Surge in clean hydrogen demand highlights importance of CCS in energy transition

The global demand for clean hydrogen is surging as nations strive to transition to sustainable energy systems. As a versatile energy carrier, hydrogen is pivotal in decarbonising sectors that are difficult to electrify, such as heavy industry and long-haul transportation. Its ability to store and transport energy over long distances makes it a crucial component of renewable energy integration, particularly for balancing intermittent sources like wind and solar power.

There are several pathways to produce clean hydrogen. These include through electrolysis using renewable energy (electrolytic hydrogen), or from natural gas with carbon capture (CCS-enabled (blue) hydrogen). Countries are investing heavily in hydrogen infrastructure, with ambitious projects and collaborations emerging worldwide. The European Union, Japan, South Korea, and Australia lead the charge, establishing hydrogen strategies and funding research and development. This growing commitment underscores hydrogen's essential role in achieving net-zero emissions and fostering a sustainable, resilient energy future.

The International Energy Agency (IEA) estimates that 450 Mt of clean hydrogen will be required per annum by 2050 to achieve a successful energy transformation. Currently, the US produces approximately 10Mt annually, of which over 95% is grey hydrogen. Its H₂ Strategy calls for 10Mt of clean hydrogen by 2030.

It will take many years, even decades, for electrolytic hydrogen to scale up to the required levels. In the meantime, if we are to address the need for the significant increases in hydrogen production required to meet decarbonisation targets, we need CCS-enabled hydrogen to play a considerable part while we wait for renewable resources for electrolytic hydrogen to ramp up to meet demand.

With a substantially lower levelised cost of hydrogen compared to standard technologies, latest low-carbon hydrogen technology can provide a strategic advantage. It makes low-carbon (CCS-enabled) hydrogen an economically viable and environmentally responsible choice and represents a readily available solution for delivering high-purity low carbon hydrogen at scale.

Leading the way in lowering carbon intensity of hydrogen is Johnson Matthey’s LCH™ technology, which can capture up to 99% of CO₂ emissions generated during hydrogen production. Compared to traditional steam methane reforming (SMR) methods, it offers superior efficiency, cost-effectiveness, and a significant reduction in plant CAPEX and OPEX requirements.

SMR and advanced gas reforming (AGR) are the principal CCS-enabled hydrogen production technologies. AGR consists of either an Autothermal Reformer (ATR) or an ATR coupled with a Gas Heated Reformer (GHR).  Where there is a requirement to capture CO₂, it is recognised that AGR is a more appropriate technology for the generation of CCS-enabled hydrogen due to its provision of a more suitable stream for CO₂ capture.

The technology of a plant using LCH technology

Purified natural gas is first pre-heated and reformed in the GHR before entering the ATR. In the GHR, 30% of the hydrocarbons react with steam to form syngas. Next, oxygen is added to the ATR, causing some partially reformed gas to combust and raise the process gas temperature. This gas then passes through a reforming catalyst bed within the same vessel for further reforming. Operating at high temperatures and steam flows minimises the methane content of the product gas exiting the reformer, as equilibrium limits the reaction. Any residual methane at this stage will increase overall CO₂ emissions. The hot gas leaving the ATR returns to the GHR, supplying the necessary heat for the reforming reaction in the GHR.

The critical difference between the LCH technology and SMR flowsheets is the source of energy driving the reaction. With LCH technology, oxygen is introduced to the ATR, which can be supplied by an air separation unit (ASU). An SMR, on the other hand, relies on burning natural gas. An air separation unit (ASU) can supply the oxygen for the ATR. Combustion with oxygen provides the required heat for reforming. Significantly, the ATR operates at temperatures above 1000°C, enhancing the conversion of hydrocarbons and reducing methane slip, a level of efficiency that SMR cannot achieve.

The technology of GHR

The efficiency of a flowsheet is closely tied to its ability to manage energy, particularly exergy, which measures energy's potential to perform work. The key is minimising combustion and reducing the thermal gradients over which heat is transferred.

JM's LCH technology exemplifies these principles by incorporating a GHR. This reduces the combustion needed for converting hydrocarbons to carbon oxides and minimises thermal gradients by transferring heat into endothermic reforming reactions within the GHR. This approach maximises energy efficiency, which is essential for sustainably producing hydrogen.

In the LCH technology, the GHR works alongside an ATR, enhancing energy efficiency. The GHR, a heat exchange reformer, performs chemical reactions in its tubes, reducing combustion requirements compared to a solely ATR-based system. This maximises exergy and reduces oxygen needs, allowing for smaller ASUs.

Furthermore, the LCH technology configuration offers a 10% reduction in natural gas consumption and CO₂ capture duty per unit of hydrogen produced. This results in smaller, more efficient operations and improved carbon efficiency. These operational enhancements bring economic benefits, including lower natural gas costs and reduced CO₂ disposal expenses.

Improving energy efficiency with LCH

The LCH technology boasts significantly lower methane slip than the typical 4.35 mol % (dry) in an SMR, thanks to the high temperatures achieved at the exit of the ATR. This results from the higher reforming equilibrium temperature that an oxygen-fired ATR can reach. Additionally, the GHR flowsheet in LCH technology allows heat recovery at much higher temperatures than the 250-300°C steam raising in an SMR. Consequently, LCH technology uses 10% less natural gas per unit of hydrogen produced, leading to lower overall CO₂ emissions.

Like SMR, LCH technology requires substantial steam to be added to the feed natural gas. In the process, about 60% of the steam is generated through the saturator circuit, 20% from the ITS converter, and the remaining from the steam boiler. Steam generation using the Saturator circuit and the ITS is more efficient in terms of quality compared to an SMR, which uses the 860°C stream at the reformer exit to raise medium-pressure steam, thereby degrading heat quality. This means that LCH technology achieves higher energy efficiency, with an efficiency rate of 80.5% compared to SMR's 73.3% (LHV basis).

The importance of LCH for CO2 emissions and capture

The efficiency of LCH technology is achieved by operating the ATR at high temperatures to minimise methane slip, thus reducing CO₂ emissions when the PSA tail gas is combusted. Additionally, a highly efficient shift converter maximises reaction conversion, further minimising CO slip and CO₂ emissions during the combustion of PSA tail gas.

CO₂ can be removed cost-effectively and with a higher capture rate in LCH technology than in SMR. Using LCH technology, all CO₂ is contained within the product stream at high pressure and high concentration, making it easy to remove using standard industry technologies. Conversely, in an SMR with CCUS, the flue gas CO₂ stream is at low pressure and diluted with nitrogen from combustion, necessitating a larger and more expensive CO₂ capture system.

The partial pressure of CO₂, crucial for sizing the CO₂ removal system, is 30 times higher in LCH technology than in SMR. This allows for significant intensification of the CO₂ removal system, reducing CAPEX and associated plot plans and enabling higher H₂ production intensity per square meter of land.

The global surge in demand for clean hydrogen underscores the critical role of CCS in the energy transition. Hydrogen's versatility makes it essential for decarbonising hard-to-electrify sectors and integrating renewable energy. While electrolytic hydrogen will take time to scale, CCS-enabled hydrogen offers an immediate solution to meet decarbonisation targets.

Advanced technologies like LCH technology provide significant advantages, including higher efficiency, lower CO₂ emissions, and economic benefits. By incorporating GHR and ATR, LCH technology maximises energy efficiency and reduces natural gas consumption. As nations invest in hydrogen infrastructure, these technologies will play a pivotal role in achieving a sustainable and resilient energy future.