- Email: [email protected]
Technological and economic evaluation of conversion of potential flare gas to electricity in Nigeria
Available online at www.sciencedirect.com
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Available Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Procedia Manufacturing 00 (2018) 000–000
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www.elsevier.com/locate/procedia
Procedia Manufacturing 17 (2018) 444–451 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia
28th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2018), June 11-14, 2018, Columbus, OH, USA
Technological and economic evaluation of conversion of potential Manufacturing Engineering Society International Conference 2017, MESIC 2017, 28-30 June 2017, Vigo (Pontevedra), Spain flare gas to electricity in Nigeria Costing models for capacityPaper optimization ID: (143) in Industry 4.0: Trade-off betweenEmeka used capacity and operational efficiency Nnanna Ojijiagwo , Chike F. Oduoza , Nwabueze Emekwuru a
a
b
University of Wolverhampton, Faculty of Science and Engineering. Wolverhampton, United Kingdom b Coventry University, Facultyaof Engineering, Environment and Computing. Coventry, United a,* b b Kingdom a
A. Santana , P. Afonso , A. Zanin , R. Wernke
Abstract
a
University of Minho, 4800-058 Guimarães, Portugal b Unochapecó, 89809-000 Chapecó, SC, Brazil
Globally, over 100 billion cubic metres (BCM) of gas is flared annually and, this is linked to an annual emission of 400 million tons of carbon dioxide. In Nigeria the annual gas production is valued at 33.21 BCM, out of which more than 50% is wasted Abstract through flaring, thereby emitting about 35 million tons of carbon dioxide. About 14.94 BCM of gas produced in Nigeria is used for a variety of activities generation. processes Despite thiswill scenario, Nigeria is to generate and distribute Under the concept of including "Industryelectricity 4.0", production be pushed to still be unable increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization enough electricity for the citizenry. This paper therefore evaluates the use of gas to wire technology as the option to minimise gas goes beyond the traditional aim of capacity maximization, contributing also for organization’s profitability and value. flaring in Nigeria while minimising the associated environmental impacts. The research methodology was based on interviewing Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of top level managers an electricity generation company, and gas models Production well as topic the researchers’ site maximization. The in study of capacity optimization and costing is anCompany, importantasresearch that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical observations within the two case companies. Results from this study showed that electricity generation could be improved from model for capacity management based on different costing models (ABC and TDABC). A generic model has been its current daily production rate of 4358 MW to about 12000 MW from the use of part of 18.27 BCM of gas flared annually in developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s Nigeria.The Thistrade-off serves as capacity fuel for 50 units of gas turbine with power output of is 150highlighted MW each, with a potential in daily value. maximization vs operational efficiency and it is shownincrease that capacity optimization might hide operational inefficiency. electricity generation of 7500 MW. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency Peer-review under responsibility of the scientific committee of the 28th Flexible Automation and Intelligent Manufacturing (FAIM2018) Conference.
1. Introduction The cost of idle capacity is a fundamental information for companies and their management of extreme importance 2351-9789 © 2018 The Authors. Published by Elsevier B.V. in modern production systems. In general, it is defined as unused capacity or production potential and can be measured This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) in several under ways: tons of production, of manufacturing, The management of (FAIM2018) the idle capacity Peer-review responsibility of the scientificavailable committeehours of the 28th Flexible Automationetc. and Intelligent Manufacturing * Paulo Afonso. Tel.: +351 253 510 761; fax: +351 253 604 741 Conference. E-mail address: [email protected]
2351-9789 Published by Elsevier B.V. B.V. 2351-9789 ©©2017 2018The TheAuthors. Authors. Published by Elsevier Peer-review underaccess responsibility of the scientific committee oflicense the Manufacturing Engineering Society International Conference 2017. This is an open article under the CC BY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/3.0/) Peer-review under responsibility of the scientific committee of the 28th Flexible Automation and Intelligent Manufacturing (FAIM2018) Conference. 10.1016/j.promfg.2018.10.068
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© 2018 The Authors. Published by Elsevier B.V. Ojijiagwo, This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/) Ojijiagwo, Oduoza, Oduoza, Emekwuru Emekwuru Peer-review under responsibility of the scientific committee of the 28th Flexible Automation and Intelligent Manufacturing Ojijiagwo, Oduoza, Emekwuru (FAIM2018) Keywords: GasConference. to Electricity; Gas Turbines; Gas Flare Reduction; Nigeria Keywords: Gas Keywords: Gas
to Electricity; Gas Turbines; Gas Flare Reduction; Nigeria to Electricity; Gas Turbines; Gas Flare Reduction; Nigeria
1. 1. Introduction Introduction 1. Introduction Gas Gas flare flare activities activities take take place place during during oil oil exploration exploration processes processes for for disposal disposal of of associated associated gas, gas, basically basically for for safety safety and operational reasons. Nevertheless, the past 3 – 5 decades have experienced global awareness towards natural gas andGas operational reasons. Nevertheless, 3 – 5 decades have for experienced global awareness gas flare activities take place duringthe oilpast exploration processes disposal of associated gas, towards basicallynatural for safety sustainability and the environmental concerns. sustainability and the environmental concerns. and operational reasons. Nevertheless, the past 3 – 5 decades have experienced global awareness towards natural gas sustainability and the environmental concerns. According According to to World World Bank Bank [1], [1], the the year year 2015 2015 witnessed witnessed about about 147 147 BCM BCM of of global global gas gas flare, flare, even even though though there there is is reduction in quantities flared by the six countries mainly responsible for this practice (Figure 1). Russia is top reduction in quantities by the countries mainly responsible for this (Figure top on on According to World flared Bank [1], thesix year 2015 witnessed about 147 BCM of practice global gas flare, 1). evenRussia thoughisthere is the BCM, Nigeria about aa given it noteworthy that the list list with with 21 BCM, and and Nigeria flaring about 88 BCM BCM inresponsible given year. year. However, it is is(Figure noteworthy that on on isaverage, average, reduction in 21 quantities flared by theflaring six countries mainlyin forHowever, this practice 1). Russia top on about total in about 50% of21the theBCM, total gas gas produced in Nigeria Nigeria is8practically practically flared [2]. the list50% withof and produced Nigeria flaring aboutis BCM in aflared given[2]. year. However, it is noteworthy that on average, about 50% of the total gas produced in Nigeria is practically flared [2].
