HSL Technologies (€16 million to develop liquid hydrogen carriers for safe hydrogen storage and transport)

HSL Technologies (formerly known as HySiLabs), a French hydrogen energy startup founded in 2015, has developed liquid siloxane hydrogen carriers for hydrogen transportation and storage.

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Challenges: hydrogen storage

Hydrogen (H₂), the most abundant element in the universe, is not just a fundamental building block of stars—it’s also a vital ingredient in the synthesis of ammonia. Production of ammonia plays a crucial role in producing a wide range of products we use on a daily basis, including fertilizers for crop nourishment and plastics for modern life.

Traditionally, the world has relied heavily on steam methane reforming (SMR) to produce over 60 million tons of hydrogen annually. However, this method comes with a significant environmental cost. It’s an energy-intensive process that contributes approximately 2% to global carbon dioxide (CO₂) emissions, releasing between 5 and 9 tons of CO₂ for every ton of hydrogen it generates.

There are cleaner paths to producing hydrogen, such as water electrolysis and methane pyrolysis.

After production, transporting hydrogen to end-users is necessary. Gaseous hydrogen is commonly delivered by trucks called tube trailers. These vehicles compress hydrogen to high pressures (180 bar or higher) in long cylinders stacked on the trailer. Hydrogen is also liquefied and transported in specially insulated trucks or ships.

Alternative solutions to hydrogen transport are emerging, including hydrogen carriers. Hydrogen carriers are either solid-state or liquid-state materials that have the ability to store hydrogen and release it when needed.

Solid-state carriers include metallic hydrides that enable the uptake of hydrogen by adsorption onto metal particles, resulting in metal hydride. Among them, magnesium hydride is stable at low pressure and standard temperature, making it convenient to transport and store. When needed, the material is heated to release the hydrogen gas. Solid-state solutions have been identified as best suited for same-site reversible processes of energy storage from renewable energies. Indeed, handling solid materials is not as convenient as handling gas or liquid ones.

Liquid hydrogen carriers can be any liquid-state material able to release hydrogen under specific conditions. Among the liquid hydrogen carriers, Liquid Organic Hydrogen Carriers (LOHC) are the most represented. Typically, the organic hydrogen carrier is unsaturated or aromatic hydrocarbons, such as toluene and fluorenone.

During the hydrogenation process, hydrogen is chemically bonded to the liquid organic carrier in the presence of a catalyst under heating. The resulting saturated hydrocarbon is transported in a liquid state at standard temperature and pressure. Then the hydrogen is released from the saturated hydrocarbons by a process called the dehydrogenation reaction, which occurs in the presence of a catalyst and heating.

HSL Technologies Technology

HSL Technologies has developed liquid cyclic siloxane hydrogen carriers. The liquid siloxane hydrogen carriers are stable, non-toxic, and non-explosive. They release hydrogen in large quantities with high efficiency in a short time. The resulting solid byproducts can be reused to regenerate liquid siloxane hydrogen carriers. HSL Technologies allows for low-cost and safe hydrogen transport and delivery, enabling on-site hydrogen production for a variety of applications.

HSL Technologies hydrogen carriers

The diagram below depicts the molecular structure of HSL Technologies liquid siloxane hydrogen carriers.

The cyclic siloxane hydrogen carriers present tremendous advantages compared to their poly(hydromethyl)siloxane analogs (ROMeₙHₙSiₙOₙR′), which contain carbon fragments in their backbone.

For example, poly(bis(hydro))siloxane can release more than twice the amount of hydrogen gas when compared to poly(hydroxymethyl)siloxane. Also, poly(bis(hydro))siloxane compounds can be recycled completely without adding any carbon when they are used to make hydrogen and siloxanes again.

Liquid cyclic siloxane hydrogen carriers have the following properties:

dynamic viscosity: 0.2−50 mPa·s (20 ºC and 1.01325 x 10⁵ Pa)
molecular weight: 130−800 g/mol.
refractive index: 1−2 (20 ºC)
boiling point: 50−150 ºC.
flash point: 50−500 ºC.

How HSL Technologies hydrogen carrier works

In the presence of water, cyclic siloxane hydrogen carriers, such as tri(bis(hydro)cyclosiloxane, release hydrogen through a chemical reaction:

HSL Technologies siloxane hydrogen carrier releases hydrogen (ref. US20210269305A1).

The liquid siloxane hydrogen carrier can release a lot of hydrogen in a very short time without any energy input. This is possible by adding hydrogen release initiators (like aqueous sodium hydroxide solution) and catalysts (like hexamethylphosphoramide or tetrabutylammonium fluoride) to the reactants.

Recycling solid silica byproducts can regenerate liquid siloxane hydrogen carriers.

There are several methods for using silica to regenerate siloxane hydrogen carriers (ref. US20210269305A1). For example, silica can first undergo a halogenation step to produce silicon tetrahalide:

Hydrogen gas then reduces the silicon tetrahalide to produce halosilane:

This reduction step allows for the storage of hydrogen gas.

Finally, a hydrolysis process converts the halosilane into a liquid siloxane hydrogen carrier:

Regeneration of the liquid siloxane hydrogen carriers occurs without the need for carbon-containing reactants and without significant carbon emissions.

