Power generation
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The document discusses power generation from non-conventional renewable energy sources. It notes that renewable sources like solar, wind, tidal, and hydroelectric power are inexhaustible, while fossil fuels are finite and cause environmental pollution. It highlights the need for renewable energy due to the depletion of fossil fuels and the negative impacts of fossil fuel use, such as air pollution, global warming, and increasing import costs. The document then provides details on various renewable energy technologies and their operation, like solar, wind, hydroelectric, biomass, and geothermal. It also discusses the seasonal variations and intermittent availability of some renewable sources like solar and wind energy.
Power generation
- 1. Power Generation by Non-Conventional Energy Sources Prepared By Prof. Akanksha Sharma
- 2. Renewable & Non-Renewable Energy Sources • Renewable energy is energy obtained from sources that are essentially inexhaustible. – ex- Wind power, solar power, geothermal power, tidal power & hydroelectric power. – The most important feature of renewable energy is that it can be harnessed without the release of harmful pollutants. • Non-renewable energy is the conventional fossil fuels such as coal, oil, gas & nuclear energy. – These forms of energy is exhaustible & likely to deplete with passage of time.
- 3. Need of Renewable Energy • Conventional sources of energy are depleting. Oil is likely to last around 52 years & coal around 110 years. • Oil, gas & coal causes air pollution which is causing global warming & climate changes all over the world. It is also increasing the level of sea, elimination of certain species, impacting life of plant, animal & marine life. • Import of oil bill is increasing due to increasing energy needs. • The need for cheap and obtainable resources is greatly needed.
- 4. • In view of above, we need to reduce our dependency on oil, coal & nuclear fuels & their imports. We need to look for alternate sources of energy for increasing power needs. • Renewable energy technologies are clean sources of energy that have a much lower environmental impact than conventional energy technologies. • Alternative energy possibilities – Solar photovoltaic – Solar thermal – Wave – Tidal – Wind – Geothermal – Bio
- 5. Fossil Fuel Based Systems • The main type of conventional power plants used for power generation are: – Steam power plants using coal, oil or nuclear energy. – Internal combustion engine plants working on gas, petrol, diesel. – Gas turbine power plant • Fossil fuels, which are main source of energy, are getting depleted. As a consequence the cost of fossil fuels are increasing. Further, the fossil fuel based systems produce detrimental effects on the environments. This in turn will affect our health.
- 6. Impact of Fossil Fuel Based Systems i. Global warming ii. Green house effects iii. Health problems iv. Societal problems
- 7. Disadvantages of Fossil Fuels • Environmental Hazards: – Environmental pollution is one of the major disadvantage of fossil fuels. – It is a known fact that carbon dioxide, gas released when fossil fuels are burnt, is one of the primary gas responsible for global warming. – Rise in temperature of earth has resulted in melting of polar ice caps, flooding of low lying areas and rise in sea levels. – If such conditions continue, our plant Earth might face some serious consequences in near future. • Rising Prices: – Middle-east countries have huge reserves of oil and natural gas and many other countries are dependent on them for constant supply of these fuels. – Organization of the Petroleum Exporting Countries (OPEC) is a group of 13 countries including Iran, Iraq, Kuwait, Qatar, Saudi Arabia and UAE. – They are responsible for 40 percent of the world’s oil production. OPEC constantly monitors the volume of oil consumed and then adjusts its own production to maintain its desired barrel price. – This results in worldwide price fluctuations, according to the U.S. Department of Energy.
- 8. • Acid Rain: – Sulphur dioxide is one of the pollutant that is released when fossil fuels are burnt and is a main cause of acid rain. – Acid rain can lead to destruction of monuments made up of brickwork or marbles. Even crops can affected due to this. • Effect on Human Health – Pollution from vehicles and coal powered power plants can cause serious environmental hazards. – Pollution related diseases range from mild to severe and can significantly affect one’s quality of life. – Air pollution can result in asthma, lung cancer. – Long-term exposure may increase respiratory infections in general population.