Figure Figure 1: 1: Top Top six six gas gas flaring flaring countries countries [1] [1] Figure 1:has Top six gas flaring countries [1] Nigeria an estimated reserve of natural Nigeria has an estimated reserve of natural gas gas of of 5.3 5.3 trillion trillion cubic cubic meters meters (187 (187 trillion trillion cubic cubic feet) feet) [3, [3, 4]. 4]. Its Its annual annual production of gas is 33.21 BCM, annual gas utilized is 14.94 BCM and the annual flared gas averages 18.27 BCM production is 33.21reserve BCM, of annual gasgas utilized 14.94 cubic BCM meters and the(187 annual flared gas feet) averages 18.27 BCM Nigeria hasof angas estimated natural of 5.3istrillion trillion cubic [3, 4]. Its annual [5]. Gas flare is associated with environmental, economic and health impacts and it is responsible for the release of [5]. Gas flare with environmental, economic and BCM healthand impacts and it flared is responsible for the release of production of is gasassociated is 33.21 BCM, annual gas utilized is 14.94 the annual gas averages 18.27 BCM per year into the environment [6], as well as pollution of the environment by other about 300 million tons of CO 2 per year into the environment [6], as well as pollution of the environment by other about 300flare million tons of CO [5]. Gas is associated with environmental, economic and health impacts and it is responsible for the release of 2 greenhouse gases. also the ecology, and British Petroleum losses greenhouse gases. It Ittons alsoofdestabilizes destabilizes the into ecology, and according according toas British Petroleum [7], Nigeria losses $2.5 $2.5bybillion billion the environment [6],to well as pollution[7], of Nigeria the environment other about 300 million CO2 per year annually to oil processing. annually due duegases. to gas gasItflare flare during oil and and gas processing. greenhouse also during destabilizes thegas ecology, and according to British Petroleum [7], Nigeria losses $2.5 billion
annually due to gas flare during oil and gas processing. In In this this study, study, the the use use of of potential potential flare flare gas gas has has been been highlighted highlighted as as aa means means to to generate generate electricity electricity and, and, preliminary study has reviewed the technological and economic implications of the use of this GTW technology for preliminary study has the technological implications use to of generate this GTWelectricity technologyand, for In this study, the reviewed use of potential flare gasand haseconomic been highlighted as of a the means electricity generation, particularly in Nigeria. electricity particularly Nigeria. preliminarygeneration, study has reviewed theintechnological and economic implications of the use of this GTW technology for electricity generation, particularly in Nigeria. 2. 2. Literature Literature review review 2. Literature review 2.1 2.1 Gas Gas flare flare reduction reduction through through gas-to-wire gas-to-wire technology technology Electricity generation with power cycle one Electricity generation with power cycle is istechnology one of of the the methods methods suitable suitable for for systemic systemic reduction reduction and and elimination elimination of of 2.1 Gas flare reduction through gas-to-wire gas flare. The basic principle of the power cycle requires use of gas turbine (GT) to produce electricity. Gas gas flare. The basic principle ofpower the power requires of gassuitable turbinefor (GT) to produce electricity. Gas turbines turbines Electricity generation with cyclecycle is one of the use methods systemic reduction and elimination of are used for where substantial of gas abundant [6, are increasingly usedprinciple for electricity electricity generation especially where substantial quantities of natural natural gas are are Gas abundant [6, gas increasingly flare. The basic of the generation power cycleespecially requires use of gas turbine quantities (GT) to produce electricity. turbines 8]. generate high power at efficiencies and low and be in cycle 8]. Turbines generate highelectricity power outputs outputs at high high efficiencies andsubstantial low emissions emissions and can can also be used used in simple simple cycle are Turbines increasingly used for generation especially where quantities of also natural gas are abundant [6, mode for base load mechanical power and electricity generation in the oil and gas sector where natural gas and mode for base load mechanical electricity generation in emissions the oil andand gascan sector where gascycle and 8]. Turbines generate high power power outputsand at high efficiencies and low also be usednatural in simple mode for base load mechanical power and electricity generation in the oil and gas sector where natural gas and
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process gases have been used as fuel; and their maintenance costs are much lower than those for liquid fuels. According to Meetham [9], the gas turbine has its advantages, which include the following: Fuel flexibility: the gas turbine has the capability to burn various qualities of gases than other reciprocating engines. Few number of moving parts (cheaper cost of maintenance with few moving parts). High availability. Less vibration and noise. It is compact. Figure 2 shows the Brayton cycle, which is one of the most efficient cycles for the conversion of gas fuels to electricity [10]. It shows that air enters the compressor from the atmosphere as the pressure is increased from atmospheric pressure to 23 bars. Compressed air later moves to a combustion chamber and then mixes with natural gas as combustion takes place. At point 3 of the cycle, hot gases are directed to the gas turbine where they expand to the atmospheric pressure and gas energy is converted to mechanical energy which generates electricity. Exhausted gases are subsequently discharged from the gas turbine thereafter.
Figure 2: A Flowchart of the Brayton Cycle (Adapted from Rahimpour et al. [8] Figure 3 shows the temperature versus specific entropy (T-S) diagram, which is a conceptual thermodynamic cycle made up of a very small set of components. This cycle could either be an open gas turbine cycle or a closed gas turbine cycle; and is made up of two adiabatic and two constant processes. It also involves four processes, with either a gas or a mixture of gases as working fluid. The first process is known as an adiabatic compression, the second process is the heat supply at constant pressure, the third process is an adiabatic expansion, and the fourth process is known as a release heat at constant pressure.
