Coal city on the brink: how Huainan is untangling industry, environment and carbon

In the rolling plains of northern Anhui Province, the Chinese city of Huainan has spent more than six decades digging itself out of the ground. As one of the country’s fourteen billion-ton coal bases and a cornerstone of East China’s power supply, the city has cumulatively extracted roughly 1.95 billion tons of raw coal and still holds reserves of 16.86 billion tons, along with vast coalbed methane deposits. That endowment made Huainan rich in energy and poor in flexibility: coal-related industries have long accounted for the overwhelming majority of its industrial value-added, binding the city’s fortunes to a single, carbon-intensive commodity. Now a new study published in Environmental and Sustainability Indicators offers the most detailed picture yet of whether such a city can genuinely escape that trap, and the answer is a cautious, data-driven yes, provided the right levers are pulled in the right order.

A research team led by Huijun Wu and Chang Su constructed what they call the IEC nexus, a unified framework linking industrial structure, ecological environment and carbon emissions into a single analytical system. The approach borrows from the ‘nexus’ thinking first proposed at the 2011 Bonn Conference for water, energy and food, in which interdependent systems mutually reinforce or constrain one another. Rather than treating economic transformation, pollution and greenhouse gases as separate policy files, the team measured all three simultaneously for Huainan between 2000 and 2022, using entropy-weighted indicators drawn from national and provincial statistical yearbooks, energy inventories and local environmental bulletins. Carbon emissions were calculated following IPCC guidelines, converting the physical consumption of coal, oil and natural gas into carbon dioxide using fuel-specific heating values, carbon contents and oxidation rates.

The centerpiece of the analysis is the coupling coordination degree, a metric that ranges from zero to one and captures how well the three subsystems evolve together rather than at each other’s expense. The results tell a story in three acts. In the early period from 2000 to 2008, the industrial subsystem lagged badly behind, with its evaluation index fluctuating between just 0.13 and 0.44 while environmental and carbon indices ran higher. During a difficult transition from 2008 to 2016, the accumulated costs of coal dependence became visible: the coordination degree actually slipped from 0.753 in 2012 to 0.741 in 2016 as environmental quality briefly deteriorated. Then, from 2016 onward, the system entered what the authors describe as a high-quality development stage, with the overall coordination degree climbing from 0.552 in 2000 to 0.832 in 2022, crossing from ‘barely coordinated’ into the ‘good coordinated development’ band.

Perhaps the most striking finding is how lopsided the progress has been. The industrial structure index surged to about 0.52 by 2020 and the ecological environment index climbed to roughly 0.94, yet the carbon emissions index crawled along at only about 0.40. In other words, Huainan has learned to restructure its economy and clean its air far faster than it has learned to decarbonize. The coupling degree itself remained stubbornly high throughout, ranging from 0.754 to 0.991, which the researchers interpret as evidence that the three subsystems are locked into tight mutual dependence: improvements in one cannot be sustained for long without corresponding movement in the others.

To identify what was actually holding the city back, the team applied an obstacle degree model that decomposes the coordination deficit into individual indicators. The verdict shifted dramatically over the two decades studied. In 2000, the industrial structure subsystem accounted for a dominant 71.04 percent of the total obstacle, driven largely by weak tertiary-sector employment and stagnant rural incomes. By 2022 that share had fallen to 45.07 percent, while the ecological environment subsystem more than doubled its contribution from 15.03 percent to 37.48 percent, and carbon emissions rose from 13.93 percent to 17.46 percent. The bottleneck has migrated: as structural constraints eased, pollution intensity, particularly sulfur dioxide emissions per unit of GDP, and the lingering weight of coal-linked industry became the new front line.

The study then turned from diagnosis to prophecy, pairing the STIRPAT model, a regression framework relating environmental pressure to population, affluence and technology, with a Grey GM(1,1) forecasting model. Because the six explanatory variables, including population, per capita GDP, urbanization, secondary-industry share, energy intensity and energy structure, showed substantial multicollinearity, the team calibrated the model with ridge regression, setting the ridge parameter at 0.14 and achieving an R-squared of 0.868 with an average fitting error of 6.18 percent. The authors are careful to note that only the population coefficient reached even marginal statistical significance, so the projections should be read as conditional scenarios rather than firm causal predictions.

