Assessment of Comprehensive Effects and Optimization of a Circular Economy System of Coal Power and Cement in Kongtong District, Pingliang City, Gansu Province, China

sustainability

Article Assessment of Comprehensive Effects and Optimization of a Circular Economy System of Coal Power and Cement in Kongtong District, Pingliang City, Gansu Province, China

Suocheng Dong 1, Zhe Wang 1,2, Yu Li 1, Fujia Li 1,*, Zehong Li 1, Feng Chen 1,2 and Hao Cheng 1 1 Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; [email protected] (S.D.); [email protected] (Z.W.); [email protected] (Y.L.); [email protected] (Z.L.); [email protected] (F.C.); [email protected] (H.C.) 2 University of Chinese Academy of Sciences, Beijing 100049, China * Correspondence: [email protected]; Tel.: +86-10-6488-9842

Academic Editors: Giuseppe Ioppolo and Marc A. Rosen Received: 6 January 2017; Accepted: 22 April 2017; Published: 11 May 2017

Abstract: The idea of a circular economy (CE), which differs from traditional linear economy with a high consumption of natural resources and pollution, has captured much interest and attention. This paper uses a CE system of coal power and cement in Kongtong District, Pingliang City, Gansu Province, China as a case study to analyze the comprehensive effects of CE paradigm. Our simulation results, based on system dynamics (SD) modeling, infer that the transformation of manufacturing towards a CE system can prominently help coal power and cement enterprises reduce waste emission and increase economic proﬁts. Through solid waste exchanges, a power plant can achieve over RMB 80 million of additional revenue per year at the highest level. CE also contributes to the reduction of regional pollution, saves mineral resources, and improves the atmospheric environment, an accumulated total of 14.11 million t of natural gypsum and 22.67 million t of coal can be saved. This sets a promising example for coal power and cement plants worldwide. Effective regulatory measures and further optimization towards a circular economy system are essential in maintaining the stable development of a CE system due to the risk of surplus production of upstream industries and other defects.

Keywords: circular economy; China; coal power; cement; system dynamics; effects assessment

1. Introduction The concept of a CE was first put forward by Pearce and Turner, two British environmental economists [1]. Unlike a traditional linear economy of take-make-dispose with high consumption, emission, and pollution, a CE system is regarded as a closed system, much like a natural ecological system in which all elements are circular and the production departments in a shared circular cycle can form an industrial symbiosis mimicking the natural food cycle [2,3]. The distinguished principles of “Reduce, Reuse, and Recycle” (3Rs) are the basic theoretical philosophical and principles behind CE. The main content of CE is to reap economic, ecological, and social benefits through eco-design in the manufacturing process and further realize the goal of sustainability [4–7]. In recent years, most worldwide case studies concerning CE can be classified into four scales: national, regional, industrial, and enterprise. Studies on national or regional scales have been mainly focused on assessing the development of CE through the analysis of key indicators [8–10], and summarizing performance and problems during the developing process of CE in a certain country or region [11–13]. Studies on an industrial scale mainly discussed the achievements of cleaner

Sustainability 2017, 9, 787; doi:10.3390/su9050787 www.mdpi.com/journal/sustainability Sustainability 2017, 9, 787 2 of 16 production and economic benefits through the design of CE systems and analyzed problems, which coveredSustainability industries 2017, such9, 787 as papermaking [14], building materials [15–18], metals [19,20], chemicals2 of 16 [21], logistics [22], etc., and the industrial symbiosis between the various departments in a certain industrial parkproduction [23–25]. and economic benefits through the design of CE systems and analyzed problems, which Oncovered the whole,industries these such studies as papermaking explored [14], the building connotations materials and [15–18], realization metals path[19,20], of chemicals CE from [21], different perspectives;logistics however,[22], etc., mostand the studies industrial focused symbiosis more on between macro-scale the various analysis departments and less on in the a quantitativecertain analysisindustrial of the park process [23–25]. of CE system on enterprise scale. Therefore, by using the case of a CE system of On the whole, these studies explored the connotations and realization path of CE from different coal power and cement in Kongtong District, Pingliang City, Gansu Province, China, this paper built perspectives; however, most studies focused more on macro-scale analysis and less on the an SDquantitative model to simulateanalysis of the the comprehensive process of CE system effects on of enterprise a CE system scale. on Therefor coal powere, by using and cement,the case of before makinga CE recommendations system of coal power to improveand cement system in Kongtong performance. District, Pingliang City, Gansu Province, China, Coalthis paper power built plants an SD are model widely to distributedsimulate the aroundcomprehensive the world, effects especially of a CE insystem regions on coal with power abundant coal resources.and cement, Amongbefore making the various recommendatio kinds ofns power to improve generation, system performance. coal power has occupied over 40% of the globalCoal total power from plants 2010 are and, widely in China, distributed this share around reached the world, 80% [26 especially,27]. Coal in power regions plants with have the advantageabundant coal of low resources. costs; Among however, the severe various issues kinds ofof unsustainabilitypower generation, suchcoal power as the has consumption occupied of freshover water 40% and of pollutionthe global causedtotal from by 2010 fly ash,and, desulfurizationin China, this share gypsum, reached and 80% other [26,27]. solid Coal waste power affects manyplants cities have without the advantage supporting of industrieslow costs; tohowever, reuse thesevere solid issues waste. of unsustainability In contrast, the such example as the set by consumption of fresh water and pollution caused by fly ash, desulfurization gypsum, and other Kongtong District provides a promising example for the sustainable development of the coal power solid waste affects many cities without supporting industries to reuse the solid waste. In contrast, and cementthe example industries. set by However, Kongtong market District risks provid arees big a disadvantagespromising example for CE for system the sustainable of coal power and cement,development and shouldof the coal not power be ignored. and cement Hence, industri fores. further However, optimization market risks and are popularization big disadvantages of a CE systemfor inCE the system coal of power coal power and cement and cement, industries, and should the not comprehensive be ignored. Hence, effects for of further CE system optimization need to be quantitativelyand popularization studied. of a CE system in the coal power and cement industries, the comprehensive effects of CE system need to be quantitatively studied. 2. Case Study 2. Case Study Kongtong District is located in Northwest China (Figure1), and has abundant mineral resources such as coal,Kongtong limestone, District gypsum, is located clay, asin wellNorthwest as well-developed China (Figure industries 1), and ofhas coal abundant mining, mineral coal power, and theresources manufacture such as ofcoal, building limestone, materials. gypsum, In clay, China, as well CE as development well-developed has industries been motivated of coal mining, by national coal power, and the manufacture of building materials. In China, CE development has been policy and planning, thus, in the past five years, Kongtong has attracted significant amounts of capital motivated by national policy and planning, thus, in the past five years, Kongtong has attracted in the field of CE to build a host of new projects using high technology to achieve certain benefits. Key significant amounts of capital in the field of CE to build a host of new projects using high technology enterprisesto achieve include: certain (1)benefits. TheHuaneng Key enterprises Pingliang includ Thermale: (1) The Huaneng Power Plant Pingliang (HPTPP) Thermal (Pingliang, Power Plant China), which(HPTPP) belongs (Pingliang, to the China China), Huaneng which Groupbelongs and to the has China the largest Huaneng capacity Group installed and has (2.4 the millionlargest kW) in Northwestcapacity installed China; and(2.4 million (2) Conch kW) Cementin Northwest Ltd. China; (Wuhu, and China), (2) Conch the Cement largest cementLtd. (Wuhu, brand China), in China. The keythe categorieslargest cement of industry brand in in China. this study The key highlights categories the of important industry in status this ofstudy Pingliang’s highlights industrial the structureimportant (Figure status2). of Pingliang’s industrial structure (Figure 2).

