Researchers propose hydrogen storage using existing infrastructure in lakes and reservoirs

In a new Natural communications In this study, researchers propose a new method of storing hydrogen using existing pipelines located at the bottom of lakes and reservoirs.

Hydrogen has emerged as a promising alternative to fossil fuels for energy production in several sectors. There is a particular focus on green hydrogen, produced by electrolysis of water using renewable energy sources such as solar, wind and air power.

However, widespread adoption of green hydrogen has faced challenges, mainly due to the lack of adequate storage solutions.

This study recommends the use of high-density polyethylene (HDPE) pipes as a means of storing green hydrogen. HDPE pipes are used at the bottom of lakes, reservoirs or hydroelectric storage systems for water management.

Phys.org spoke with the study’s first author, Dr. Julian David Hunt, a research scientist at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia.

He noted that his previous work on deep-sea compressed air energy storage (CAES) inspired him in his exploration of new hydrogen storage strategies.

Limitations of current storage solutions

Several hydrogen storage options are available today, varying depending on how the hydrogen is stored.

As an example, compressed hydrogen must be stored in specialized tanks under high pressure, liquid hydrogen must be stored at extremely low temperatures, and underground storage solutions depend on the specific region.

With region-dependent solutions, such as salt caverns and depleted natural gas reservoirs, the method is not very scalable. Indeed, these resources may not be geographically available where hydrogen storage is needed.

Dr Hunt and his team’s use of HDPE pipes is a more widely applicable method, as these pipes are already found at the bottom of lakes, reservoirs and other hydroelectric energy storage systems.

However, pursuing this option has proven difficult due to the lack of information about the underwater depths of seabeds, river beds, lakes and other bodies of water.

Dr Hunt said: “The main problem is the lack of bathymetric data on lakes and reservoirs. Essentially, this data represents a topographic map of the seafloor or lake bottom, providing information on the shape, characteristics and composition of submerged areas.

Purpose of HDPE pipes

The real purpose of HDPE pipes is water management in water bodies. They can be used to transport water for a variety of purposes including agriculture, consumer needs and drainage.

The material is designed to withstand high pressures underwater, making it very durable. It is also resistant to corrosion and degradation, making it suitable for long-term use.

Additionally, gravel is added around these pipes to ensure that they are stable and do not move due to water currents, thus acting as support for the pipes.

These factors are also desirable if HDPE pipes are to be used for hydrogen storage.

HDPE pipes as storage

Hydrogen can be injected into these pipes from above, thereby forcing the water out into the pipes. Hydrogen must be stored at a certain pressure to avoid unnecessary expansion or compression. This is naturally achieved by the pressure of the water column above the pipes.

By keeping the internal hydrogen pressure at the same level as the external water pressure, the system ensures that the hydrogen does not expand and put stress on the pipes.

When water levels and, therefore, water pressure fluctuate, pressure relief valves are in place to adjust the flow of water and hydrogen, thereby maintaining a constant pressure in the pipes.

If heavy rains cause the water level to rise, it will cause an increase in pressure. In such a scenario, pressure relief valves are used to extract the hydrogen, letting in excess water to maintain pressure in the pipe.

This only works because hydrogen is insoluble in water, making this process harmless to aquatic life and minimizing environmental impact.

Endless possibilities

Researchers used data from California’s Oroville Reservoir to understand the potential of the proposed storage solution.

They found that the levelized cost of storing hydrogen using the proposed method was approximately $0.17 per kilogram at a depth of 200 meters per year.

They further found that the method is more space efficient than solar power generation, requiring approximately 38 times less storage space than installing solar panels.

In addition, this technology demonstrates great versatility, making it compatible with current hydroelectric infrastructures. It can also adapt to different water levels in tanks, increasing storage capacity when those levels rise.

The researchers also used data from artificial lakes and reservoirs.

Data indicates that the global hydrogen storage capacity in lakes and reservoirs is estimated at 15 PWh (petawatt hours), including 12 PWh in natural lakes and 3 PWh in artificial reservoirs.

The Caspian Sea alone represents more than half of this potential (6.4 PWh).

“The possibility of storing hydrogen in hydroelectric reservoirs and lakes significantly increases the possible locations for large-scale hydrogen storage, particularly close to energy demand (cities, industrial areas) or energy supply renewable (solar, wind and hydropower plants)” said Dr Hunt.

The future hydrogen economy

“Hydrogen storage with gravel and pipes in lakes and reservoirs provides a competitive alternative for long-term hydrogen storage and can support the development of future hydrogen economies,” explained the Dr. Hunt.

Since the method uses existing infrastructure, it is cost-effective. Additionally, since hydrogen is insoluble in water, this approach poses no risk to the environment.

However, Dr Hunt highlighted: “The main environmental impact is the existence of large pipelines at the bottom of the lake/reservoir, which could disrupt the flora and fauna at the bottom of the reservoir. »

The lack of comprehensive data in this area poses something of a problem, with Dr Hunt hinting that this may be an area of ​​research he would like to explore.

“An interesting research (topic) would be to combine all possible options for large-scale hydrogen storage in a single database, including geological storage, reservoirs, lakes and ocean storage,” a- he concluded.

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