The Coal Based Power Plants Environmental Sciences
The sustainable development of India primarily depends on its ability to strategise and establish effective methods of harnessing energy from a plethora of renewable sources available. The growth of a developing economy calls for the careful planning and application of resources. But, with India being the sixth highest energy consumer in the world, it seems that the energy demand has to be satisfied by its primary energy sources, some of which are fast depleting and raising global environmental concerns. Policy reforms and their following enforcement can prove to be a major catalyst in drastically curbing the potential hazards posed by Greenhouse gas emissions. With India's dominant influence in the global energy and emission structure, it must strive to take significant steps in developing methods of producing clean energy and most importantly, reduce CO2 emissions. India is placed third in CO2 emitter in the world. Top 10 CO2 emitting countries are tabulated in figure 1.
Figure.1 Top 10 CO2 Emitting countries in the world
The primary sources of energy available to India are:
Biofuels and waste
Carbon dioxide emission is basically due combustion of fossil fuels. In 2009, total CO2 emission in India is 1585.8 million tonnes of CO2 with the contribution from different sectors. CO2 emission distribution for various sectors of India is shown in figure 2.
Figure.2 CO2 emission in India by sectorPower generation sector:
Indian power generation sector (electricity) had a total installed capacity of 205.34 Gigawatts (GW) in the mid of 2012. Thermal power generation accounts to 66% of total power generation and mostly based on coal and natural gas. Distribution of various power generation methods in India is shown in figure 3.
Figure.3 Electricity production by various sectors
Power generation by fossil fuels will lead to emission of greenhouse gas and causes global warming. Coal and natural gas fired power plants are the major players in CO2 emission. Power generation sector in India alone contribute to 855.7 million tonnes of CO2 emission out the national total emission of 1585.8 million tonnes.
Coal based power plants
The generation of power through the pulverisation and combustion of coal is essentially controlled by the Government of India. Although 56% of India's energy comes from coal-fired power plants, the environmental hazards posed by these plants are irrefutable and consequent calls for the mitigation of the Greenhouse gas (GHG) emissions have not gone unnoticed. The coal demand in the country amounts to 244.18 Mtoe, a sixth of which is imported. E, F and G are the common grades of coking coal used, with ash content of 30-50% and a low calorific value of 4500 kcal/kg, and the total electricity produced from coal-based plants is 616,584 GWh. The carbon dioxide emissions, attributed to the production of power from coal, stands at a dangerous 980 gCO2/kWh, which requires drawing immediate attention to policy reforms regarding mitigation of these emissions. 56% of the total installed capacity lies in the southern and western parts of India, while the northern region does not possess private operators whereas 36% of the plants in the south are privately owned. Uttar Pradesh is the state with the highest generating capacity with a share of 13.28%, but it is also accountable for being the highest emitter of CO2 in India.
The mitigation of CO2 emissions can be achieved either by performing suitable variations in existing technologies or by introducing new methods.
For reducing the CO2 emissions without affecting the balance of power generation, following are suggested.
Repowering of the coal plants can be carried out, wherein a system would see a rise in the pressure of the flue gases and allow their subsequent capture. Also, since the combustion temperature would increase the thermal efficiency and hence, the output power generated will be higher.
The possibility of operating the plant in combined cycle mode could also be explored. The gas turbine generator is responsible for the primary generation of electricity and the remaining heat, possessed by flue gases, could be used to produce steam and in turn, generate more electricity.
Captive power plants could be encouraged.
Natural gas based:
Natural gas is abundantly available in nature, which comprises a large percentage of methane, along with carbon dioxide, nitrogen and hydrogen sulphide. As of 2009, 111.206 TWh of electricity was produced and this accounts for 12.36% of the total power produced from primary energy sources in India.
Natural gas can be used to generate power by its application in gas and steam turbines, also in combined cycle operation. Also, power produced from Natural gas is used to support electricity grids, which are run by renewable sources, such as solar and wind energy. At least 70% of India's natural gas reserves are located in the Bombay High basin (Maharashtra, West India) and Gujarat (West India). The coast of Andhra Pradesh (Krishna Godavari Basin) and that of Tamil Nadu (Cauvery Basin) consists of offshore reserves whereas onshore reserves are located in Gujarat and the North Eastern states (Assam and Tripura). The burning of Natural gas is found emit 30% less carbon dioxide than burning petroleum and 45% less than burning coal, which supports the argument of using Natural gas as opposed to other sources of energy.
Although the above statement favours natural gas, it also contributes to GHG emissions, whose effect lasts for 12 years in the atmosphere, as opposed to the effect of CO2, which can last for 500 years.
Suggestions: Use Carbon capture and sequestration to remove CO2 from natural gas.
For maximum eradication of CO2 emission based on power generation following methods are suggested.
India is equipped with potential in solar energy due to its geometric location of it. It receives one of the highest solar irradiance having more than 300 sunshine days. With the growing demand for the power generation in the country, Government of India has launched a national solar energy mission called Jawaharlal Nehru national solar mission. India is planning to build many solar power plants that offer 20 GW capacities before 2020.