FigureFigure 1. The 1. The location location of of Kongtong Kongtong District,District, Pingliang Pingliang City, City, Gansu Gansu Province, Province, China. China. SustainabilitySustainability 20172017,, 99,, 787787 33 ofof 1616 Sustainability 2017, 9, 787 3 of 16

Coal Mining and Washing Coal Mining and Washing Manufacture of Non-metallic ManufactureMineral Products of Non-metallic Production and Supply of Mineral Products ProductionElectricity and and Heat Supply of Other Categories of Industry Electricity and Heat Other Categories of Industry

Figure 2. The proportion of the production value of key categories of industry in Pingliang’s Figureindustrial 2. structure.TheThe proportion proportion of of the the production production value value of key categories of industry in Pingliang’s industrial structure. 2.1. Successes Achieved by a CE System of Coal Power and Cement 2.1. Successes Achieved by a CE Sy Systemstem of Coal Power and Cement To show the differences between the traditional linear manufacturing paradigm and a fully implementedTo showshow thetheand differencesdifferenceswell-run CE betweenbetween manufacturing thethe traditionaltraditional system linear have manufacturingbeen illustrated paradigm (Figure 3).and Negative a fully implementedeffects have been andand well-run removedwell-run CE andCE manufacturing positivemanufacturing effects system hasystveem have been have been achieved been illustrated illustrated through (Figure a (Figuremove3). Negative towards 3). Negative effects a CE haveeffectssystem. been have removed been removed and positive and positive effects have effects been ha achievedve been achieved through athrough move towards a move a towards CE system. a CE system.

Figure 3. A comparison between past and present manufacturing paradigms.paradigms. Figure 3. A comparison between past and present manufacturing paradigms. 2.1.1. Circular Utilization Utilization of of Solid Solid Waste Waste between between Co Coalal Power Power Plants Plants and and Building Building Materials Materials Industries Industries 2.1.1. Circular Utilization of Solid Waste between Coal Power Plants and Building Materials Industries Fly ashash hashas aa high high use use value value in in the the construction construction and and building building materials materials industries. industries. Following Following the risethe rise ofFly construction ofash construction has a high and useand the buildingvaluethe building in the materials construction material industriess industries and inbuilding Pingliang, in Pinglian materials theg, demandthe industries. demand for fly forFollowing ash fly andash desulfurizationtheand rise desulfurization of construction gypsum gypsum and exceeds the exceeds building supply, supply, whichmaterial thoroughlywhichs industries thoroughly solves in Pinglian thesolves issueg, the ofthe solidissue demand wasteof solid for pollution fly waste ash causedandpollution desulfurization by caused coal power. by coalgypsum power. exceeds supply, which thoroughly solves the issue of solid waste pollutionDry andcaused wet by flyfly coal ashash power. producedproduced byby HPTPPHPTPP reachedreached thethe secondsecond levellevel ofof thethe NationalNational Standards of ChinaDry withwith and aa wet finenessfineness fly ash lessless produced thanthan 20%.20%. by DesulfurizationDesulfurizationHPTPP reached gypsumthe second has level the of samesame the ingredientsNationalingredients Standards asas naturalnatural of gypsum,China with butbut a has finenesshas a highera higher less purity, than purity, which20%. whichDesulfurization saves costssaves in co the stsgypsum grinding in the has processgrinding the same during process ingredients cement during production. as naturalcement gypsum,production. but has a higher purity, which saves costs in the grinding process during cement production.

Sustainability 2017, 9, 787 4 of 16

2.1.2. Utilization of Waste Heat and Height Difference Potential in Cement Plants According to survey data from Conch Cement Ltd., a pure low-temperature waste heat-power generation system with an installed capacity of 2 × 7.3 MW went into operation in 2011 and provides 32.18% of total power usage. During the process of limestone mining, a height difference potential power generation system can provide 2.15% of total power use through transmission belts with a height difference of 230 m. In 2014, two cement plants in Kongtong consumed only 94.28 kg of standard coal per capita, which was far below the national average level (136 kg).

2.1.3. Combined Heat and Power Generation and Reclaimed Water Utilization A traditional distributed heat supply may easily cause dust emissions in winter, but also has a lower thermal efﬁciency. In comparison, the biggest advantage to the pattern of cogeneration is enhanced utilization efﬁciency of fuel and improvements in urban air quality. In 2010, the latest sewage-treatment system in the coal power plant took waste water from the city area and the plant as a resource to produce recycled water. The present consumption of reclaimed water is 250 t/h, which reduces the consumption of fresh water. The purity of the reclaimed water does not reach the standards of boiler feed-water, but is satisfactory for use as cooling water and supplementary water for machine sets mainly because the concentration of suspended substance of reclaimed water is less than 30 mg/L and does not reach 5 mg/L.

2.1.4. Taking Municipal Waste as Alternative Fuels for Cement Manufacture Greatly increased municipal waste leads to higher treatment difficulties and costs. Generally, disposal methods of municipal waste often include landfill, incineration, compost, and methane generation. According to the National Bureau of Statistics of China, in 2014, 60.15% of municipal waste was disposed through landfill. Municipal waste contains large quantities of organic fuel with a high heat value. Thus, if waste sorting costs are too high, incineration is an appropriate method that has been adapted to regional realities. Furthermore, a cement kiln co-disposal incineration system (CKCDIS) can additionally solve the problem of dioxin pollution effectively through a disposal process of homogenizing, crushing, and gasifying. After decomposing, hazardous substances can be assimilated by cement clinker. Incombustibles ultimately become slag and can be utilized as alternative raw materials for cement manufacture. In 2014, a CKCDIS (with a disposal capacity of 100,000 t) built by Conch Cement Ltd. was put into operation, and has helped to avoid land and groundwater pollution caused by waste landfill. According to survey data, heat per capita can reach over 1000 kilocalorie per 1 kg waste, which can be utilized as an alternative fuel to save coal.

2.2. Market Risks the CE System of Coal Power and Cement May Face In China, the coal power industry faces a severe market downturn as China’s economic development and consumption of power slows down. As newly-built coal power projects are still large-scale, there is a severe problem of excess production capacity [28], as well as an obvious regional imbalance of supply and demand due to China’s vast territory. Areas with abundant coal resources, such as Kongtong, often have lower levels of manufacture and living standards, which leads to lower power consumption [29]. Furthermore, as there is rising market competition against coal power due to the strong encouragement of non-fossil fuel based energy such as hydroelectric power, photovoltaic power, and wind power generation, the amount of power generated by Kongtong reduced sharply in 2015 and reached over 6 billion kWh, which only occupied about 50% of production capacity despite the power generation process also achieving cleaner production targets through the method of strict desulfurization, denitration, and dedusting. Thus, one question that still remains is how to sustainably develop a CE system in the face of adverse market situations. Sustainability 2017, 9, 787 5 of 16

