12 Introduction
and used for power generation. The advantages of electrolysis are high energy
density, quick response times, zero carbon footprint and potential use in large
scale 33. In gure 1.12 a comparison of the various energy storage technologies
can be seen, based on power scale and discharge duration. Hydrogen production
can cover large scale operation and are suited for response and discharge in a
dynamic range between hours and whole seasons.
Figure 1.12: An overview graph showing various energy storage technologies. The
comparison is based on the power scale as function of discharge duration. The power
scale is divided into three main applications, end-user, transmission and distribution
(T&D) and generation. Other technologies included on this chart are Supercapacitors,
Flywheel, Battery, Pumped Hydro Storage (PHS) and Compressed Air Energy Storage
(CAES). Figure taken from 32.
Furthermore, a major advantage for hydrogen production is the option of
generating a high value fuel which can be used in the transport sector. With
small scale fuel cell systems the hydrogen can be converted into electrical energy
in cars, trucks or boats. Hydrogen is also used as a feedstock in various chemical
processes and is already produced at a large scale. Currently, most of this
hydrogen is made from methane and only 8 GW of electrolysis is currently installed
worldwide 34. Therefore, a shift to electrolysis for hydrogen production
has an extremely large potential for reducing CO2 emissions as well as providing
energy storage and sustainable fuels for the future energy infrastructure. In the
following section an introduction to electrolyzers will be presented.