Nuclear energy presents a unique opportunity to decarbonize coal gasification for hydrogen production by replacing traditional fossil-derived heat with clean, high-temperature process heat. This integration can significantly reduce the carbon footprint of coal-based hydrogen, especially when combined with carbon capture and storage (CCS), resulting in what is often termed "blue hydrogen." The approach leverages the high thermal efficiency and low-carbon attributes of nuclear reactors while utilizing coal as a feedstock, offering a transitional pathway toward cleaner hydrogen production.

Coal gasification typically involves reacting coal with oxygen and steam at high temperatures to produce syngas, a mixture of hydrogen, carbon monoxide, and carbon dioxide. The conventional process relies on partial oxidation of coal, which generates substantial CO2 emissions. By substituting nuclear heat for combustion-based heat, the need for oxygen-blown gasification is reduced or eliminated, lowering both energy losses and carbon emissions. Nuclear reactors, particularly high-temperature gas-cooled reactors (HTGRs) or molten salt reactors (MSRs), can provide the necessary heat at temperatures exceeding 700°C, making them compatible with gasification requirements.

The carbon intensity of coal-derived hydrogen is primarily dictated by the energy source used for gasification and subsequent carbon management. Traditional coal gasification emits approximately 18-20 kg of CO2 per kg of hydrogen produced. Introducing nuclear heat can reduce direct emissions by eliminating the need for combustion, while CCS captures residual CO2 from syngas processing. Studies indicate that nuclear-assisted coal gasification with CCS can achieve carbon intensities as low as 1-3 kg CO2 per kg H2, comparable to steam methane reforming with CCS and significantly lower than conventional coal gasification.

Technically, coupling nuclear reactors with coal gasification requires careful integration to ensure efficient heat transfer and process stability. HTGRs are particularly suitable due to their ability to deliver heat at temperatures up to 950°C via an intermediate helium loop, which can be directly interfaced with the gasifier. Challenges include material compatibility, heat exchanger design, and maintaining consistent gasifier performance under variable heat inputs. Pilot projects and theoretical models have demonstrated feasibility, but large-scale deployment would require further validation of system dynamics and safety protocols.

From an environmental perspective, nuclear-assisted coal gasification with CCS offers a middle ground between fossil-based and fully renewable hydrogen pathways. It reduces reliance on natural gas, which is subject to price volatility and methane leakage concerns, while still utilizing coal reserves in a more sustainable manner. However, it does not eliminate all environmental impacts. Nuclear energy brings its own challenges, including radioactive waste management, uranium mining impacts, and public acceptance issues. Coal mining and ash disposal remain concerns, though CCS mitigates atmospheric CO2 release.

Economically, the viability of this approach depends on several factors, including nuclear capital costs, coal prices, and CCS infrastructure availability. Nuclear reactors require high upfront investments but offer stable long-term operating costs. Coal gasification plants are capital-intensive as well, but the integration of nuclear heat can reduce operational expenses by avoiding oxygen plants and lowering fuel consumption. When CCS is included, the levelized cost of hydrogen from nuclear-assisted coal gasification is estimated to range between $2.0 and $3.5 per kg, competitive with other low-carbon hydrogen methods but highly sensitive to policy support and carbon pricing.

Comparatively, alternative hydrogen production pathways present different trade-offs. Green hydrogen from electrolysis using renewable electricity has near-zero emissions but faces challenges related to scale, intermittency, and high electricity demands. Steam methane reforming with CCS is currently the most cost-effective low-carbon hydrogen source but depends on natural gas availability and carbon storage capacity. Nuclear-assisted coal gasification occupies a niche where coal resources are abundant, and nuclear infrastructure is established, offering a pragmatic solution for regions transitioning away from unabated fossil fuels.

In summary, nuclear heat can play a pivotal role in reducing the carbon intensity of coal-derived hydrogen by displacing fossil-based heat inputs and enabling efficient carbon capture. The technical feasibility of integrating nuclear reactors with gasification has been demonstrated in principle, though scaling the technology requires further engineering refinement. Environmental and economic trade-offs position this method as a transitional rather than permanent solution, bridging the gap between fossil-dependent and fully renewable hydrogen economies. Its adoption will depend on regional energy policies, resource availability, and advancements in both nuclear and CCS technologies.