sustainability Article A Life Cycle Analysis of Deploying Coking Technology to Utilize Low-Rank Coal in China Yan Li 1, Guoshun Wang 1, Zhaohao Li 2, Jiahai Yuan 3 , Dan Gao 2,* and Heng Zhang 2 1 School of Business, Central South University, Changsha 410083, China; [email protected] (Y.L.); [email protected] (G.W.) 2 School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China; [email protected] (Z.L.); [email protected] (H.Z.) 3 School of Economics and Management, North China Electric Power University, Beijing 102206, China; [email protected] * Correspondence: [email protected] Received: 12 May 2020; Accepted: 10 June 2020; Published: 15 June 2020 Abstract: At present, the excess capacity in China’s coke industry can be deployed to utilize some low-rank coal, replacing coking coal with potential economic gains, energy efficiency, and environmental benefits. This study presents a life cycle analysis to model these potential benefits by comparing a metallurgical coke technical pathway with technical pathways of gasification coke integrated with different chemical productions. The results show that producing gasification coke is a feasible technical pathway for the transformation and development of the coke industry. However, its economic feasibility depends on the price of cokes and coals. The gasification coke production has higher energy consumption and CO2 emissions because of its lower coke yield. Generally speaking, using gasification coke to produce F-T oils has higher economic benefits than producing methanol, but has lower energy efficiency and higher carbon emissions. Keywords: coal coking; life cycle analysis; gasification coke; metallurgical coke; low-rank coal 1. Introduction Since the beginning of the new century, the rapid development of China’s urbanization and industrialization has driven the rapid development of the coke industry and the rapid expansion of its domestic coke capacity. China’s coke production totaled 438 million tons in 2018, accounting for over 60% of the world’s total coke production, and China is the world’s largest coke country [1]. From the statistics of coke consumption structure by industry, coke consumption in the steel industry accounts for about 85% of the country’s total coke consumption [1]. However, the steel industry has faced supply-side structural reforms recently in China, which have forced coke companies to reduce capacity under tremendous pressure. On the other hand, there are fewer coking coal resources for producing coke. China has more proven reserves of low-rank coal, with reserves of about 875.73 billion tons, accounting for 59% of proven reserves [2]. Utilizing excess coke capacity, replacing some high-quality coking coal with low-rank coal with large reserves and low cost, and producing gasification coke for the chemical industry will be conducive to the sustainable development of the coke industry [3]. Life cycle analysis (LCA) is an environmental impact assessment analysis tool that is used to evaluate the activity, process, and product. Using LCA, one can study the environmental impact and corresponding energy use throughout the life cycle (LC) of the research object [4]. At present, LCA has been widely used in chemical catalysts [5,6], biofuels [7–9], solar energy [10,11], wind energy [12,13], power generation [14,15], and the coal chemical industry [16–18]. Among them, using LCA in the coal chemical industry can analyze the coal-based synthetic natural gas (SNG) life cycle (LC) [19,20], Sustainability 2020, 12, 4884; doi:10.3390/su12124884 www.mdpi.com/journal/sustainability Sustainability 2020, 12, x 2 of 17 Sustainability 2020, 12, 4884 2 of 17 in the coal chemical industry can analyze the coal-based synthetic natural gas (SNG) life cycle (LC) [19,20], coal-to-methanol alternative fuel [21–23], and coal to olefins [24,25]. Ou et al. studied fuel consumptioncoal-to-methanol and alternative CO2 emission fuel throughout [21–23], and the coal LC to process olefins [with24,25 a]. focus Ou et on al. the studied carbon fuel emissions consumption [26]. Ouand et CO al.2 emissionused the throughoutLCA method the to LC evaluate process traditional with a focus gasoline on the fuels, carbon coal emissions-based methanol [26]. 