Energy efficiency assessment of fixed asset investment projects – A case study of a Shenzhen combined-cycle power plant

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Renewable and Sustainable Energy Reviews 59 (2016) 1195–1208

Contents lists available at ScienceDirect

Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser

Energy efﬁciency assessment of ﬁxed asset investment projects – A case study of a Shenzhen combined-cycle power plant Li Yingjian a,n, Yousif A. Abakr b, Qiu Qi a, You Xinkui a, Zhou Jiping c a

College of Chemistry & Chemical Engineering, Shenzhen University, Shenzhen 518060, PR China Department of Mechanical,Materials and Manufacturing Engineering, The University of Nottingham Malaysia Campus, Malaysia c Shenzhen State High-Tech Industrial Innovation Center, Shenzhen 518057, PR China b

art ic l e i nf o

a b s t r a c t

Article history: Received 7 May 2015 Received in revised form 10 January 2016 Accepted 13 January 2016

The assessment of ﬁxed asset investment projects of energy conservation is based on a scientiﬁc and systematic approach to analyze the energy production, consumption and management and helps to analyze whether the use of energy is in line with the national and local industrial policies and whether the project design meets China's energy saving design outlines and industry standards. The level of energy consumption is compared to the domestic and international advanced levels regarding the project energy use and process analysis, in all aspects of energy production and energy consumption, taking technically feasible, economically reasonable and environmentally and socially responsible measures and effective and rational use of energy, to reduce consumption and losses and to stop waste, while investigating if the project has a certain advanced and rational use of energy. This study provides a full consideration of whether there is a scientiﬁc and rational use of energy to avoid low-level repetition construction, to avoid blind expansion trends, and to promote the upgrading of industrial structure. This paper takes as an example a gas turbine power plant in Shenzhen as an assessment case study of the potential energy savings. The project is expected to have an annual power supply of 37.89 108 kW h and an annual heat supply of 5.43 104 GJ. The consumption of power generation in tons of coal equivalent units is expected to reach 208 g per kW h. The comprehensive annual average thermal efﬁciency is 77.16%, and the average heat-to-power ratio is 40.65%. These technical indicators are thought to be one of the best compared to similar level projects in the country. & 2016 Elsevier Ltd. All rights reserved.

Keywords: Fixed asset investment Energy assessment Gas turbine power plant Energy efﬁciency Energy-saving measures

Contents 1.

2.

3.

4.

n

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1. Energy assessment signiﬁcance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2. Evaluation of the main project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3. Basis for this assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4. Project energy consumption levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5. The inﬂuence of the environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description of the project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1. Fuel supply sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Reference units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3. Heat balance and thermal economic performance indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4. Water supply system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Energy consumption increment and its impact on the project's location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Incremental energy consumption and energy-savings control objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Electricity demand forecasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Estimated energy efﬁciency of the projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Corresponding author. Tel.: þ 86 755 26538802; fax: þ86 755 26536141. E-mail addresses: [email protected] (L. Yingjian), [email protected] (Y.A. Abakr).

http://dx.doi.org/10.1016/j.rser.2016.01.042 1364-0321/& 2016 Elsevier Ltd. All rights reserved.

1196 1196 1198 1198 1198 1198 1199 1199 1199 1199 1199 1199 1199 1200 1200

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4.1. 4.2. 4.3. 4.4. 4.5.

Major energy systems and equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1200 The main economic indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1200 Assessment of the overall energy consumption level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1200 Technical solutions for energy savings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201 Major energy processes and energy consumption indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201 4.5.1. Energy savings analysis of the energy conversion process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201 4.5.2. Energy savings analysis of the energy transfer process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203 4.5.3. Level and indicator of energy consumption for the auxiliary systems and the power system . . . . . . . . . . . . . . . . . . . . . . . . . 1203 5. Assessment of the energy-savings measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203 5.1. Measurements of the level of energy-savings of the equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203 5.2. Process energy saving measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203 5.3. Analysis of the energy-savings effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204 6. Energy utilization of the project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204 6.1. The processing and conversions of the energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204 6.1.1. Gas turbine process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204 6.1.2. Heat recovery process in boilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204 6.1.3. The power generation process of the steam turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204 6.2. The situation of energy use in the feasibility study stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204 6.3. Energy end-use conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204 6.4. The energy balance of the project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1205 7. The assessment of the energy consumption and the energy efﬁciency level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1205 7.1. Accounting of the integrating energy consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1205 7.2. The assessment of the integrated energy consumption level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207 7.3. Various energy coefﬁcients converted into tons of coal equivalent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207 8. Energy assessment conclusions and recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207

1. Introduction 1.1. Energy assessment signiﬁcance Energy audits, performed through ﬁeld investigation, data veriﬁcation and necessary tests, analysis of energy utilization and conﬁrmation of its energy utilization levels, are very crucial to ﬁnd the problems and defects, tap the business potential for energy savings, implement energy-saving measures and propose practical recommendations to help energy companies improve the energy management level while promoting economic and environmental sustainability [1]. The energy conservation assessment in ﬁxed asset investment projects is performed as an assessment of the energy use status on the investment project. The energy conservation assessment (ECA) in a ﬁxed asset investment is similar to an environmental impact assessment in different departments to improve the energy efﬁciency of new and existing projects. Although the ECA system has been established for only a relatively short period of time, it has obviously made remarkable achievements in improving China's energy efﬁciency and has played an important role in reducing greenhouse gas emissions [2]. With implementation of the ECA system, China will be able to obtain the beneﬁts of energy efﬁciency, help address climate change and make signiﬁcant contributions [3]. The overall results of the energy input–output analysis showed that the increase in domestic investment in China has brought a signiﬁcant national energy consumption growth. China's construction industry and equipment manufacturing combined accounted for more than 90% of its investment-led domestic energy consumption; the results reﬂect the fact that China's rapid urbanization and industrialization required the expenditure of huge amounts of energy. In 2007, the construction industry consumed 793.74 million tons of coal equivalent, which was about 29.6% of the total China's national energy consumption [4]. Given this fact, we can conclude that the short life of buildings and infrastructure [5] and variety of China's many industrial sectors

has led to inefﬁcient use of capital, energy and consumption of other resources corresponding to the related investment activities. From our perspective, based on the study implemented to increase the energy saving potential of the mining Chinese economy, China's policy makers should increase their national energy efﬁciency requirements [6]. In China's current energy pricing system, the advantages of gasﬁred power plants, which have low investment costs and high efﬁciency, have not been able to offset the low price of coal. Gasﬁred power plants, both in the downstream of the liqueﬁed natural gas (LNG) industry and in the upstream of the power industry, are faced with a problem: policy guidelines are required to solve the problems they face as well as to ensure future development of gas-ﬁred power projects [7]. Gas-ﬁred power generation competitiveness relative to coal powered plants depends on three factors: the price of natural gas relative to coal, the investment costs of a natural gas power plant compared to a coal-ﬁred power plant and the price of carbon. Given reasonable fuel prices and investment cost reduction, implementing a series of economic reform policy interventions is in line with China's broader goals of energy policy. In contrast with the traditional view, applications of natural gas peaking power systems in China are already cost competitive [8]. Meet the future electricity demand and current environmental regulations, is considered to be the main driving force to upgrade the existing coal-ﬁred power plants. In this context, the integration of the gas turbine is an effective technology to improve power plant capacity and operational ﬂexibility [9]. India has a mix of energy resources, including fossil fuels (coal, lignite, oil and gas) and renewable energy (wind, solar, small hydro, biomass, etc.). Approximately three-ﬁfths of the country's power generation capacity depends on fossil fuels, mainly based on the domestic coal reserves. In the past decade, due to the lower capital requirements, shorter construction period and higher efﬁciency, the natural gas generation capacity is also growing very rapidly in the overall power generation capacity [10].

