Start-up pilots liquid salt hydrogen storage in Germany

Start-up Akros Energy has started storing hydrogen in a liquid salt solution at a pilot project in Germany, which it claims could support low-cost, safe hydrogen imports.

Installed at its parent company H2Apex’s 2MW green hydrogen plant in Laage, Rostock, the new pilot is demonstrating Akros’ solution, which is slated as a pressureless, non-toxic hydrogen storage and transportation technology.

Speciality chemical company Evonik and technology major Siemens both contributed to the project, which secured funding from the German state of Mecklenburg-Vorpommern and the EU.

The plant is showcasing a process that reacts hydrogen with a potassium bicarbonate solution to form potassium formate, chemically infusing it into a liquid carrier. Akros says this can “indefinitely” store hydrogen in a non-flammable state.

When hydrogen is needed, the reaction is reversed in a catalytic reactor operating at 60ºC.

While the pilot’s storage capacity has not been revealed, Johannes Emigholz, CEO of Akros, claimed the plant was showing the technology’s potential to offer a “safe, low-cost, and infrastructure-light pathway” for importing hydrogen.

According to Akros’ website, the reaction consumes 8.4kWh per kilogramme of hydrogen stored, compared to 12.6kWh for liquid hydrogen and 16.9kWh for ammonia.

Although the potassium formate’s hydrogen content is just 2.4%, the company claims it can offer a levelised cost of storage of $3.90 per kilogramme and shipping costs of $0.6 per kilogramme.

It comes as Europe seeks to import vast volumes of green hydrogen to meet its decarbonisation targets, amid structurally high costs to produce the molecule on the continent.

Germany expects imports to account for around 70% of its 2030 green hydrogen demand.

However, transporting hydrogen over long distances faces major trade-offs in terms of efficiency losses in converting and reconverting into easy-to-handle carriers.