Aurora Hydrogen ($16M for microwave pyrolysis of natural gas to produce clean hydrogen)

Aurora Hydrogen, a Canadian cleantech startup founded in 2021, develops microwave pyrolysis technology for clean hydrogen production. The technology uses efficient microwave energy to heat natural gas in the absence of oxygen and water and produces hydrogen without generating carbon dioxide emissions.

Challenges: hydrogen fuel

The majority of the world’s hydrogen (over 60 million tons) is currently produced via steam methane reforming (SMR) process. This process requires a significant amount of energy input and emits a substantial amount of CO₂. The SMR process emits between 5 and 9 tons of CO₂ per ton of hydrogen (H₂) produced.

Aurora Hydrogen Technology

Aurora Hydrogen develops microwave methane pyrolysis technology that efficiently converts natural gas into hydrogen and solid carbon without emitting CO₂. The reactor system is scalable and can be installed anywhere, from small fueling stations to large industrial applications.

The schematic diagram below depicts the microwave pyrolysis reactor system. The system mainly consists of a microwave generator, a waveguide, a pyrolysis reactor, a heat exchanger, a particle separator, and a hydrogen separator.

Aurora Hydrogen's microwave pyrolysis reactor system (from patent CA 3173801 ). — Aurora Hydrogen’s microwave pyrolysis reactor system (from patent CA 3173801 ).

The microwave generator generates microwaves that are then guided through the waveguide into the pyrolysis reactor. The pyrolysis reactor contains initial solid carbon which acts as pyrolysis reaction catalysts. The feedstock natural gas is introduced to the heat exchanger, which then introduces the preheated natural gas to the pyrolysis reactor. Methane pyrolysis reaction occurs upon the solid carbon in the reactor being heated to 1,600 K by microwaves. The hot carbon transfers heat to methane molecules and catalyzes the decomposition of methane into hydrogen and carbon with over 90% efficiency.

The produced hydrogen and solid carbon are then introduced into the heat exchanger, where their heat is transferred to the natural gas feedstock that is about to enter the pyrolysis reactor. Cooled hydrogen and solid carbon are then introduced into the particle separator, where they are separated. The solid is collected after leaving the particle separator. Hydrogen exits the particle separator and enters the hydrogen separator, where pure hydrogen exits and residual gas containing unreacted natural gas enters the feedstock input for further pyrolysis reaction.

The reactor vessel is composed of materials, such as quartz and stainless steel, which do not absorb microwaves. If the reactor vessel is composed of materials that are heated by microwave, the reactor may become fouled, resulting in slow and inefficient pyrolysis reaction. Materials that allow microwaves to transmit include polytetrafluroethylene (PTFE), alumina-based ceramics, corundum, fused quartz, boron nitride, silicon nitride, aluminum nitride, etc. Materials that reflect microwaves include stainless steel, carbon steel, brass, bronze, iron, copper, silver, gold, aluminum, zinc, lead, chromium, manganese, titanium, molybdenum, tungsten, etc.

Initial solid carbon in the reactor serves as the primary microwave susceptor. Preferred are pure forms of solid carbon, such as carbon black or graphitic carbon produced by the methane pyrolysis reaction. The solid carbon should be free of metal impurities and oxygen-containing species.

If metal impurities in the solid carbon are relied upon to drive the reaction, the newly formed solid carbon will deposit on the impurities, shielding the methane from metal impurities that act as catalytic sites and preventing the catalytic reaction. If oxygen-containing impurities, such as water, are present, pyrolysis does not occur and CO₂ is produced.

Natural gas feedstock should be sulfur-free, as sulfur can reduce the catalytic effect of carbon.

The energy requirement across the pyrolysis reactor is 31 MJ/kg H₂ and the total energy requirement is 38 MJ/kg H₂. The energy required to make hydrogen by the electrolysis of water is 193 MJ/kg H₂. Thus, the electricity required to make hydrogen by the microwave pyrolysis is 20% of that required to produce hydrogen through electrolysis.

Aurora Hydrogen Patent

CA3173801A1 Methods for preparing hydrogen and solid carbon from a gaseous hydrocarbon source using microwaves and/or radio waves
WO2022232942A1 Methods for preparing hydrogen and solid carbon from a gaseous hydrocarbon source using microwaves and/or radio waves