Power Station Industrial Visit - Assignment Example

Torrens Island power station industrial visit report Name Institution Date Table of Contents Table of Contents 2 Introduction 3 Analysis 3 Conclusion 17 Reference 17 Introduction Torrens Island power station is one of the biggest energy harnessing companies in Australia and the largest in the entire south of Australia. Due to location and experience of operation, Torrens Island power station provides a better platform for the study of steam power plants. The paper below addresses on issues regarding understanding the operation of steam power plant, their efficiency, power output , the environmental impact an d finally methods of enhancing efficiency[5]. Analysis This section addresses various question s as shown in the analysis below Background to Torrens Island power station Torrens Island power station is the largest power station in South Australia. The company is located in Torrens Island just close to Adelaide and currently managed by AGL Energy. Torrens Island power station was started in 1963 and by 1967 the first section which generates 480MWA was completed. The B section was completed 10 years later and it generates 480MWA. The station has a multi-approach in that it can burn either natural gas or fuel oil. Changes came in recently in 2014 when AGL taken station A out of service from July to sept 2014 in awe of the increase of wind and solar generation especially in Southern Australia. The decision came as a result of the cost comparisons and the decision by AGL is not permanent since change in market condition might trigger its reopening Discuss power generation process in a steam power plant from gas to electricity. The operation of a steam power plant is based on the based on the principle of Rankine cycle and the process entails conversion of heat energy into electric energy. In cases where the turbine is steam driven, water is first heated and turn into steam, which subsequently spin the turbine and drive the electric generator [3]. The water is recycled immediately after it is condensed while the steam turbine drives the electric generator. Design variation is possible especially since different heat sources are used such as fossil fuel or solar. Figure one below illustrates the Rankine cycle and how it operates. Fig 1: Rankine cycle schematics 1-2: The pressurized water is heated to evaporation point in the boiler (heat input) 2-4: The steam expands resulting to mechanical output. The mechanical energy is then transformed to electrical energy by the generator. 4-5: The expanded steam condensed back to water resulting to heat output 5-1: The condensed water is pressurized before being delivered back into the boiler by the feed pump. Fortunately, the efficiency of the process can be enhanced by ensuring the stream enter turbine at high temperature as possible. The superheating of steam occurs between processes 2-3 while pre-heating occurs between (5-6). Fig 2: Rankine cycle (T-s Diagram) The T-s diagram can also be used to depict the steam power plant where the temperature is plotted verses entropy’s [3]. The aim of the process is to maximize the orange area which is the useful energy while the blue area should be reduced as possible since it is heat loss at condenser. The condensation should take place at lowest temperature possible while superheating (2-3) should also take place at high temperature as possible. Discuss the steam power plant cycles used by Torrens Island i.e. Number of turbines inclusion of regeneration, reheat, superheat etc. Draw the steam turbine flow diagram including all the seven feed water heaters. Torrens Island power plant just like any other steam power plant undergo through same process of electricity generation. However, the major difference is normally the source of fuel and the capacity which is determined by very many factors. Torrens is one of the steam power plants with the most turbines under operation. Cumulatively, Torrens Island power plant has 8 turbines. The technology is based on the Rankine cycle technology where the efficiency is enhanced using superheating techniques. Power plant that run on fossil fuel normally have superheating section where steam passes through after getting dried to pick up more energy from the hot gases outside the tube and the temperature subsequently rises to above the saturation temperature. Power plants sometimes have reheating section where steam his passed through tubes exposed to hot temperatures. The purpose is same to superheating which is to pick up more heat energy which raises the operation efficiency. The generator is used to convert the mechanical energy to electrical energy before passing the generated electric energy through a step up transformer to magnify the power just before it get into the national grid. The condenser’s function is to condense the steam from the turbine exhaust to allow it to be pumped [2]. Boilers are used to heat the steam or simply to generate steam at high pressure and temperature. The boiler has to be equipped with internal steam distribution piping, internal perforated pipes, perforated trays and the boiler feed water system [4]. However, turbines are machine components used to convert kinetic energy in fluids of a moving fluid to a rotational energy that can be used to drive a dymo for electricity generation. Fig 5: Torrens Island power station schematics Efficiency of Torrens Island Power Plant – what measures have been introduced to improve overall efficiency what further improvements can you suggest improving efficiency. The efficiency of the power plants can be improved in several ways such as: Raising boiler temperature: This can be achieved by increasing the compressor pressure which subsequently causes a shift in saturation of to a point much higher hence attain a commendable average temperature. Expanding turbine after saturation: This process though risky can increase due to the droplet s hitting the blade tips, the expansion allow absorption of more energy from the steam and that increase the overall efficiency. Cycle improvements Reducing the auxiliary power consumption Flue gas reheat recovery Double reheat Making condenser cooler: Making condenser cooler will reduce the exhaust steam pressure and that subsequently increase the cycle pressure. Steam turbine improvements