1. Few chemicals carry as much hope and aspiration as hydrogen. Over the last few years, the first element in the periodic table has gone from a global buzzword to one of the most promising routes to decarbonizing industry, power generation and transport.
2. As production of the gas using low-carbon resources ramps up around the globe, the vision of a green hydrogen-powered economy faces a number of challenges. Alongside scaling production and lowering costs, one of the biggest challenges is hydrogen storage.
WHY IS HYDROGEN ENERGY STORAGE VITAL?
1. Hydrogen has the potential to address two major challenges in the global drive to achieve net zero emissions by 2050. First, it can help tackle the perennial issue of the intermittency of renewable energy sources such as wind and solar. By converting excess power generated on windy or sunny days into hydrogen, the gas can store renewable energy that can then be dispatched at times of peak demand as a clean fuel source for power generation. Second, hydrogen can replace fossil fuels to decarbonize sectors where electrification alone won’t suffice, such as domestic heating, industry, shipping and aviation.
2. The hitch is that, while an excellent medium for renewable energy storage, hydrogen itself is hard to store.
3. This is because it has a low volumetric energy density compared to other gases — such as natural gas — meaning it takes up significantly more space. Also, hydrogen has a boiling point close to absolute zero and requires cryogenic storage. And while it does not typically corrode storage containers, it can cause cracks in metals under certain conditions.
4. Here are four hydrogen storage solutions that could help address these challenges, as mapped out by Hydrogen Europe.
1. GEOLOGICAL HYDROGEN STORAGE
1. One of the world’s largest renewable energy storage hubs, the Advanced Clean Energy Storage Hub, is currently under construction in Utah in the US. This hub will bring together green hydrogen production, storage and distribution to demonstrate technologies essential for a future decarbonized power grid.
2. Mitsubishi Power, a power solutions brand of Mitsubishi Heavy Industries (MHI), is providing the technology for producing hydrogen from renewable energy, which will then be stored in a series of salt caverns. They will be constructed deep underground in a salt dome that covers more than 4,800 acres. Each cavern will be about 67 meters in diameter and 580 meters in height.
3. Mitsubishi Power is also involved in a similar project with Texas Brine in the US, where salt is being extracted from giant caverns to make room for hydrogen storage.
4. Gas storage in salt caverns is an established method, enabling easy knowledge transfer. Other options for geological storage include depleted oil fields and aquifers.
2. LIQUIFIED HYDROGEN
1. As well as storing hydrogen in its gaseous state, it can also be stored as a liquid. MHI Group, along with the space industry as a whole, has used liquefied hydrogen to fuel rockets for many years.
2. But liquid hydrogen storage is technically complex and, as such, has historically been very costly.
3. Hydrogen has to be cooled to -253°C and stored in insulated tanks to maintain this low temperature and minimize evaporation. This requires a complex plant.
4. Complexity and cost have limited the use of liquified hydrogen to date. Some of the biggest users include the semiconductor chip industry and the application hydrogen is probably best known for: as rocket fuel for space launches.
5. The International Energy Agency highlighted in its most recent hydrogen report that critical technologies such as liquefaction still needed to be scaled up. It pointed to the launch of the first shipment of liquefied hydrogen between Australia and Japan in early 2022 as a major milestone.
6. With the proliferation of renewable hydrogen supply and demand, greater economies of scale will make liquefaction a more viable storage and transport option.
3.COMPRESSED HYDROGEN STORAGE
1. Like any gas, hydrogen can also be compressed and stored in tanks, and then used as needed. However, the volume of hydrogen is much larger than that of other hydrocarbons — nearly four times as much as natural gas. For practical handling purposes, hydrogen therefore needs to be compressed. For example, fuel-cell powered cars run on compressed hydrogen contained in large, highly pressurized containers.
2. If an application requires hydrogen volume to be reduced further than compression can achieve, it can be liquefied. The two techniques — compression and liquefaction — can also be combined.
3. Hydrogen’s low energy density, high volume and need for cryogenic storage are some of the biggest barriers to its growth. This is especially true for mobility applications such as heavy transport, where the space and other requirements for hydrogen storage would drastically reduce the room for passengers and cargo. The same applies to vehicles, where a balance needs to be struck between passenger space and range.
4. One solution is a new type of tank for the automotive sector — one of many hydrogen infrastructure projects supported by the European Union.
4. MATERIALS-BASED STORAGE
1. An alternative to compressed and liquefied hydrogen is materials-based storage. Here, solids and liquids that are chemically able to absorb or react with hydrogen are used to bind it. This includes creating metal hydrides from elements such as palladium — which can absorb 900 times its own volume in hydrogen — as well as magnesium, aluminum and certain alloys.
