The research, led by Yuanyuan Yang, Tengfei Xu, Tong Guo, Dapeng Mei, Bo-Tao Huang, and Tianyu Xie, focuses on steel fiber-reinforced concrete and ultra-high-performance concrete, two advanced materials prized for their exceptional toughness, tensile strength, and crack resistance. Unlike conventional concrete, whose carbon emissions are dominated by cement production, these fiber-reinforced composites introduce a second major emission source: the steel fibers themselves. Steel fibers are manufactured through an electric arc furnace short-process route followed by extensive wire drawing, and this production chain is extraordinarily electricity-hungry. Around 58.4 percent of the total energy consumed in making steel fibers is used during the wire drawing phase alone, which stretches hot-rolled wire down to fibers as thin as 0.15 millimeters.

That electricity dependence is what makes the new findings so striking. While the carbon emissions of cement are largely locked in by the chemistry of clinker calcination, a process that accounts for roughly 90 percent of cement’s footprint and is essentially independent of where it is made, the emissions of steel fibers swing wildly depending on the carbon intensity of the regional grid supplying the factory. Across the 31 provinces of mainland China, grid carbon emission factors range from 0.04 to 0.97 kilograms of carbon dioxide equivalent per kilowatt-hour, a nearly 24-fold difference. The consequence is dramatic: the carbon emission factor for a kilogram of steel fiber can range from 0.72 to 4.35 kilograms of carbon dioxide equivalent, purely because of where it was produced.

The study’s authors built a spatiotemporally explicit life cycle assessment framework that replaces the single, static national average emission factor used in most conventional carbon accounting with province-level and season-level values. They compiled provincial power generation mixes for 2022 and 2024, calculated fuel-specific emission factors for thermal power including upstream fuel emissions, accounted for inter-provincial electricity transfers and transmission losses, and then applied these refined factors to the cradle-to-gate emissions of concrete mixes spanning strength grades from C30 to C180. The results expose how badly national averages distort the picture. Using a unified national average overestimates emissions in clean-energy provinces by up to 177.5 percent while underestimating them by 25.5 percent in coal-dependent regions.

The geography of China’s power system explains the pattern. Southwestern provinces such as Yunnan, Sichuan, and Xizang, along with Qinghai in the northwest, draw more than 80 percent of their electricity from renewable sources, mostly hydropower, giving them grid emission factors as low as 0.04 kilograms of carbon dioxide equivalent per kilowatt-hour. At the other extreme, 21 provinces classified as thermal power-dominant, concentrated in North and Northeast China, average 0.83 kilograms per kilowatt-hour because of their heavy reliance on coal. The sensitivity analysis confirmed that for ordinary steel fiber-reinforced concrete, the grid emission factor and the steel fiber content are the two dominant parameters governing total emissions, with sensitivity coefficients of roughly 0.55 for C30 mixes, while transport distance barely registers at around 0.1.

The temporal dimension proved equally important. Because hydropower output surges during wet seasons and wind power fluctuates with the seasons, grid carbon intensity changes dramatically through the year. In Yunnan, hydropower’s share of generation climbed from 54.56 percent in the first quarter to 84.37 percent in the third, driving the provincial emission factor down from 0.35 to 0.13 kilograms of carbon dioxide equivalent per kilowatt-hour. In Hunan, the factor plunged from 0.67 to 0.42 in the second quarter as spring rains boosted hydropower. For a cubic meter of SFRC C30, that seasonal swing translated into emissions falling from 483.90 to 378.62 kilograms of carbon dioxide equivalent in Yunnan, a 21.76 percent reduction, simply by shifting production timing.

Perhaps the most provocative concept in the study is the carbon emission break-even distance, the transport distance at which shipping steel fiber from a clean-grid province produces less total carbon than manufacturing it locally in a coal-dependent one. Analyzing all 930 directional inter-provincial pairs, the researchers found that 87.5 percent of potentially beneficial routes could deliver calculated carbon savings, with 46.02 percent achieving at least 0.6 kilograms of carbon dioxide equivalent saved per kilogram of fiber. A case study made the counterintuitive logic vivid: for a Beijing project, sourcing fiber from neighboring Hebei, just 310 kilometers away, yields 4.15 kilograms of carbon dioxide equivalent per kilogram, while sourcing from Hubei, 1468 kilometers away, yields only 2.67, a 35.7 percent reduction despite nearly five times the transport distance. Grid carbon intensity, in other words, can outweigh distance as the decisive emission driver.

The real-world industrial geography makes this opportunity even more tantalizing. A survey of China’s steel fiber manufacturers revealed that production capacity is heavily concentrated in northern and eastern provinces, with 890 registered manufacturers in Hebei alone, while clean-energy-rich Yunnan has just 16 and Sichuan only 7. The prevailing local-supply model thus locks the industry into relatively high-carbon supply chains. The authors frame their findings as a potential extension of China’s famous West-to-East Electricity Transmission strategy into a West-to-East Material Transfer concept, in which electricity-intensive materials are produced where the power is clean and shipped to where the demand is.

Seasonal scheduling offers an even simpler intervention. By reallocating 40 percent of quarterly production to the lowest-carbon quarter, a manufacturer in Yunnan could cut emissions by 6.02 percent and one in Hunan by 5.17 percent, with no equipment upgrades or capital investment. The researchers estimate that a single 100,000-ton steel fiber producer in Jiangsu shifting 15 percent of its output to the first quarter could avoid more than 1,000 tons of carbon dioxide equivalent annually. Scaled across China’s steel and other electricity-intensive material industries, the cumulative potential is substantial, though the authors caution these figures are calculated projections not yet validated in engineering practice.

The study also draws a crucial distinction between material types. Steel fiber-reinforced concrete, where fibers contribute 40 to 63 percent of emissions in lower grades, is genuinely energy-sensitive and benefits enormously from spatiotemporal optimization. Ultra-high-performance concrete, by contrast, is material-dominated: its enormous cement content, up to nearly 800 kilograms per cubic meter in the C180 mix, keeps its emissions comparatively grid-insensitive, so binder optimization matters more than location. Yet even UHPC holds a surprise when judged by the study’s carbon intensity index, which normalizes emissions by compressive strength. SFRC C80 achieved the lowest strength-adjusted carbon efficiency of all five mixes under every grid scenario, and UHPC C180 performed well despite its high absolute emissions, suggesting that high-strength concretes can be carbon-efficient when their mechanical performance is factored in. The researchers hope their high-resolution framework will push carbon accounting standards toward incorporating temporal adjustment factors and incentivize green electricity consumption, transforming carbon footprinting from a passive accounting exercise into an active tool for low-carbon supply chain design.

Subject of Research: Spatiotemporal variation in power grid carbon intensity and its effect on the embodied carbon of steel fiber-reinforced concrete in China

Article Title: Spatiotemporal variations in power grid carbon intensity and their impact on steel fiber-reinforced concrete emissions

Article References: Yang, Y., Xu, T., Guo, T., Mei, D., Huang, B.-T., & Xie, T. (2026). Spatiotemporal variations in power grid carbon intensity and their impact on steel fiber-reinforced concrete emissions. Case Studies in Construction Materials, 25, Article e06598. https://doi.org/10.1016/j.cscm.2026.e06598

Image Credits: AI Generated

DOI: 10.1016/j.cscm.2026.e06598

Keywords: steel fiber-reinforced concrete, ultra-high-performance concrete, life cycle assessment, power grid carbon intensity, embodied carbon, China, cement emissions, hydropower, carbon accounting, supply chain optimization, seasonal electricity, decarbonization