xii UK Focus


SWIRL AND VORTEX METERS WILL AID GREEN HYDROGEN PRODUCTION


The route to net zero will require big changes in the way we generate energy. In this article, David Bowers, Product Manager UK & Ireland Measurement & Analytics, describes how technology innovation is making clean energy possible.


Climate change and pollution in general are major challenges facing the modern world. Much of the unwelcome effects on the environment that we are seeing today are down to an over reliance on fossil fuels in the past. Burning fossil fuels to generate electricity not only produces greenhouse gases such as CO2 and methane, it also leads to elevated levels of gases such as carbon monoxide and nitrous oxide that are harmful to health.


The COP26 summit in Glasgow encouraged countries to draw up ambitious emissions reduction targets for 2030, and thereafter aiming to reach net zero carbon emissions by the middle of the century.


Achieving these targets will mean moving to forms of energy that do not rely on carbon emitting fossil fuels, but which are based on renewable sources.


This means that the search is on for an energy source that can offer much of the convenience and ubiquity of fossil fuels, with few or none of their drawbacks.


Some of the major advantages of fossil fuels is that they can be easily stored and transported and so are ready when needed and have a high ratio of energy to volume (energy density). They can be used in a wide range of applications, from large power plants to district heating schemes, furnaces and boilers for smaller factories, individual houses and in transport. They can also act as a chemical feed stock for industrial processes.


An alternative is renewable sources such as wind and solar. Although these can help reduce emissions, they are intermittent, and it is diffi cult to store the electricity produced.


Hopes for hydrogen


Hydrogen is considered one of the key fuels to help de-carbonize energy use, as it offers many of the advantages of both fossil fuels and wild and solar – it can be produced with low or zero emissions, can be stored and transported readily, is clean burning (producing only water as a by-product) and can be used in further chemical processing or production.


It can be used as fuel for transport and electricity peaking plants (power plants fi red up to meet fl uctuating or peak demands of energy demand), while burning hydrogen can also provide heat for many types of industries and both residential and commercial buildings. Hydrogen can also act as a feedstock for chemicals such as fertilizers, fuel refi ning and plastics.


Although inherently clean, the production method chosen for hydrogen has a big effect on its environmental credentials. In the most polluting method, it can be produced by burning coal, while green hydrogen, the most ecologically friendly type, is produced by electrolysis using renewables or nuclear energy - hydrogen is generally classifi ed as green, grey, blue, brown or white depending on the method used.


If hydrogen is to make a signifi cant contribution to mitigating climate change, most must be in the form of green hydrogen.


The International Energy Agency (IEA) estimates that achieving Net Zero emissions by 2050 will mean that total hydrogen demand from industry will have expanded by 44 percent by 2030 – some 21 million tons will be made up of with low carbon hydrogen [1] Some progress has already been made, with nearly 70 MW of electrolysis capacity installed in 2020, doubling the previous year’s record. [2]


To encourage the production of green hydrogen, a number of countries have put strategies in place to develop a viable domestic hydrogen sector. Europe is expected to lead the fi eld and in fact already has a number of green hydrogen plants in operation. This will rise through signifi cant government investments and the EU aims to produce 10 million tons of renewable hydrogen by 2030 and to import 10 million tons by 2030. [3]


In addition to EU ambitions, most European countries also have their own hydrogen strategies, as do Canada, Chile, USA, China, South Korea, Japan, Australia, Saudi Arabia, Qatar, UAE, India and Israel.


Three major green methods


Three main electrolysis methods can be used to produce green hydrogen.


Possibly the most mature and commercial method is alkaline electrolysis. By avoiding the use of precious metals, it has relatively low capital costs compared to other electrolyzer technologies. However, it does a have a signifi cant drawback in that the process is diffi cult to start up or shut down and output cannot be quickly ramped up to meet increasing demand.


Another method is the PEM (Proton Exchange Membrane) electrolyzer. This uses pure water as an electrolyte solution,


SwirlMaster


avoiding the need to recover and recycle the potassium hydroxide electrolyte solution used for alkaline electrolyzers. Plants using the method can be small and so suitable for brownfi eld urban locations. It can also produce highly compressed hydrogen at between 30–60 bar for decentralised production and storage at refueling stations.


The third and newest method is Solid Oxide Electrolysis Cells (SOECs). These use ceramics as the electrolyte and have low material costs. They operate at high temperatures and with a high degree of electrical effi ciency. As they use steam for the electrolysis process, they also require a heat source.


To make a success of green hydrogen production, there must be accurate and cost-effective methods of measuring parameters, such as fl ow. To encourage development in the industry, these must be suitable for both brown fi eld sites and greenfi eld developments.


Managing production


The production of green hydrogen requires a number of analytics and instrumentation stages to measure parameters such as hydrogen purity, pressures, temperatures and fl ow rates. This starts at the water input to the electrolyzer and the output of hydrogen and continue through to the hydrogen input to the purifi er and sending hydrogen for storage or to a distribution grid.


One of the most important measurements is the fl ow rate of both water, essentially the feedstock of the process, and the produced hydrogen.


Some of the most effective technologies for this are vortex and swirl fl ow meters.


IET SEPTEMBER / OCTOBER 2024


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