EE1451-RENEWABLE ENERGY SOURCES -CIA-1 ANSWER KEYPART-A 1. The energy sources available can be divided into three categories. They are • Primary energy sources • Secondary fuels • Supplementary sources 2. In solar tower concentration system (tower power concept)the incoming solar radiation is focused to a central receiver or a boiler mounted on a tall tower using thousands of plane reflectors which are steerable about two axes are called heliostats. 3. Energy yield ratio is given by 4. Solar constant is defined as the amount of energy received in unit time on a unit area perpendicular to the sun’s direction at the mean distance of the earth from the sun. 5. Energy Conservation means reduction in energy consumption but without making any sacrifice in the quality or quantity of production. In other words, it means increasing the production from a given amount of energy input by reducing losses/wastage and maximizing the efficiency. 6. The direct conversion of solar energy into electrical energy by means of the photovoltaic effect, that is, the conversion of light (or other electromagnetic radiation) into electricity. The photovoltaic effect is defined as the generation of an electromotive force as a result of the absorption of ionizing radiation. 7. The energy we receive from sun in the form of light is a shortwave radiation (not visible to human eye). When this radiation strikes a solid or liquid it is absorbed and transformed in to heat, the material becomes heat and conducts it to surrounding materials (air, water or liquids) or reradiates in to other materials of low temperature as long wave radiation. 8. Advantages: Reflecting surfaces required less material hence cost of material is low. The absorber area of a concentrator system is smaller than that of a flat type. Little or no anti-freeze is required. Disadvantages: High initial cost. Non-uniform flux on the absorber. Additional optical losses such as reflectance loss and the intercept loss. 9. Working fluids are as follows Foluene Monochloro benzene Frifuluroethanol Hexa flura benzene 10. Applications of solar PV system Water pumping Railway signaling equipment Battery charging Street lighting PART –B 1. Various sources of Non-conventional Energy are given in table below R.ARIVAZHAGAN, LECTURER/EEE Page 1 EE1451-RENEWABLE ENERGY SOURCES -CIA-1 ANSWER KEY 2. Solar energy application A straightforward method of generating electricity from solar energy is to use concentrators to produce high temperatures that can drive either a Stirling or a Rankine (steam) engine. The collector consisted of sun-tracking at mirrors forming a gigantic heliostat capable of focusing the sun's energy on a boiler. A thermal storage system was incorporated permitting the plant to deliver some energy during night time. Turbine drives the generator which feds electrical energy, such that solar energy is converted into electrical energy therefore this method is called Solarthermal system. The mirrors are made of a sandwich of two glass panes with a silver layer between them. This protects the reflecting layer from corrosion. When not in use, the mirrors are placed in a horizontal position to protect them from the destructive action of wind storms. This also reduces abrasion from wind carried sand. A pump is used to recycle the fuel exiting from outlet of turbine. SOLAR WATER HEATER FOR DOMESTIC PURPOSE Flat type Collector receives solar radiation which heats up the water inside the tube connected to water tank. Controller checks the water level in tank and if water level is above the threshold level, vapour reaches the tank and heats up the water which is further utilized. Tank sensor gives signal about water level in the tank; pump circulates the water in up & down direction as shown. When the storage tank is filled, cold water inlet is closed by using shut-off valve R.ARIVAZHAGAN, LECTURER/EEE Page 2 EE1451-RENEWABLE ENERGY SOURCES -CIA-1 ANSWER KEY 3. GLOBAL WARMING Global warming is the increase in the average measured temperature of the Earth's near-surface air and oceans since the mid-20th century, and its projected continuation. Effects of Global Warming Climatic change Observations show that global temperatures have risen by about 0.6 °C over the 20th century. Climate models predict that the global temperature will rise by about 6 °C by the year 2100. Food shortages and hunger Water resources will be affected as precipitation and evaporation patterns change around the world. This will affect agricultural output. Food security is likely to be threatened and some regions are likely to experience food shortages and hunger. Rise in sea level The mean sea level is expected to rise 9 - 88 cm by the year 2100, causing flooding of low lying areas and other damages. Coral bleaching Sedimentation problem Loss of bio-diversity Some of the Climate Change Impacts in India • Rajasthan- Drought • Mumbai-Salt water intrusion • Kerala –Productivity of Forest • Tamil Nadu-Coral bleaching • Ganges – Sedimentation problem • Sunderbans-Sea level raise • Northwest India-reduction In rice yield The Intergovernmental Panel on Climate Change (IPCC) said, global warming will exacerbate the conditions and could lead to conflicts and war. One and only solution for global warming is reduction in emission of Green house gases to atmosphere. R.ARIVAZHAGAN, LECTURER/EEE Page 3 EE1451-RENEWABLE ENERGY SOURCES -CIA-1 ANSWER KEY 4. KYOTO PROTOCOL MAIN FEATURES OF PROTOCOL In 1988, the Intergovernmental Panel on Climate Change (IPCC) was created by the United Nations Environment Programme (UNEP) and the World Meterological Organization (WMO) United Nations Framework Convention on Climate Change (UNFCCC), signed by over 150 countries at the Rio Earth Summit in 1992 and Kyoto Protocol (1997, w.e.f. 2005). 100 world leaders, where India will be represented by External Affairs Minister S M Krishna and Environment Minister Jairam Ramesh have met at United Nations and Group 20 meeting in Pittsburg to discuss ways to curb climate change without affecting economic growth. India, the G-77 countries and China together made another submission on technology cooperation & joining forces to fight carbon tariffs from US and EU. India among top 10 emitters of CO2, per capita emissions is still one sixth of the global average. New Delhi has a well defined goal of conventional and renewable energy and economic development, to improve environmental quality and limit human health hazards from air pollution. A citizen of a developing nation emits approximately 5.5 tons of carbon per year, against the rate of 0.25 tons by that of an Indian. The Kyoto Protocol is designed to not only undo the climatic ill-effects of industrialization but also to identify the economic beneficiaries of the same and make them more accountable in damage control. It deserves high applause for its flexible approach and concern in letting the business and economies continue while doing the damage control. The outcome was the Kyoto Protocol, in which the developed nations agreed to limit their greenhouse gas emissions,relative to the levels emitted in 1990 or pay a price to those that do. 5. CONCEPT OF CLEAN DEVELOPMENT MECHANISM The purpose of CDM is to: i. contribute to sustainable development in developing countries; ii. help Annex I-countries under the Kyoto Protocol to meet their target With the help of CDM, countries which have set themselves an emission reduction target under the Kyoto Protocol (Annex I countries) can contribute to the financing of projects in developing countries (non-Annex I countries) which do not have a reduction target. These projects should reduce the emission of greenhouse gases while contributing to the sustainable R.ARIVAZHAGAN, LECTURER/EEE Page 4 EE1451-RENEWABLE ENERGY SOURCES -CIA-1 ANSWER KEY development of the host country involved. The achieved emission reductions can be purchased by the Annex I country in order to meet its reduction target. An investor from a developed country, can invest in, or provide finance for a project in a developing country that reduces greenhouse gas emissions so that they are lower than they would have been without the extra investment – i.e. compared to what would have happened without the CDM under a business as usual outcome. The investor then gets credits – carbon credits - for the reductions and can use those credits to meet their Kyoto target. If the CDM works perfectly it will not result in more or less emission reductions being achieved than were agreed under the Kyoto Protocol, it will simply change the location in which some of the reductions will happen. R.ARIVAZHAGAN, LECTURER/EEE Page 5
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