Sustainability3. Methodology2017, 9, and 787 Data Sources 5 of 16 SD is a methodology and mathematical modeling technique used to frame, understand, and 3.discuss Methodology dynamic andbehaviors Data Sources and issues of complex systems by setting variables with positive and negative feedback, and is integrated by management science and computer simulation technology SD is a methodology and mathematical modeling technique used to frame, understand, and [30,31]. The comprehensive effects of an industrial symbiosis system can be quantitatively analyzed discuss dynamic behaviors and issues of complex systems by setting variables with positive based on an interpretation of a situation and ecological, social, and economic subsystem trends in and negative feedback, and is integrated by management science and computer simulation the real world through the introduction of SD into the field of CE [32–34]. Vensim–software technology [30,31]. The comprehensive effects of an industrial symbiosis system can be quantitatively developed by Ventana Systems Inc. (Harvard, America), USA–can provide a graphical modeling analyzed based on an interpretation of a situation and ecological, social, and economic subsystem interface with stocks, flows, and causal loop diagrams for researchers to conveniently build SD trends in the real world through the introduction of SD into the field of CE [32–34]. Vensim–software models. Hence, this paper selected Vensim as the tool for modeling a manufacture CE system in developed by Ventana Systems Inc. (Harvard, America), USA–can provide a graphical modeling Kongtong. interface with stocks, flows, and causal loop diagrams for researchers to conveniently build SD models. Parameters of each variable in the SD system were from enterprise and government survey Hence, this paper selected Vensim as the tool for modeling a manufacture CE system in Kongtong. data and local statistics yearbooks. For quantitatively studying a CE system of coal power and Parameters of each variable in the SD system were from enterprise and government survey data cement at an enterprise scale, we carried out field research in February 2015 and July 2015. Through and local statistics yearbooks. For quantitatively studying a CE system of coal power and cement at an interviews with leaders and technicians in key enterprises and government staff in departments enterprise scale, we carried out field research in February 2015 and July 2015. Through interviews with relating to coal power and cement industries, detailed information and data on the manufacture leaders and technicians in key enterprises and government staff in departments relating to coal power process were achieved and includes four parts: (1) The production flow chart; (2) the introduction of and cement industries, detailed information and data on the manufacture process were achieved and progress of manufacture transition towards CE; (3) the utilization amounts of different categories of includes four parts: (1) The production flow chart; (2) the introduction of progress of manufacture raw material, energy, fuel, products, waste; and (4) the approximate price of products and raw transition towards CE; (3) the utilization amounts of different categories of raw material, energy, fuel, materials. products, waste; and (4) the approximate price of products and raw materials.

4. Model Description The SD model contained one coal power plant, HPTPP, andand twotwo cementcement plants,plants, ConchConch CementCement Ltd. and and Qilianshan Qilianshan Cement Cement Ltd. Ltd. (Pingliang, (Pingliang, China). China). In the In theSD model, SD model, the time the timestep stepwas set was as set year, as year,initial initial time timeand andfinal ﬁnal time time were were split split into into 2014 2014 and and 2025. 2025. The The performance performance period period of of the modelmodel crossed China’s 13th and 14th Five Year Plans.Plans. In Figure 44,, thethe variablesvariables areare connectedconnected byby arrows,arrows, whichwhich indicatesindicates causalcausal relationships in the SD systemsystem where the variable before an arrow affects the variablevariable behindbehind thethe arrow. arrow. The The market market demand demand of of products products→ →yield yield→ →demand demand of materialsof materials or fuelor fuel→ supply-demand→ supply-demand difference difference (SDD) (SDD) is the is th basice basic causal causal chain chain of theof the system. system.

Unutilized Upstream Capacity Firms (1) Optimization Production Measures Capacity (1) Raw Materials Demand (1) Yield (1) Consumption Market Sales Revenue (1) Background (1) Wastes SDD Saving Costs Decrease of Economic Effects Pollutants Materials Ecological Effects Background (2)

Demand (2) Yield (2) Saving Mineral Resources

Downstream Raw Materials Unutilized Production Capacity Capacity (2) (2)

Figure 4. Logical framework of the SD model. Sustainability 20172017,, 99,, 787 6 of 16

4.1. Sub-System of Operation Structure 4.1. Sub-System of Operation Structure Based on the logical framework presented in Figure 4, the operation structure of a CE system of coalBased power on and the logicalcement frameworkcan be framed presented through in th Figuree Vensim4, the software. operation In structureFigure 5, ofthe a power CE system yield of coalHPTPP power affected and cementtotal consumption can be framed and through further theaffected Vensim the software. amount of In solid Figure waste,5, the including power yield fly ofash, HPTPP desulfurization affected total gypsum, consumption and slag. and Furthermore, further affected the cement the amount demand of solid affects waste, the cement including yield fly ash,and desulfurizationfurther affects gypsum,the demand and slag.of alternative Furthermore, materials. the cement Thus, demand the SDD affects of thekey cementrecycling yield waste and furtherneeding affects to be balanced the demand is a of key alternative conflict in materials. the system Thus, as a the short SDD supply of key of recycling key materials waste can needing lead to beinstability balanced ofis industrial a key conflict symbiosis in the and system excessive as a short supply, supply which ofkey means materials high disposal can lead costs to instability of solid ofwaste. industrial In the symbiosissystem, the and amount excessive of fly supply, ash and which slag results means from high the disposal coal consumption costs of solid of waste. the HPTPP, In the system,as well as the a amountportion ofof flyslag ash produced and slag resultsby CKCDIS. from theThe coal amount consumption of desulfurization of the HPTPP, gypsum as well results as a portionfrom the of amount slag produced of sulfur by content CKCDIS. in Thecoal amountand limestone of desulfurization consumption. gypsum Considering results from the difficulty the amount of ofobtaining sulfur content data, we in coalassumed and limestone that there consumption. was a 70% of Considering fly ash from the HPTPP difficulty sold of obtainingto other building data, we assumeddepartments. that there was a 70% of fly ash from HPTPP sold to other building departments.

Costs of Denitration After Costs of Denitration Introduction of Catalyst Regeneration Technologies Electricity Sales Sales Revenue (1) Coefficient of Influence from the Belt and Road Initiative Yie ld o f HPTPP Risk Coefficient of Building Industry Sales House-service Growth Rate (3) Revenue Unutilized Consumption of Wastes Capacity of HPTPP Production of Power Demand of Capacity (1) Cement Coal Consumption for Power Consumption Gro wt h Ran g e (6) Power Generation from Cement Production Slag from HPTPP Unutilized Desulfurization Capacity Gypsum From HPTPP Fly Ash from HPTPP Total Coal of Cement Cement Stock Consumption of Cement Yield Cement Sales HPTPP

SDD of Limes tones Desulfurizat SDD of ion Gypsum Production Fly Ash Capacity (2) Sulfur Dioxide Sales Revenue Demand of Demand of Demand of Fly Ash Alternative Materials Desulfurization Gypsum Amount of Heat Fly Ash Utilized by Demand of Slag Heat Supplied Other Department During Calcination by Coal Supplement of Heat Power Generation from Costs Saving of Power Generation SDD of Elevation Difference Power of Cement from Waste Heat Slag Potential Energy Plants Saving of Coal of Cement Plants Coal Consumption of Cement Production Amount of Municipal Slag from CKCDIS Waste Disposal

Figure 5. Operation structure of the CE system.

