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September 2015: First hydrogen additions in full scale
Over the summer period from July to August this summer (2025), researchers from the Electrogas project carried out the first full scale hydrogen additions to the anaerobic digester at Aarhus University in Foulum.

A first prototype of a gas mix system for mass transfer of hydrogen into digester liquid was develop and installed at the full scale (1200 m3) reactor).  The injector system was equipped with a high precision mass flow controller (from Insatech) in order to perfectly mass balance the hydrogen and methane balance in the reactor.

The fate of the injected hydrogen was monitored via on line gas chromatography, and a first mass balance is currently under calculation.

The full scale experimental reactor (1200 m3).

The reactor is ideal for experimenting with mass transfer through gas mix since the height of the reactor is comparable to industrial reactors such the injected hydrogen experience the end product like geometry with respect to travel time, bubble formation and CH4 wash out.

In front of the reactor is the Electrogas mobile laboratory, where GC and researchers are operating during measurement campaigns.

For the time being, hydrogen is added from a 20 bottle (200 bar) hydrogen battery via 2 pressure reduction steps and into the mass flow controller installed on the injector. 

Each bottle contains 10 m3 hydrogen so up to 200 m3 hydrogen can be added pr. experiment. Later, a hydrogen generator will be installed which can supply hydrogen continuously up to 100 m3 pr. hour.

The first prototype of the Electrogas injector.

Liquid is dravn from the reactor by the black pump, mixed with the pressurized hydrogen, and injected through a conically shaped gas mix nozzle. Partner Landia has developed and supplied this first injector attempt.