In the quest for a hydrogen-powered future, scientists are delving deep underground to unlock the secrets of large-scale hydrogen storage. A recent study led by Sadegh Ahmadpour from the Department of Energy Resources at the University of Stavanger in Norway has shed light on a significant challenge that could impact the viability of using depleted gas fields for hydrogen storage: the generation of hydrogen sulfide (H2S) through a process known as thermochemical sulfate reduction (TSR).
Hydrogen is touted as a clean energy carrier with the potential to decarbonize heavy industry and revolutionize the aviation sector. However, the infrastructure to support a hydrogen economy is not yet in place. Large-scale hydrogen storage is crucial to balance the intermittent supply and demand. Depleted gas fields, with their existing infrastructure and pipeline networks, seem like ideal candidates for this purpose. But there’s a catch.
Ahmadpour’s research, published in the journal ‘Deep Underground Science and Engineering’ (translated from Norwegian as ‘Dyp Underjordisk Vitenskap og Ingeniørfag’), reveals that TSR, a process that occurs at high temperatures, can consume hydrogen and generate substantial amounts of H2S. This is a problem because H2S is not only toxic but also corrosive, posing significant environmental and safety risks.
The study used a one-dimensional diffusion-based mass transport model to simulate the conditions within depleted gas fields. The results were eye-opening. “We found that the presence of iron minerals, like pyrite and hematite, is crucial for H2S generation through TSR reactions,” Ahmadpour explained. Moreover, the study showed that an increase in temperature leads to an increase in H2S concentration in both the brine and gas phases.
However, the findings also challenged conventional wisdom. “Most of the H2S formation comes from pyrite dissolution, and this process is still strong at lower temperatures,” Ahmadpour noted. This means that simply choosing lower temperature conditions may not be an effective strategy to avoid H2S formation.
So, what does this mean for the future of hydrogen storage? The research underscores the need for careful consideration of the geochemical processes at play in depleted gas fields. It highlights the importance of understanding and mitigating the risks associated with TSR to ensure the safe and efficient storage of hydrogen.
As the energy sector looks to hydrogen as a key player in the transition to a low-carbon future, this research serves as a timely reminder of the complexities involved. It’s a call to action for further investigation and innovation to overcome these challenges and unlock the full potential of hydrogen as a clean energy carrier.
In the words of Ahmadpour, “Precautions must be taken to ensure that activation of TSR does not pose significant environmental problems.” This research is a step in that direction, providing valuable insights that will shape the development of hydrogen storage technologies and strategies in the years to come.