Performance matrix standardization Identify and train workers on best practices such real time online monitoring of efficiency and replacement of air heater seals, conductors, boilers and other tube component. Reduce air, water, stream and flue and leakages. Suggestion for further improvement Carbon capture and storage: To ensure the cost of carbon dioxide is kept as low as possible and that will possibly increase efficiency as shown in the figure below. Fortunately this idea is currently being materialized and it target to eliminate large amount of carbon dioxide from the air. Fig 6: Net efficiencies of the overall stream steam power plant without CO capture How is the power plant operation and cycle efficiency controlled and monitored? The efficiency of the plant can be monitored and controlled by manipulating areas in the process that enhances increase in efficiency. The most notable areas to control are areas such as The boiler inlet temperature Reheating and superheating temperature. Estimate the annual greenhouse gas emission from the Power station. Gas emission from power plants can be based on several emission estimation techniques (EETs) such as mass balance, engineering calculation which is based on fuel composition, sampling and direct measurement, emission factors and approved alternatives. TIPS greenhouse gas emission approximately 0.624 tonne/MWhr Annual emission= (number of hours per year * rate of emission per hr.) = (0.624*52*7*24) = 5,451.264 tonne/MW What are the other environmental impacts of Torrens Island Power Station? Power stations have lot of environmental impacts apart from emission of green gasses. Torrens Island Power Station will most likely affect the environment through: 1. Air and water pollution: During the power generation, emissions such as co and so cause pollution to the water and air especially in the areas around the facility. Thermal heat pollution normally occur since the plants uses water for cooling and such water is returned back to the water body[5]. The warmed water can attract fish and make them lose the normal pattern of natural water behavior leading to possible eutrophication. Unfortunately heavy metals and chorines discharged in the water mass have possible negative effects on the seal life. 2. Noise pollution: The heavy machineries involved in the production process such as gas compressors contribute to noise pollution since they make noise that surpass the EPA limits. The noise pollution is due to high pressure steam and running of motors and fans. 3. Impact on the scenic, historical and cultural resources: Due to the size and geographical coverage if this large structures, they normally interfere with the natural view as they dwarfs everything nearby and that causes loss of value natural sites [3]. 4. Land degradation: The fly ash deposit which is deposited in million tonnes occupies prime land and subsequently affects the agricultural and forest land [2]. What measures are used to reduce its environmental impacts, how can its environmental impacts be further reduced? Adoption of renewable energy: Examples Renewable energy is like solar and wind energy. The growth of renewable source of energy in South Australia has rapidly. South Australia 36+ percent of energy used come from renewable sources and the region already target achieving 50% renewable energy contribution by 2025. Maintaining and enhancing carbon sink Capacity: The southern Australia region hold key the contribution of vegetation in absorbing emission like carbon dioxide. The vegetation therefore act as carbon sinks/ greenhouse gas sinks hence South Australia has been at the forefront in plantation encouragement and vegetation thickening. Currently Energy company AGL and French industrial gas company Air Liquide is currently building a plant to capture about 50,000 tonnes a year of carbon dioxide emission. Compare Torrens Island with other local and interstate power plants Torrens Island power station is one of the main power stations in the south of Australia and produces the highest power at 1,280 MW. However, very few power stations in the south of Australia are run from steam turbine with only other close ally being Whyalla steelworks which only produce 57.5MW and run using 3 turbines. While Torrens Island is run on natural gas, whyalla steelwork sources its fuel from coke oven and blast furnace gas/oil. Most of the power station in southern Australia are fueled on natural gas and have capacity ranging from 4.4 MW-487 MW. Only Hallet power station has more turbines than Torrens Island power station. Few PowerStation like Northern and Playford B are fueled from black bituminous coal based on open cut mining and rely on the sea as the coolant. Unfortunately unlike in other states, only few power stations in South Australia is hydro-electric. Carbon capture and storage is being developed as a means of reducing global warming impact. Can it be integrated into Torrens Island? What are the main requirements? Carbon capture and storage is a technique where the carbon emission is re-directed and stored underground. Carbon dioxide (CO2) is a major greenhouse gas whose atmospheric concentration has greatly increased over the past two decades. The increasing presence of Carbon dioxide (CO2) is due to human activity especially burning of fossil fuel. Carbon dioxide Capture and Storage (CCS) is achieved by collecting the carbon dioxide at its source and storing it away in underground over a long period of time in ocean or in the earth surface (Benson, 2013, Pg 4). The development is still crucial since the energy production through use of fossil fuel will continue still approximately 2050 when other sources will surpass the targets. Several factors can be considered to determine if carbon dioxide capture is a viable option namely: The emission size Whether the emission is stationary or mobile The nearness of the potential storages How concentrated the Co emission. The best option is capture of Co emission is where the source of emission is stationary and is located near a potential storage facility. Unfortunately small mobile sources are in homes or businesses are never a viable option. Therefore Torrens Island is a viable option where the Carbon dioxide Capture and Storage (CCS) capture technique can be successfully exploited. Fig 3: Major