(January 7, 2014) "Power to gas" is a key concept
when it comes to storing alternative energy. This process converts short-term
excess electricity from photovoltaic systems and wind turbines into hydrogen.
Combined with the greenhouse gas CO2, renewable hydrogen can be used to produce
methane, which can be stored and distributed in the natural gas network. Empa
researchers have now succeeded in further optimising this process.
The Sabatier reaction,
which produces combustible methane from hydrogen and CO2, has been known for a
long time. Now researchers in the Empa "Hydrogen and Energy"
Department have succeeded in greatly optimising the process. A catalyst is
required to bring about the reaction of CO2 with hydrogen using as little energy
as possible; this catalyst can, for example, be made of nickel. The gas
molecules react more easily with each other on the surface of such a catalyst,
reducing the energy required for the reaction to take place. This is referred
to as sorption catalysis. Empa researcher, Andreas Borgschulte, and his team
have now combined a nanoscale nickel catalyst with a zeolite. Zeolites are
crystalline aluminosilicates with the ability to absorb water molecules and
release them again when heated.
The methanation process uses CO2, for example from biogas
production, and this combined with hydrogen (H2) from excess renewable
electricity, produces methane, which can not only be distributed simply and
cost-effectively in the natural gas network, but can also be stored for longer
periods of time. This means renewable energy is being used to produce a
"quasi-fossil" fuel – the basic principle of "power to
gas".