L. Yingjian et al. / Renewable and Sustainable Energy Reviews 59 (2016) 1195–1208

Due to the increasing demand for electricity and the increasing impact of population growth, Malaysia, an industrialized country, is considering many options for their future energy generation approaches. In addition to the traditional four fuel mix, including renewable energy and nuclear energy in several countries under a ﬁve diversiﬁed fuel mix strategy, was introduced and provided resources. Given that Malaysia will become a net energy importer by 2020, the increase in the contribution of alternative energy sources should provide more energy safety as well as more economically and environmentally friendly energy sources [11]. The pro-ecological characteristics of the energy policy set within the EU framework and the hopes to increase the country's energy security enable the conditions that are conducive to the development of energy technologies based on the application of fuels other than coal; in particular, a technology based on the heat, electricity cogeneration combined cycle power and heat approach is being promoted [12]. The relationship between carbon dioxide emissions, electricity consumption, economic growth and ﬁnancial development in the Gulf Cooperation Council (GCC) countries was investigated by Salahuddin et al. [13] using the panel data during the period of 1980–2012. The econometric techniques such as dynamic ordinary least squares (DOLS), fully modiﬁed ordinary least squares (FMOLS) and dynamic ﬁxed effect model (DFE) were employed to estimate the long-run relationship. Besides, based on the panel DOLS and FMOLS, Ozturk and Usama [14] found that the consumption in natural gas energy positively affected the GCC's countries GDP growth. Moreover, the results from the Granger causality test revealed the bidirectional causality between natural gas energy consumption and GDP growth, conﬁrming the feedback hypothesis. The results of GMM model demonstrated that natural gas consumption had positive, but statistically insigniﬁcant impact on economic growth. In the short- run, there was a bi-directional causality between natural gas consumption and economic growth. The relationship between economic growth and the consumption of the natural gas is positive (i.e. an increase of GDP by, say, 1% leads to the increase in the consumption of the natural gas by 0.13%) [15]. As far as power generation is concerned, on the one hand, governments should develop energy policies to use their own resources efﬁciently, considering the decreasing fossil fuel sources and increasing prices. On the other hand, governments should reduce environmental pollution associated with fossil fuel based power generation because of the serious pressure on the ecosystem and human health caused by such pollution. Thus, in the design stages of a fossil-fuel based power systems, the main objective should be maximizing the energy output with minimum fuel consumption [16]. There are many cases of successful implementation of energy conservation systems of natural gas power plants, such as natural gas processing performance (NGPP) with the combined cooling, heating and power (CCHP) scheme. In this scheme, one utilizes waste heat from gas turbine exhaust gases to generate process steam in a waste heat recovery steam generator (WHRSG). Part of the steam generated is used to power double-effect water–lithium bromide (H2O–LiBr) absorption chillers that provide the gas turbine compressor inlet air-cooling. Another part of the steam is utilized to meet some of the furnace heating load [17]. About 97% electricity produced in Algeria comes from natural gas, which is burnt in open cycle gas turbines (OCGTs) and combined cycle gas turbines (CCGTs). The performance of these power plants is severely affected by the atmospheric conditions, high temperature resulting in a decline in their output. Algeria, besides hot temperatures, also presents high solar radiation, which makes

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it an ideal place for solar hybrid power [18]. For the existing fossil fuel gas turbine, with the strict regulation of government policy and carbon consumption, solar hybrid gas turbine is one of the most recent applicable technologies in medium and large power plant [19]. Dong et al. [20] analyzed the main opportunities and obstacles of natural gas power generation and conducted a technical and economic evaluation of natural gas, taking into account the role and the interaction of the multiple stakeholders in the natural gas industry chain. Taking as an example a power plant fuelled with the natural gas transported by the second West-to-East Pipeline, it is found that the on-grid power price ﬂuctuates upward with the increase in the gas price and downward with the increase in the annual utilization hours; in addition, the inﬂuences of tax policies on the on-grid power price proved to be highly signiﬁcant. Zhang et al. [21] analyzed the interactions among China's economic growth and its energy consumption, air emissions and air environmental protection investment during 2000–2007. Conventional energy and emergy analyses were applied to quantify the energy consumption and the impact of emissions, respectively. The following ﬁve indicators (based on money, energy and emergy) are presented to depict the relationships among economic growth and energy consumption and the impact of air emissions and air environmental protection investment: ratio of nonrenewable energy to renewable energy (RNR), energy use per unit GDP (EUPG), environmental cost per unit GDP (ECPG), impact of emissions per unit energy consumption (IEPEC), and environmental beneﬁt per unit environmental protection investment (EBPEI). Zhou et al. [22] proposed a Malmquist energy conservation and emission reduction performance index (MECERPI) to assess the performance changes in energy use and pollutant emissions over time. This index was built upon the non-radial directional distance function and could be derived by solving data envelopment analysis. With the development of the new generation power supply, the difference between the maximum and minimum power requirements from a grid is growing. However, peak power installed capacity is too small, such as pumped-hydro energy storage, gasﬁred power, it is difﬁcult to meet the requirements of regulation. China's coal based energy resources structure determines the coalﬁred power plant to become the main source of power generation [23]. The results show that the effect of energy price on economic growth is affected by stock price, real exchange rate, government consumption and unemployment rate. In turn, real interest rate and investment captures a small effect of energy price on economic growth [24]. In order to evaluate the efﬁciency of three parallel industries in China's economic system, that is to evaluate the primary, secondary and tertiary industries, this paper proposes a parallel slacks-based approach. In this method, the energy efﬁciency and energy saving potential of the economic system are deﬁned. With this method, the energy efﬁciency of the whole economic system and the industrial system can be estimated simultaneously [25]. Around 21% of the world’s power production is based on natural gas. Energy production is considered to be the signiﬁcant sources of carbon dioxide (CO2) emissions. This has a signiﬁcant effect on the global warming. Improving power plant efﬁciency and adding a CO2 capture unit into power plants, have been suggested to be a promising countermeasure against global warming [26]. The relationship between natural gas consumption and economic development in China and Japan was studied by employing ARDL method. The results show some interesting similarities and

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Table 1 Thermal power project reference data (design values)a. Order Unit type

1 2 3 4

1000 MW Ultrasupercritical 600 MW Ultrasupercritical 600 MW Supercritical 600 MW Supercritical

Cooling mode

Reference data Coal consumption for power Coal consumption for power generation (gce/kWe h) supply (gce/kWe h)

Power consumption rate (%)

Boiler efﬁciency Heat consump tur(%) bine (kJ/kWh h)

Wet cooling

280.25

269.79

3.7

94.0

7 336

Wet cooling

285.36

272.29

4.3

93.6

7 380

Wet cooling

290.71

277.08

4.3

93.5

7 582

Air cooling

309.16

286.05

6.1

93.2

7 725

a In the indicators, the power supply coal consumption for core Indicators of the energy is used to determine the efﬁciency level in thermal power projects; in addition, the differences between the design values of power supply coal consumption and the run values that were estimated have a larger deviation.

