Pre-combustion fuel reforming in gas turbines: Hydrocarbon and carbon-neutral fuel pathways

Gas turbines are a cornerstone of modern power generation, providing reliable and dispatchable electricity across the globe. However, their significant contribution to global CO 2 emissions has become increasingly untenable under international climate agreements such as the Paris Agreement. This creates a critical imperative to develop technologies that can improve the efficiency and sustainability of existing and future gas turbine fleets without compromising their operational flexibility. While the long-term vision is a fully renewable energy system, the intermittent nature of sources like wind and solar necessitates the continued use of thermal power for grid stability in the foreseeable future. Within this context, the transition to low-carbon and carbon-neutral fuels – such as hydrogen, ammonia, and methanol – has emerged as a key decarbonization pathway. However, the direct use of these fuels in conventional gas turbines is hampered by challenges related to combustion stability, flame speed, NO x formation, and, in some cases, fuel infrastructure and storage. Pre-combustion fuel reforming offers a transformative solution to these challenges. By harnessing waste heat from the turbine exhaust – or external, low-grade heat sources like solar thermal energy – to drive endothermic reforming reactions, primary fuels are converted into hydrogen-rich gas prior to combustion. This process of the use of exhaust heat to drive pre-combustion fuel reforming, known as thermochemical recuperation (TCR), achieves a dual benefit: it upgrades low-grade thermal energy into high-value chemical energy stored in the reformate, thereby enhancing the overall cycle efficiency, and it produces a fuel with superior combustion properties, including higher flame speed and wider flammability limits. Gas turbines implementing this strategy are termed Chemically Recuperated Gas Turbines (CRGTs). While CRGT upgrades fuel via waste heat recuperation – thereby increasing the share of work output from the more efficient gas turbine cycle – an alternative hybrid pathway integrates a fuel cell with a gas turbine (FC-GT), where the fuel cell converts the majority of the fuel’s chemical energy electrochemically. This fundamental difference enables FC-GT systems to achieve even higher electrical efficiencies (60%–70%). This review provides a comparative analysis between FC-GT systems and CRGT, focusing on their primary constraints. This paper presents a comprehensive and critical review of the potential of pre-combustion reforming to redefine the role of gas turbines in a low-carbon energy future. The analysis is structured around three primary fuel pathways: natural gas, where steam methane reforming offers a route to significant efficiency improvements; ammonia, where pre-combustion cracking is critical for achieving stable and efficient combustion with a carbon-free footprint; and methanol, which acts as a convenient hydrogen carrier and offers a carbon-neutral pathway when produced from renewable sources. For each fuel, the review examines the underlying thermodynamics, catalyst development, reformer design, combustion characteristics of the resulting hydrogen-rich gas, and integration into various gas turbine cycles — from simple and reheat configurations to advanced combined cycles. Furthermore, the work explores the innovative integration of concentrated solar thermal energy to drive the pre-combustion fuel reforming process, creating solar-hybrid gas turbine systems that offer a dispatchable, partially renewable power generation solution. Key technical hurdles are identified and discussed, including catalyst durability under moderate operating conditions, combustion dynamics and NO x control for hydrogen-rich fuels, materials challenges in high-temperature reformers, and the techno-economic viability of scaling such integrated solar-gas turbine systems. By synthesizing decades of research from fundamental kinetics to system-level analysis, this review aims to provide a clear roadmap for future development. It concludes that pre-combustion fuel reforming is not merely an incremental improvement but a pivotal enabling technology that can accelerate the decarbonization of the power sector by making gas turbines compatible with a sustainable, fuel-flexible, and high-efficiency future. • Pre-combustion fuel reforming using exhaust heat increases thermal efficiency. • Ammonia reforming overcomes combustion challenges for carbon-free power. • Methanol reforming enables hydrogen-rich fuel for stable gas turbine operation. • Pre-combustion solar-driven reforming integrates renewable energy with dispatchable power. • Hydrogen-rich reformate improves combustion and reduces NOx emissions.