Hydrogen Storage: Challenges, Prospects, and the Path Ahead

As we explore new ways to store energy, hydrogen has emerged as a promising candidate. However, while hydrogen is abundant and produces only water when heated, it is also challenging to store, transport, and use efficiently.

We researched the available solutions of overcoming these challenges and identified the most cost-effective and efficient methods for storing and transporting hydrogen.

After extensive analysis, we arrived at a previously unfamiliar approach: storing hydrogen in solid form using metal hydrides holds great potential in meeting energy storage needs in a safe, cost effective and sustainable way.

Here are some of our findings and observations. Keen to hear what others think about this niche market.

The Basics

·        BloombergNEF estimates that the energy storage market will grow to a cumulative capacity of 411 GW/1,194 GWh by 2030, which is 15 times the current capacity at the end of 2021

·        Due to its low weight and high gravimetric energy density of approximately 33 kWh/kg, Hydrogen can serve as an efficient carrier for storing and transporting energy, surpassing the energy storage capacity of gas or Li-ion batteries.

·        Hydrogen, the earth's most abundant element, is increasingly being considered for decarbonizing difficult sectors such as long-haul transportation, aviation, industrial chemicals, and mineral processing.

·        It can be produced with close to zero CO2 emissions. In specific, Green Hydrogen is produced by electrolysis which separates the hydrogen and oxygen atoms in water molecules producing pure hydrogen gas.

Estimated Demand

·        Projected hydrogen demand by 2050 varies from 150 to 500 million tonnes annually, which represents a potential increase of up to fivefold from current levels of less than 100 million tonnes in 2021

The Challenge

·        The low volumetric energy density of hydrogen, at approximately 2.8 Wh/l, presents a major challenge for its efficient storage and transportation, thus requiring innovative transformation methods.

Susten’s Review of current Solutions

(Source: US Department of Energy)

·        Compressed hydrogen is the most commonly used mechanical storage method due to well-known costs and technology. However, it is not the most efficient method due to:

• Low volumetric density; 870 Wh/l for under 350 bar; 1,400 Wh/l for under 700 bar

• Energy consumption. Compressing consumes ~15-16% of the energy.

• Safety concerns. Special tanks needed to endure compression and meet safety requirements.

• Gas leakages

·        Liquified hydrogen has higher volumetric density and high purity. However it has several drawbacks including:

• Costly equipment, energy-intensive: 11.9 – 15 kWh / kg of H2 resulting in current liquefaction cost: $2.5-$3.0 per kg of LH2,

• High boil-off losses during storage, transportation and handling which can consume up to 40% of its available energy,

• Difficulties in storage due to the need for sophisticated tanks and facilities to maintain temperatures as low as -253°C

• Lack of safety standards and regulation that can impede the development of liquid hydrogen infrastructure.

·        Liquid Organic Hydrogen Carriers (LOHC) is a method of hydrogen storage in which hydrogen is absorbed by organic compounds and released through chemical reactions. This method offers several advantages including:

• Comparatively high energy density, especially by volume, although it may not always compete with other storage solutions like metal hydrides in terms of hydrogen storage capacity

• Stability and safety, as LOHCs do not require high pressure or extreme temperatures for storage

• Compatibility with existing infrastructure, such as pipelines and tanks, which can reduce the cost of hydrogen adoption

• Prolonged storage without energy losses and long-distance transport capabilities

• Energy can be released in a controlled manner at the time and location it’s needed the most.

However, the process of hydrogen absorption and release by LOHCs can be relatively inefficient. Some LOHCs can be expensive to produce and can require additional purification steps, which increases the cost of using them as a hydrogen carrier.

·        Metal hydrides Metal hydrides is a method of hydrogen storage that involves forming a chemical compound between hydrogen and a metal.

This method offers several advantages including:

• Good volumetric capacity, up to 18 wt% of H2, making them suitable for onboard applications. However, hydrogen release temperatures may be quite high (can range from below 100 C to 400 C),

• The most promising ones are light metal hydrides which have higher gravimetric storage capacity and can be released in lower temperature.

However, metal hydrides face several challenges, including:

• Maintaining their efficiency at commercial scale

• Reducing the cost of metal hydride production and implementation

Comparing efficiency

·        We have analyzed the energy density of different fuels and carriers under the lens of the efficiency of the engines that use them, such as hydrogen fuel cells, methanol fuel cells, and internal combustion engines (ICEs)

·        Hydrogen and methanol fuel cells are considerably more efficient, with efficiency rates of 40-60% and 40-50%, respectively, compared to gasoline or diesel ICEs, which have efficiency rates of 25-38% and 30-45%, respectively

·        This higher efficiency increases the overall performance of hydrogen carriers in terms of energy density compared to conventional energy carriers, making metal hydrides and some chemical hydrogen more competitive in terms of hydrogen storage capacity. 

Applications

·        Metal hydrides and liquid organic hydrogen carriers (LOHCs) have promising applications in various industrial sectors, including energy storage in residential and industrial settings, and as power sources for unmanned aerial vehicles (UAVs) such as drones.

·        Although metals are relatively heavy in their solid form, when combined with other substances that can alter their solid state, metal hydrides can become a feasible option for transportation and portable applications.

In conclusion, hydrogen storage has the potential to revolutionize the way we store and transport energy, offering a clean and efficient alternative to traditional fossil fuels. With continued innovation and investment, we can expect to see even more promising developments in this field.

We welcome your feedback and thoughts on the prospects of hydrogen storage developments and their potential applications. Let us know if you agree or disagree with our analysis, or if you have any ideas or insights to share on this exciting and rapidly evolving field.