differences. The main similarity is that there is a long-term equilibrium relationship between natural gas consumption and economic development in both countries. The main discrepancy concerned the causal direction in the natural gas consumption and economic development relationship. Therefore, one-way causal relationship from the natural gas consumption to the economic development was found in China, but the causality was bidirectional in Japan [27]. 1.2. Evaluation of the main project The evaluation of the project consists of the following main key factors: (1) Whether the projec's construction complies with the national, provincial and industry energy-saving related laws and regulations, policy requirements and standards. (2) Project technology plan (installed programs, energy use systems), i.e., whether to implement a new technology and new processes of higher energy efﬁciency. (3) Project implemented without using installations prohibited by the state, as well as the elimination of backwards technology and equipment regarding major energy-using equipment and the energy efﬁciency index. (4) Energy resources assessment in the project location and analysis of the energy species selection to determine whether it is reasonable and whether there is security of energy supply. The impact assessment of the energy consumption projects on the location and determination of whether the project meets the requirements of local energy planning. (5) Calculation of the energy consumption and the structure of the project, the level of energy efﬁciency and energy efﬁciency indicators and other indicators, computation of the energy consumption indicators per unit product (output) of the project and comparison of the indicators with the relevant provisions of the indicators, enabling analysis of the project design speciﬁcations in the industry and identiﬁcation of its levels. (6) Project resource utilization and adoption of energy-saving measures and effectiveness evaluations. (7) Project energy management and energy measurement apparatus suitable to the situation. (8) Assessment of the project's scientiﬁc and rational use of energy as well as the energy efﬁciency problems and suggestions. 1.3. Basis for this assessment

(1) The relevant laws, regulations, and programs.

(2) Industry access conditions and industrial policy. (3) The relevant standards and speciﬁcations, including the design of the management standards and speciﬁcations, the product energy consumption limits, equipment (products) energy standards (national standards, local standards, or related industry standards are applicable, but more stringent standards may be required). (4) Reﬂecting the advanced level data of the same industry, both domestic and foreign. (5) National or regional recommended list of energy-saving technologies and products. (6) Lists of state banned and eliminated use of energy products, equipment, production technology and other directories. (7) “Fixed assets investment projects energy assessment guide”. (8) Other relevant documents. 1.4. Project energy consumption levels The national energy conservation center conducted a statistical analysis of thermal power plants for coal ﬁred power generation projects involving the coal consumption, power consumption rate and other major energy efﬁciency indices (design value) [28]; the reference data are presented in Table 1. According to China's national development and reformation commission, the thermally generated electricity average coal consumption provided data per kilowatt-hour. China's electricity supply per kilowatt-hour declined from 392 g coal equivalent in 2000 to 360 gce in 2011. The primary energy factor of power on grid is as follows: PEFgrid ¼0.360 7000/860 ¼2.93. Until 2020, the gram coal consumption per kilowatt-hour is estimated to reach 320 gce [29], which is Germany's 2012 level of gce consumption per kilowatt-hour. PEFgrid ¼0.320 7000/860 ¼2.6, that is, 1 kg coal equivalent power generation is approximately 3 kW h [30]. 1.5. The inﬂuence of the environment The natural gas-ﬁred technologies are considered as clean sources of energy; the optimal uses of these resources help to minimize environmental impacts, produce minimum secondary wastes and are sustainable, based on current and future economic and social needs [31]. There is a need to fundamentally change the methodology used to produce electricity for the United States that achieves signiﬁcant reduction of carbon dioxide emissions. Lafrancois [32] proposed an alternative to fossil fuels via alternative investments to reduce emissions. The power sector will reduce carbon dioxide emissions by 23–42% and reduce all of the U.S. total carbon dioxide emissions by 9–17%. Turkey's power generation is mainly based on fossil fuels (in 2010, about 65% of the total installed capacity), with NG having the

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Table 2 “The second West-to-East Pipeline” natural gas composition and combustion parameters. Constituent

CH4

C2H6

C3H8

i-C4H10

N-C4H10

i-C5H12

N-C5H12

C6 þ

CO2

N2

Mol%

93.661

2.838

0.410

0.047

0.082

0.018

0.020

0.039

0.686

2.199

largest share, accounting for about 36% of the total installed capacity. Although Turkey has a lot of renewable energy and domestic energy potential, the importance of NG in the energy generation will continue. Another point to make is that that the natural gas power generation is one of the largest contributors to the reduction of CO2 emissions [33]. The clean energy use can improve a country's total-factor emissions reduction efﬁciency (TFCE), total-factor technical efﬁciency (TFTE), and total-factor economy output efﬁciency (TFYE). However, at present, due to the high cost of clean energy, the promotion effects on TFTE and TFYE are not obvious. As can be seen from the above comparison, clean energy use gives rise to energy waste, probably due to the difﬁculty of clean energy storage. European countries have higher comprehensive efﬁciency in economic growth, energy conservation, and emissions reduction. International cooperation is needed to facilitate technology transfer and reduce the gap in efﬁciency [34]. Carbon tax can be supplemented by technology-speciﬁc regulations and can be further combined with emission trading. By combining carbon tax with emission trading, plants which show signiﬁcant carbon abatement are able to sell their surplus emission allowances to the industries/plants that need additional permits. As a result, the GDP losses induced by CO2 reduction would be compensated. Besides, monitoring the GHG emissions will help choose the best price mechanism to abate GHGs [35]. Wang et al. [36] investigated the spatiotemporal variations of carbon dioxide (CO2) emissions caused by energy consumption and the relevant impact factors in China. The study focused on a provincial panel data set for the period of 1995–2011 with an extended STIRPAT model which was in turn examined using System-Generalized Method of Moments (Sys-GMM) regression. The study ﬁndings are of great importance for policy makers and urban planners to improve the technology level, accelerate the development of tertiary industry, and boost recycling and renewable energies.

Table 3 Heating performance of a combined cycle reference unit. Operational combined cycle unit rated heating performance The total output power of the generator Combined heat, power total energy use efﬁciency (LHV) Total heat for units

MWe % GJ/h

363,080 77.16% 571

4 billion cubic meters of gas per year (equivalent to a supply of natural gas of approximately 300 million tons per year). “The second West-to-East Pipeline” is now completed [38]. The natural gas relative density and caloriﬁc value are 0.590, 33.61(LHV) MJ/ m3 and 37.28 (HHV) MJ/m3, respectively. The natural gas composition and properties are presented in Table 2. 2.2. Reference units Two sets of class F (modiﬁed) combined gas–steam cycle heating units are adopted; the two units are able to fully meet the power plant heating and cooling capacity requirements. The heating performance combined cycle reference units are presented in Table 3, and the gas consumption of a single unit is presented in Table 4. 2.3. Heat balance and thermal economic performance indicators The proposed project meets the required target “technical requirements of the feasibility study on the combined heat and power project” [39] of the annual average thermal efﬁciency of 77.16% and the thermal-to-electrical ratio of 40.65%. The combined heat and power technology and economic indicators are presented in Table 5. 2.4. Water supply system

2. Description of the project China's National Development and Reform Commission encourage the distribution of the major electricity load and the natural gas requirements to be locally sufﬁcient. In the development of projects for peak power generation for the use of 30 104 kW and above, central heating units combining heat and power, as well as heat, electricity, cold multi-joint production are used. The original data in Tables 3–6, 10, 11, 13–23 about the Shenzhen Power Co. all come from the report [37].