2. Using ammonia — a compound of hydrogen and nitrogen — as a carrier for hydrogen is, arguably, the option with the most potential. Its energy density by volume is nearly double that of liquefied hydrogen, making it far easier to store and transport.
3. This means that hydrogen is converted to ammonia, transported to its destination and then “cracked” to release the hydrogen at its point of use. Ammonia cracking is still in the early development stage and conversion rates remain low — around a third at best.
4. It has been suggested that ammonia could become the “workhorse” of a future hydrogen society, especially where direct use of hydrogen is not an option. Countries such as Japan and South Korea are looking to import ammonia as they have less opportunity to produce hydrogen and get it to direct offtakers. For example, MHI’s shipbuilding division is designing a vessel that will be powered by and also ship ammonia.
5. Most countries in Europe and the US are more likely to prioritize hydrogen as it can be more easily produced and consumed locally, such as within industrial clusters or via pipelines.
6. Of the more than 100 low-carbon hydrogen projects listed in Wood Mackenzie’s Hydrogen Project Tracker, over 85% integrate ammonia and hydrogen to serve domestic and export markets.
SOLVING THE HYDROGEN STORAGE PROBLEM THROUGH RETICULAR CHEMISTRY
1. The US-based company H2MOF believes that molecularly engineered materials can provide the much-needed solution for the hydrogen storage conundrum. Pamela Largue spoke to Magnus Bach and Dr Neel Sirosh to learn more about the magic behind the science.
2. When Nobel Laureate and Professor Sir Fraser Stoddart and Professor Omar Yaghi joined forces to solve challenges associated with energy transition, focusing specifically on hydrogen storage, it was clear from the outset that this partnership could produce magic.
3. In 2021, these two great chemistry scientists co-founded H2MOF, which aims to use novel materials called MOFs or Metal–Organic Frameworks for solid-state hydrogen storage.
4. A scientific breakthrough in this field could have a far-reaching impact on the decarbonisation of our energy systems, which is why Dr Neel Sirosh, CTO at H2MOF, and Magnus Bach, Vice President of Business Development, are inspired by the opportunity to work on such a critically important challenge with people they refer to as “some of the sharpest minds on earth”.
THE PROBLEMS WITH HYDROGEN STORAGE
1. Bach and Sirosh elaborated on the challenges of hydrogen storage, the inspiration behind H2MOF’s solution.
2. Bach didn’t mince his words stating: [Hydrogen] is the ultimate dark horse that once and for all can solve this decarbonisation challenge that humanity is facing.”
3. But the existing technologies will not easily scale because of cost and energy inefficiencies, he explains. Therefore, the wider adoption of hydrogen is challenged.
4. “To utilise hydrogen to the extent that we can decarbonise the energy system…We need transformational technologies rather than incremental improvements on the existing technologies because they’re just not going to fly at the end of the day.”
H2MOF’S MULTI-PRONGED SOLUTION
1. Sirosh provided details concerning the complexity of hydrogen storage, a key focus for H2MOF’s solution.
2. “We can liquefy hydrogen and transport it in very large quantities. But liquefaction takes up almost 40% of the energy content of hydrogen produced and it’s very expensive. The delivered cost of liquid hydrogen is very high due to the high cost of liquefaction and boil-off losses.”
3. “Hydrogen is produced as a low-pressure gas, we compress or liquefy it to enhance its density for storage and transportation, which significantly increases the delivered cost of the fuel.
4. “If hydrogen does not need to be compressed to 350 or 700 bar, but rather goes through one or two stages of compression to a much lower pressure, the net effect is lower cost hydrogen.”
5. In other words, H2MOF keeps it at a low pressure and transports it at similar densities as compressed hydrogen, lowering the cost to the customer.
6. In this way, H2MOF’s solution is lowering the levelized cost of hydrogen, explains Sirosh, while helping to boost the demand side by facilitating transportation and use in industrial applications or power generation.
7. Bach continues: “There’s also the safety metric to consider in the sense that it’s associated with some safety concerns to store and transport hydrogen at super high pressure or as cryogenic liquid at 253 degrees minus.” Those concerns can be mitigated, but it comes with costly safety measures.
8. H2MOF solid-state solutions do not require these safety measures while also avoiding the energy penalty and consumption linked to both liquification and compressed storage, which according to Bach, makes this a “potential game changer.”
Source:
https://spectra.mhi.com/4-ways-of-storing-hydrogen-from-renewable-energy
https://www.powerengineeringint.com/hydrogen/solving-the-solid-state-hydrogen-storage-problem-through-reticular-chemistry/
