Hydrogen is a very valuable energy carrier that can solve many of the challenges we see today. The introduction of large amounts of fluctuating renewable energy requires temporary energy storage solutions, e.g. hydrogen. In case of ferries and trucks that need fast filling of energy in large amount, hydrogen has a great advantage over electricity. Furthermore, hydrogen-powered cars have also gained increasing focus. Hydrogen is also an important chemical. Hydrogen can be produced via electrolysis of water (water is decomposed into hydrogen and oxygen) but large-scale production is made primarily from natural gas via a reforming and shifting process, followed by a gas separation process. The project OxHyPro will simplify the process by making the separation directly in the shift process. The use of natural gas is an important step in a transition period to ensure the supply of hydrogen to society. The process will also provide a more environmentally friendly perspective on the use of natural gas for hydrogen production if CO2 is captured and stored.
Biogas will also be one of the future energy sources that also need CO2 capture to achieve climate goals for 2050. The project OxHyPro will convert and separate biogas into pure CO2-containing and hydrogen-containing gas streams. This will be achieved by using energy storage materials that can transfer thermal energy and reduction energy from the combustion reaction to the energy-intensive water splitting reaction. With this, a thermal neutral process can be achieved.
The challenge lies in developing metal oxides that are stable through repeated oxidations and reductions, but also in the development of a composition that provides optimal energy storage capacity under the given conditions.
So far, 8 metal oxides have been developed that are stable during reduction and are being tested. Their oxygen storage has been mapped as a function of gas composition and is now being tested in reactors to optimize hydrogen production using natural gas or biogas. Exsolution of nano-catalysts from the metal oxide is part of the systems that are being investigated, so direct reduction of the metal oxides via methane can be achieved without the use of reforming catalysts.
Chemical looping hydrogen production (CLHP) using a three-reactor system (methane, steam and air) has attracted lots of interest due to inherent CO2 separation, production of pure H2 without the need of expensive separation processes, thermal neutrality, and reduced economic sensitivity towards process scale as compared to the conventional SMR. Iron oxide is often used as an oxygen carrier material (OCM) for CLHP as this material has favorable phase changes, but disadvantages are related to the materials lifetime due to agglomeration and formation of Fe, especially when the materials are circulated among three reactors at high temperatures. Therefore, it is urgent to develop novel and stable OCMs with the required functionality, stability, catalytic activity, reaction rate to ensure a high conversion of steam into hydrogen and a full conversion of CH4 to CO2.
The OxHyPro project addresses these challenges and takes as starting point the discovery of new perovskite systems with high steam conversion into H2 obtained in a preceding EU project. The project combines catalysis, solid-state electrochemistry, solid state ionics, chemical looping technologies, and ceramic engineering to develop stable, robust novel OCMs and utilise non-stoichiometric oxides with tailored thermodynamics in order to achieve autothermal operation. This will be exemplified in this project with the development of OCMs with a H2 yield >80% and oxygen transfer capacity of 3-8wt% stable for 1000 redox cycles. Reactor tests with a fixed bed design will be performed on developed OCMs for verification of the concept. The project is coordinated by SINTEF with University of Oslo as the collaborator and has an advisory board including industries from biogas companies such as Antec Biogas and Biogass Oslofjord, and materials fabrication company Cerpotech, etc. to ensure industrial relevance. It trains one PhD and lasts for four years.