cScience

Inaugural Statement on the First Issue of cScience

Hydrogen Direct Reduction: History and Pathways for Cost Reduction

The steel industry, a critical pillar of global economic development, is highly energy-intensive, accounting for approximately 7%–9% of global energy-related CO2 emissions. The transition from traditional carbon-intensive metallurgy to hydrogen-based metallurgy represents a pivotal pathway for the green and sustainable development of the steel industry. This review elaborates on the evolution of hydrogen direct reduction technologies, highlighting early pilot- and commercial-scale plants that primarily utilized fluidized bed reactors with natural gas reforming or ammonia plant exhaust gases as reducing agents. These early efforts demonstrated the feasibility of hydrogen reduction but could not achieve long-term stable operation. The urgent need for decarbonization has resulted in renewed focus on research and development in hydrogen direct reduction, with steel companies proposing diverse technological solutions and advancing industrial demonstrations globally. Despite significant progress, the cost of hydrogen production has become a significant barrier to its widespread adoption. Strategies to lower costs include enhancing the reaction efficiency, integrating green electricity to supply heat, utilizing low-grade ores, and leveraging renewable, off-peak, and surplus electricity for hydrogen production. As the price of hydrogen is 0.7 ¥·Nm−3 (Standard volume), the cost of the hydrogen direct reduction–electric arc furnace process is comparable to that of the blast furnace–basic oxygen furnace process. Hydrogen direct reduction is expected to gradually replace the conventional blast furnace ironmaking method, which is emerging as a mainstream steel production process that underpins the green, low-carbon, and sustainable development of the global steel industry.

From Innovation to Integration: The Evolving Role of Carbon Capture and Storage in Global Decarbonization

Carbon capture and storage (CCS) has evolved from a conceptual mitigation option into a cornerstone of global decarbonization strategies. This review provides a comprehensive synthesis of CCS’s technological, intellectual, and institutional evolution, emphasizing its transition from isolated engineering applications to system-wide integration. Drawing on a bibliometric analysis of more than 19,000 publications (2001–2025) from the Web of Science Core Collection visualized through CiteSpace, we map the global research landscape and reveal the field’s thematic shift from capture and sequestration processes toward integrated approaches that couple CCS with hydrogen, bioenergy, and digital optimization frameworks. Technologically, CCS has advanced through three primary pathways—post-combustion, pre-combustion, and oxy–fuel combustion—each with distinct capture mechanisms, energy penalties, and retrofit potentials. At the deployment level, CCS expansion remains geographically uneven: industrialized economies such as China, the United States, and the United Kingdom dominate operational capacity, whereas emerging and developing economies face barriers related to infrastructure, financing, and governance. By integrating bibliometric, technological, and comparative analyses, this review develops a multidimensional framework encompassing policy design, institutional capacity, and deployment structure. The findings highlight that CCS’s future effectiveness depends not only on technological efficiency but also on coordinated governance, cross-border storage networks, and its alignment with broader innovation ecosystems driving the global net-zero transition.

Inaugural Statement on the First Issue of cScience

Hydrogen Direct Reduction: History and Pathways for Cost Reduction

The steel industry, a critical pillar of global economic development, is highly energy-intensive, accounting for approximately 7%–9% of global energy-related CO2 emissions. The transition from traditional carbon-intensive metallurgy to hydrogen-based metallurgy represents a pivotal pathway for the green and sustainable development of the steel industry. This review elaborates on the evolution of hydrogen direct reduction technologies, highlighting early pilot- and commercial-scale plants that primarily utilized fluidized bed reactors with natural gas reforming or ammonia plant exhaust gases as reducing agents. These early efforts demonstrated the feasibility of hydrogen reduction but could not achieve long-term stable operation. The urgent need for decarbonization has resulted in renewed focus on research and development in hydrogen direct reduction, with steel companies proposing diverse technological solutions and advancing industrial demonstrations globally. Despite significant progress, the cost of hydrogen production has become a significant barrier to its widespread adoption. Strategies to lower costs include enhancing the reaction efficiency, integrating green electricity to supply heat, utilizing low-grade ores, and leveraging renewable, off-peak, and surplus electricity for hydrogen production. As the price of hydrogen is 0.7 ¥·Nm−3 (Standard volume), the cost of the hydrogen direct reduction–electric arc furnace process is comparable to that of the blast furnace–basic oxygen furnace process. Hydrogen direct reduction is expected to gradually replace the conventional blast furnace ironmaking method, which is emerging as a mainstream steel production process that underpins the green, low-carbon, and sustainable development of the global steel industry.

From Innovation to Integration: The Evolving Role of Carbon Capture and Storage in Global Decarbonization

Carbon capture and storage (CCS) has evolved from a conceptual mitigation option into a cornerstone of global decarbonization strategies. This review provides a comprehensive synthesis of CCS’s technological, intellectual, and institutional evolution, emphasizing its transition from isolated engineering applications to system-wide integration. Drawing on a bibliometric analysis of more than 19,000 publications (2001–2025) from the Web of Science Core Collection visualized through CiteSpace, we map the global research landscape and reveal the field’s thematic shift from capture and sequestration processes toward integrated approaches that couple CCS with hydrogen, bioenergy, and digital optimization frameworks. Technologically, CCS has advanced through three primary pathways—post-combustion, pre-combustion, and oxy–fuel combustion—each with distinct capture mechanisms, energy penalties, and retrofit potentials. At the deployment level, CCS expansion remains geographically uneven: industrialized economies such as China, the United States, and the United Kingdom dominate operational capacity, whereas emerging and developing economies face barriers related to infrastructure, financing, and governance. By integrating bibliometric, technological, and comparative analyses, this review develops a multidimensional framework encompassing policy design, institutional capacity, and deployment structure. The findings highlight that CCS’s future effectiveness depends not only on technological efficiency but also on coordinated governance, cross-border storage networks, and its alignment with broader innovation ecosystems driving the global net-zero transition.