steps of carbon capture and storage process schematic (Benson, 2013, Pg 4) It is projected that Carbon dioxide Capture and Storage (CCS) has a potential of capturing approximately 12% of carbon dioxide globally by 2020 and between 21-45% by 2050. What happens during peak demand periods when our need for power is greater than Torrens Island can provide? Currently the situation in Southern Australia is so good that that section of A of Torrens Island is switch of and the deficit is sourced from renewable resources like solar and wind energy. However, if the demand outsmarts the supply, then the immediate option is to put section A back in play. Alternatively the step up efficiency can be added to increase the overall output. The Repower Port Augusta Alliance (Beyond Zero Emissions report 2012) produced a proposal to replace the retiring Northern (capacity 520 MW ) and playford B (capacity 240 MW) brown coal power plants located in Port August with 6 solar thermal plants and 95 wind turbines. Compare this proposal against replacing the power plants with combined gas power plant in terms of economic, environmental and social benefit. What is your preferred option? The idea of replacement of a staggering amount of power output using solar and wind or gas power plant is interesting and the comparison can be based on many variables. However, in this case, we take into consideration only three factors namely: taking environment, the social aspect and economic reasons. Environmental consideration When the environment is taken as the baseline, then 6 solar thermal plants and 95 wind turbines take precedence since combined gas power plant just like other fossil fuels, have serious environmental implication compared to the former option [7]. Combined gas power plant STILL affect the environment through four fronts namely emission of global warming increasing gases, air pollution, land use and wildlife, earthquakes and water use and pollution. Combined gas power plant is more efficient compared to other fossil fuel sources. However, the option only reduces the environmental pollution by 40 to 50 percent of carbon dioxide and 15 to 20 percent less heat trapping gases. The greatest headache or menace is during the gas extraction since methane which is another pollutant gets leaked to the atmosphere during extraction [9]. According to DOE analysis, every 10000 homes powered with natural gas save the environment annual emission of 1,900 tons of NOx, 3,900 tons of SO2, and 5,200 tons of particulates compared to if the homes were powered on coal. However, the natural gas is still more polluting to the environment compared to solar and wind sources. The figure below clearly illustrates why solar and wind is the best option in terms of environmental concerns. Fig 7: Global emission comparison Economic comparison Unfortunately the solar and wind energy doesn’t perform better compared to compound gas sources and other fossil fuels when it comes to economic comparisons. Region like Southern Australia which rely on solar and wind energy continue to pay more per annum compared to other states which rely on energy from fossil based sources [8]. The figure below clearly compares most of the global sources of energy with solar and solar registering some highest value possible. Fig 8: Comparison of economic cost of various energy sources Fortunately in the recent past, statistics shows that the cost of solar and wind energy are gradually dropping especially with the rise in technology. Therefore the future of solar and wind with the rise of technology and the expectation of the fossil fuel depletion by approximately 2050 is encouraging. Social consideration The social consideration basically revolves around sustainability and ability to meet demand. The renewable sources like solar and wind are more sustainable compared to the gas sources which will soon face depletion and that is why the global concerns is on finding a brake through in ensuring that the new sustainable sources like wind and solar are efficient [6]. Countries like Australia and states like California has challenged the use of sources like wind and solar which are convenient, environmental friendly and efficient. Other social aspect will be energy security and the impact of waste in our environment. This is because certain waste has detrimental effect on other inhabitants of the same environment like Haman, wildlife and vegetation. Therefore based on social aspects, the power plants should be replaced by solar and wind energy sources since compared to the compound gas energy sources. Conclusion Torrens Island power station is one of the biggest power plants in southern Australia and the most efficient. The above stated means can be used to enhance efficiency. However, southern Australia is a region that has really adopted use of renewable sources of energy like solar and wind and forcing AGL to shut off part of the company to reduce fossil related fuel and relies renewable energy sources. Reference [1]M. Raut, "ENVIRONMENTAL IMPACT OF EMISSION OF POWER PLANTS", Slideshare.net, 2013. [Online]. Available: http://www.slideshare.net/MrMrunalRaut/environmental-impact-of-emission-of-power-plants. [Accessed: 30- May- 2016]. [2]A. Layne, "Next-generation turbine systems [steam power plants]", IEEE Power Engineering Review, vol. 21, no. 4, pp. 18-23, 2001. [3]V. Kotler and D. Sosin, "A modern thermal power station operating on high-moisture lignite", Thermal Engineering, vol. 56, no. 6, pp. 526-528, 2009. [4]A. Akinyomi, A. Babajide and H. Okoro, "Environmental Studies of Thermal Power Station Effluents: (A Case Study of Egbin Thermal Station, Ikorodu).", Ethiop. J. Env Stud & Manag, vol. 8, no. 3, p. 283, 2015. [5]"The Electricity Trust of South Australia (Torrens Island Power Station) Act 1962", vol. 11, no. 1, 1962. [6] 10. World Nuclear Association, "Sustainable Energy: Renewable Energy: World Nuclear Association - World Nuclear Association", 2, vol. 7, no. 2, 2015. [7] Union of Concerned Scientists, "Environmental Impacts of Wind Power", Environmental Impacts of Wind Power, vol. 4, no. 2, 2016. [8] Energy Innovations, "Comparing the levelized cost of energy technologies.", vol. 4, no. 3, pp. 12-34, 2014. [9]J. Tollefson, "Methane leaks erode green credentials of natural gas", vol. 4, no. 3, pp. 12-15, 2014. Read More