Figure 3: T – S Diagram illustrating the stages in Joule-Brayton Cycle [11] The use of GTW technology for gas flare reduction has been simulated in a refinery environment in Iran by Rahimpour et al. [8]. It showed that the estimated capital investment is high; however, it also showed that the rate of return of investment is high. Their simulation was carried out using gas flow rate of 356.5 million standard cubic
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feet of gas per day (MMSCFD) into the turbine. This process produced 2130 MW of electricity daily. Therefore, GTW could be a way forward for gas flare minimization, which also comes along with financial incentives from sales of electricity. 3. Methodology Data for this study was collected using semi structured interviews from five highly placed members of staff from three specially chosen companies. These include two electricity generation and distribution companies (ELEGEN 1 & 2), and one gas production and flaring firm (GASPROC). ELEGEN 1 & 2 were chosen because they are two major electricity production and distribution companies in Nigeria; and GASPROC was chosen because it is one of the pioneer gas production company in Nigeria. The interviewees from these case companies were chosen based on their knowledge and experience on gas flaring and electricity generation. This enabled the study to establish gas to wire technology as effective means of gas flare reduction, particularly in Nigeria. Table 1 shows profile of key staff interviewed for the study as well as their levels of experience in the industry. Table 1: Demographics of Key Personnel from the Interviews Case company Key personnel Years of experience ELEGEN 1 Power plant operator 11 Operations and maintenance manager 18 Electrical maintenance repairer 12 Technical manager 6 Shift supervisor 22 ELEGEN 2 Power plant operator 10 Operations and maintenance manager 5 Electrical maintenance repairer 16 Technical manager 2 Shift supervisor 7 GASPROC Production manager 20 Health and safety manager 23 Operations supervisor 15 Field operator 1 22 Field operator 2 10 This study also used secondary data from official company documents such as Minutes of meetings, administrative documents, and progress reports, newspaper articles from the case companies. This source of data collection helped towards provision of reports concerning plant inspection, equipment status, workflow, and staff strength within these case companies. Qualitative data analysis was carried out using the NVivo software. The collected data was coded into nodes and put into categories which covered major areas of concern such as gas production, utilisation, flaring, and impediments to gas to wire technology. Categories were further grouped into themes such as gas flare management and gas production and utilisation themes. 4. Discussions The gas production and utilisation subsection of the discussion highlights the volume of gas produced and flared by GASPROC, and utilised by ELEGEN 1 & 2; while the second subsection addresses the major factors inhibiting effective application of gas to wire technology in Nigeria.
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4.1 Electricity Generation in Nigeria Using Gas to Wire Technology This technology involves a linkage of processes which include gas gathering and transportation system (which involves pipelines), processing plant, storage facilities (reservoir to contain gas), and the gas turbine for electricity generation. Figure 4 shows the sequence of activities for gathering and utilisation of the flare gas. As a routine during oil exploration, the associated natural gas is mostly wasted either through flaring or venting. However, instead of wasting the gas, the proposal is to gather the waste gas in a reservoir through pipelines and then subsequently supplied to the power station for electricity generation, while any excess is converted to liquefied natural gas (LNG).
Figure 4: Flow chart showing gathering and utilization of flare gas 4.2 Gas production, flaring, and utilisation with GASPROC and ELEGEN 1 & 2 The daily gas production by GASPROC is 240 million standard cubic feet (mmscfd). 50 mmscfd and 120 mmscfd of gas are supplied to ELEGEN 1 & 2 respectively for electricity generation; while 50 mmscfd is delivered to a third organisation through pipeline. Ironically, GASPROC flares 20 mmscf of gas daily which could increase depending on requirements by ELEGEN 1 & 2; although, in a situation whereby the demand is less, there is a regulatory feedback system which signals the gas production plant to minimise production in order to minimise flaring. Further data collection from this study showed that the current annual gas production in Nigeria is 33.21BCM; gas utilisation is 14.94 BCM, while the flaring is 18.27 BCM. It is also inconceivable that despite the huge volume of gas flared, Nigeria still faces poor electricity generation. The average daily electricity demand is 12,000 MW, whereas the current electricity generated is about 4,358 MW. 4.3 Barriers to gas to wire technology The gas to wire technology seems an ideal solution to achieve gas flare reduction in Nigeria, while boosting electricity generation and distribution; however, it still faces several challenges. Inefficient gas utilisation, reduction in gas utilisation by power stations, plant shutdown, separation of condensate, plant overhaul, lack of funds, lack of spare parts, lack of trained local maintenance engineers or personnel, irregular gas supply, presence of faulty turbines in power stations, lack of turbine maintenance are the major factors that were identified by this study that inhibit the effective application of GTW technology, especially in Nigeria.
