Technology

In this system, coal is pulverised, dried, purified and subjected to surface pre-treatment before being fed into the anode chamber of the cell.

Oxygen is supplied to the cathode, and within the cell, the fine coal powder undergoes electrochemical oxidation across an oxide membrane, yielding electricity directly – without any intermediate steam cycle or mechanical turbine.

At the anode outlet, the high-purity carbon dioxide generated by the reaction is captured in situ and catalytically converted into valuable chemical feedstocks such as synthesis gas or mineralised into compounds like sodium bicarbonate. The entire process is silent and clean.

Conventional coal power relies on burning coal to produce heat, which then boils water into steam to spin a turbine generator – a chain of conversions that remains hostage to the Carnot efficiency limit of internal combustion engines.

“This process is bound by the Carnot cycle, capping energy efficiency at around 40 per cent. In the ZC-DCFC, by avoiding the efficiency losses associated with combustion and thermal engines, it enables substantially higher theoretical efficiency,” Xie noted in his paper, which appeared in the peer-reviewed journal Energy Reviews.

Since 2018, Xie’s team has pushed the technology forward step by step, solving problems in materials, cell durability, fuel treatment and continuous coal feeding along the way.

Earlier generations of direct carbon fuel cells were plagued by low power density and short operational lifetimes. The newly developed cell, however, incorporates improvements in stack scalability, long-term stability, carbon conversion efficiency and overall system integration – areas the team has targeted in their paper.

“This concept can also be extended to deep coal seams located 2km (1.2 miles) underground,” Xie said.

Traditional mining of coal from such depths is prohibitively expensive. This technology could convert the coal to electricity on site, with only the power needing transmission to the surface. This approach could help ease pressure as shallow coal reserves gradually dwindle.

Xie’s group is also spearheading a landmark project under the National Science and Technology Major Project for Deep Earth Probe and Mineral Resources Exploration, launched in 2025.

Adapting the ZC-DCFC to withstand high temperatures, pressures and corrosive environments would enable the fuel cell to serve the deep-earth exploration initiative directly.

The research aligns squarely with China’s goal of achieving carbon neutrality by 2060. Yet expecting this laboratory-scale innovation to displace the nation’s existing coal-fired power fleet any time soon would be unrealistic.

Wei Zhijiang, a senior engineer at HBIS Group Xuansteel, said that by the end of 2025, coal power made up about 45 per cent of China’s total installed capacity but still supplied nearly 60 per cent of the nation’s electricity.

Meanwhile, half of those coal plants had been running for just 15 years – still young in industrial terms.

Pointing out the practical hurdles, Wei said moving the direct coal fuel cell from the lab to wide commercial use would take time and careful cost planning. Therefore, he believed the technology would not be cost-competitive until after 2045.

Carbon neutrality has become an international consensus under the requirements established by the Paris Agreement. Accordingly, countries worldwide, especially developing nations, have formulated their own carbon neutrality policies. Owing to differences in regional development histories and resource endowments, as well as the intermittency of new energy, developing countries will continue to rely on coal to meet their energy demands for sustainable economic and social development in the near future. However, conventional coal-fired power generation technologies can hardly achieve low-carbon or even negative-carbon emissions. It is therefore urgent to develop novel carbon-free coal power technologies. This perspective proposes the concept of Zero-carbon-emission direct coal fuel cells (ZC-DCFC) for power generation as a disruptive technological paradigm for efficient coal utilization. The technological architecture of ZC-DCFC is discussed, including fuel supply, key materials, and in-situ CO2 conversion. The technical challenges and future development directions are also identified. ZC-DCFC is expected to open up a new pathway for near-zero-emission coal utilization, transforming coal from a traditional fossil fuel into a feasible clean energy source in the global low-carbon transition.