In order to replace fossil fuel based power plants, concentrated solar thermal energy should used in India, especially in the states of Rajasthan and Gujarat where the solar intensity is maximum. Currently no solar thermal power plants were in operation and few in progress.
Installation of roof mount Photovoltaic panels in residential and commercial building will help them to meet the peak electricity demand. If this system is introduced in metropolitan cities then 33% of percent of CO2 emission by power generation will be eradicated.
Off shore wind mills are still not employed in India, there is huge potential in the country for this type of power generation. Being a peninsula, India has a large stretch of coastal region which can be utilized for cleaner energy production.Transportation:
People in India heavily rely on railways and roadways for the transportation compared to airways and waterways. The transport by airways and waterways is almost negligible compared to the transport by both rail and road. In 1950, on an average a person in India travels 185kms per year by both rail and road. In the span of 50 years, Usage of transportation facilities has been increased drastically to 3470km per person. The growth on road based transportation is at a higher rate compared to railways from the past decades. Road share on the transportation sector was increased to 87% in 2000 compared to 35% in 1950.
This steep increase in usage of road based transports has some adverse effects on energy and environment. Transportation sector is one of major consumer of energy especially petroleum based fuels and leading to environmental damages by CO2 emissions in particular. The liberation of CO2 by the transportation sector is been a global problem causing global warming and climate change.
In India, Transport sector accounts to 150.1 million tonnes of CO2 out of total emission of 1585.4 million tonnes. Out of which 134.1 million tonnes of CO2 emission is solely due to roadways. Indian CO2 emission by transportation sectors accounts to 6.7% of worldwide emission in this sector.Methods to reduce CO2 emissions in transportation sector:
Usage of Biodiesel
Biodiesel often considered to lesser greenhouse gas emission compared to fossil fuels, but in some cases it liberates CO2 similar to that of fossil fuels. The CO2 released by the biomass will be absorbed by the plant feedstock used for the production of the biodiesel. Itâ€™s like a cyclic process of liberating and absorbing back again, so carbon footprints on the atmosphere is reduced by using it.
Indiaâ€™s biodiesel reserve mainly depends on Jatropha oil production, as it can be cultivated in non agricultural dry land with affecting food reserves of the country. By 2014, at least 20% transportation by roadways should be using biodiesel in order to reduce the CO2 emissions. Certainly cultivation of Jatropha is in the initial stages and will aggressively improve in coming years. Along with Jatropha production, rice husk is also produced in plenty. This can also be utilized for biodiesel production along side with Jatropha oil.
Certainly Indian railways using biofuel made of Jatropha for some limited trains operated by southern railways as an initial step towards eradicating the CO2 emissions. Similar policies on road transport should be imposed in order to make carbon neutral transportation system.
Usage of electrics scooters and cars will help in reduce the usage of fossil fuel in turn reduces the CO2 emissions as well. Electric scooters powered by Lithium ion battery are currently employed in the production. Currently 110 thousand electric scooters are used in India and increasing at a good rate. If the 2 wheelers running with petrol and diesel are replaced by electric type in next ten years, then tile pipe emission will be completely eradicated. In car sector, hybrid models which use both electrical and IC engines should be widely used instead of fossil fuel powered cars.
CO2 emissions by manufacturing sectors in India
In 2007 Estimation, the manufacturing and the construction industries accounted for a total of 412.55 million tonnes of CO2.The major industries which contribute for the emissions includes minerals, metals, cements and chemicals industries.
The cement industry accounts for 129.92 million tonnes of CO2 which is 32% of total CO2 emissions. The CO2 emissions are mainly from the pre calciner stage where the limestone is converted into lime by releasing CO2.this mixture is burned in the rotary kiln which further releases CO2.
Methods to be adopted in cement industry
1. By phasing out inefficient kilns and by adding preheaters.
2. By increasing clinker substitutes in order to decrease co2 emissions.
3. Efficient grinding systems to be implemented.
(ii) Iron and Steel industry
The estimated CO2 emissions of around 117.32 million tonnes are emitted by steel and iron industry. The major part of CO2 emissions in the iron industry is due to the consumption of coal for melting the crude iron. The most of emission is from the basic oxygen process where the iron ore is reduced to pig iron in which carbon monoxide is produced.
Ways to reduce CO2 emissions
1. By replacing open hearth furnaces and efficient utilisation of scrap.
2. Better recovery of gases and heat integration between blast furnace and basic oxygen furnace.
3. By adopting efficient methods for the final crude steel product.
(iii) Chemical industry:
The chemical industry account s for around 33 million tonnes which is 8.1% of total co2 emissions. The main co2 emission takes place in steam cracking process where the hydrocarbons are broken down to smaller hydrocarbons where these CHG gases are emitted.
Methods to be adopted for cutting down emissions:
1. With implementations of the efficient reactor designs with heat integration and energy recovery.
2. By developing and integrating novel membrane separation technologies.
Article name: The Coal Based Power Plants Environmental Sciences essay, research paper, dissertation