- 9. • Non-Renewable: – As of today, fossil fuels are being extracted at an exorbitant rate to meet the gap between demand and supply and it is estimated that they will be finished in next 30- 40 years. – Since they are non-renewable, it is more likely that fuel expenses will face a steep hike in near future. – It would take millions of years to replace coal, and oil, and this means that we will not be able drive cars anymore unless we switch to electric cars that use energy from renewable energy sources. – This means once these non-renewable sources are completely used up, there is nothing more left. • Impact on Aquatic Life by Oil Spill: – Fossil fuels are needed in huge reserves wherever their plants are set up. – This requires them to be transported to the desired location via truck, train, ship or airplane. – Often we hear of some leaks in oil tankers or ship getting drowned deep under the sea that were carrying crude oil to get refined. – The impact of this is that crude oil contains some toxic substances which when mixed up with water poses serious impact on aquatic life by lessening the oxygen content of water.
- 10. • Coal Mining: Extraction of coal from areas that have huge reserves is not only a difficult and dangerous task but also poses a serious health hazard to the lives of several workers who work there. The coal mining destroys wide areas of land and results in ecological imbalance. • Need Huge Amount of Reserves: The coal power plants requires huge and regular supply of coal to produce large amount of energy on a constant basis. This means that these plants need train-loads of fuel near power stations to carry out the process of generating power. This is needed as many countries are still dependent on coal as a major source for producing power.
- 14. Non-conventional energy – seasonal variations and availability • Dominant resources for renewable electricity generation are solar and wind power. Solar power is generally seen as having the largest global technical potential, while the latter is on an implementation track leading to a significant percentage of the global electricity production. Solar • The insolation (solar radiation power per square meter at the earth’s surface) is daily modulated between zero and a maximum that depends on the latitude on earth and the season.
- 16. • For instance in Edmonton in Canada, Delft in the Netherlands, and Astana in Kazakhstan (52° North), there is a factor of 6 between the insolation in mid summer and mid winter due to the reduced instantaneous light intensity and time of daylight. • In Mexico City, the Western Sahara and Nagpur in central India (19.5° North), the factor between summer and winter reduces but still reaches a sizeable factor 1.5. • Thus in principle a factor of 6 to 1.5 difference per solar power collecting footprint between seasons occurs, next to the diurnal day and night fluctuations, and varying cloud covers.
- 17. Wind • Wind resources within a continent sized electricity grid depend on the instantaneous wind speeds averaged over the grid surface area. • Besides this seasonal variations there is also a diurnal periodicity. • The general insight gained is that there is a diurnal variation in wind speeds with significant amplitude, where the peak in wind amplitudes occurs in the afternoon and the minimum 12 h earlier in the early morning.
- 18. • The wind speed amplitude has such diurnal pattern because it is driven by the surface temperature, i.e., the solar radiation heating the surface and atmosphere above it drives the observed wind speeds. • During the day the land warms relatively fast due to solar light absorption and the cooler and denser air from the adjacent ocean flows over the land. • At night the land cooling takes place and the air flows reverse.
- 19. • The sea breeze can extend several 100 km into the sea which means that the (future) wind turbines in those regions are under the influence of such diurnal wind patterns. • It is also noted that in winter time the temperature difference between land and ocean is reduced and the sea breeze largely disappear. Wind and Solar diurnal and seasonal variations require energy storage
- 20. Renewable energy – sources and features 1. Hydropower – Hydropower systems use the energy in flowing water for mechanical purposes or to produce electricity. – Hydroelectric plants use the kinetic energy of moving water to spin the turbine generator. – There are concerns over the detrimental environmental effects of hydroelectric power, which include siltation and erosion, weed growth, floods due to dam failures, and disease spread by small organisms that live in stagnant water.
- 21. 2. Biomass & Bio-gas – Biomass materials such as wood, agricultural crop wastes, animal wastes, and even garbage can be used as renewable sources of energy to generate heat and power. – Bio-gas is a gaseous fuel which is obtained by fermenting the biomass anaerobically in absence of oxygen. – Its main constituent is methane (55-65%) & CO2 (30-40%) & rest impurities like N2, H2S, H2 etc. – This biogas can be used to generate electric power in a heat engine or for cooking purposes.