4.2. Sub-System of Ecological and Economic Effects 4.2. Sub-System of Ecological and Economic Effects The main positive ecological effects include saving mineral resources and reducing pollutants The main positive ecological effects include saving mineral resources and reducing pollutants and greenhouse gasses (illustrated as variables in Figure 6). In the system, a decrease in emissions and greenhouse gasses (illustrated as variables in Figure6). In the system, a decrease in emissions and and savings on coal consumption were calculated through comparing data in a practical scenario savings on coal consumption were calculated through comparing data in a practical scenario that the that the CE paradigm has already been implemented and a hypothetical scenario where a traditional CE paradigm has already been implemented and a hypothetical scenario where a traditional pattern pattern would not have been improved. Based on survey data, we set the sulfur and ash content would not have been improved. Based on survey data, we set the sulfur and ash content proportion proportion of coal Kongtong utilized separately as 0.5% and 11%, efficiency of combustion, of coal Kongtong utilized separately as 0.5% and 11%, efficiency of combustion, desulfuration, and desulfuration, and dedusting of traditional small-size boilers as 72, 97.8, and 16.7%, respectively. The dedusting of traditional small-size boilers as 72, 97.8, and 16.7%, respectively. The carbon emissions carbon emissions from coal burning were calculated by the formula E = EC × EF × f in which EC is from coal burning were calculated by the formula E = EC × EF × f in which EC is the consumption of the consumption of coal, EF is the coefficient of carbon emission of coal, and f is the coefficient of coal, EF is the coefficient of carbon emission of coal, and f is the coefficient of standard coal (0.7143). standard coal (0.7143). EF was set as 0.7266 [35]. Carbon emissions from cement production were EF was set as 0.7266 [35]. Carbon emissions from cement production were also divided into two also divided into two categories: carbon emissions from the process of calcination, and carbon Sustainability 2017, 9, 787 7 of 16 emissions caused by coal burning. The first category occupied nearly 50% of the total amount of carbon emission resulted from the decomposition reaction of CaCO3, thus limestones could be replaced by alternative raw materials containing CaO content, which can dramatically reduce carbon emissions. Compared to a traditional manufacturing pattern, apart from product sales revenue, positive economic effects include additional benefits such as the reuse of materials and energy, sales revenue Sustainabilityof the by-products.2017, 9, 787 Negative effects are embodied in increased costs caused by higher costs7 of of 16 recycled water treatment and denitration based on selective catalytic reduction catalysts. Like the ecological effects calculation mentioned above, both positive and negative economic effects can also becategories: calculated carbon by comparing emissions data from in the the process CE paradigm of calcination, and hypothetical and carbon emissionsscenario that caused traditional by coal patternsburning. would The first not category change. occupied To simplify nearly the 50% simulation, of the total we amount assumed of carbonthat the emission raw material resulted ratio from of cementthe decomposition and the prices reaction of raw of CaCOmaterials,3, thus products limestones and could energy be would replaced not by vary alternative dramatically raw materials during thecontaining run time CaO of the content, model. which can dramatically reduce carbon emissions.

Area of Decentralized Area of Heat-supply Heat-supply Service Service in Cogeneration Growth Range (7) Pattern

Coal Consumption in Decentralized Sources Coal Consumption of HPTPP

Practical Sulfur Practical Smoke Practical Coal Dioxide Emission Dust Emission Consumption

Decrease of Sulfur Saving of Coal Decrease of Smoke Consumption for Heat Dioxide Emission Dust Emission Supply

Decrease of Carbon Emission in Heat Supply Sulfur Dioxide Emission if Smoke Dust Emission if Coal Consumption if Traditional Pattern would Traditional Pattern would Traditional Pattern would not Improved not Improved not Improved

Saving of Carbon Emission from Limestones Process of Calcination

Limes tones (b) Limestones (a) Saving of Clay Yield > Saving of Reclaimed Water Gypsum Consumption in Consumption in CE Clay (b) Consumption Slag Traditional Pattern Pattern Desulfurization Sulfate Slag Natural Gypsum (b) Fly Ash Gypsum

Costs of Water in Coal Gangue Costs of Water in High Silicon CE Pattern Natural Gypsum (a) Clay (a) Traditional Pattern Sandstones Mining Waste Rocks Costs of Basic Costs of Alternative Increase of Materials Materials Cos ts of Water of HPTPP Costs Costs of Materials in Saving of Costs of Materials Materials of Traditional Pattern in CE Pattern Cement Plants

Figure 6. Ecological and economic effects of the CE system. Figure 6. Ecological and economic effects of the CE system.

Compared to a traditional manufacturing pattern, apart from product sales revenue, positive economic effects include additional beneﬁts such as the reuse of materials and energy, sales revenue of the by-products. Negative effects are embodied in increased costs caused by higher costs of recycled water treatment and denitration based on selective catalytic reduction catalysts. Like the ecological effects calculation mentioned above, both positive and negative economic effects can also be calculated by comparing data in the CE paradigm and hypothetical scenario that traditional patterns would not change. To simplify the simulation, we assumed that the raw material ratio of cement and the prices of raw materials, products and energy would not vary dramatically during the run time of the model. Sustainability 2017, 9, 787 8 of 16

4.3. Sub-System of Market Demand

4.3.1. Sub-System of Market Risks and Solutions Already Taken

SustainabilityIn this2017 subsystem,, 9, 787 we assumed that the amount of power produced by HPTPP totaled 56.43%8 of of 16 Pingliang during the performance period and that this proportion would not change observably (Figure 7). In 2014, the power delivered outside (PDO) was 79.9% of the amount from Pingliang and 4.3.a paramount Sub-System influence of Market factor Demand to the HPTPP. Furthermore, local power consumption can usually be attributed to residents, manufacturing, tertiary industries, and so on, which can be predicted based 4.3.1. Sub-System of Market Risks and Solutions Already Taken on statistics. InUnutilized this subsystem, capacity, we one assumed of the thatkey theconflicts amount in ofthe power system, produced affects the by HPTPPstability totaled of the 56.43%whole ofsystem Pingliang and results during in the regulation performance regarding period PDO and that and this manufacturing proportion would investment not change (Figure observably 5). Local (Figuregovernment7). In 2014,may be the stimulated power delivered to strive outside for more (PDO) chances was 79.9%to attract of the manufacturing amount from investment Pingliang andand aPDO paramount to make inﬂuence up for HPTPP’s factor to theloss. HPTPP. Therefore, Furthermore, we set PDO local regulating power consumption coefficients, can manufacture usually be attributedinvestment to coefficients, residents, manufacturing,and a delay coefficient tertiary of industries, two years, and to simulate so on, which the government’s can be predicted action based and onthe statistics.time difference between decision-making and projects being put into effect.

Power Consumption from Residents per capita Growth Range (1) Growth Range (2) Power Consumption Population from Residents Growth Range (3)

Power Consumption of Tertiary Industry Gro wt h Ra t e (1)

Other Power Growth Rate (2) Consumption Gro wt h Ra n g e (4)

Power Consumption Consumption of Pingliang from Industry Gro wt h Ra n g e (5) Coefficient of Risk in Power Market Amount of Manufacture Electricity Investment Production Coefficient Coefficient of

Power Delivered Delay Coefficient PDO to Outside Regulating Coefficient

Figure 7. Scenario simulation of powerpower production in Kongtong.

The West–East Electricity Transmission Project (WEETP) can relieve the power deficit in East Unutilized capacity, one of the key conflicts in the system, affects the stability of the whole system China, and also exploit the advantages of areas with affluent power resources such as Kongtong. and results in regulation regarding PDO and manufacturing investment (Figure5). Local government Thus, the coefficient of WEETP was set to simulate a scenario where Pingliang would be absorbed may be stimulated to strive for more chances to attract manufacturing investment and PDO to make up into the WEETP, where PDO can increase dramatically. Considering the progress of relative power for HPTPP’s loss. Therefore, we set PDO regulating coefficients, manufacture investment coefficients, transmission projects, we assumed two scenarios in which the coefficients of WEETP were 0 initially and a delay coefficient of two years, to simulate the government’s action and the time difference and increased individually from 2019 and 2023. Furthermore, the risk coefficient was divided into between decision-making and projects being put into effect. low-risk and high-risk scenarios, to simulate the difficulties and uncertainty Kongtong faces in The West–East Electricity Transmission Project (WEETP) can relieve the power deficit in East striving for PDO. China, and also exploit the advantages of areas with affluent power resources such as Kongtong. The demand of cement is affected by multiple elements including the development of the Thus, the coefficient of WEETP was set to simulate a scenario where Pingliang would be absorbed building industry, macro-economic situation, and urbanization, etc., so it is hard to achieve an into the WEETP, where PDO can increase dramatically. Considering the progress of relative power accurate prediction of the demand of cement. Accordingly, considering the stability of the cement transmission projects, we assumed two scenarios in which the coefficients of WEETP were 0 initially market in Pingliang and surrounding areas, we set the random risk coefficient of the building and increased individually from 2019 and 2023. Furthermore, the risk coefficient was divided into industry in the system to simulate possible narrow fluctuations of cement production (Figure 5). low-risk and high-risk scenarios, to simulate the difficulties and uncertainty Kongtong faces in striving In addition, the strategy of the Belt and Road Initiative proposed by China focuses on the for PDO. connectivity and cooperation among countries in Asia and Europe, gives rise to the wave of The demand of cement is affected by multiple elements including the development of the building infrastructure construction in Northwest China and countries along the Silk Road Economic Belt, industry, macro-economic situation, and urbanization, etc., so it is hard to achieve an accurate prediction of the demand of cement. Accordingly, considering the stability of the cement market in Pingliang and surrounding areas, we set the random risk coefficient of the building industry in the system to simulate possible narrow fluctuations of cement production (Figure5). Sustainability 2017, 9, 787 9 of 16