The amount of industrial water supplied is approximately 1088 m3 per hour, which is 544.8 104 m3 per year. The sewage treatment plant processes the reclaimed water of 80,000 m3 per year as supplementary water. The project takes the reservoir water as a reserve water supply to supplement the water supply system. Table 6 presents the details of the amount of fresh water consumption.

3. Energy consumption increment and its impact on the project's location

2.1. Fuel supply sources The fuel source in the Shenzhen power plant is Turkmenistan gas, which is “the second West-to-East Pipeline” and China's ﬁrst large-scale pipeline project. According to the agreement, for the next 30 years, China will import 30 billion cubic meters of natural gas per year (there is a new contract for an annual increase of 10 billion cubic meters, increasing it to 65 billion cubic meters per year). The pipeline is of 8580 km in length, and it will transport an amount of 30 billion cubic meters until 2015. The West-to-East Pipeline route via Shenzhen to Hong Kong branch supplies

3.1. Incremental energy consumption and energy-savings control objectives Guangdong province's total energy consumption in 2010 was 269.08 million tons of coal equivalent, while the GDP was 4.086 trillion Yuan; as a result, the unit GDP energy consumption was 0.664 t of coal equivalent per 104 Yuan. Shenzhen city's “Twelve Five” GDP target values are presented in Table 7. Table 8 presents the impact assessment as a ﬁxed asset investment on the local energy saving targets.

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The project has a comprehensive energy consumption of 217,600 t of coal equivalent per year (energy caloriﬁc value), accounting for the Guangdong province period “Twelve Five” energy consumption increment of 0.39%. Shenzhen accounted for the period “Twelve Five” energy consumption increments of 0.99%. 3.2. Electricity demand forecasting The electricity demand forecasts surrounding Shenzhen are presented in Table 9.

4. Estimated energy efﬁciency of the projects

When the project is completed and placed into commercial operation, the normal annual industrial output value is expected to reach a value of 2.7356 billion Yuan (including electricity sales of 23.111 108 Yuan and heating sales of 4.245 108 Yuan). The comparison of the results of the comprehensive energy consumption indicator is presented in Table 12. From the table above, a total of 0.7603 t of coal equivalent per 104 Yuan output value for the project is observed. The energy consumption per 104 Yuan GDP output value is higher than that of Guangdong province of 0.664 t of coal equivalent per 104 Yuan GDP output value in 2011. The power consumption of 297.08 kW h per 104 Yuan output value is far below the average level of 1002.36 kW h in Guangdong province in 2009.

4.1. Major energy systems and equipment Table 10 presents the performance parameters for the new and old system main engines and for a reference engine. Guaranteed conditions refer to environmental conditions 27.53 °C, 1.0039 bar (a), 83.33% relative humidity, combined cycle combustion engine with full load, and the rated extraction steam turbine.

Table 6 The amount of fresh water consumption. Amount of water (m3/h)

Order Item

4.2. The main economic indicators 1

The main technical and economic indicators are presented in Table 11

2 3

4.3. Assessment of the overall energy consumption level After the completion of the expansion project, the annual production capacity of power generation increased to 38.70 108 kW h and the plant electricity consumption increased to approximately 8127 104 kW h, the ﬁnal electricity on grid reached approximately 37.8873 108 kWh, with an annual heat supply of 5.71 106 GJ (5.43 106 GJ). According to the on-grid electricity price of 597.18 Yuan per MW h (excluding tax), the heating price was calculated as 74.35 Yuan per GJ (excluding tax).

4 5 6 7 8 9 10 11

Water supply for the cooling tower Water supply for the chemical treatment system Water supply for the air conditioning used water Domestic water Factory ﬂoor washing water and greening water Unforeseen amount of water Water loss of the reclaimed water in the depth treatment system Water loss of cooling tower in the depth treatment Unforeseen water in the urban water Hourly water supply Amount of annual water recharge (104 m3)

Heating condition

Pure condensing condition

481

969

533

50

5

5

1 3.5

1 3.5

1.5 12

1.5 10

10

3

88

59.7

1088 544.8

1038.7 514.2

Table 4 Natural gas consumption (1 430 MWe) Unit operating conditions

load

Ambient temperature (°C)

Guarantee conditions

100% 27.53

Consumption per hour (t/h)

Consumption per year (104 t/a)a

54.13

28.85

a

For the combined cycle heating unit, under the assured work condition, as well as the ISO condition and the single unit heating condition, the listed amount of natural gas would be consumed annually.

Table 7 GDP targets of the “Twelve Five” period in Shenzhen city. Unit

2010

2015

GDP energy consumption (tce/104 Yuan) GDP (108 Yuan) Quantity of energy consumption (104 tce)/a

0.51 9511 4851

0.47 15,000 7050

Table 5 Technology and economic indicators of the combined heat and powera. Item

Extraction turbine under ensure conditions

Condensate turbine under ensure conditions

Extraction steam temperature (°C) Extraction steam pressure (MPa) Steam enthalpy (kJ/kg) Quantity of heat supply (GJ/h) Gross output of power generation (kWe) Heat, electricity ratio (%) Consumption of natural gas hourly (Nm3/h) Value of natural gas LHV (kJ/Nm3) (20 °C) Overall thermal efﬁciency (%) Gross gas consumption rate of electrical (N m3/kWe h) Gas consumption rate of heating (N m3/GJ)

280 1.2 3003 571 363,080 40.65% 76 529 33,610 77.16% 0.1645 31.32

/ / / / 397,435 / 772 14.3 33,610 56.18% 0.179 /

a 1. Above indicators under a unit of 100% load, the average heat load (guaranteed working condition), and under pure condensate condition were calculated. 2. Data is calculated by the GT-Pro software.

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Table 8 Impact of ﬁxed asset investment completed to energy-saving targets at the location. Energy consumption added to the project take up location “Twelve Five” percentage of control number for energy consumption increment (m%)

Energy consumption added value of the project affected proportion of energy consumption in location unit GDP (n%)

Impact

m r1 1 om r3 3 om r10 10o mr 20 m 420

nr 0.1 0.1 on r 0.3 0.3 o nr 1 1o nr 3.5 n4 3.5

Less affected Some inﬂuence Greater impact Signiﬁcant impact Decisive inﬂuence

Table 9 The electricity demand forecasts in Shenzhen city: central section and western and eastern sectionsa. Demands

Society electricity consumptionb (108 kWe h) Growth rate (%) Peak load electricity for the entire society (103 kWe) Growth rate (%) Among: 1. Central and western (103 kWe) Growth rate (%) 2. Eastern (103 kWe) Growth rate (%)

2010 year (actual results)

2015 year (forecast)

2020 year (forecast)

653

900

1060

8.2 12,310

6.6 17,588

3.3 21,095

9.8

7.3

3.7

10,198

13,858

16,230

10.0 2112 8.8

6.3 3730 12.0

3.2 4865 5.5

a 2010, 2015, and 2020 annual growth rates corresponding to the “Eleventh Five-Year”, “Twelve Five-Year”, and “three Five-Year” annual average growth rates, respectively. b Residential electricity consumption of Shenzhen, including the Hong Kong to Shako supplied power.