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4.4 Evaluation of GTW Technology An economic evaluation of adopting GTW technology for electricity generation in Nigeria was carried out using the ALSTOM GT13E2 turbine, whose performance parameters are stated in Table 2. Table 2: Primary performance parameters for GT13E2 [12] Fuel Frequency Gross Electricity Output Gross Electricity Efficiency Thermal Efficiency Turbine Speed Fuel Gas Temperature
Natural Gas 50 Hz 150 MW 36.4% 36% 3000 rpm 31 oC
A unit of ALSTOM GT13E2 consumes a total of 0.93 million cubic meters (mcm) of gas per day and generates 150 MW of electricity. This information enabled economic estimation of the potential to adopt GTW for electricity generation, and gas flare reduction in Nigeria. According to Table 3, it is feasible that 16.97 billion cubic metres (BCM) of gas could be utilised to generate extra 7,500 MW of electricity per annum, using 50 units of turbines. The key driver is the availability of gas, but since the volume required for this operation is lower than the average yearly gas flare in Nigeria, there should potentially be no issue with enough gas supply. Table 3: Estimated Gas Usage and Electricity Generation in Nigeria Using GTW Technology Daily Electricity Yearly Gas Usage Yearly Electricity No. of Gas Turbine Daily Gas Usage Gen. (MW) (M3) Gen. (150 MW (M3) (MW) Capacity/Turbine) 930,000 150 339,450,000 54,750 1 1,860,000 300 678,900,000 109,500 2 4,650,000 750 1,697,250,000 273,750 5 9,300,000 1,500 3,394,500,000 547,500 10 18,600,000 3000 6,789,000,000 1,095,000 20 27,900,000 4,500 10,183,500,000 1,642,500 30 37,200,000 6,000 13,578,000,000 2,190,000 40 16,972,500,000 7,500 16,972,500,000 2,737,500 50 Tables 4 and 5 demonstrate the economic implication of the application of GTW technology in Nigeria, using the factors stated earlier such as units of turbine, amount of generated energy, and volume of gas utilised. Table 4 highlights that the major capital investment goes into acquisition of equipment such as turbines, spare parts, as well as inflation cost. The total estimation for capital investment in Nigeria is £1,643,185,000. Table 4: Estimated Capital Investment for a Nigerian Power Plant DESCRIPTION
COST (£)
Equipment (50 Units of Gas Turbine)
1,051,575,000 (140.210/kw)
Installations of equipment and Piping
360,900,000
Maintenance/Working Cost. Royal to Host Community Total capital investment 4.5 Estimated electricity generation and financial output
230,610,000/year 100,000 1,643,185,000
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It appears that residential tariff system is commonly used in Nigeria, where a kWh of electricity costs £0.07. Therefore, it was utilised as a basis for the calculation for income from sales of electricity. Based on this, a calculation is provided to demonstrate the financial output from a unit of turbine at 150 MW capacity each. 1 MW = 1000KW A unit of gas turbine capacity of 150 MW is equivalent to 150,000 KW: Cost of electricity per KWh in Nigeria = £0.07 So, daily income from operating one turbine = 150,000 x 0.07 = £10,500 And yearly income per turbine = £10,500 x 365 = £3,832,500 However, since this is gross income, net of operating / maintenance costs would be much less than this figure. Subsequently, this study considered some variables as seen in Table 5, which were applied towards estimated financial income. Table 5: Estimated Income and Return Cost Statement. Caption (a): Cost of sale of electricity (b): Total cost of electricity sale/year
Value £0.07/kwh £4,599,000,000
(c): Product Cost for turbines operation
£0.007/kWh
(d): Total product cost for turbines/year
£459,900,000
(e): Fixed Charges (f): Break-even Point Capacity (g): Yearly income in B.E.P Capacity (h): Capacity of turbines Per Year
£689,850,000/Year 10,950,000,000 kWh £766,500,000 65,700,000,000 kWh
(i): Total Cost
£2,792,935,000
(j): Total Yearly Income
£4,599,000,000
(k): Gross Profit
£1,806,065,000/year
(l): Net Profit
£1,264,245,500/year
(m): ROI
16.3%/year
The economics of this assessment includes huge financial investment requirement of about £1.6b for an estimated capital investment; however, on a yearly basis, the investment potentially generates a net profit of £1.2b, which could be attributed to cost of electricity in Nigeria (£0.07 per kWh); very high amount of electricity produced from the turbines and; high demand of electricity in Nigeria. Also the period of return on investment (ROI) is a positive motivation for potential investors because recuperation of the capital investment should be about 6 years.
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5. Conclusion This study concludes by presenting some recommendations that encourage utilization of gas to wire technology, to reduce waste and its associated environmental impacts in Nigeria:
The success of this approach will depend on actions taken firstly by the government. Therefore, it is suggested that government impose and monitor policies that encourage GTW technology. Such policies should mandate oil and gas operators to install and operate gas-gathering and transportation facilities (pipeline). Also, an Act that revokes licenses for noncompliance of gas reduction laws and frameworks should be promulgated. Government should encourage existing and potential investors through subsidy support to sustain the current level of infrastructural requirement; and also expand coverage to enable millions of citizens without access to electricity. Provision of more power stations and gas turbine units, in various locations of Nigeria. There is the need to have these power stations in many different locations in Nigeria considering the high levels of power outages in the country.
6. Reference [1] The World Bank (2016) New Data Reveals Uptick in Global Gas Flaring. Available [Online] from http://www.worldbank.org/en/news/press-release/2016/12/12/new-data-reveals-uptick-in-global-gas-flaring. Viewed 16th December 2017. [2] Anomohanran, O. (2012) Determination of greenhouse gas emission resulting from gas flaring activities in Nigeria. Energy Policy 45, 666-670. [3] Ahmed, M.M., Bello, A.A., Idris, M.N. (2012) Natural Gas Utilization and the Nigerian Gas-To-Liquid Project; An Opportunity To End Gas Flaring. International Journal of Emerging Trends in Engineering and Development 2, 2 240-256. [4] NLNG, (2011) Facts and Figures on NLNG. Available [Online] from Viewed 21/09/2017. [5] Giwa, S.O., Oluwakayode, O.A., Olasunkanmi, O.A (2014) Baseline Black Carbon Emission for Gas Flaring in the Niger Delta Region of Nigeria. Journal of Natural Gas Science and Engineering 20, 373-379. [6] Abas, N., Kalair, A., Khan, N. and Kalair, A.R. (2017). Review of GHG emissions in Pakistan compared to SAARC countries. Renewable and Sustainable Energy Reviews, 80, pp.990-1016. [7] British Petroleum (2015). Statistical Review of World Energy. Available [Online] from < http://www.bp.com/en/global/corporate/energy-economics/statistical-review-of-worldenergy. html> Viewed 07/01/2016. [8] Rahimpour, M.R., Jamshidnejad, Z., Jokar, S.M., Karimi, G., Ghorbani, A., Mohammadi, A.H. (2012) A comparative study of three methods for flare gas recovery of Asalooye gas refinery, J. Nat. Gas Sci. Eng. 4, 17–28. [9] Meetham GW. (2012). The development of gas turbine materials. Springer Science & Business Media. [10] Pra, F., Tochon, P., Mauget, C., Fokkens, J. and Willemsen, S. (2008). Promising designs of compact heat exchangers for modular HTRs using the Brayton cycle. Nuclear Engineering and Design, 238(11), pp.3160-3173. [11] Jansohn, P (2013) Modern Gas Turbine Systems. High Efficiency, Low Emission, Fuel Flexible Power Generation. 1st Edition. Woodhead Publishing. [12] ALSTOM Power (2010). Plant Data Sheet for ALSTOM Gas Turbine GT13E2 within Open Cycle Plant in Port Harcourt, Nigeria. Part of Documentation from Case Study.