In addition, the strategy of the Belt and Road Initiative proposed by China focuses on the connectivitySustainability 2017, and 9, 787 cooperation among countries in Asia and Europe, gives rise to the wave9 of of 16 infrastructure construction in Northwest China and countries along the Silk Road Economic Belt, whichwhich will will stimulate stimulate the the development development of of the the cement cement industry industry to to some some extent. extent. Thus, Thus, we we set set a a rising rising coefﬁcientcoefficient to to simulate simulate this this effect. effect.

4.3.2.4.3.2. Sub-System Sub-System of of Demand Demand of of Municipal Municipal Heat Heat TheThe amount amount of heatof heat supply supply was simulated was simulated based on ba thesed specialized on the specialized planning of theplanning concentrated of the heatconcentrated supply of Pingliang.heat supply The of heating Pingliang. supply The area heating of cogeneration supply area in Kongtong of cogeneration reached 8in million Kongtong m2 inreached 2012 and 8 million will reach m2 23.5in 2012 million and will m2 in reach 2016 23.5 according million to m planning.2 in 2016 according to planning.

5.5. Results Results and and Analysis Analysis

5.1.5.1. Analysis Analysis on on Ecological Ecological Effects Effects ProﬁtProfit from from the the implementation implementation of of the the CE CE paradigm, paradigm, consumption consumption of of clay clay and and natural natural gypsum gypsum cancan be be reduced reduced to to 68.3% 68.3% and and 73.7%, 73.7%, respectively, respectively, through through the the utilization utilization of of alternative alternative raw raw materials. materials. DuringDuring 2014–2025, 2014–2025, the the accumulated accumulated savings savings of of clay clay and and natural natural gypsum gypsum will will reach reach 2.48 2.48 million million t t and and 14.1114.11 million million t t (Figure (Figure8). 8). The The accumulated accumulated saving saving of of limestones limestones is is only only 236.3 236.3 thousand thousand t duet due to to low low CaOCaO content content in in alternative alternative raw raw materials, materials, 3.2% 3.2% in in ﬂy fly ash ash and and 2.8% 2.8% in in slag. slag. However, However, compared compared to to casescases introduced introduced by by [36 [36],], the the consumption consumption of of limestone limestone in in Kongtong Kongtong is is relatively relatively high. high.

Save of Natural Resources Reduction of Pollutants Emission 300 .3

4444 4 11111 1111 150 225 2 .15 22 1 ten thousand thousand tonsten 5 222 22222 5 ten thousand tons thousand ten 5 5 2 0 111 111 33333 2014 2016 2018 2020 2022 2024 0 Time (Year) 2014 2016 2018 2020 2022 2024 Saving of Natural Gypsum : General 111 Saving of Clay : General 2222 Time (Year) Saving of Limestones : General 3333 Decrease of Sulfur Dioxide Emission : General 11111 Saving of Coal Consumption for Heat Supply : General 44 Decrease of Smoke Dust Emission : General 222222 Recycling Water Consumption : General 555 Carbon Emission from Process of Calcination

600 1 1 1 1 1

550 1

500 1 1 1 1 ten thousand tons thousand ten 450

400 2014 2016 2018 2020 2022 2024 Time (Year) Carbon Emission from Process of Calcination : General 1111

FigureFigure 8. 8.Simulation Simulation of of ecological ecological effects effects of of the the system system (Unit: (Unit: 10 104 4t). t).

The combined heat and power generation facilities have more advanced technical standards on The combined heat and power generation facilities have more advanced technical standards on desulfuration and dedusting and higher coal combustion efficiency, thus, the advantages are desulfuration and dedusting and higher coal combustion efﬁciency, thus, the advantages are reﬂected reflected in reducing coal consumption and pollution compared with traditional small-size boilers. in reducing coal consumption and pollution compared with traditional small-size boilers. These These ecological effects will reach a peak in 2016 when areas of heat supply reach 23.5 million m2 ecological effects will reach a peak in 2016 when areas of heat supply reach 23.5 million m2 (Figure8). (Figure 8). During 2014–2025, the accumulated savings of coal will reach 22.67 million t, the reduction of SO2 and dust will reach 22.8 and 13.9 thousand t, respectively, which will positively improve the air quality of Kongtong. However, heat loss caused by the direct emission of 30 °C steam in HPTPP should not be ignored. Sustainability 2017, 9, 787 10 of 16

During 2014–2025, the accumulated savings of coal will reach 22.67 million t, the reduction of SO2 and dust will reach 22.8 and 13.9 thousand t, respectively, which will positively improve the air quality ◦ ofSustainability Kongtong. 2017, However, 9, 787 heat loss caused by the direct emission of 30 C steam in HPTPP should10 notof 16 be ignored. ByBy harmlessly harmlessly disposing disposing of of all all the the municipal municipal waste waste of of Kongtong, Kongtong, CKCDIS CKCDIS assists assists Conch Conch Cement Cement Ltd.Ltd. to to save save 794 794 t t of of coal, coal, which which was was equal equal to to 0.2% 0.2% of of the the coal coal consumption consumption of of Conch Conch Cement Cement Ltd. Ltd. As As aa result, result, a a decrease decrease of of 519 519 t t of of carbon carbon emissionsemissions cancan bebe achievedachieved andand thisthis effecteffect willwill reachreach a a peak peak in in 20252025 along along with with the the increase increase of of cement cement yield. yield. CKCDIS CKCDIS can can also also save save an an accumulation accumulation of of 0.2 0.2 km km2 2land land duringduring 2014–2025. 2014–2025.

5.2.5.2. Analysis Analysis on on Economic Economic Effects Effects TheThe economic economic beneﬁts benefits achieved achieved by by the the HPTPP HPTPP and and cement cement plants plants through through recycling recycling and and reuse reuse are illustratedare illustrated in Figure in Figure9. The 9. sales The revenuesales revenue of waste of wa fromste HPTPPfrom HPTPP resulted resulted from thefrom power the power yield, yield, so two so scenariostwo scenarios were simulatedwere simulated which which considered considered risk and risk WEETP. and WEETP. It was It obvious was obvious that regardless that regardless of these of scenarios,these scenarios, the sales the revenue sales revenue of solid of waste solid fromwaste the from HPTPP the HPTPP will grow will in grow general. in general. The savings The savings in the costin the of powercost of from power cement fromplants cement is alsoplants a high-levelis also a high-level proﬁt from profit waste from heat waste and the heat height and differencethe height indifference energy power in energy generation power will generation make up will 30% make of power up 30% consumption. of power consumpt The peakion. of sales The revenuepeak of willsales berevenue achieved will in be 2022 achieved or 2025 in due 2022 to or increased 2025 due power to increased yield. power yield.