4.4. Technical solutions for energy savings The use of the gas-steam combined cycle units (namely, using the waste heat from the gas turbine exhaust to heat the boiler feed water in a waste heat boiler and subsequently using the high temperature and pressure steam produced to do work in the steam turbine, resulting in a corresponding increase in storage and conversion efﬁciency between the fuel chemical energy to mechanical work) constitute the entire process of energy cascade utilization. The combined power generation efﬁciency increases up to approximately 59%, which is even higher than the theoretical cycle efﬁciency of a coal-ﬁred power plant; this result represents a great step forward in the energy conversion sector. This project uses combined cycle units for gas-steam; the power generation efﬁciency reached approximately 59%. The combined heat and power mode, after the steam expands in the back-pressure turbine, supplies heat to the users, thereby reducing the sensible heat loss. Compared to the efﬁciency of the pure condensing steam turbine, the efﬁciency is found to be improved by 20% to 30%. The energy cascade utilization is shown schematically in Fig. 1. 4.5. Major energy processes and energy consumption indicators The production of thermal power is an energy conversion process. Efforts to improve the process consist of the use of advanced equipment to reduce energy consumption (power consumption of the main and auxiliary production system) and to determine the ﬁnal power supply of the project. The energy loss level in the heat and electricity transport and distribution processes not only affects the thermal efﬁciency of the unit but also affects the ﬁnal effective output of the whole project.

Accordingly, in this investigation, the following three aspects were discussed: ﬁrst, the processing and conversion of energy; second, the transport and distribution of energy; and third, the electricity consumption of the auxiliary power system. 4.5.1. Energy savings analysis of the energy conversion process The thermodynamic cycle of the combined cycle gas-steam turbine sets is divided into two parts: gas cycle and steam cycle. The gas medium circulating in the gas cycle is air and high temperature ﬂue gas after combustion, while conventional steam and water are circulating in the conventional steam cycle system. (1) Improvement of the efﬁciency of the gas turbine In the gas–steam combined cycle, the gas turbine efﬁciency is the main factor affecting the power supply efﬁciency. Currently, the gas turbine sequence combined cycle in the domestic power plant is in accordance with the series of capacity models: 6B, 9E and 9 F, etc. The current unit selection does not consider types 6B and 9E. In Table 13 for MHI, for example, units M701F3 (hereinafter referred to as “F3”) and M701F4 (hereinafter referred to as “F4”) would be compared to 9 F on the normal and the improved performance conditions. As observed from Table 13, the inlet temperature of the F3type gas turbine rotor is 1400 °C, the exhaust temperature is 586 °C, the efﬁciency of combined-cycle power generation is approximately 57.0%, and the heat consumption is smaller than that of the F4-type. This result is because the F4 gas turbine is an improvement of the F3 gas turbine and uses more mature technologies of the G-type gas turbine. For example, advanced multi-arc airfoil compressor blades are adopted; the burners are equipped with acoustic liner structure and MGA2400 material with excellent thermal performance. As a measure to avoid instability in the burner, the ﬁrst four turbine rotor blades of the F4-type are longer compared to F3-type to reduce losses at high speed. Thus, the F4-type gas turbine has more advantages compared to the F3-type in terms of ensuring heating supply, increasing economic efﬁciency and energy savings and reducing emissions from the power plant. The project selected a combined cycle of gas–steam with a cogeneration unit composed of improved “F” grade gas turbine components; the temperature at the inlet of its ﬁrst grade turbine is 1427 °C, which is internationally considered as mature and advanced gas turbine technology. Therefore, the project not only improves the energy efﬁciency but also meets the requirements of the thermal load, heat and electricity ratio of greater than 30%. (2) Increasing the thermal efﬁciency of the steam–water system After passing through the shaft seal heater, the condensate is passed by the condensate pump to the feed pump and then fed to a waste heat boiler. Some other techniques were used to improve the thermodynamic cycle efﬁciency of the power plant, as detailed in the following points:

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Table 10 Performance parameters for reference units in old and new systems. Stage 1 Two S109 existing gas–steam combined cycle power generating units with an installed power capacity of 2 180 MWe

2 Plans to build two sets of 9F-grade improved gassteam combined cycle reference units of installed capacity of 2 430 MWe

3 The main project and part of ancillary facilities

Thermal power systems

a. Combustion engine adopting the gas turbine generator sets Put into operation in 2004. PG9171E, produced by the U.S. GE company. b. The waste heat boiler is a drum boiler of three pressure values, vertical, and unﬁred forced circulation produced by the Hangzhou boiler plant, boiler Model: Q1153/526-174 (33.9) -5.8 (0.62)/ 500 (254.8). c. The steam turbine are pure condensing units of a dual-voltage, single-cylinder, impulsive produced by Harbin turbine Co., Steam turbine model: N60-5.6/0.56/529/253. d. At conditions of ambient temperature of 30 °C, atmospheric pressure of 101.3 kPa and a relative humidity of 70%, when fueled by natural gas, a set of S109E combined cycle has an output of 174.5 MWe, heat consumption rate 7 140.8 kJ/kWh h, power generation efﬁciency of 50.42%, and volumetric gas consumption per electrical power 0.178 Nm3/kWe h a. Combustion engine adopting a class 9FB multi-axial combined cycle Two units will be put into operation in June 2014 and September 2014. units with an installed capacity of 430 MWe manufactured by GE company. The capacity is 390 MWe at ensuring working conditions. The initial temperature of the gas turbine with ﬁre gas is greater than 1370 °C. The capacity of the gas turbine is approximately 290 MWe magnitude models at the ISO working conditions. b. The waste heat boiler is an unﬁred heat recovery boiler with ultrahigh pressure grade, three pressure reheat and horizontal, natural circulation. The high pressure stage evaporation of waste heat boiler is approximately 311 t/h. c. The steam turbine is a twin cylinder axial exhaust steam turbine, which is a reheat condensing steam turbine with ultra-high pressure level. The capacity of the steam turbine is approximately 140 MW in magnitude under the ISO working conditions. d. The combined cycle unit is a biaxial three pressure reheat. The main steam system is a high-pressure type. To save fresh water, this project uses a mechanical draft cooling tower with a secondary circulating cooling system (tentative). The steam water cycle uses three pressure reheat system to improve the efﬁciency of generating units and to reduce the fuel consumption. The waste heat boiler conﬁguration is a natural circulation type, of a horizontal layout; the waste heat boiler has no supplementary ﬁring. This project is an expansion based on preliminary engineering; some facilities were built in the same building, with consideration of sharing some facilities. In addition to the combined cycle cogeneration unit constructed for this project, there is some auxiliary production capacity for the supporting and living facilities, mainly for water treatment facilities (water treatment plant) and other ancillary facilities (air compressor room, spare parts store, repair workshop/laboratory and other metals).