ScienceDirect
Available Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Procedia Manufacturing 00 (2018) 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia
Procedia Manufacturing 17 (2018) 444–451 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia
28th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2018), June 11-14, 2018, Columbus, OH, USA
Technological and economic evaluation of conversion of potential Manufacturing Engineering Society International Conference 2017, MESIC 2017, 28-30 June 2017, Vigo (Pontevedra), Spain flare gas to electricity in Nigeria Costing models for capacityPaper optimization ID: (143) in Industry 4.0: Trade-off betweenEmeka used capacity and operational efficiency Nnanna Ojijiagwo , Chike F. Oduoza , Nwabueze Emekwuru a
a
b
University of Wolverhampton, Faculty of Science and Engineering. Wolverhampton, United Kingdom b Coventry University, Facultyaof Engineering, Environment and Computing. Coventry, United a,* b b Kingdom a
A. Santana , P. Afonso , A. Zanin , R. Wernke
Abstract
a
University of Minho, 4800-058 Guimarães, Portugal b Unochapecó, 89809-000 Chapecó, SC, Brazil
Globally, over 100 billion cubic metres (BCM) of gas is flared annually and, this is linked to an annual emission of 400 million tons of carbon dioxide. In Nigeria the annual gas production is valued at 33.21 BCM, out of which more than 50% is wasted Abstract through flaring, thereby emitting about 35 million tons of carbon dioxide. About 14.94 BCM of gas produced in Nigeria is used for a variety of activities generation. processes Despite thiswill scenario, Nigeria is to generate and distribute Under the concept of including "Industryelectricity 4.0", production be pushed to still be unable increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization enough electricity for the citizenry. This paper therefore evaluates the use of gas to wire technology as the option to minimise gas goes beyond the traditional aim of capacity maximization, contributing also for organization’s profitability and value. flaring in Nigeria while minimising the associated environmental impacts. The research methodology was based on interviewing Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of top level managers an electricity generation company, and gas models Production well as topic the researchers’ site maximization. The in study of capacity optimization and costing is anCompany, importantasresearch that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical observations within the two case companies. Results from this study showed that electricity generation could be improved from model for capacity management based on different costing models (ABC and TDABC). A generic model has been its current daily production rate of 4358 MW to about 12000 MW from the use of part of 18.27 BCM of gas flared annually in developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s Nigeria.The Thistrade-off serves as capacity fuel for 50 units of gas turbine with power output of is 150highlighted MW each, with a potential in daily value. maximization vs operational efficiency and it is shownincrease that capacity optimization might hide operational inefficiency. electricity generation of 7500 MW. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency Peer-review under responsibility of the scientific committee of the 28th Flexible Automation and Intelligent Manufacturing (FAIM2018) Conference.
1. Introduction The cost of idle capacity is a fundamental information for companies and their management of extreme importance 2351-9789 © 2018 The Authors. Published by Elsevier B.V. in modern production systems. In general, it is defined as unused capacity or production potential and can be measured This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) in several under ways: tons of production, of manufacturing, The management of (FAIM2018) the idle capacity Peer-review responsibility of the scientificavailable committeehours of the 28th Flexible Automationetc. and Intelligent Manufacturing * Paulo Afonso. Tel.: +351 253 510 761; fax: +351 253 604 741 Conference. E-mail address: [email protected]
2351-9789 Published by Elsevier B.V. B.V. 2351-9789 ©©2017 2018The TheAuthors. Authors. Published by Elsevier Peer-review underaccess responsibility of the scientific committee oflicense the Manufacturing Engineering Society International Conference 2017. This is an open article under the CC BY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/3.0/) Peer-review under responsibility of the scientific committee of the 28th Flexible Automation and Intelligent Manufacturing (FAIM2018) Conference. 10.1016/j.promfg.2018.10.068
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© 2018 The Authors. Published by Elsevier B.V. Ojijiagwo, This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/) Ojijiagwo, Oduoza, Oduoza, Emekwuru Emekwuru Peer-review under responsibility of the scientific committee of the 28th Flexible Automation and Intelligent Manufacturing Ojijiagwo, Oduoza, Emekwuru (FAIM2018) Keywords: GasConference. to Electricity; Gas Turbines; Gas Flare Reduction; Nigeria Keywords: Gas Keywords: Gas
to Electricity; Gas Turbines; Gas Flare Reduction; Nigeria to Electricity; Gas Turbines; Gas Flare Reduction; Nigeria
1. 1. Introduction Introduction 1. Introduction Gas Gas flare flare activities activities take take place place during during oil oil exploration exploration processes processes for for disposal disposal of of associated associated gas, gas, basically basically for for safety safety and operational reasons. Nevertheless, the past 3 – 5 decades have experienced global awareness towards natural gas andGas operational reasons. Nevertheless, 3 – 5 decades have for experienced global awareness gas flare activities take place duringthe oilpast exploration processes disposal of associated gas, towards basicallynatural for safety sustainability and the environmental concerns. sustainability and the environmental concerns. and operational reasons. Nevertheless, the past 3 – 5 decades have experienced global awareness towards natural gas sustainability and the environmental concerns. According According to to World World Bank Bank [1], [1], the the year year 2015 2015 witnessed witnessed about about 147 147 BCM BCM of of global global gas gas flare, flare, even even though though there there is is reduction in quantities flared by the six countries mainly responsible for this practice (Figure 1). Russia is top reduction in quantities by the countries mainly responsible for this (Figure top on on According to World flared Bank [1], thesix year 2015 witnessed about 147 BCM of practice global gas flare, 1). evenRussia thoughisthere is the BCM, Nigeria about aa given it noteworthy that the list list with with 21 BCM, and and Nigeria flaring about 88 BCM BCM inresponsible given year. year. However, it is is(Figure noteworthy that on on isaverage, average, reduction in 21 quantities flared by theflaring six countries mainlyin forHowever, this practice 1). Russia top on about total in about 50% of21the theBCM, total gas gas produced in Nigeria Nigeria is8practically practically flared [2]. the list50% withof and produced Nigeria flaring aboutis BCM in aflared given[2]. year. However, it is noteworthy that on average, about 50% of the total gas produced in Nigeria is practically flared [2].