Simulation of Economic Benefits Simulation of Economic Benefits 10,000 2 10,000 2 2 2 2 2 2 2 2 2 2 5000 2 5000 ten thousand ten

3 thousand ten 3 33 2 3 3 3 33 ￥ 33 ￥ 3 3

4 4 4 0 4 4 1114 4 0 114 14 11114 114 11 4 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 Time (Year) Time (Year) Costs Saving of Materials of Cement Plants : Scenario of High Risk (b) 1 Costs Saving of Materials of Cement Plants : Scenario of Low Risk (a) 1 Sales Revenue of Wastes of HPTPP : Scenario of High Risk (b) 22 Sales Revenue of Wastes of HPTPP : Scenario of Low Risk (a) 22 Costs Saving of Power of Cement Plants : Scenario of High Risk (b) 33 Costs Saving of Power of Cement Plants : Scenario of Low Risk (a) 3 Increase of Costs of Water of HPTPP : Scenario of High Risk (b) 444 Increase of Costs of Water of HPT PP : Scenario of Low Risk (a) 44

FigureFigure 9. 9.Simulation Simulation of of economic economic beneﬁts benefits of of the the system system (Unit: (Unit: RMB RMB 10 106).6).

The higher cost of recycled water in HPTPP, approximately RMB 10 per ton is equal to 2.5 times The higher cost of recycled water in HPTPP, approximately RMB 10 per ton is equal to 2.5 times the price of fresh water for coal power in the Gansu Province (RMB 0.003/kWh), is a negative the price of fresh water for coal power in the Gansu Province (RMB 0.003/kWh), is a negative economic economic effect of the system, but can be made up by revenue from the sale of waste. effect of the system, but can be made up by revenue from the sale of waste. Under legal pressure from environment protection departments, the high costs of the Under legal pressure from environment protection departments, the high costs of the denitration denitration process bring difficulties to the HPTPP. In 2014, the costs of denitration reached RMB process bring difﬁculties to the HPTPP. In 2014, the costs of denitration reached RMB 0.23 billion based 0.23 billion based on the unit price of RMB 0.025/kWh, and the maximum will reach RMB 0.45 billion on the unit price of RMB 0.025/kWh, and the maximum will reach RMB 0.45 billion per year, which is per year, which is another negative economic effect that should be optimized. another negative economic effect that should be optimized.

5.3.5.3. Analysis Analysis of of Supply Supply and and Demand Demand Conflicts Conflicts of of Recycling Recycling Wastes Wastes InIn thethe CECE system,system, flyfly ashash andand desulfurizationdesulfurization gypsumgypsum areare alreadyalready keykey materialsmaterials ofof thethe down-streamdown-stream building building materials materials industry. industry. However, However, the the low low power power yield yield results results in in an an unfavorable unfavorable situationsituation that that recycling recycling waste waste cannot cannot meet meet the the demand demand of of downstream downstream enterprises, enterprises, which which will will result result inin a a greater greater consumption consumption of of natural natural resources resources by by downstream downstream enterprises. enterprises. Fortunately,Fortunately, as as seen seen in in FigureFigure 10 10,, the the benefits benefits from from a a nationally nationally supported supported project, project, even even under under the the worst worst scenario, scenario, will will be be improvedimproved by by growth growth in in power power yield yield and and the the SDD SDD will wi becomell become positive. positive. Peak Peak value value will appearwill appear in 2022 in or2022 2025 or because 2025 because of peak of value peak of value power of yieldpower shown yield inshown Figures in 11Figures and 12 11. Itand should 12. It be should noted be that noted an that an oversupply of fly ash may appear after the situation of the coal power industry is improved. At that time, a stockpile of fly ash will bring negative effects to the system. Sustainability 2017, 9, 787 11 of 16 oversupply of fly ash may appear after the situation of the coal power industry is improved. At that time,Sustainability a stockpile 2017, 9, of 787 fly ash will bring negative effects to the system. 11 of 16 Sustainability 2017, 9, 787 11 of 16 SDD of Recycling Materials SDD of Recycling Materials SDD of Recycling Materials SDD of Recycling Materials 75 1 75 75 1 75 75 1 75

1 1 1 1 1 1 1 25 1 1 1 25 1 25 1 1 1 1 1 25 1 1 25 1 1 1 1 1 25 1 1 1 1 1 1 1 1 1 1 1 1 1 1