Table 11 Main technical and economic indicators. Order Items 1 2 3 4 5 6 7 8 9 10 11

Commissioning date

Capacity of unit (MWe) Capacity of annual power generation (GWe h) Capacity of annual heating supply (104 GJ) Natural gas consumption of power generation (N m3/kWe h) (Economic evaluation) Natural gas consumption of heating supply (N m3/GJ) (Economic evaluation) Power consumption rate (%) Natural gas prices (Yuan/N m3) Static investment of power generation engineering (107 Yuan) Unit cost (Yuan/kWe) Dynamic investment of generate electrical engineering (107 Yuan) Total project program funding (104 Yuan) Unit cost (Yuan/kWe) Production costs of power generation unit (Yuan/MWe h)

Data 2 430 3870 571 0.18 31.32 2.3 2.74 294.15 3420 305.37 309.28 355 537

a. Using three pressures, reheats, horizontal and natural circulation boilers The water circulation system in the boiler utilizes the natural convection circulation produced by the density difference in

the ﬂuid; additional forced circulation is provided by the circulation pump. According to the steam-water cycle, the steam pressure generated by the heat recovery boiler can be divided into ﬁve types, that is, single pressure non-reheat cycle, dualpressure non-reheat cycle, dual-pressure reheat cycle, three pressure non-reheat cycle and three pressure reheat cycle. The more complex the cycle, the higher is the efﬁciency and the higher is the investment cost. The steam-water cycle adopts three pressure reheat and a horizontal natural circulation boiler, making full use of the surplus heat cycle of the system to improve the electricity efﬁciency generated. The high pressure steam, the medium pressure steam, the reheat steam, and the low pressure steam are used to provide the turbine power, and heat recovery boilers of the unﬁred type are used to greatly improve the output and efﬁciency of the system. b. Improving the initial parameter of the steam Generally, the higher the steam turbine inlet steam parameters, the higher is the efﬁciency. Gas turbine companies proposed the steam turbine parameters of combined cycle based on dual-pressure and non-reheat for use in the process involving three pressure-and-reheat cycles. The steam turbine has a power range of 30–300 MW, the main steam pressure is between 5.5–14 MPa, and the temperature range is 500–

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Table 12 Comparison of the Project's results with the local comprehensive energy consumption index of the same industrya. Item

Energy consumption index for projects (ECV)

Average level of Shenzhen citya

Average level of Guangdong provinceb

Average level of coal-ﬁred power (Guangdong Province)

Comprehensive energy consumption per unit of product (electricity supply) (kgce/kW h) Comprehensive energy consumption per unit of product (heating) (kgce/GJ) Power consumption per unit output value (kW h /104 Yuan) Comprehensive energy consumption for output value (tce/104 Yuan)

0.057

/

/

0.2022

40.07

/

/

a b

297.08

/

1002.36

0.7954

0.472b

0.563b

/ a

1240.2 4.058

Statistical yearbooks of Guangdong province in 2011 [40]. Bulletin of energy consumption and other indicators partitioned by prefecture-level cities in 2011 per ten thousand Yuan of GDP [41].

Combined heat, power Combined cycle Efficiency

ST Steam Simple cycle

GT power

ST Power

ST Power

GT power

GT power

4.5.3. Level and indicator of energy consumption for the auxiliary systems and the power system The power consumption of the process systems of the project include the power consumption in each of the following: gas turbine, steam turbine, heat recovery boiler, gas regulator station, circulating water system, chemical water system, air compressor, and ventilation and air conditioning of front module. The energy consumption in each process is mainly the power consumption of the fans and pumps. The electricity load and the consumption statistics of the main process systems are presented in Table 14.

Cycle mode Fig. 1. Schematic of energy cascade utilization for different technology programs. Table 13 Performance comparison of the combined cycle unit based on the M701F3 and M701F4 models. Order

Gas Turbine Model

M701F3

M701F4

1 2 3 4 5 6 7 8 9

Time (the ﬁrst design) Gas turbine output (MW) Combined cycle output (MW) Heat consumption (kJ/kW h) Efﬁciency of combined cycle LHV (%) Turbine inlet temperature (°C) Gas turbine exhaust temperature (°C) Air ﬂow (kg/s) Pressure ratio

2002 270.3 398 8858 57.0 1400 586 652 17

2009 312.0 465 8235.7 59.5 1427 597 703 8

565 °C. The steam turbine units in the domestic range of 50– 125 MW are also high or ultra-high pressure type.

5. Assessment of the energy-savings measurements 5.1. Measurements of the level of energy-savings of the equipment The choice of a high-efﬁciency generator of a capacity that matches the parameters of the steam turbine enables reduction of the generator losses, improving the efﬁciency of the generator, using a reasonable cooling mode and reducing power loss. Because transformers of the high-voltage and the low-voltage types are used for the plant, it was also necessary to adopt a low loss transformer type to reduce the losses. Various types of pumps and fans of energy-efﬁcient motors are used to reduce the auxiliary power. High-pressure feed pumps and condensate pumps of variable speed drives are used to save energy at low load operating conditions. In accordance with the regulations and codes and the experience of operating imported equipment in other domestic plants, a reasonable choice of the auxiliary standby coefﬁcients and motor spare capacity can reduce the power consumption rate signiﬁcantly.

4.5.2. Energy savings analysis of the energy transfer process 5.2. Process energy saving measurements (1) Energy-efﬁcient analysis in the heat transmission and distribution process The thermal insulation of the heating equipment and the piping to maintain it is in good condition, which reduces the heat loss of power plant equipment and the steam piping. The options of the ranges of pipeline ﬂow rates in the design are consistent with the existing norms, and the ﬂuid pressure drop is lower than the allowable limit; the piping design is based on the dynamic characteristics of a good ﬂow pattern distribution, pipe ﬁttings and layout to reduce energy consumption. (2) Energy-savings analysis in the power transmission and distribution process A low-loss transformer to reduce the transformer load loss (iron loss and stray loss) and load losses (copper losses) was used to improve the efﬁciency of the transformer.

(1) The load distribution between the units can be controlled automatically to operate at the highest principal integrated efﬁciency, thus ensuring economies of overall plant operation. (2) The thermal system uses variable pressure operation, with unit's variable initial parameters; this system is simple, safe and reliable. (3) The steam turbine has high, medium and low pressure bypass systems of 100% capacity, which reduces the unit working medium loss when starting and stopping and in the case of an accident. The pipe and equipment water drainage is performed by expansion or is directly recycled into the condenser. (4) The plant motor power supply uses a suitable cable material and cross-section, thus reducing the energy losses in the cable lines.

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(5) Optimization of the integrated water supply system determines the best area of the condenser, cooling rate, pump operating mode and the drain pipe diameter for economic conﬁguration.

generator is 2.53 109 kW h, which corresponds to an ECV of tons of coal equivalent of 3.11 105 tce. The power generation efﬁciency of the gas turbine, ηe, is 35.79%. The energy analysis of the gas turbine process is presented in Table 16.

5.3. Analysis of the energy-savings effect

6.1.2. Heat recovery process in boilers The gas turbine exhaust carries an amount of 16.34 106 GJ of heat to enter the heat recovery boiler, which produces the steam that drives turbines to generate electricity. The efﬁciency of the heat recovery boilers and the pipes is considered to be 87% with a heat output of 14.22 106 GJ. Energy analysis of the heat recovery boilers process is presented in Table 17.

The primary energy consumption indicators of the project are as follows: combined cycle unit at the rated heating working conditions with total energy efﬁciency of approximately 77.16% (LHV). When the unit is under the rated conditions, the gas consumption is 0.181 m3 per kW h of power generation and the gas consumption rate is approximately 31.32 m3 per GJ of heat supplied. The total number of hours of utilization of the power generation equipment is assumed to be 4500 h, and the total number of hours of heating equipment utilization is taken as 4923 h. The annual power generation capacity is 3870 GW h, and the annual heat supply is 571 104 GJ. The combined heat and power project, compared with producing the heat and power separately, has a higher energy usage efﬁciency, with annual savings reaching 23.43 104 t of coal equivalent. The calculation results are summarized in Table 15.