Figure Figure 1: 1: Top Top six six gas gas flaring flaring countries countries [1] [1] Figure 1:has Top six gas flaring countries [1] Nigeria an estimated reserve of natural Nigeria has an estimated reserve of natural gas gas of of 5.3 5.3 trillion trillion cubic cubic meters meters (187 (187 trillion trillion cubic cubic feet) feet) [3, [3, 4]. 4]. Its Its annual annual production of gas is 33.21 BCM, annual gas utilized is 14.94 BCM and the annual flared gas averages 18.27 BCM production is 33.21reserve BCM, of annual gasgas utilized 14.94 cubic BCM meters and the(187 annual flared gas feet) averages 18.27 BCM Nigeria hasof angas estimated natural of 5.3istrillion trillion cubic [3, 4]. Its annual [5]. Gas flare is associated with environmental, economic and health impacts and it is responsible for the release of [5]. Gas flare with environmental, economic and BCM healthand impacts and it flared is responsible for the release of production of is gasassociated is 33.21 BCM, annual gas utilized is 14.94 the annual gas averages 18.27 BCM per year into the environment [6], as well as pollution of the environment by other about 300 million tons of CO 2 per year into the environment [6], as well as pollution of the environment by other about 300flare million tons of CO [5]. Gas is associated with environmental, economic and health impacts and it is responsible for the release of 2 greenhouse gases. also the ecology, and British Petroleum losses greenhouse gases. It Ittons alsoofdestabilizes destabilizes the into ecology, and according according toas British Petroleum [7], Nigeria losses $2.5 $2.5bybillion billion the environment [6],to well as pollution[7], of Nigeria the environment other about 300 million CO2 per year annually to oil processing. annually due duegases. to gas gasItflare flare during oil and and gas processing. greenhouse also during destabilizes thegas ecology, and according to British Petroleum [7], Nigeria losses $2.5 billion
annually due to gas flare during oil and gas processing. In In this this study, study, the the use use of of potential potential flare flare gas gas has has been been highlighted highlighted as as aa means means to to generate generate electricity electricity and, and, preliminary study has reviewed the technological and economic implications of the use of this GTW technology for preliminary study has the technological implications use to of generate this GTWelectricity technologyand, for In this study, the reviewed use of potential flare gasand haseconomic been highlighted as of a the means electricity generation, particularly in Nigeria. electricity particularly Nigeria. preliminarygeneration, study has reviewed theintechnological and economic implications of the use of this GTW technology for electricity generation, particularly in Nigeria. 2. 2. Literature Literature review review 2. Literature review 2.1 2.1 Gas Gas flare flare reduction reduction through through gas-to-wire gas-to-wire technology technology Electricity generation with power cycle one Electricity generation with power cycle is istechnology one of of the the methods methods suitable suitable for for systemic systemic reduction reduction and and elimination elimination of of 2.1 Gas flare reduction through gas-to-wire gas flare. The basic principle of the power cycle requires use of gas turbine (GT) to produce electricity. Gas gas flare. The basic principle ofpower the power requires of gassuitable turbinefor (GT) to produce electricity. Gas turbines turbines Electricity generation with cyclecycle is one of the use methods systemic reduction and elimination of are used for where substantial of gas abundant [6, are increasingly usedprinciple for electricity electricity generation especially where substantial quantities of natural natural gas are are Gas abundant [6, gas increasingly flare. The basic of the generation power cycleespecially requires use of gas turbine quantities (GT) to produce electricity. turbines 8]. generate high power at efficiencies and low and be in cycle 8]. Turbines generate highelectricity power outputs outputs at high high efficiencies andsubstantial low emissions emissions and can can also be used used in simple simple cycle are Turbines increasingly used for generation especially where quantities of also natural gas are abundant [6, mode for base load mechanical power and electricity generation in the oil and gas sector where natural gas and mode for base load mechanical electricity generation in emissions the oil andand gascan sector where gascycle and 8]. Turbines generate high power power outputsand at high efficiencies and low also be usednatural in simple mode for base load mechanical power and electricity generation in the oil and gas sector where natural gas and
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process gases have been used as fuel; and their maintenance costs are much lower than those for liquid fuels. According to Meetham [9], the gas turbine has its advantages, which include the following: Fuel flexibility: the gas turbine has the capability to burn various qualities of gases than other reciprocating engines. Few number of moving parts (cheaper cost of maintenance with few moving parts). High availability. Less vibration and noise. It is compact. Figure 2 shows the Brayton cycle, which is one of the most efficient cycles for the conversion of gas fuels to electricity [10]. It shows that air enters the compressor from the atmosphere as the pressure is increased from atmospheric pressure to 23 bars. Compressed air later moves to a combustion chamber and then mixes with natural gas as combustion takes place. At point 3 of the cycle, hot gases are directed to the gas turbine where they expand to the atmospheric pressure and gas energy is converted to mechanical energy which generates electricity. Exhausted gases are subsequently discharged from the gas turbine thereafter.
