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Attention was directed towards our fossil fuel dependency and the vulnerability of our energy system in 1973 with the oil crisis. This again occurred after the turn of the millennium with increased focus on climatic changes due to increasing levels of carbon dioxide in the atmosphere. Now, today, in the twenty twenties, climatic changes are slowly becoming a visible reality.

Since the start of industrialization, the global energy demand has increased exponentially, partly due to the expanding world population. However, we have plenty of available renewable energy resources, such as sunlight and wind, but these fluctuate strongly over time and geography. The most difficult challenge appears to be efficient, reliable, and long-term storage of renewable energy, over days, weeks, and maybe months, which can level out the fluctuating energy sources and integrate with our varying energy consumption.

Today, a sustainable energy system based on renewable energy has a high position on the long list of societal challenges we are facing, and scientists have significant responsibility to contribute. We need fundamentally new and ground-breaking ideas, not just incremental improvements of known technologies, in order to create a sustainable energy system based on renewable energy. Hydrogen and metal hydrides may be of key importance in designing new energy storage and conversion technologies, also providing the potential of closing the carbon cycle.

Hydrogen reacts with most other elements and forms diverse types of chemical bonds. Therefore, metal hydrides present a very diverse class of materials. The research focus was initially to use metal hydrides for energy storage as hydrogen in the solid state. Several reversible systems were discovered and some used in demonstration units or commercialised or appear as promising systems for the future applications, e.g. based on 2LiBH4-MgH2, MgH2, or Mg(BH4)2. Metal hydrides are also considered for storage of concentrated solar thermal power and to close the carbon cycle by a reaction with carbon dioxide. Recently, metal hydrides received much attention as electrolytes for future battery materials for solid-state batteries. They have extraordinary high ionic conductivity at moderate temperatures and also a large electrochemical stability window.

The aim of this symposium and summer school, HydEM 2020, is to combine the knowledge from experienced scientists with the creativeness and scientific curiosity from young scientist. Many high-profile invited speakers will present talks starting with an introductory component, followed by frontier research results, and ending with a discussion of possible future utilization.

Our hope is that HydEM 2020 will catalyse discussions and new collaborations among scientists, young and experienced, and from diverse research fields, thus inspiring novel ideas, completely unknown today.


The Figure [1] illustrates that water can be ‘split’ into oxygen and hydrogen (green arrows), and most of the energy used in this process can be released again when hydrogen reacts with oxygen. A carbon-based energy carrier system is also illustrated (blue arrows), but hydrocarbons are currently energy-consuming and difficult to produce from biomass or CO2 from the atmosphere.

Notice that a sustainable future can only be created with closed-materials cycles for all chemicals and materials that we use. Today, most materials are unfortunately ‘single-use’ and not re-cycled. Likewise, CO2 produced from fossil fuels is discarded into the atmosphere symbolized by personal vehicles and industrial emission ultimately leading to global warming (black arrow, picture row).  


[1] "Complex hydrides for hydrogen storage – new perspectives", Morten B. Ley, Lars H. Jepsen, Young-Su Lee, Young Whan Cho, José Bellosta von Colbe, Martin Dornheim, Masoud Rokni, Jens Oluf Jensen, Michael Sloth, Yaroslav Filinchuk, Jens Erik Jørgensen, Flemming Besenbacher, Torben R. Jensen, Mater. Today, 2014, 17(3), 122-128