How HSL Technologies releases hydrogen onsite

HSL Technologies has developed hydrogen release devices that mix two reactants to produce hydrogen gas and solid silica and separate solid silica by products in a simple manner. The diagram below depicts a hydrogen release device.

HSL Technologies hydrogen release device (ref. WO2022219027A1).

The device is a cylindrical reactor. A center shaft rotates relative to the reactor surface. The shaft has two nozzles that spray, respectively, two liquid reactants on the reactor surface. One liquid reactant is a mixture of siloxane and a catalyst, and the other is an aqueous sodium hydroxide (NaOH) solution.

The contact between the two liquids sprayed on the realtor surface undergoes hydrolytic oxidation of the siloxane hydrogen carrier in a short time. The reaction generates solid silica and hydrogen gas, as described above.

A scraper attached to the shaft separates the solid silica byproduct from the reactor surface. The scraper has a sufficient distance from the nozzles to let the reagents react.

Another similar hydrogen release device is described in the patent of US20240017227A1.

The most important advantage of HSL Technologies is the continuous process of hydrogen release and regeneration of liquid siloxane hydrogen carriers are continuously released and regenerated. One can operate such a continuous process without the need for raw material input or by-product emissions.

HSL Technologies Patent

US20210269305A1 Hydrogen carrier compounds
WO2022219027A1 Device for controlled production of a gas from two fluid reagents deposited on a surface
US20240017227A1 System for on-demand production of hydrogen from a carrier fluid and disposal of solid byproducts
AU2019389082A1 Catalysed process of production of hydrogen from silylated derivatives as hydrogen carrier compounds
ES2962238T3 Amino compound-catalyzed hydrogen production from silylated derivatives as hydrogen carriers
EP3816204B1 Process for producing and regenerating hydrogen carrier compounds

HSL Technologies Technology Applications

Overseas hydrogen transportation

HSL Technologies enables the safe and efficient transport of hydrogen over long distances, particularly for overseas shipping. Its liquid form at ambient temperature and pressure makes it easier to handle and transport compared to compressed or liquefied hydrogen.

Strategic storage

The stability of siloxane hydrogen carriers at ambient conditions allows for strategic storage of hydrogen without the need for specialized high-pressure or cryogenic storage facilities.

On-board maritime mobility:
HSL Technologies is adapting their hydrogen release technology for marine applications through their Marinization project. This involves testing the system under simulated marine conditions to verify its performance in maritime environments.

Fuel cell integration

The Qualifhy project focuses on testing the hydrogen release process and its connection with fuel cells, exploring potential applications in fuel cell technologies.

Renewable energy storage

As part of the Sun-to-X project, HSL Technologies’ solution could play a role in storing hydrogen produced from solar energy, contributing to renewable energy systems.

Port infrastructure

The H2 Gate project involves HSL Technologies in creating a large-scale hydrogen import, storage, and distribution hub in the Port of Amsterdam, demonstrating the technology’s applicability in port infrastructure.

HSL Technologies Products

HSL Technologies (formerly HySiLabs) has developed an innovative hydrogen storage and transportation solution called HydroSil.

HSL Technologies has been involved in several projects. These projects demonstrate HSL Technologies’ commitment to advancing hydrogen storage and transportation solutions across various sectors, including maritime, industrial, and renewable energy applications.

H2 Gate project

HSL Technologies is part of a consortium working on the H2 Gate project, which aims to create a large-scale hydrogen import, storage, and distribution hub in the Port of Amsterdam. The project’s goal is to establish facilities with a throughput capacity of 1 million tonnes of hydrogen per year. This initiative started in January 2021 and involves collaboration with major players in the sector, including Port of Amsterdam, Evos, Electriq Global, and Hydrogenious.

Qualifhy project

This consortium project, which began in November 2021, focuses on testing the hydrogen release process and its connection with fuel cells. HSL Technologies is working alongside Helion Hydrogen Power (fuel cell manufacturer), Enogia (ORC turbine manufacturer), and Ecole National Supérieure des Arts et Métiers (engineering school). The project aims to understand the interactions between HSL’s hydrogen release device and fuel cells through bench testing.

Sun-to-X project

Part of the Horizon 2020 program, this project started in September 2020 and aims to develop a system for converting solar energy into storable chemical fuel for use in the energy and transport sectors. HSL Technologies’ involvement likely relates to their hydrogen storage technology, which could play a role in this solar-to-fuel conversion process.

EIC accelerator project

This project, which began in October 2020, focuses on commercializing HSL Technologies’ disruptive technology among major energy companies. The goal is to provide a carbon-free alternative for the transition to a hydrogen economy, leveraging existing logistic infrastructure for fossil fuels to revolutionize hydrogen delivery.

HyPlant project

Starting in July 2020, this project involves the design and manufacture of two industrial demonstrators to produce HydroSil (the hydrogen liquid carrier) and release hydrogen from this carrier. These demonstrators will be installed near HSL Technologies’ headquarters at Technopôle de l’Environnement de l’Arbois, allowing the company to begin industrial-scale production of HydroSil and start the certification process for this new molecule.

Marinization project

This innovation project, which began in October 2022, focuses on adapting the hydrogen release technology for marine applications. It includes testing under simulated marine conditions (swell simulation) and vibration profiles to verify the performance of the reactor and stored HydroSil in maritime environments. This project is funded by the Region and the French government as part of the France 2030 Plan.