Figure 2: A Flowchart of the Brayton Cycle (Adapted from Rahimpour et al. [8] Figure 3 shows the temperature versus specific entropy (T-S) diagram, which is a conceptual thermodynamic cycle made up of a very small set of components. This cycle could either be an open gas turbine cycle or a closed gas turbine cycle; and is made up of two adiabatic and two constant processes. It also involves four processes, with either a gas or a mixture of gases as working fluid. The first process is known as an adiabatic compression, the second process is the heat supply at constant pressure, the third process is an adiabatic expansion, and the fourth process is known as a release heat at constant pressure.
Figure 3: T – S Diagram illustrating the stages in Joule-Brayton Cycle [11] The use of GTW technology for gas flare reduction has been simulated in a refinery environment in Iran by Rahimpour et al. [8]. It showed that the estimated capital investment is high; however, it also showed that the rate of return of investment is high. Their simulation was carried out using gas flow rate of 356.5 million standard cubic
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feet of gas per day (MMSCFD) into the turbine. This process produced 2130 MW of electricity daily. Therefore, GTW could be a way forward for gas flare minimization, which also comes along with financial incentives from sales of electricity. 3. Methodology Data for this study was collected using semi structured interviews from five highly placed members of staff from three specially chosen companies. These include two electricity generation and distribution companies (ELEGEN 1 & 2), and one gas production and flaring firm (GASPROC). ELEGEN 1 & 2 were chosen because they are two major electricity production and distribution companies in Nigeria; and GASPROC was chosen because it is one of the pioneer gas production company in Nigeria. The interviewees from these case companies were chosen based on their knowledge and experience on gas flaring and electricity generation. This enabled the study to establish gas to wire technology as effective means of gas flare reduction, particularly in Nigeria. Table 1 shows profile of key staff interviewed for the study as well as their levels of experience in the industry. Table 1: Demographics of Key Personnel from the Interviews Case company Key personnel Years of experience ELEGEN 1 Power plant operator 11 Operations and maintenance manager 18 Electrical maintenance repairer 12 Technical manager 6 Shift supervisor 22 ELEGEN 2 Power plant operator 10 Operations and maintenance manager 5 Electrical maintenance repairer 16 Technical manager 2 Shift supervisor 7 GASPROC Production manager 20 Health and safety manager 23 Operations supervisor 15 Field operator 1 22 Field operator 2 10 This study also used secondary data from official company documents such as Minutes of meetings, administrative documents, and progress reports, newspaper articles from the case companies. This source of data collection helped towards provision of reports concerning plant inspection, equipment status, workflow, and staff strength within these case companies. Qualitative data analysis was carried out using the NVivo software. The collected data was coded into nodes and put into categories which covered major areas of concern such as gas production, utilisation, flaring, and impediments to gas to wire technology. Categories were further grouped into themes such as gas flare management and gas production and utilisation themes. 4. Discussions The gas production and utilisation subsection of the discussion highlights the volume of gas produced and flared by GASPROC, and utilised by ELEGEN 1 & 2; while the second subsection addresses the major factors inhibiting effective application of gas to wire technology in Nigeria.
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4.1 Electricity Generation in Nigeria Using Gas to Wire Technology This technology involves a linkage of processes which include gas gathering and transportation system (which involves pipelines), processing plant, storage facilities (reservoir to contain gas), and the gas turbine for electricity generation. Figure 4 shows the sequence of activities for gathering and utilisation of the flare gas. As a routine during oil exploration, the associated natural gas is mostly wasted either through flaring or venting. However, instead of wasting the gas, the proposal is to gather the waste gas in a reservoir through pipelines and then subsequently supplied to the power station for electricity generation, while any excess is converted to liquefied natural gas (LNG).
Figure 4: Flow chart showing gathering and utilization of flare gas 4.2 Gas production, flaring, and utilisation with GASPROC and ELEGEN 1 & 2 The daily gas production by GASPROC is 240 million standard cubic feet (mmscfd). 50 mmscfd and 120 mmscfd of gas are supplied to ELEGEN 1 & 2 respectively for electricity generation; while 50 mmscfd is delivered to a third organisation through pipeline. Ironically, GASPROC flares 20 mmscf of gas daily which could increase depending on requirements by ELEGEN 1 & 2; although, in a situation whereby the demand is less, there is a regulatory feedback system which signals the gas production plant to minimise production in order to minimise flaring. Further data collection from this study showed that the current annual gas production in Nigeria is 33.21BCM; gas utilisation is 14.94 BCM, while the flaring is 18.27 BCM. It is also inconceivable that despite the huge volume of gas flared, Nigeria still faces poor electricity generation. The average daily electricity demand is 12,000 MW, whereas the current electricity generated is about 4,358 MW. 4.3 Barriers to gas to wire technology The gas to wire technology seems an ideal solution to achieve gas flare reduction in Nigeria, while boosting electricity generation and distribution; however, it still faces several challenges. Inefficient gas utilisation, reduction in gas utilisation by power stations, plant shutdown, separation of condensate, plant overhaul, lack of funds, lack of spare parts, lack of trained local maintenance engineers or personnel, irregular gas supply, presence of faulty turbines in power stations, lack of turbine maintenance are the major factors that were identified by this study that inhibit the effective application of GTW technology, especially in Nigeria.
