The already enormous energy demand in the world is predicted to continue to rise and by the year 2050 it is estimated that 30 TW/year will be needed. At the same time, fossil fuel resources are being depleted at a (much) faster rate than they are formed and there are great concerns regarding the influence of CO2 emissions on the global climate. Therefore, alternative energy sources are being developed. However, the main renewable energy sources, wind and solar power, does not supply a steady output of power. An energy carrier is needed.
For this purpose, hydrogen is a top
candidate. It can either be used to make conventional synthetic fuels such as
methane, methanol, gasoline or diesel. These fuels can easily be used with
existing infrastructure. It could also be mixed into the natural gas lines to
dilute and increase the quality of the fossil gas. Alternatively, hydrogen
could be stored as ammonia (NH3) or as pressurized or liquified
hydrogen and used in power generators or fuel cells.
Figure: Use of renewable energies for carbon-free hydrogen applications
One of the main advantages with using hydrogen as an energy carrier is that it can readily be produced with existing technology. Electricity from solar and wind power plants is produced in excess on sunny and windy days. This electric power can be used to run an electrolyzer, which decompose water into oxygen and hydrogen. The remaining challenge with the technology is simply to make it efficient and economically competitive.
An important step for this to happen is to develop better catalysts, which are necessary both for the manufacturing of synthetic fuels and for the water decomposition process to run smoothly. Presently, platinum group metals (Pt, Pd, Ir, Rh and Ru) are essential components in many of these catalysts. These metals are expensive and scarce and are not mined in Europe to any larger extent. Designing catalysts based on other, more abundant and cheaper materials, that perform equally well or better is therefore of great importance for the transition from the fossil based energy system we have today, to a more sustainable, hydrogen based system.