into electricity, but the mechanism that replenishes the water is powered by the sun. Roughly, 95 percent of all renewable energy is solar in origin. The remainder is from geothermal energy. Tidal energy, having its origin mainly in the gravitational force between Earth and Earth's moon, is used in some parts of the world.
Solar energy is the most readily available source of energy. It is also the most important of the non-conventional sources of energy because it is non-polluting and, therefore, helps in lessening the greenhouse effect. solar panels absorb the energy of the sun to provide heat for cooking and for heating water. Such systems are available in the market and are being used in homes and factories.
In India too, the Indian Renewable Energy Development Agency and the Ministry of Non-Conventional Energy Sources are formulating a programme to have solar energy in more than a million households in the next few years. However, the people's initiative is essential if the programme is to be successful.
India is one of the few countries with long days and plenty of sunshine, especially in the Thar desert region. This zone, having abundant solar energy available, is suitable for harnessing solar energy for a number of applications. In areas with similar intensity of solar radiation, solar energy could be easily harnessed. Solar thermal energy is being used in India for heating water for both industrial and domestic purposes. A 140 MW integrated solar power plant is to be set up in Jodhpur but the initial expense incurred is still very high.
Solar energy can also be used to meet our electricity requirements. Through Solar Photovoltaic (SPV) cells, solar radiation gets converted into DC electricity directly. This electricity can either be used as it is or can be stored in the battery. This stored electrical energy then can be used at night. SPV can be used for a number of applications such as:
If the means to make efficient use of solar energy could be found, it would reduce our dependence on non-renewable sources of energy and make our environment cleaner.
Programme being implemented:
Solar Cooker Programme
Solar Water Heating Systems Programme
Solar Passive Architecture Programme
SOLAR COOKER PROGRAMME
For solar cooking there are two methods of collecting sun's energy
-Trapping it in a box (e.g. a box type solar cooker)
-Focussing it to a point to cook (e.g. a parabolic / dish type concentrating solar cooker).
A dish type solar cooker consists of a dish of 1.4 m diameter made of thin bright anodized
Aluminium reflectors erected on a powder coated MS stand.
A Dish type solar cooker can cook food for about 10 to 15 people in 1½ to 2 hours.
SOLAR WATER HEATING SYSTEM PROGRAMME
Solar water heating is a most efficient and techno-economically viable technology for meeting the hot water requirement in 60 to 120 degree temperature ranges.
These systems are suitable for Hotels, Dairies, restaurant, Hospitals, Homes and Process industries were Hot Water is Required.
It works for almost 300 sunny days in a year.
A solar water heater works on the principle of the property of black bodies to absorb heat faster. A collector has a specially black coated copper sheet which absorbs the solar energy and transfers it to the water flowing through tubeson its back side. The hot water being lighter, rises up and is stored in the insulated hot water tank. This hot water can be used when required.
SOLAR AIR HEATING / STEAM GENERATION
Solar Thermal Systems for Air Heating/ Steam Generating Applications
Under Solar Air Heating(SAH) or Steam Generating(SG), Solar Flat Plate Collector (FPC) have been found to be very useful specially in agriculture and food industries for air heating.These industries generally require hot air at low temperature (50-80Deg.C.) as process heat for drying of various products such as tea leaves, coffee beans and also for processing of fruits, spices, cereals, mushroom, papad, vegetables, fish, sea food etc.Hot air is also required in industries such as leather, textile, chemicals, rubber, paper, pharmaceuticals etc. (4)
SUPPLIERS
SOLAR WATER HEATING SYSTEM
THERMAL ENERGY
Efficient capture and effective use of thermal energy is critical to successful CHP, from both the technical and financial perspective. In most CHP applications, the exhaust gas from the electric generation equipment is ducted to a heat exchanger to recover the thermal energy in the gas. Generally, these heat exchangers are air-to-water heat exchangers, where the exhaust gas flows over some form of tube and fin heat exchange surface and the heat from the exhaust gas is transferred to make hot water or steam. In the majority of installations, a flapper damper or "diverter" is employed to vary flow across the heat transfer surfaces of the heat exchanger to maintain a specific design temperature of the hot water or steam generation rate. The hot water or steam is then used to provide hot water or steam heating and/or to operate thermally activated equipment, such as an absorption chiller for cooling or a desiccant dehumidifier for dehumidification. * Thermal power plants increase suspended particle matter in air,rains despoil the land, choke the drainage system. These are amenable to technological solution by way of installation of precipitators and scrubbers and provision of tall stacks, ash ponds etc.* (6)
Heat Recovery Steam Generators
Heat Recovery Steam Generators or "HRSG" - are essentially boilers that captures or recovers the exhaust of a prime mover such as a combustion turbine, natural gas or diesel engine to create steam.
The system consists of a bank of tubes that is mounted in the exhaust stack. Exhaust gases at temperatures 800°F to 1200°F heat these tubes. Water is then pumped and circulated through the tubes and can be held under high pressure to temperatures of 370°F or higher resulting in the production of high pressure steam. Since the flue gas never comes in direct contact with the water, the steam can be safely used in thermally activated cooling equipment.
HRSG, which range from 10 - 250 MW and have an efficiency of 60-85%, are typically found in many combined cycle power plants. (5)
WIND ENERGY
Wind Energy is the Energy produced by the Movement of Wind. The huge turbines tends to convert Wind into energy. Wind farms are clusters of wind turbines that generate electricity. They tend to be located in areas with reliable and favorable wind speeds that are near electric power transmission lines and, in some instances, large cities. Wind turbines require large areas of land with strong, steady winds, certain parts of the country have the potential to be a significant player in the future development of wind farming. Iowa is the third largest producer of wind energy in the United States, ranking behind only Texas and California. According to Iowa State University's Iowa Energy Center, the potential for wind energy is the highest in northwest and north central Iowa, with average wind speeds of 15.7-17.9 mph. In 1996, the Iowa legislature approved the creation of the Alternative Energy Revolving Loan Programme (AERLP), a program designed to promote the development of wind energy production across the state. Since its creation, the AERLP has provided nearly $10.5 million of financing for renewable energy production, including financing of ten independent owners of wind turbines across Iowa is the third largest producer of Wind Energy. (3)
Biogas
Biogas is the Energy produced by the sewage treatment plant employing anaerobic digestion process of the waste materials. Biogas can also be as used as a fuel for running city bus service with a non-polluting exhaust. Such a management of organic garbage will give particulate matter free,cheap fuel,organic fertilizer with no flyash problem. With time entire organic matter may be managed to be converted to biogas and pollution of garbage be substantially tackled. (6)