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4.4 Evaluation of GTW Technology An economic evaluation of adopting GTW technology for electricity generation in Nigeria was carried out using the ALSTOM GT13E2 turbine, whose performance parameters are stated in Table 2. Table 2: Primary performance parameters for GT13E2 [12] Fuel Frequency Gross Electricity Output Gross Electricity Efficiency Thermal Efficiency Turbine Speed Fuel Gas Temperature
Natural Gas 50 Hz 150 MW 36.4% 36% 3000 rpm 31 oC
A unit of ALSTOM GT13E2 consumes a total of 0.93 million cubic meters (mcm) of gas per day and generates 150 MW of electricity. This information enabled economic estimation of the potential to adopt GTW for electricity generation, and gas flare reduction in Nigeria. According to Table 3, it is feasible that 16.97 billion cubic metres (BCM) of gas could be utilised to generate extra 7,500 MW of electricity per annum, using 50 units of turbines. The key driver is the availability of gas, but since the volume required for this operation is lower than the average yearly gas flare in Nigeria, there should potentially be no issue with enough gas supply. Table 3: Estimated Gas Usage and Electricity Generation in Nigeria Using GTW Technology Daily Electricity Yearly Gas Usage Yearly Electricity No. of Gas Turbine Daily Gas Usage Gen. (MW) (M3) Gen. (150 MW (M3) (MW) Capacity/Turbine) 930,000 150 339,450,000 54,750 1 1,860,000 300 678,900,000 109,500 2 4,650,000 750 1,697,250,000 273,750 5 9,300,000 1,500 3,394,500,000 547,500 10 18,600,000 3000 6,789,000,000 1,095,000 20 27,900,000 4,500 10,183,500,000 1,642,500 30 37,200,000 6,000 13,578,000,000 2,190,000 40 16,972,500,000 7,500 16,972,500,000 2,737,500 50 Tables 4 and 5 demonstrate the economic implication of the application of GTW technology in Nigeria, using the factors stated earlier such as units of turbine, amount of generated energy, and volume of gas utilised. Table 4 highlights that the major capital investment goes into acquisition of equipment such as turbines, spare parts, as well as inflation cost. The total estimation for capital investment in Nigeria is £1,643,185,000. Table 4: Estimated Capital Investment for a Nigerian Power Plant DESCRIPTION
COST (£)
Equipment (50 Units of Gas Turbine)
1,051,575,000 (140.210/kw)
Installations of equipment and Piping
360,900,000
Maintenance/Working Cost. Royal to Host Community Total capital investment 4.5 Estimated electricity generation and financial output
230,610,000/year 100,000 1,643,185,000
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It appears that residential tariff system is commonly used in Nigeria, where a kWh of electricity costs £0.07. Therefore, it was utilised as a basis for the calculation for income from sales of electricity. Based on this, a calculation is provided to demonstrate the financial output from a unit of turbine at 150 MW capacity each. 1 MW = 1000KW A unit of gas turbine capacity of 150 MW is equivalent to 150,000 KW: Cost of electricity per KWh in Nigeria = £0.07 So, daily income from operating one turbine = 150,000 x 0.07 = £10,500 And yearly income per turbine = £10,500 x 365 = £3,832,500 However, since this is gross income, net of operating / maintenance costs would be much less than this figure. Subsequently, this study considered some variables as seen in Table 5, which were applied towards estimated financial income. Table 5: Estimated Income and Return Cost Statement. Caption (a): Cost of sale of electricity (b): Total cost of electricity sale/year
Value £0.07/kwh £4,599,000,000
(c): Product Cost for turbines operation
£0.007/kWh
(d): Total product cost for turbines/year
£459,900,000
(e): Fixed Charges (f): Break-even Point Capacity (g): Yearly income in B.E.P Capacity (h): Capacity of turbines Per Year
£689,850,000/Year 10,950,000,000 kWh £766,500,000 65,700,000,000 kWh
(i): Total Cost
£2,792,935,000
(j): Total Yearly Income
£4,599,000,000
(k): Gross Profit
£1,806,065,000/year
(l): Net Profit
£1,264,245,500/year
(m): ROI
16.3%/year
The economics of this assessment includes huge financial investment requirement of about £1.6b for an estimated capital investment; however, on a yearly basis, the investment potentially generates a net profit of £1.2b, which could be attributed to cost of electricity in Nigeria (£0.07 per kWh); very high amount of electricity produced from the turbines and; high demand of electricity in Nigeria. Also the period of return on investment (ROI) is a positive motivation for potential investors because recuperation of the capital investment should be about 6 years.
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5. Conclusion This study concludes by presenting some recommendations that encourage utilization of gas to wire technology, to reduce waste and its associated environmental impacts in Nigeria:
The success of this approach will depend on actions taken firstly by the government. Therefore, it is suggested that government impose and monitor policies that encourage GTW technology. Such policies should mandate oil and gas operators to install and operate gas-gathering and transportation facilities (pipeline). Also, an Act that revokes licenses for noncompliance of gas reduction laws and frameworks should be promulgated. Government should encourage existing and potential investors through subsidy support to sustain the current level of infrastructural requirement; and also expand coverage to enable millions of citizens without access to electricity. Provision of more power stations and gas turbine units, in various locations of Nigeria. There is the need to have these power stations in many different locations in Nigeria considering the high levels of power outages in the country.
6. Reference [1] The World Bank (2016) New Data Reveals Uptick in Global Gas Flaring. Available [Online] from http://www.worldbank.org/en/news/press-release/2016/12/12/new-data-reveals-uptick-in-global-gas-flaring. Viewed 16th December 2017. [2] Anomohanran, O. (2012) Determination of greenhouse gas emission resulting from gas flaring activities in Nigeria. Energy Policy 45, 666-670. [3] Ahmed, M.M., Bello, A.A., Idris, M.N. (2012) Natural Gas Utilization and the Nigerian Gas-To-Liquid Project; An Opportunity To End Gas Flaring. International Journal of Emerging Trends in Engineering and Development 2, 2 240-256. [4] NLNG, (2011) Facts and Figures on NLNG. Available [Online] from