Hydrogen can provide a viable source of energy that can cover the world’s energy requirements in the coming years. There are three colours of hydrogen based on how they are produced and processed. Grey hydrogen is made using fossil fuels like oil and coal, which emit CO2 into the air as they combust. Blue hydrogen is made in the same way, but carbon capture technologies prevent CO2 being released, enabling the captured carbon to be safely stored deep underground or utilized in industrial processes.
As its name suggests, green hydrogen is the cleanest variety, producing zero carbon emissions. It is produced using electrolysis powered by renewable energy, like solar and wind energy, to produce a clean and sustainable fuel.
Using renewable energy for green hydrogen production is eco-friendly, while high purity of hydrogen can be obtained from water electrolysis. Water electrolysis is one of the most promising technologies since hydrogen is produced at high rates with high cell efficiency. Additionally, if the electrolysis process utilizes renewable sources (solar, wind, etc) it will be more feasible economically and commercially to produce hydrogen.
The Sultanate of Oman has one of the highest percentages of potential solar radiation in the world, and the southern coastal region has a good potential for wind energy. Fortunately, Duqm has an advantage due to the availability of wind and solar energy, as well as large accessibility on and offshore, giving the country a big advantage in harnessing both energies for green hydrogen production.
One of the major factors for hydrogen energy development is to provide a safe, cost efficient and compacted type of hydrogen storage. The goal of storing hydrogen is generally to minimize the cost of delivered hydrogen through balancing the supply and demand or to use it later as required.
These demands of energy have sub sequential impact on the operation of storage capacity. The known technology for storing hydrogen underground is in porous rock (depleted oil and gas reservoir) and in artificial spaces (salt cavern). These types of technologies for storing hydrogen gas are still lacking hands-on experiences for development. Also, hydrogen production in the Middle East is not very well known across the region.
The concept of storing gas underground in geological formations has been embraced worldwide for hundreds of years with petroleum companies utilising this concept even for underground storage of carbon dioxide (Carbon Capture and Storage – CCS). A depleted reservoir can be defined as a reservoir in sub-surface sand or rock formation that has previously produced oil or gas and is used for storing natural gas. In depleted oil and gas fields the reservoir conditions are usually suitable for storage since most of the surface facilities and subsurface data are available for further development. However, the adaptability for hydrogen storage needs extensive research on technical development, material requirement and safety standard procedures.
On the other hand, salt basins can be considered a good candidate for underground storage, due to the large salt basin that is available in Oman. Adding to that, hydrogen was previously stored in salt deposits at Teesside in the UK, and at two sites in Texas, USA. Salt basins are basically a depression in the earth’s crust that is filled with salt. Gas can be stored inside the salt by creating salt caverns, which are artificial chambers created for gas storage purposes. The salt’s unique properties enable the containment of the gas.
In Oman, we have three evaporitic basins: Fahud Salt Basin in the North East side, Ghaba Salt Basin in the centre, and South Oman Salt Basin in the South East part of Oman. The latter extends for more than 500 km in length and 150 km in width.
In conclusion, salt caverns can be the preferred option in Oman’s case, not least because the technology is proven. Despite the good potential for underground energy storage in Oman, the future of the type and size of storages will depend to large extent on whether hydrogen will be used for production, conversion, transport and consumption. However, more work is needed to confirm the feasibility of producing green hydrogen in Oman and the technical characteristics of the salt deposits.