- 22. 3. Passive Solar Heating – Passive solar heating for buildings is a common application of renewable energy. – A passive solar heating system collects energy from the sun. It uses this energy to heat a space directly, or to heat a fluid that later radiates heat to a space. – Solar systems are dependent on the weather conditions and number of daylight hours. Their effectiveness is greatly affected by climate, season, building orientation, and site conditions.
- 23. 4. Active Solar Systems or Photovoltaic systems • Photovoltaic systems are another way of capturing the sun’s energy. These systems use solar cells to directly produce electricity from solar radiation. • The solar cell is made of two semiconducting materials— generally silicon-based—with a boundary between them. • Some homes and businesses use solar cells to reduce the amount of power they buy from the electric utility. Some experimental cars also use photovoltaic cells to power electric motors.
- 24. • At this time, photovoltaic systems are relatively expensive to build and maintain. They also require a back-up source of power, or batteries, to provide power when sunshine is inadequate. • Since semiconductors contain toxic materials, the environmental impacts of manufacturing and disposing of solar cells and their batteries are also a concern.
- 25. 5. Solar Thermal Electricity Solar thermal electricity is another variation on solar energy. These plants use a highly curved mirror to focus sunlight onto a pipe, concentrating the heat to boil water and create steam. That steam is then used to turn a turbine generator to make electricity.
- 26. 6. Wind Power • Wind power uses energy from the moving air to turn large blades on windmills. • Very large, wide open windy spaces are needed for this system to be efficient. • Although wind energy makes noise and can harm birds, it produces no air or water pollution. • The major constraint to wind power is the limited availability of sites with steady wind. • Today, costs of electricity from wind are generally higher than costs of power from other sources. • These costs have been declining as wind turbines are made more efficient and long-lived.
- 27. 7. Geothermal Energy Systems • Geothermal energy or earth’s heat manifests itself on earth’s surface in form of geysers, hot springs & pool of boiling mud. •By drilling a hole 3 km deep in thermal fields (found near regions showing seismic activity), the steam & water comes out from earth’s surface at temp. up to 500° C. •This energy can be used to generate electric power. •The hot springs at lower depth can be used for space heating & other industrial applications. • Even though vast amounts of energy are available within the earth, our ability to use it is limited by site considerations.
- 28. • Today’s geothermal heat pumps are also more costly than conventional heating systems. • Due to the geological location of Iceland (over a rift in continental plates), the high concentration of volcanoes in the area is often an advantage in the generation of geothermal energy, the heating and making of electricity. • Five major geothermal power plants exist in Iceland, which produce approximately 26.2% (2010) of the nation's electricity.
- 29. 8. Tidal Energy – Tidal energy is a form of hydropower that converts the energy obtained from tides into useful forms of power, mainly electricity. – Tides are periodic rises and falls of large bodies of water. Tides are caused by the gravitational pull between the Earth and the Moon and sun. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon.
- 31. 9. Ocean Thermal Energy • Ocean Thermal Energy Conversion (OTEC) is a marine renewable energy technology that harnesses the solar energy absorbed by the oceans to generate electric power. • The sun’s heat warms the surface water a lot more than the deep ocean water, which creates the ocean’s naturally available temperature gradient, or thermal energy. • OTEC uses the ocean’s warm surface water with a temperature of around 25°C (77°F) to vaporize a working fluid, which has a low-boiling point, such as ammonia. • The vapor expands and spins a turbine coupled to a generator to produce electricity. The vapor is then cooled by sea water that has been pumped from the deeper ocean layer, where the temperature is about 5°C (41°F).
- 32. • That condenses the working fluid back into a liquid, so it can be reused. • This is a continuous electricity generating cycle. • The efficiency of the cycle is strongly determined by the temperature differential. The bigger the temperature difference, the higher the efficiency. • The technology is therefore viable primarily in equatorial areas where the year-round temperature differential is at least 20 degrees Celsius or 36 degrees Fahrenheit.