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Li et al. the studied fuel consumption the production and processCO2 emission of SNG were and the power key problems.cogeneration Studies [29]. of In s theome research, research the pathways fuel consumption of synthetic and natural CO2 emissiongas found were that thesynthetic key problems. natural gasStudies can ofreduce some researchfuel consumption pathways ofand synthetic CO2 emission. natural gasBased found on that the syntheticabove literature natural, gas however, can reduce no studiesfuel consumption specifically and investigated CO2 emission. coal liquefaction Based on the LCA above to supply literature, vehicle however, power. no studies specifically investigatedThis paper coal uses liquefaction LCA to study LCA tothe supply impact vehicle and economic power. potential of coal coking transformation technologies.This paper Some uses research LCA to coal study coking the impact pathways and economicare studied potential in detail of for coal their coking economic transformation benefits, energytechnologies. consumption Some research, and CO2 coal emissions. coking In pathways Section 2, are the studied modeling in detail detail fors and their equations economic of LCA benefits, are introduced.energy consumption, In Section and 3, COthe2 economy,emissions. energy, In Section and2, theenvironment modeling detailsal performance and equations of some of LCA typical are researchintroduced. pathways In Section of 3coal, the coking economy, are energy, compared. and environmental In Section 4, some performance findings of with some perspective typical researchs are concludedpathways of. coal coking are compared. In Section4, some findings with perspectives are concluded. 2. Mathematic Mathematic M Modelingodeling Section 22 presents a a mathematic mathematic modeling modeling coal coal-coking-related-coking-related pathways pathways LCA. LCA. In this In this paper, paper, the lowthe- low-rankrank coal coal used used was was the thelong long flame flame coal, coal, which which came came from from the the Shenfu Shenfu coalfield coalfield in in Yulin Yulin City, City, Shaanxi Province. Long Long fla flameme coal coal is is the the bituminous bituminous coal coal with with the the lowest lowest degree degree of of metamorphism, and its main characteristics are high volatilityvolatility (volatile(volatile onon drydry ash-freeash-free volatilevolatile VVdafdaf > 37%) and no cohesion or weak cohesion (caking index G < 5). In In Figure Figure 11,, thethe processesprocesses fromfrom coalcoal toto thethe finalfinal products related toto thethe coal-coking-relatedcoal-coking-related pathways pathways are are shown. shown. Four Four parts parts make make up up Figure Figure1. 1. Tables Tables1 1and and2 list 2 thelist coal-coking-related the coal-coking-related research research pathways pathways and the inputand andthe outputinput and of typical output metallurgical of typical metallurgicalcoking and gasification coking and coking gasific processes.ation coking processes. Coal Product Coal mining transportation Production distribution Coking Metallurgical Railway Coking Truck Steelmaking coal Coke raw materials Gasification Railway Coking Truck Low coke rank coal Chemical Methanol Tanker raw materials Methanol synthesis truck Fischer-Tropsch Gasoline & Tanker Transportation synthesis diesel truck fuel Figure 1. FourFour coal coal-coking-related-coking-related research pathways pathways.. TableTable 1. CoalCoal-coking-related-coking-related research pathways. AbbreviationAbbreviation Mining Mining Transportation Transportation Production Production Distribution Distribution Coking coal RailwayRailway TruckTruck long long delivery MCMC Coking coal mining CoalCoal coking coking mining transportationtransportation toto Steelmaking Steelmaking CokingCoking coal coal and and Railway Truck long delivery GC Low-rank coal Railway Coal coking Truck long delivery GC Low-rank coal transportation Coal coking to chemical mining transportation to chemical mining Coking coal and Tanker Truck long Coking coal and Railway CoalCoal coking coking and and GC-M Low-rank coal Railway Tankerdelivery Truck to long GC-M Low-rank coal transportation methanolmethanol synthesis mining transportation deliverychemical to chemical mining synthesis Coking coal and Tanker Truck long Coking coal and Railway Coal coking and Tanker Truck long GC-O Low-rank coal Railway Coal coking and delivery to fuel GC-O Low-rank coal transportation F-T synthesis delivery to fuel mining transportation F-T synthesis station mining station Sustainability 2020, 12, 4884 3 of 17 Table 2. Input