ten thousand tons thousand ten 1 3 tons thousand ten 1 1 1 1 1 3 3 3 3 3 33 1 1 331 1 3 ten thousand tons thousand ten 2 2 3 2 3 2 332 tons thousand ten 3 3 1 3 3 ten thousand tons thousand ten 2 3 3 2 22 ten thousand tons thousand ten 2221 3 1 3 3 3 32 3 3 2 2 3 33 1 3 3332 3 32 3 1 2 2 32 2 2 32 2 2 2 123 2223 333 2 3 3 22 23 2 2 2 2 2 2 13 2222 2 2 22 23 32 2 2 2 -25 -25 2 -25 -25 -25 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 2014 2016 2018Time 2020 (Year) 2022 2024 2014 2016 2018Time 2020 (Year) 2022 2024 Time (Year) Time (Year) SDD of Fly Ash : Scenario of Low RiskTime (a) (Year)11111 SDD of Fly Ash : Scenario of High RiskTime (b) (Year)1111 SDDSDD of ofFly Desulfurization Ash : Scenario Gypsum of Low :Risk Scenario (a) of Low 11111Risk (a) SDD of Fly Ash : Scenario of High Risk (b) SDD of Fly Ash : Scenario of Low Risk (a) 111112222 SDDSDD of ofFly Desulfurization Ash : Scenario Gypsum of High : RiskScenario (b) of High 1111Risk (b) 222 SDDSDD of ofDesulfurization Slag : Scenario Gypsum of Low : RiskScenario (a) of Low Risk (a) 2222 SDD of Desulfurization Gypsum : Scenario of High Risk1111 (b) SDD of Desulfurization Gypsum : Scenario of333333 Low Risk (a) 2222 SDDSDD of ofDesulfurization Slag : Scenario Gypsum of High : RiskScenario (b) of333333 High Risk (b) 222 SDD of Slag : Scenario of Low Risk (a) 333333 SDD of Slag : Scenario of High Risk (b) 333333222 SDD of Slag : Scenario of Low Risk (a) 333333 SDD of Slag : Scenario of High Risk (b) 333333 Figure 10. Simulation of SDD of fly ash, desulfurization gypsum, slag under scenario of WEETP put Figure 10.10. SimulationSimulation of SDD ofof ﬂyfly ash,ash, desulfurizationdesulfurization gypsum,gypsum, slagslag underunder scenarioscenario ofof WEETPWEETP putput Figure 10. Simulation of SDD of fly ash, desulfurization gypsum, slag under4 4 scenario of WEETP put intointo practice practice in in 2019 2019 or or 2023 2023 and and high high or or low low risk risk of of power power market market (Unit: (Unit: 10 104 t). t). into practice in 2019 or 2023 and high or low risk of power market (Unit: 104 t). Simulation of Electric Power Yield Simulation of Electric Power Yield Simulation of Electric Power Yield Simulation of Electric Power Yield 200 200 200 1 200 2 1 200 1 200 2 1 2 1 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 100 2 2 2 100 2 100 2 100 2 2 100 2 100 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0 2 0 0 0 0 0 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 2014 2016 2018Time 2020 (Year) 2022 2024 2014 2016 2018Time 2020 (Year) 2022 2024 Time (Year) "Production Capacity (1)" : Scenario ofTime High Risk(Year) (a) "Production Capacity (1)" : Scenario of LowTime Risk (a)(Year) 11111 Time (Year) 1111 "ProductionElectric Power Capacity Yield (1)" of HPTPP: Scenario : Scenario of Low Riskof Low (a) Risk (a) 11111 "ProductionElectric Power Capacity Yield (1)" of HPTPP: Scenario : Scenario of High ofRisk High (a) Risk (a)1111 "Production Capacity (1)" : Scenario of Low Risk (a) 2222 "Production Capacity (1)" : Scenario of High Risk (a) 222 Electric Power Yield of HPTPP : Scenario of Low Risk (a) 111112222 Electric Power Yield of HPTPP : Scenario of High Risk (a) 1111222 Electric Power Yield of HPTPP : Scenario of Low Risk (a) Electric Power Yield of HPTPP : Scenario of High Risk (a) 222 2222 Figure 11. Simulation of power yield under scenario of WEETP put into practice in 2019 and high or Figure 11. Simulation of power yield under scenario of WEETP put into practice in 2019 and high or Figure 11.11. Simulation of power yield8 under scenario of WEETP put into practice in 2019 and high or low risk of power market (Unit: 1088 kWh). lowlow riskrisk ofof powerpower marketmarket (Unit:(Unit: 10108 kWh). Simulation of Electric Power Yield Simulation of Electric Power Yield Simulation of Electric Power Yield Simulation of Electric Power Yield 200 200 200 1 200 1 200 1 200 1 1 1 2 2 2 2 2 2 2 2 2 100 2 100 2 2 2 2 2 2 2 2 100 2 100 2 2 2 2 100 2 2 2 2 100 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0 2 0 0 0 0 2014 2016 2018 2020 2022 2024 0 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 2014 2016 2018 2020 2022 2024 2014 2016 2018Time 2020 (Year) 2022 2024 2014 2016 2018Time 2020 (Year) 2022 2024 Time (Year) Time (Year) "Production Capacity (1)" : Scenario of TimeHigh Risk (Year) (b) 1111 "Production Capacity (1)" : Scenario of LowTime Risk (Year) (b) 1111 "ProductionElectric Power Capacity Yield (1)" of HPT: Scenario PP : Scenario of High ofRisk High (b) Risk (b)1111 "Production Capacity (1)" : Scenario of Low Risk (b) "Production Capacity (1)" : Scenario of High Risk (b) 11112222 "ProductionElectric Power Capacity Yield (1)" of HPT: Scenario PP : Scenario of Low Riskof Low (b) Risk (b) 11112222 Electric Power Yield of HPT PP : Scenario of High Risk (b) 2222 Electric Power Yield of HPT PP : Scenario of Low Risk (b) 11112222 Electric Power Yield of HPT PP : Scenario of High Risk (b) 2222 Electric Power Yield of HPT PP : Scenario of Low Risk (b) 2222 Figure 12. Simulation of power yield under scenario of WEETP put into practice in 2023 and high or Figure 12. Simulation of power yield under scenario of WEETP put into practice in 2023 and high or Figure 12.12. Simulation of power yield8 under scenario of WEETP put into practice in 2023 and high or low risk of power market (Unit: 108 kWh). low risk of power market (Unit: 108 kWh). lowlow riskrisk ofof powerpower marketmarket (Unit:(Unit: 10108 kWh). 5.4. Analysis on Market Risks 5.4. Analysis on Market Risks Different scenarios of power production have been illustrated in Figures 11 and 12. The trends Different scenarios of power production have been illustrated in Figures 11 and 12. The trends andDifferent peaks of scenarioslines of power of power yield prod areuction affected have by been coefficients illustrated about in Figures market 11 risk and and 12. influenceThe trends of and peaks of lines of power yield are affected by coefficients about market risk and influence of andWEETP peaks explained of lines ofin Sectionpower yield4.3.1. Ifare Pingliang affected isby successfully coefficients absorbed about market into the risk WEETP and influence before 2018, of WEETP explained in Section 4.3.1. If Pingliang is successfully absorbed into the WEETP before 2018, WEETPpower explainedyield will indemonstrate Section 4.3.1. a Ifgrowth Pingliang trend is successfully despite fluctuation, absorbed intoand thethe WEETP difference before between 2018, power yield will demonstrate a growth trend despite fluctuation, and the difference between powerproduction yield capacitywill demonstrate and yield awill growth shrink. trend Under de aspite low-risk fluctuation, scenario, and powe ther yielddifference will reachbetween 13.2 production capacity and yield will shrink. Under a low-risk scenario, power yield will reach 13.2 productionbillion kWh capacity in 2019 and 17.8yield billion will shrink. kWh (peak Under value) a low-risk in 2022. scenario, An increase powe ofr the yield risk will coefficient reach 13.2 will billion kWh in 2019 and 17.8 billion kWh (peak value) in 2022. An increase of the risk coefficient will billioncause kWhcertain in 2019negative and 17.8effects billion on power kWh (peak generation value); inhowever, 2022. An even increase in a ofhigh-risk the risk coefficientscenario power will cause certain negative effects on power generation; however, even in a high-risk scenario power Sustainability 2017, 9, 787 12 of 16

5.4. Analysis on Market Risks Different scenarios of power production have been illustrated in Figures 11 and 12. The trends and peaks of lines of power yield are affected by coefficients about market risk and influence of WEETP explained in Section 4.3.1. If Pingliang is successfully absorbed into the WEETP before 2018, power yield will demonstrate a growth trend despite fluctuation, and the difference between production capacity and yield will shrink. Under a low-risk scenario, power yield will reach 13.2 billion kWh in

2019Sustainability and 17.8 2017, billion 9, 787 kWh (peak value) in 2022. An increase of the risk coefﬁcient will cause certain12 of 16 negative effects on power generation; however, even in a high-risk scenario power yield still can be keptyield at still a healthy can be level kept byat successfula healthy level generation by succe ofssful opportunities generation for of WEETP opportunities based onfor advantages WEETP based of loweron advantages costs, capacity, of lower and costs, technology. capacity, and technology. Next,Next, we we simulated simulated a relatively a relatively pessimistic pessimistic scenario scenario where where Pingliang Pingliang is absorbed is absorbed into the WEETPinto the afterWEETP years after from years 2018. from Under 2018. this Under scenario, this the scenario, difference the betweendifference production between production capacity and capacity yield will and beyield kept will at a be high kept level, at a whichhigh level, will notwhich be improvedwill not be until improved 2023. until 2023. TheThe simulation simulation shows shows that that the the cement cement yield yield manifests manifests a a small small decline decline from from 2015–2017 2015–2017 and and rises rises afterafter 2017 2017 from from proﬁts profits from from the the construction construction of of infrastructure infrastructure and and the the export export of of cement cement products products stimulatedstimulated by by the the Belt Belt and and Road Road initiative, initiative, and and will will reach reach production production capacity capacity in in 2025 2025 (Figure (Figure 13 13).).

Cement Production 600

1 21 1 1 1

500 1 1

ten thousand tons thousand ten 1 1 1 400 2014 2016 2018 2020 2022 2024 Time (Year) Cement Yield : General 1111111 "Production Capacity (2)" : General 2222 FigureFigure 13. 13.Simulation Simulation of of cement cement production production (Unit: (Unit: 10 104 t).4 t).

6.6. Optimization Optimization Measures Measures of of Industrial Industrial Symbiosis Symbiosis System System BasedBased on on the the SD SD modeling modeling results, results, this paperthis paper puts forwardputs forward several several optimization optimization measures measures aimed ataimed existing at existing problems problems to further to improvefurther improve the ecological the ecological and economic and economic effects of effects the CE of system. the CE system.

