1 Launch of the world’s leading tonnage Mg-based solid-state hydrogen storage and transportation trailer
Large-scale, safe, and efficient hydrogen storage has long been considered as the bottleneck to the worldwide application of hydrogen energy in human society and industries [
1–
6]. Recently, a tonnage Mg-based solid-state hydrogen storage and transportation trailer (named as MH-100T) (Fig.1) developed jointly by Shanghai Jiao Tong University and Shanghai Hyfun Energy Technology Co., Ltd., was officially unveiled both in Shanghai and World Hydrogen Technology Convention (WHTC, May 22nd‒26th, 2023) held in Foshan, marking a new breakthrough in the field of hydrogen storage and transportation. Profs. Jianxin Zou, Wenjiang Ding, and their team provide key technical support for the development of this solid-state hydrogen storage and transportation trailer.
2 How does MH-100T work?
The MH-100T, equipped with 12 Mg-based solid-state hydrogen storage tanks fitted in a standard 40-inch container, has the ability to store as high as 1.03 tons of hydrogen, which is 3‒4 times of the conventional high pressure gaseous hydrogen storage tube trailer (based on 20 MPa). The principle of such a tonnage hydrogen storage and transportation trailer is to store hydrogen in about 14.4 tons of porous Mg-Ni-based alloy pellets filled in 12 hydrogen storage tanks by chemical absorption to form Mg-based hydrides, which changes the way of transporting hydrogen gas to the transportation of solid powder/particles (Fig.2). Impressively, the whole system has excellent hydrogen ab/de-sorption kinetic performances of achieving a ton level re/de-hydrogenation in the Mg-based solid-state hydrogen storage alloys within 12 h. The MH-100T has the advantages of large hydrogen storage capacity, high gravimetric and volumetric hydrogen density, long-term cycling stability (> 3000 cycles for Mg-based pellet materials with less than 10% capacity loss), and is ready for industrial level large scale storage and transportation of hydrogen with considerable safety and efficiency.
During the hydrogen absorption process, the off-board heat-conducting oil is heated to about 200 °C, and then pumped into the hydrogen storage tanks through the pipelines embedded in the Mg-based hydrogen storage pellets. After the material is heated to designed temperatures by the heat-conducting oil, hydrogen gas with 0.5‒1.2 MPa pressure is allowed to flow into the tanks and the Mg-based materials start to absorb hydrogen and transfer to Mg-based hydrides. The heat released from the hydrogen absorption process (~75 kJ/mol for the formation of MgH
2) is taken out by the conducting oil and can be used to generate water vapor for industrial utilization or as an input for solid oxide electrolysis cells to generate hydrogen. Otherwise, the heat can be stored in phase change materials for the subsequent hydrogen release process if the Mg-based hydrogen system is used in a stationary scenario [
7,
8].
When the stored hydrogen needs to be released, the Mg-based hydrides in tanks are heated to above 300 °C by the heat-conducting oil. The released hot hydrogen is cooled down to below 100 °C through the hydrogen-water heat exchanger to supply hydrogen for hydrogen-using devices or compressors to further raise its pressure. The whole absorption and desorption processes can be remotely controlled by a computer-based program for better safety in an energy-saving manner.
3 Why does that matter?
Hydrogen is considered as the ultimate carbon-neutral energy source. A suitable and low-cost hydrogen storage and transportation technology is an important link between hydrogen production and hydrogen utilization in the whole industrial chain of hydrogen energy. The tonnage Mg-based solid-state hydrogen storage trailer first enables large-scale hydrogen storage and transportation in terms of volumetric hydrogen storage density, cost, and safety. It is worth emphasizing that the traditional high-pressure gaseous tube trailer (based on 20 MPa) can only transport around 280‒350 kg of H2, while the MH-100T can store over 1000 kg H2 in a container of the same size and weight, and the cost of hydrogen transportation is nearly 1/3 of the high-pressure tube trailer (20 MPa). Furthermore, the MH-100T can serve as an energy storage reservoir to store the unstable power generated from photovoltaic and wind sources in high density. Impressively, the tonnage Mg-based solid-state hydrogen storage and transportation trailer opens up a new avenue for significantly reducing the cost of hydrogen in the supporting chain for hydrogen energy, and broadens the range of applications for hydrogen with high safety. Such a tonnage Mg-based solid-state hydrogen storage and transportation trailer will play an important role in the coming sustainable energy revolution.
4 Future trends and application scenarios
In the future, Prof. Zou and his group plan to work with industrial partners to build a complete industrial chain for the production of raw Mg production → Mg-based alloy → Mg-based solid hydrogen storage pellet materials → Mg-based solid hydrogen storage and transportation trailer → Mg-based hydrogen utilization systems for different scenarios. At the same time, they will put the exploration of Mg-based solid-state hydrogen storage materials in energy storage and solid oxide fuel cells on the agenda to steadily expand its marketing scale. Prof. Zou has a bright vision of the new energy infrastructure of “hydrogen production via renewable energy-Mg-based solid-state hydrogen storage and transportation—Hydrogen energy application scenarios” (Fig.3) in the future: Hydrogen can be produced by electrolysis of water (or photocatalytic water splitting if commercially applicable) using electricity generated from clean energy sources like wind and solar [
9–
11]. Such green hydrogen will be stored in large-scale through Mg-based hydrogen storage tanks and transported to application scenarios for power generation using fuel cells or other industry usages (green ammonia production, hydrogen metallurgy, etc.) [
12,
13]. In turn, waste heat generated by PEMFCs/SOFCs can be directly used to provide energy for continued hydrogen release from the Mg-based hydrogen storage tanks through a thermal managing system. For stationary hydrogen storage, the Mg-based hydrogen storage tanks can be used in combination with thermal storage materials (e.g., molten salt, MgO, Al
2O
3, and MgO/H
2O) to store the heat released from the hydrogen absorption of Mg, and such heat is used to release hydrogen from MgH
2. For example, the hydration and dehydration of MgO/Mg(OH)
2 involve high density heat generation and consumption, which might be an efficient solution for heat issues raised in Mg-based hydrogen storage systems [
7,
14]. Impressively, such a tonnage Mg-based hydrogen storage trailer can provide ~1.6 MWh (can be extended to ~3.2 MWh for stationary applications) of electricity based on the up-to-date PEMFCs, which is much higher than that of the commercially available lithium-ion batteries within a container of the same size (~1 MWh) and has the virtue of long-term storage stability.
Magnesium, as a light metal and a hydrogen carrier, is rich both in the earth’s crust and in ocean water, which will promote the key applications of hydrogen energy and usher in a new era of future “hydrogen economy.”
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