Hydrogen can store energy for heavy transport and industry, but storing it is not as simple as filling a tank. A coolant choice may shorten the storage cycle—while demanding far more pumping power. Hydrogen is widely recognized as a promising clean energy carrier for future energy systems, with demand expected to increase because of industrial and transport applications.

Batteries are increasingly used for short-distance or light transport, but hydrogen is preferred for long-distance, heavy transportation and industrial uses. The reactor has a basic heat problem: taking hydrogen in releases a great deal of heat, while giving hydrogen back requires the reactor to absorb heat.

A coolant helps manage heat transfer in the storage material, and this study examines ethylene glycol mixed with water as the working fluid. The model’s predictive capability was evaluated by comparing simulation results with published experimental data. The comparison used the simulated and experimental average bed temperature during hydrogen absorption, and the reported agreement was high.

The numerical model was validated by comparing it with published experiments, and the model and experimental results showed good agreement under similar operating conditions, despite some initial differences. The experiments used a water-cooled setup, and no independent experiments were performed for the new coolant mixtures.

The study measures coolant performance by how quickly the reactor reaches its target hydrogen concentration: faster concentration times mean better coolant efficiency. Under the numerical assumptions, pure ethylene glycol produced the shortest predicted cycle time, reducing the time compared with water by 10.7 percent.

Pure ethylene glycol had the lowest normalized cycle time, indicating improved hydrogen absorption and release. But the improvement came with pumping power rising nearly sixfold because ethylene glycol is much more viscous than water. Ethylene glycol also carries heat less effectively than water unless it flows faster, adding another practical trade-off.

For hydrogen storage, speed matters because each cycle determines how quickly the system can be used again. The results indicate that pure ethylene glycol has the shortest overall cycle time among the mixtures studied, while absorption and release times change separately as the blend changes.

Among the coolant compositions considered, pure ethylene glycol had the smallest hydrogen absorption, desorption, and total cycle times. Compared with water, pure ethylene glycol produced the shortest hydrogen-storage cycle, with an approximately 10.7 percent reduction. The results still need confirmation: experiments with ethylene glycol and water mixtures should be performed, and the pumping power they require should be analyzed.

The simulated results still need experimental confirmation, including analysis of the required pumping power, before they can be treated as a complete engineering answer. In this simulation, pure ethylene glycol gave the shortest hydrogen-storage cycle, about ten percent shorter than water.

But the faster cycle came with much greater pumping demands, so real systems must balance speed against cost and power.