The Case for Solid Hydrogen

Hydrogen has received much attention as an energy source, with governments worldwide incorporating it into their plans for a zero-carbon future. However, the management of the resource is still an open question, with experts not yet agreed whether it’s best used, transported, and stored as a liquid, gas, or solid compound. With this question in mind, we spoke to Keen Yee, CEO at Galaxy FCT, who makes the case for solid hydrogen in the form of sodium borohydride (NaBH4).

Keen Yee has not always been a regular in the hydrogen space. In fact, for most of his career his focus was telecommunications. His patents in the field found use globally in a range of communication devices and allowed him ultimately to retire. However, seven years ago, on a visit to Taiwan, Keen came across a project that turned his attention to hydrogen – and back to work.

That project, investigating hydrogen fuel cells in unmanned aerial vehicles (UAV), started in 2008 and following $10 million spend on R&D in eight years, failed to produce the intended results. Hydrogen and fuel cells technology used in UAV’s were simply an idea too early for its application. But, after examining the project, Keen understood its potential. He realised that researchers were on to something extremely interesting. In order to overcome the weight issues, instead of using hydrogen as a gas, a solid chemical, also known as Sodium borohydride (NaBH4), was used and if offered tremendous potential.

Hydrogen is the most abundant element in the universe. That’s part of what makes it such a potent resource. However, as we know, it is often bonded naturally in compounds such as water, while for practical use it needs to be in gaseous form. That brings its difficulties.

“There is no longer the need to go against the grain of physics and fight hydrogen as a gas. It is cheaper to package, transport, store and distribute hydrogen as a solid”

“The main challenge for the hydrogen space,” Keen tells us, as we talk about his work, “is the problem of energy storage and efficiency in hydrogen supply logistics.” Gaseous hydrogen needs to be stored under immense pressure, he explains, making it difficult, expensive, and dangerous to handle. But the common alternative – liquid hydrogen – needs to be stored at -253 Celsius, a highly energy intensive process that depends on extensive infrastructure. That leaves hydrogen in its solid form, a solution about which Keen is optimistic: “There is no longer the need to go against the grain of physics of fight hydrogen as a gas. It is cheaper to package, transport, store and distribute hydrogen as a solid.”

As Keen suggests, solid hydrogen storage is possible if hydrogen molecules are able to bond with a chemical compound such as sodium borohydride (NaBH4) – a reducing agent used in many industrial processes from wastewater treatment to paper pulp bleaching. To make NaBH4 usable as a hydrogen store, green power is fed into an electrolyser that splits water into hydrogen and oxygen. Sodium, boron, and hydrogen can then be combined to make NaBH4 through the Brown-Schlesinger process. Then, once transported, hydrogen gas can be extracted from the compound using a simple hydrolysis reaction.

Chart 1: Solid Hydrogen Logistics Overview

Keen’s excitement about the prospect of this technology is palpable. “It could be a real paradigm shift in how hydrogen is handled, as packaging it as a solid compound can eliminate most if not all the inefficiencies of the gas. This is because the entire supply chain of hydrogen can be conducted at an ambient temperature, without pressure.”

That brings serious benefits. Firstly, solid hydrogen would eliminate the explosion risk and the need for cooling and new infrastructure. But perhaps its most appealing benefit is its energy density compared to liquid and compressed gas. “In hard numbers, hydrogen captured as sodium borohydride carries approximately 120kg of hydrogen per cubic metre. That compares to 71kg/m³ for liquid and 42 kg/m³ for gas at 700 bar pressures.”

Chart 2: Hydrogen Storage & the Key Advantages of Using Solid

Yet, solid hydrogen does have its drawbacks, as Keen is well-aware. The round-trip cycle efficiency is low, due to the need to change hydrogen’s state along the supply chain. NaBH4 production also struggles to compete on cost with gas or liquid hydrogen. But on this too Keen is optimistic. “A continued focus on this technology will make production costs come down,” he insists, “just as solar photovoltaic and wind turbines have done in recent years.“

The entire concept of hydrogen hinges on it being clean. But being clean will not by itself make hydrogen a replacement for fossil fuel. “Hydrogen needs to be economically produced, distributed and used. However, while the electrolysis of green hydrogen has generated widespread commercial interest, releasing hydrogen out of a solid compound through hydrolysis has not.” Perhaps the biggest technological challenge Keen faces is ensuring the sufficient release of hydrogen gas for use and that’s exactly what Galaxy FCT are trying to achieve. “Our main innovation is focussed on the gas-releasing technology that enables the efficient release of hydrogen gas on-demand. This hydrogen generator system can be customised to support different applications.” And the hope is that this will bring further commercial interest.

Chart 3: Hydrogen Production and End-Use

As he mentions, since he set up Galaxy FCT, Keen’s company has focused on two worldwide pending patents for the process of releasing gaseous hydrogen from solid NaBH4. Now, they are offering three main solutions. Firstly, patent licencing, in which Galaxy FCT’s patents can be used by third parties. Then there is their project for developing a hydrogen generator to extract gas from NaBH4. Finally, the company wants to sell hydrogen in either solid or gaseous form to third parties.

But what does all this mean for the end-user? Theoretically, solid hydrogen could be stored as a fuel source onboard a vehicle, releasing hydrogen to power a fuel cell to in turn provide electricity. While this might not be a solution for private cars – owing to the cost and technological demands of making the storage system small – Galaxy FCT’s technology could make sense in where electricity is not accessible (beyond the electric grid) and for larger vehicles like buses, trucks, trains, ships and aeroplane.

Similarly, Galaxy FCT expertise could be well-utilised in the much-needed redesign of fuel stations. For example, today, a typical hydrogen gas station in California needs 250 to 500kg of hydrogen daily, demanding a 3,500kg of hydrogen storage per week. Dealing with those sorts of volumes brings about safety concerns, particularly in densely populated areas. That’s where Keen’s technology could come in. Solid NaBH4 storage using Galaxy FCT patents could deliver hydrogen to the station while reducing storage, delivery, operation cost and mitigating the safety issues. This way, only small volumes of gas would be stored at any moment, while enough solid capacity would be present for several days of refills.

Ultimately all hydrogen application would be in gases form. But for transport and storage, Galaxy FCT’s NaBH4 technology can reduce storage, delivery, operation cost and safety and making hydrogen application in a cost-competitive way. While the case for solid hydrogen is not new, it’s received little serious attention over the years. Now, thanks to Keen Yee, Galaxy FCT is giving it the attention it deserves.

Key Features: