Water Electrolysis and Renewable Energy Sources
Green hydrogen is a key factor in tackling climate change and facilitating the transition to a low-carbon future.
Its production process relies on water electrolysis, a technology that uses electricity to split water molecules into hydrogen and oxygen.
To be classified as “green”, the energy used must come from renewable sources such as solar and wind power. By using clean energy inputs, electrolysis ensures that the hydrogen produced is carbon-free, contributing to a greener and more sustainable energy landscape.
Water electrolysis requires an electrolyzer, a device composed of a series of electrochemical cells, each featuring an anode and a cathode — the electrodes —separated by a diaphragm or membrane. Immersed in an electrolyte solution, these electrodes use electrical energy to initiate chemical reactions, such as splitting water into oxygen and hydrogen.
An essential aspect of producing green hydrogen using renewable energy sources, like solar and wind power is the intermittent nature of such energy supplies. This means the electrolyzer operates at specific intervals and intermittently.
For example, when connected to a photovoltaic system, the electrolyzer functions during the day but remains idle at night.
Similarly, when connected to a wind turbine, it only works on windy days.
The electrodes (anode and cathode), made of a substrate and an electrocatalytic coating, must endure the stress caused by energy intermittency.
From a practical standpoint, an electrolyzer operates at a specific cell voltage to perform the water electrolysis process. This means the anode is positively charged and the cathode negatively charged, with the electric current flowing in a specific direction to produce hydrogen and oxygen. When the current stops, the electrodes switch polarity, and the electric current starts flowing in the opposite direction, creating what is known as reverse current. These reverse currents can damage the electrodes' electrocatalytic coating.
Stability of Electrocatalytic Coatings
Specifically, the electrocatalytic coatings have a stability range, meaning they are chemically stable within a specific cell voltage range. When the cell voltage is inversed, the anode oxidizes the cathode, and these electrocatalytic coatings dissolve slightly. Therefore, it is crucial to formulate coatings capable of withstanding a wide range of cell potentials to prevent chemical degradation.
This can be achieved by applying a series of metals and metal oxides on the substrate and an intermediate or top layer to the electrocatalytic coating. Therefore, protecting the electrocatalytic coating involves either formulating the actual coating and its distribution on the metal substrate.
The Importance of Data Analysis and Machine Learning
An important aspect of this research is the large amount of data scientists must analyze to evaluate electrode performance. First, it is essential to understand the amount of electrocatalytic coating present on each electrode's substrate.
This is done through X-ray fluorescence (XRF).
Second, scientists use machine learning to examine the dataset collected for each analysis, accelerating the process of evaluating performance under reverse current conditions.
De Nora’s Innovation for a Sustainable Future
De Nora’s ongoing research aims to optimize electrocatalytic coatings to withstand frequent shutdowns and prevent chemical degradation. This research is crucial for green hydrogen large-scale production, in order to decarbonize the energy sector and achieve net zero emissions by 2050.