6. Energy utilization of the project

6.1.3. The power generation process of the steam turbine The power generation process of the steam turbine accepts steam from the heat recovery boiler; it carries an amount of 14.22 106 GJ of heat to generate electricity of 1.34 109 kW h, which is converted into EEV of tons of coal equivalent of 4.18 105 tce and ECV of 1.647 105 tce. The system also supplies 57.1 105 GJ of external heating, which corresponds to an ECV of tons of coal equivalent of 1.95 105 tce. The energy analysis of the power generation process for steam turbine is presented in Table 18. 6.2. The situation of energy use in the feasibility study stage

6.1. The processing and conversions of the energy

The major energy efﬁciency indicators are presented in Table 19

The main processes of the energy conversion in the project, including gas turbine electricity generation, heat recovery in the boilers and the steam turbine electricity generation, are discussed in the following three sections. 6.1.1. Gas turbine process The gas turbine process consumes a volume of 75.72 107 m3 of natural gas (at 20 °C, LHV ¼33,610 kJ per m3), and the natural gas and high-pressure air are mixed and burned to form a hightemperature gas acting as the mechanical power generation source. The gas turbine power is 514 MW. Under rated heat supply conditions, the annual utilization hours used of gas turbine equipment is 4923 h, and the output power of the ﬁnal turbine

6.3. Energy end-use conditions The power supply on the grid is the capacity of power generation minus the quantity of electricity consumed by the plant. After the energy assessment, the consumption rate of electricity in the plant is 2.1%. The quantity of electricity used in the plant is 8127 104 kW h, which is equivalent to 1.6904 104 tce and an ECV tons of coal equivalent of 9988 tce. When the exhaust or extracted steam from the turbine for heating and cooling is delivered to the consumers, heat loss amounts to 2.8 105 GJ. The case of energy end usage of the project is presented in Table 20 below.

Table 14 Power consumption index of the main process systems. Order

Process facilities

1 2 3 5 6 8 9 10 11

Main produce system

Auxiliary produce system

Gas turbine Steam turbine Heat recovery boiler Circulating water system Chemical water system Air compressor system Ventilation and air conditioning Lighting system

Other

Computing power (kW)

Working hours (h)

Indicators of annual power consumption (kW h)

732.8 2210.8 4995 7020 760.85 648.9 119 78 /

4500 4923 4923 4500 4500 4500 4500 3000 /

3,297,600 14,364,329 24,590,385 31,590 000 3,423,825 2,920,050 535,500 234,000 314,311

Table 15 The energy efﬁciency of the combined heat and power approach in comparison with having heat and power produced separatelya. Item

Installed programs

Yearly amount of heat (104 GJ)

Annual electricity supply (108 kW h)

Annual tons of coal equivalent (104 tce)

Combined heat and Power Heat, power produced separately

2 430 MW Decentralized heating boiler room Efﬁcient condensing units

543 571

37.89 0

86.84 29.97

0

37.89

80.3

a

The annual power supply in the table is with the pipe network losses deducted.

Sum 110.27

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Table 16 The energy consumption analysis of the gas turbine process. Order

Variety of energy

Quantity of energy (unit)

Energy equivalent value (tce)

Energy caloriﬁc value (tce)

1 2 3 4 5 6

Input

Natural gas (m3) Consumption quantity of energy Output Electric power (kW h) Heat quantity (GJ) Total energy quantity Comprehensive energy consumption

75.72 107 75.72 107 25.30 108 16.34 106 / 0

86.84 104 86.84 104 52.62 104 / / 0

86.84 104 86.84 104 31.09 104 55.75 104 86.84 104 0

Energy equivalent value (tce)

Energy caloriﬁc value (tce)

/ / / / /

55.75 104 55.75 104 48.52 104 48.52 104 7.23 104

Table 17 The energy analysis of the heat recovery boilers process. Order

Variety of energy

1 2 3 4 5

Quantity of energy (Unit)

Input

Heat quantity (GJ) Energy consumption quantity Output heat quantity (GJ) Total energy quantity Comprehensive energy consumption

6

16.34 10 16.34 106 14.22 106 14.22 106 /

Table 18 The energy analysis of the power generation process for the steam turbine. Order 1 2 3 4 5 6

Variety of Energy

Quantity of Energy (Unit) 4

Heat quantity (10 GJ) Consumption quantity of energy (104 GJ) Output Heat quantity (104 GJ) Electric power (104 kW h) Total energy quantity (104 GJ) Comprehensive energy consumption (104 GJ) Input

1422 1422 571 134,002 / /

Energy equivalent value (tce)

Energy caloriﬁc value (tce)

27.87 / /

48.52 48.52 19.48 16.47 35.95 104 12.57

Table 19 The major energy efﬁciency index in the feasibility study stage (energy assessed before). Order 1 2 3 4 5 6 7 8

Item

Unit

Gas consumption of the generated electricity Gas consumption of heating Annual heat quantity Annual power generation capacity Annual utilization hours for the extraction of the steam heat supply in the unit Annual Quantity of gas consumption Overall thermal efﬁciency of the combined heat and power for projects The heating power ratio of the annual average

6.4. The energy balance of the project The total annual energy input is 86.84 104 t of coal equivalent (ECV), the effective power of the annual output is 46.56 104 t of coal equivalent, and the effective annual thermal output is equivalent to 18.52 104 tce. Under guaranteed conditions, processing and conversion processes energy (gas turbine, heat recovery boiler, steam turbine) loss is 19.80 104 t of coal equivalent per year, and the internal electricity consumption of the plant is 0.99 104 tce per year. The steam heat loss generated from the power plant to heat and cold end use is 28.0 104 GJ. The ﬁnal effective energy output is 650,800 t of coal equivalent per year, and the rate of the enterprise energy efﬁciency is 74.95%. Based on the primary energy such as natural gas and the secondary energy such as electricity, the intake and output of the heat have been calculated. The energy balance of the project under

3

m /kW h m3/GJ 104 GJ GW h h 107 m3 % %

Data

Remark

0.181 31.32 571 3870 4923 75.72 77.16 40.65

0.208 kg per kW h (converted into KCE) 0.0359 tce per GJ (converted into TCE)

Absolute density of natural gas is 0.762 kg per m3

working conditions is presented in Table 21, and the energy network is shown in Fig. 2.

7. The assessment of the energy consumption and the energy efﬁciency level 7.1. Accounting of the integrating energy consumption The primary energy required for this project is natural gas, and the secondary energy required is electricity, both of which belong to “General principles for calculation of the comprehensive energy consumption” (GB/T 2589-2008) [42], which is the comprehensive energy methods of calculation of energy consumption. Performing the accounting for the overall energy consumption in this project determines a value of 20.80 tce. The accounting processes are presented in Table 22.

