Role of inorganic side streams in hydrogen economy

Annually, in Finland alone, millions of tonnes of slags, fly ashes, mine tailings, municipal solid and sewage sludge waste-materials are generated from water treatment plants, construction, mining, and mineral industries. These inorganic materials comprise of Al, Si, Mg, Ti, Fe, Ni, etc. elements in silicates or oxides form. There is a huge scope to design and develop the inorganic waste materials in catalysis, membranes, energy storage materials, and CO2 utilisation applications in the framework of hydrogen economy integrated with PtX technology.



At the moment, decarbonising the whole industries is utmost critical due to climate change. Today, hydrogen economy is seen rather as a reality than hype and foreseen the future promising solution and roadmap in replacing fossil driven economy. Hydrogen is the most abundant and lightest element on the earth but not available in free form. It has the highest energy density than any other conventional fuels. The whole process and the value chain of hydrogen economy consists of hydrogen production, conversion, storage, distribution, and end user applications. Significant challenges exist in each category to implement hydrogen economy successfully.



Today, most of the hydrogen is produced via steam reforming of natural gas (grey hydrogen), which emits highest amounts of CO2 and equipped with carbon capture technology termed as blue hydrogen. Currently, turquoise and green hydrogen production methods are key for the sustainable solutions for the short to long term goals. The CO2-free hydrogen production via thermocatalytic decomposition, TCD, of methane (or biogas) is termed as turquoise hydrogen production (whereas green hydrogen is produced using renewable energies without carbon emissions). TCD holds huge potential at commercial scale due to high value carbon materials for different applications besides hydrogen (e.g., carbon application in energy storage, rubber industry, etc.) and solar hydrogen via photocatalytic hydrogen production are the key methods for the long-term solutions.



Moreover, the global challenges in tackling the food and municipal solid wastes (MSW) is huge and providing sustainable solutions is the key. Significant amounts of hydrogen (e.g., 2-3 m3/h LEL) and carbon oxides are produced by abiotic conditions over days from land-filled & incineration. MSWI waste to energy conversion (WtE) technique can be utilized in production of moderate amount of clean energy, and the bottom/fly ash to metal oxides precursor.