- 33. 10. Fuel Cells – Fuel cell is an emerging technology. – A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction of positively charged hydrogen ions with oxygen or another oxidizing agent. – Fuel cells are different from batteries in requiring a continuous source of fuel and oxygen or air to sustain the chemical reaction, whereas in a battery the chemicals present in the battery react with each other to generate an electromotive force (emf). – Fuel cells can produce electricity continuously for as long as these inputs are supplied. – It generates dc power. – At present the cost of production of fuel cells is high with low life, therefore the application of fuel cells is limited.
- 35. Distributed energy Resource (DER) systems • Distributed generation, also distributed energy, onsite generation (OSG) or district/decentralized energy is generated or stored by a variety of small, grid connected devices referred to as distributed energy resources (DER) or distributed energy resource systems. • Conventional power stations, such as coal fired, gas and nuclear powered plants, as well as hydroelectric dams and large scale solar power stations, are centralized and often require electricity to be transmitted over long distances. • By contrast, DER systems are decentralized, modular and more flexible technologies, that are located close to the load they serve, although having capacities of only 10 megawatts (MW) or less. • These systems can comprise multiple generation and storage components. In this instance they are referred to as Hybrid power systems.
- 37. • DER systems may include the following devices/technologies: – Combined heat power (CHP), also known as cogeneration – Fuel cells – Hybrid power systems (solar hybrid and wind hybrid systems) – Micro combined heat and power (Micro CHP) – Micro turbines – Photovoltaic systems (typically rooftop solar PV) – Reciprocating engines – Small wind power systems – or a combination of the above. For example, hybrid photovoltaic, CHP and battery systems can provide full electric power for single family residences without extreme storage expenses.
- 40. Microturbine • Microturbines are small combustion turbines approximately the size of a refrigerator with outputs of 25 kW to 500 kW. • It comprised of a compressor, combustor, turbine, alternator, recuperator. • Microturbines offer a number of potential advantages compared to other technologies for small-scale power generation. – small number of moving parts, – compact size, – light-weight, – greater efficiency, – lower emissions, – lower electricity costs, and – opportunities to utilize waste fuels. • They have the potential to be located on sites with space limitations for the production of power. Waste heat recovery can be used with these systems to achieve efficiencies greater than 80%.
- 41. Advantages of DER are: 1. Reduces green house gases emissions. 2. Reduces other pollutants like SO2, H2S, NOx & suspended particle matters. 3. Does not need construction of new transmission lines. 4. It is cost effective. 5. It provides improved power quality ex. Improvement in voltage profile & reliability. 6. Use of various types of energy sources improves energy security (uninterrupted availability of energy sources at an affordable price) of nation. 7. Failure of one plant does not affect the energy supply to all consumers. 8. Reduces the dependence on fossil fuels.
- 42. • Decentralized Generation can be distributed or dispersed and can be powered by a wide variety of fossil fuels. • Distributed power generation is any small-scale power generation technology that provides electric power at a site closer to customers than central station generation. • Dispersed generation is a decentralized power plant, feeding into the distribution level power-grid and typically sized between 10 and 150 MW. Distributed generation is used mainly for onsite power generation. Dispersed generation is strategically located on the transmission grid to overcome bottlenecks in the transmission and distribution system and to improve the stability of the system.
- 43. Dispersed Generation (DG) • Dispersed generation is related to decentralized power generation feeding into distribution level power grid. • The size of dispersed generation plant typically lies between 10 MW and 150 MW. • In D.G system, the smaller but highly efficient plants are built along the existing grid close to the end user consumer. • These may be solar, mini/micro hydel or wind turbine units, highly efficient gas turbines, small combined cycle plants, since these are the most economical choices. • Dispersed generation has been used for decades as an emergency backup power source. Most of these units are used only for reliability reinforcement
- 44. Advantages of DG System • Dispersed generation reduces both power transfers between regions of the power system and power imbalance in each region. • Power generation is highly flexible & it can provide power when needed. • It provides reliability and stability to the system. • Total failure can be avoided when the load centers are supported by dispersed generation. • A major outage can be avoided with the help of dispersed generation powered by reciprocating engines, by bringing power back online within 10 minutes.