Electricity and Control March 2023

MEASUREMENT + INSTRUMENTATION

Smart instrumentation for green hydrogen production As a source of power, green hydrogen is showing great promise – to become a fuel that can contribute to meeting the world’s rapidly growing energy needs and decarbonising energy production. In this article, ABB outlines the main drivers behind the push for green hydrogen, how it is produced, and the role that can be played by the latest generation of smart measurement instruments and analysers in the production process.

C ountries worldwide are looking for alternative sourc es of energy and many are turning their attention to the potential of hydrogen. In 2020, about 87 million tons of it were produced globally, and projections envisage a significant increase in the near future. Although consider ably less harmful to the environment than traditional fossil fuels, hydrogen’s impact is not negligible, particularly when it is produced using fossil fuels. Increased effort is therefore being focused on the de velopment of clean or green hydrogen, which is produced through electrolysis, splitting water into hydrogen and oxy gen, using electricity from renewable sources with low or no carbon emissions. As such, the process presents sig nificant potential to reduce energy costs and the carbon impact of energy generation. Green hydrogen is a clean-burning fuel and produces only water as a byproduct. With more renewable energy sources being brought online, the cleaner nature of green hydrogen presents a solution to reducing emissions and ensuring an abundant supply of hydrogen for use in indus trial processes. However, production of green hydrogen, especially at a large scale, presents its own challenges. To ensure ef fective and safe operation and, at the same time, achieve maximum productivity, efficiency, and purity of the hydro

gen gas product, processes need to be controlled with a high degree of precision.

Optimising electrolysis There are three main types of electrolysis technologies used to produce green hydrogen: alkaline electrolyte cells (AEC), polymer electrolyte membranes (PEM/PEMEC), and solid oxide electrolysers (SOE/SOEC). Each has its own advantages and disadvantages. PEM, for example, allows a faster ramp-up, and SOE provides high efficiency, but also requires high operating temperatures. Of the three, AEC electrolysers tend to have the lowest CAPEX requirement. Whatever their respective merits, all three methods rely on accurate measurement of a range of different parame ters, each of which is important in optimising the perfor mance of the electrolysis process. Controlling a hydrogen electrolyser of any kind is crucial to ensure safe operation, efficient power to hydrogen conversion, and appropriate quality control for purity. Temperature measurement is also required to avoid overheating in the electrolyser stack. Smart measurement devices Recent advances in measurement technologies enable the continuous measurement of the critical parameters

The diagram shows part of the green hydrogen production process

18 Electricity + Control MARCH 2023