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Table 20 Energy consumption analysis of the use process in energy end-use. Order

Type of Energy

Quantity of Energy (Unit)

Energy equivalent value (tce)

Energy caloriﬁc value (tce)

1 3 4 5 6 7

Natural gas (m3) Quantity of energy consumption Output Quantity for the heat supply (GJ) Quantity of the power supply (kW h) Quantity of the total energy Comprehensive energy consumption

75.72 107 75.72 107 543 104 378.87 107 / /

86.84 104 86.84 104 / 78.81 104 / /

86.84 104 86.84 104 18.52 104 46.56 104 65.08 104 21.76 104

Input

Table 21 Energy balance list of the project. Units: tce. Variety of Energy

Input energy

Effective energy

Purchase storage

Natural gas Quantity of energy Electric power Sum 1 Natural gas

Quantity of energy Electric power Sum 1, 1 Loss of energy Energy efﬁciency (%)

Process and conversion

Quantity of energy (Unit)

Energy equivalent value (tce)

Energy caloriﬁc value (tce)

Gas turbine

HRB process

Steam turbine

Subtotal 1

1

2

3

4

5

6

7

75.72 107(m3)

868,400

868,400

868,400

75.72 107(m3) 0 100

868,400 868,400

868,400 868,400

868,400 0 100

868,400 557,465

868,400 0 100

485,200

485,200

868,400

Plant use

Grid Subtotal2 electricity

8

9

10

11

185,200

0

185,200

185,200

475,623

9988

465,635

475,623

660,823

9988

650,835

660,823

185,200

185,200

557,465

485,200 185,200

185,200

310,935

164,688

475,623

0

465,635

465,635

660,823 0 100

0 9988

650,835 0

650,835 9988 98.49

868,400 485,200 349,888 670,423 0 72,265 135,312 197,977 100 87 72.11 77.20 650 835/868 400 ¼74.95 650 835/868 400 ¼74.95

Efﬁciency of the energy source (%)

distribution

868,400 557,465

75.72 107(m3) 75.72 107(m3)

Transported End-use

*

In the transformation process, the extracted heat from the steam turbine of 185 200 tce. The pipe network losses were subtracted.

Electricity 31.09 (35.80)

86.84

86.84

75.72×107 m3

(100)

(100)

Heating 55.75 (64.20)

Heating 48.52 (55.87)

46.56 (53.61)

Steam Turbine Generator

Natural Gas

End-Use

Electricity

Heat Recovery Boilers

(ECV)

Gas Turbine Generator

(EEV)

Transport Distribution

Process Conversion

Purchase Storage

Supply For External

Electricit1 16.47 (18.97)

Plant Own Use

Electricity 0.99 (1.14) Heating 19.48 (22.43) Heating 12.57 (14.47) Storage 0

Supply For External 18.52 (21.32) Heating 0.95 (1.09) End-Use Losses 1.94 (2.23)

Losses (0) Losses of Process Conversion 19.80 (22.80)

Total Fed Energy

86.84 (100)

Total Effective Energy Used 65.08 (74.95)

86.84 (100)

Utilization Rate of Enterprise Energy Source: 74.95%

Efficiency of Enterprise Energy: 74.95%

Fig. 2. The network diagram of the combined heat and power in the project.

L. Yingjian et al. / Renewable and Sustainable Energy Reviews 59 (2016) 1195–1208

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Table 22 Accounting tables of the integrated energy consumption in this project. Order

Variety of Energy

Quantity of energy (Unit)

Energy equivalent value (104 tce)

Energy caloriﬁc value (104 tce)

1 3 4 5 6 7

Natural gas (m3) Energy consumption Output Quantity of heat supply (GJ) Quantity of power supply (kW h) Quantity of total energy Integrate energy consumption

75.72 107 75.72 107 543 104 378.87 107 / /

86.84 86.84 / 78.81 / /

86.84 86.84 18.52 46.56 65.08 21.76

Input

Table 23 Various energy and energy consumption media converted into coefﬁcient of tons of coal equivalent. Varieties of energy

Unit

Converted into standard coal Energy equivalent value (tce)

Electric powera Natural gas Fresh water Heat

tce/104 kW h 2.08 kgce/m 4

3

tce/10 t tce/GJ

Remark

Energy caloriﬁc value (tce) 1.229

1.1468

1.1468

0.857 /

/ 0.03412

GB/T2589-2008 [42] Caloriﬁc 33,610 kJ/Nm3 GB/T2589-2008 GB/T2589-2008

a The energy equivalent value (tce) of power generation according to tons of coal equivalent consumption of generation calculated for this project.

7.2. The assessment of the integrated energy consumption level After the completion of this expansion of the project, the annual capacity of power generation reaches 38.70 108 kW h, the internal electricity consumption of plant is approximately 8127 104 kW h, the electricity quantity on grid at the end is approximately 37.8873 108 kW h, and the heat supply is 5.71 106 GJ per year. According to the electricity price on grid of 597.18 Yuan per MW h (excluding tax) and the heating supply price of 74.35 Yuan per GJ (excluding tax), the ﬁnal income of the project after completion and commercial operation is a normal year's annual industrial output value of 2.7356 billion Yuan (including electricity sales income of 2.3111 billion Yuan, hot sales income of 424.5 million Yuan). 7.3. Various energy coefﬁcients converted into tons of coal equivalent In the process of natural gas conversion to heat and electricity, a small amount of electricity as the secondary energy and new water as the working medium participate in the processing, conversion and utilization of energy. Table 23 describes the variety of energy and energy consumption media within the system, converted into units of tons of coal equivalent.

consumption of various types of energy converted into tons of coal equivalent is expected to be approximately 86.84 104 t per year (Energy equivalent value). The gas–steam combined cycle cogeneration gas turbine unit selected by the project is internationally mature technology and has advanced features; in cogeneration mode, the steam after leaving the steam turbine is supplied as heat for consumers, reducing the heat loss in a cold source. The project annual power supply is expected to be 37.89 108 kW h, and the annual heat supply is expected to be 5.43 104 GJ. The consumption of power generation in tons of coal equivalent units is expected to reach 208 g per kW h. The internal power consumption rate of the plant is 2.1% (after the energy assessment). The comprehensive annual average thermal efﬁciency of the plant is 77.16%, and the average heat-to-power ratio is 40.65%. These technical indicators are thought to be one of the best in the country for similar projects. Under guaranteed conditions, the project integrated energy consumption will reach 21.76 104 t of coal equivalent per year, accounting for a Guangdong province period “Twelve Five” energy consumption increase of 0.39%. This project has a very small incremental impact of energy consumption in Guangdong province compared with the same type of enterprises: the project comprehensive energy consumption per unit of production, the power consumption per unit value and the comprehensive energy consumption per unit output value as well as other energy consumption indicators are better than the corresponding average levels of a thermal power plant in Guangdong Province in 2010, i.e., the construction of projects to reduce the Guangdong province thermal power industry energy consumption index provides signiﬁcant beneﬁts. The expansion project was useful to fully absorb and learn from the deployment of the same type of units and the ﬁrst phase unit design. The operating experience in the design and implementation process was optimized in many aspects, thus reducing gas consumption and water consumption and improving other indicators of power generation units signiﬁcantly. Regardless of all of these improvements, there are still continuous efforts to tap the potential synergies of space.

Acknowledgments 8. Energy assessment conclusions and recommendations The power plant expands the gas–steam combined cycle cogeneration units of 2 9F class, which conforms with the national laws and regulations and the economic and social development plan, which is consistent with the national and local industrial policies and the industrial power access standards. Using this power plant, the grid power supply pressure in Guangdong province can be alleviated, while providing a more rational layout of the power distribution system and increasing the reliability of the industrial zone heating. The natural gas consumption of the project is expected to be approximately 75.72 107 m3, and the projected total

The authors thank the Bureau of Science, Technology and Information, Shenzhen, for ﬁnancial support of this research under the public technological project (Contract JCYJ2013 0329112752059). The comments of the anonymous reviewers are also appreciated.

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Energy efficiency assessment of fixed asset investment projects – A case study of a Shenzhen combined-cycle power plant

Energy efficiency assessment of fixed asset investment projects – A case study of a Shenzhen combined-cycle power plant

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