Those scenarios, however, are revealing. Under a business-as-usual pathway, Huainan’s carbon emissions would not peak until around 2035, five years past the national target, at roughly 29.6 million tons, about 1.27 times the 2020 level. Merely optimizing industrial structure barely improves that timing. The low-carbon and energy-saving scenario, which combines faster cuts in energy intensity with a cleaner energy mix, brings the peak forward to 2030 at about 28.7 million tons while preserving steady economic growth, making it the pathway the authors judge most realistic and aligned with China’s dual carbon goals. An aggressive green development scenario peaks earliest, in 2028 at just 24.9 million tons, but only by deliberately throttling population growth and urbanization. At the other extreme, an extensive development scenario that prioritizes raw economic expansion delays the peak to 2040 at a hefty 35.1 million tons.

The Grey model projections for the coordination degree itself add a further layer of nuance. Across all scenarios the index continues rising through 2036, but the green development pathway approaches perfect coordination by 2032, followed by industrial structure optimization, then the low-carbon energy pathway, with the extensive scenario trailing the field. The ordering suggests that structural adjustment delivers the quickest coordination gains, while energy-focused measures, though slower to register, are what actually bend the emissions curve. For a city where coal mining has caused land subsidence, water pollution and ecosystem degradation across some of eastern China’s most representative subsidence zones, both fronts matter.

The policy implications the authors draw are refreshingly specific. Huainan should not simply shrink its secondary sector, they argue, but upgrade its internal composition, cultivating new energy equipment manufacturing, photovoltaic and wind industries, digital economy sectors and modern logistics, while converting mining subsidence zones into wetland parks and ecological conservation areas. Coal-power plants should pursue ultra-low emission retrofits and carbon capture technologies, and the city should build a dynamic monitoring system around the very indicators the obstacle analysis flagged: tertiary employment, pollution intensity, energy intensity and energy structure. Because the constraints themselves shift over time, the authors contend, governance must be adaptive and coordinated across industrial, environmental, energy and planning departments rather than siloed.

The study is candid about its limits. A 2016 administrative boundary change, when Shou County was incorporated into Huainan, complicates comparisons of population-related indicators across the time series, and some missing data were filled by regression-based imputation. The findings from a single coal city may not transfer cleanly to regions with different resource endowments, and the forecasting models rest on assumptions about parameter stability that real-world shocks could upend. The authors also stress that their correlations describe temporal associations, not proven causal effects. Even so, the broader message travels well beyond Anhui: for the hundreds of resource-dependent cities worldwide staring down decarbonization deadlines, Huainan’s two-decade ledger suggests that industrial restructuring, ecological restoration and carbon mitigation can indeed rise together, but only if energy intensity and energy structure are treated as the decisive battleground rather than an afterthought.

Subject of Research: Coupling coordination of industrial structure, ecological environment and carbon emissions in the coal-resource city of Huainan, China

Article Title: Can coal-resource cities achieve high-quality coordination of industry, environment, and carbon? Evidence from Huainan, China

Article References: Wu, H., Su, C., Zhang, Y., Li, M., Kong, X., Liu, Y., & Gao, L. (2026). Can coal-resource cities achieve high-quality coordination of industry, environment, and carbon? Evidence from Huainan, China. Environmental and Sustainability Indicators, 32, Article 101541. https://doi.org/10.1016/j.indic.2026.101541

Image Credits: AI Generated

DOI: 10.1016/j.indic.2026.101541

Keywords: Huainan, coal-resource cities, carbon emissions, coupling coordination degree, STIRPAT model, energy transition, industrial structure, ecological environment, carbon peak, obstacle degree analysis, China dual carbon goals, GM(1,1) forecasting