6.1.6.1. Improving Improving Waste-Heat Waste-Heat Utilization Utilization of of Coal Coal Power Power Plant Plant TheThe low-grade low-grade waste waste heat heat utilization utilization in in the the HPTPP HPTPP is is still still at at a a low low level. level. By By considering considering the the technicaltechnical feasibility feasibility of of taking taking waste waste heat heat from from a a heat heat pump pump system system to to supply supply high high grade grade heat heat for for residents,residents, this this may may save save more more coal coal on on the the basis basis of of combined combined heat heat and and power power generation. generation. Other Other methodsmethods of of reuse reuse include include the the supply supply of of heat heat for for rural rural greenhouses greenhouses and and breeding breeding tropical tropical ﬁsh fish and and ﬁsh fish friesfries through through water water with with low low grade grade heat. heat.

6.2.6.2. Extending Extending Categories Categories of of Alternative Alternative Raw Raw Materials Materials and and Fuels Fuels for for Cement Cement Production Production InIn combination combination with with actual actual situation, situation, the the further further reduction reduction of of carbon carbon emissions emissions from from cement cement plantsplants in in Kongtong Kongtong can can reclaim reclaim CaO-rich CaO-rich waste, waste, such as such sewage as sludge,sewage demolished sludge, demolished building materials, building andmaterials, waste concreteand waste powder concrete as alternativepowder as rawalternative materials raw and materials waste tires,and waste animal tires, residues, animal waste residues, oil, sewagewaste oil, sludge, sewage and sludge, waste plastics and waste as alternative plastics as fuels. alternative If limestone fuels. consumption If limestone canconsumption be decreased can by be 25%,decreased an accumulated by 25%, an decrease accumulated of carbon decrease emissions of carbon will emissions reach 16 millionwill reach t during 16 million 2014–2025. t during Local 2014– government2025. Local could government also put forwardcould also stricter put goalsforward of carbon stricter emission goals reductionof carbon to emission promote lessreduction reliance to onpromote limestone less resources reliance on by limestone cement plants. resources by cement plants. However, it should be emphasized that if hazardous waste, such as waste tires and waste oil, are used as alternative fuels in the cement industry, volatile heavy metal elements are hard to solidify in cement products so severe pollutant emission may occur. Thus, for Kongtong or other cities with cement industries, the emissions process has to be monitored more closely when high ratios of alternative fuels are used in cement plants, and the pretreatment of hazardous waste is essential to prevent potential environment risks.

However, it should be emphasized that if hazardous waste, such as waste tires and waste oil, are used as alternative fuels in the cement industry, volatile heavy metal elements are hard to solidify in cement products so severe pollutant emission may occur. Thus, for Kongtong or other cities with cement industries, the emissions process has to be monitored more closely when high ratios of alternative fuels are used in cement plants, and the pretreatment of hazardous waste is essential to prevent potential environment risks.

6.3. Promoting the Local Demand of Power through Introduction of Enterprises with High Power-Dependence The relatively lower prices of coal and power are advantages of Kongtong to attract industrial transfer from enterprises in developed areas of China. To guarantee smooth regulations regarding manufacturing investment illustrated in Figure7, Kongtong has already introduced several manufacturing enterprises with high technology content to stimulate the local economy. For instance, the production line of Gansu Composite New Materials Ltd. (Pingliang, China) was initially located in Shanghai and has now moved to Kongtong for the cost savings in power. Industrial distribution should also be more reasonably planned to ensure that the power capacity of West China can be efﬁciently utilized, but also relieve the pressure of power supply in East China.

6.4. Optimizing the Denitration Equipment of HPTPP If catalyst reactivation equipment is introduced, the large scale decrease of waste selective catalytic reduction (SCR) catalysts can be achieved and the costs of denitration of HPTPP can be reduced. Under a low risk scenario, the accumulated savings of denitration during 2014–2025 could reach RMB 0.13 billion, if the rate of cost reductions were set as 60%, which is an empirical value acquired from survey data.

6.5. Further Extending the CE System To solve the issue of the present short supply of recycling waste and the future possibility of an oversupply of fly ash, it is necessary to add new manufacturing departments to the CE system and extend the consumption channel of recycling waste. Presently, production lines of coal to methanol and coal to polypropylene are in the process of construction and advancement. When put into operation, the coal chemical industry could supply more alternative raw materials for the building materials industry. Building a production line of zeolite synthesized from fly ash, which can be utilized in the demercuration of coal gas, could be a new pathway for fly ash consumption for Kongtong. Furthermore, Beijing Baogui Stone Art Technology Ltd. (Beijing, China).—a distinguished example in field of CE—reuses solid waste in an upscale way by pressing fly ash to manufacture reproduced stones with high art content and added value. It is possible that Kongtong could positively cooperate with these types of art enterprises to enhance the value of solid waste to a higher level. For the HPTPP, launching the projects of V2O5 reclaimation from waste SCR catalysts can not only help avoid further pollution, but also help the country save vanadium resources.

7. Discussion and Conclusions This paper modeled the CE system of coal power and cement in Kongtong and quantitatively analyzed its operational structure and the ecological and economic effects using the SD method and Vensim software. The following conclusions have been drawn.

(1) The simulation results show that through the efficient eco-design of the supply chain, the recycling of solid waste and waste heat can create huge benefits for the coal power and cement plants. The sales revenue of solid waste from the HPTPP can reach over RMB 80 million per year at the highest level. Waste heat and height difference energy power generation can make up 30% of power consumption of cement plants, and these benefits drive enterprises to positively develop or introduce advanced technology. Meanwhile, the CE system can also contribute to the sustainable Sustainability 2017, 9, 787 14 of 16

development of Kongtong through saving mineral resources, reducing carbon emissions, and improving air quality. During 2014–2025, an accumulated total of 14.11 million t of natural gypsum and 22.67 million t of coal can be saved; as well as reductions in SO2 and dust will reach 22.8 and 13.9 thousand t, respectively. (2) For industrial symbiosis based on the coal power industry, market risks caused by macroeconomics and the tendency of the national energy policy towards clean energy are considered negative factors. Over capacity and heavy losses of upstream enterprises, the serious SDD of recycling waste may further result in the collapse of a CE system. The sustainable development of CE cannot be separated from effective macro regulation, including the reasonable distribution of industrial symbiosis. Supportive projects, such as China’s WEETP and policies of promoting industrial spatial transfer, are crucial in assisting the stability of the CE system of coal power and cement. The introduction of enterprises with intensive uses of power is a feasible way of stimulating local power consumption. (3) Optimization measures can theoretically further improve the ecological and economic effects. In the future, the heat efficiency of coal power plants, the carbon emission reduction in the cement production process, and the optimization of the denitration equipment are important optimization elements which need to be further studied. (4) The SD method has high application value in the field of CE research as it can help researchers understand complicated causal associations in the production process of industrial symbiosis and simulate future scenarios through friendly visualization. (5) The experiences of CE development in Kongtong can be used as a reference for regions with similar industrial structures. Combining cement plants with advanced technology is an effective path to solve the problems of fly ash and desulfurization gypsum pollution and excessive stress on landfill sites.

Acknowledgments: This study is supported by the Key Research Program of the Chinese Academy of Sciences (ZDRW-ZS-2016-6) and The Natural Science Foundation of China (41301637) and the Research Program of IGSNRR (Y5V50013YE). The authors would like to thank leaders and technicians of HPTPP, Conch Cement Ltd., Qilianshan Cement Ltd. and the government staffs of Kongtong District and Pingliang who gave support to authors during field research. Author Contributions: Suocheng Dong conceived the research idea and designed general framework of the research. Zhe Wang and Fujia Li built SD model analyzed the data, and wrote the paper. Yu Li and Zehong Li. contributed theoretical guidance for the research. Feng Chen and Hao Cheng contributed data collection during field research. Conflicts of Interest: The authors declare no conflict of interest.

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