Scientists at the École Polytechnique de lausanne de lausanne have created a new system: it combines a conventional redox flow battery, which stores energy, and catalytic reactors that produce pure hydrogen from liquid.
The new system, created by the scientists, provides more flexibility and capacity for storing energy, and also produces pure hydrogen at a lower cost.
Today, the need for reliable renewable energy sources is growing rapidly as countries around the world are actively fighting climate change. But renewable energy won’t be efficiently used in power grids until a way to store it on a large scale is invented.
To create their universal system, scientists used a conventional redox flow battery. Such batteries are used to store electricity in containers with liquid electrolyte, which are passed through the battery core from positive and negative half-cells separated by a membrane. In the process of obtaining energy, the spent electrolyte is pumped through the cells, being charged during an electrochemical reaction, and returned to the storage tank.
In a new work, the authors improved this battery by adding two catalytic reactors to it: they produce hydrogen from liquid circulating in tanks.
Hydrogen is produced by a catalytic process that uses battery power to separate water molecules into their two components, hydrogen and oxygen. But such hydrogen can only be considered clean if the energy used to charge the batteries is renewable.
Danik Reynard, PhD Student, EPFL Physical and Analytical Electrochemistry Laboratory
The new technology offers a number of advantages for both hydrogen production and energy storage. Whereas conventional redox batteries, once fully charged, can no longer store energy, in the new system, a fully charged battery can discharge liquid into external reactors that generate hydrogen. It can be stored and used later to free up storage space in the battery itself.
The hydrogen produced by the system is pure and only needs to be compressed for optimal storage. The new system is also safer than conventional systems, as it generates oxygen and hydrogen separately, rather than simultaneously – so there is less risk of explosion.