Electricity from renewable sources is subject to strong fluctuations and cannot be stored. The solution is a “workaround”: Green power can be used to create hydrogen which is transported and used via the natural gas network. This presents challenges to the infrastructure of the gas network and the measurement technology, as SICK has discovered as a partner in the energy revolution.
Hydrogen from green power - reliable measurement included
Electricity from wind, water, solar or biomass is essential for the energy revolution but also presents some problems: The production fluctuates based on the weather conditions and is not calculable. It is hardly possible at present to store any excess electricity from solar and wind plants. The power-to-gas technology provides a solution to this. Water is split into oxygen and hydrogen by hydrolysis. Ideally, electricity from renewable sources is used for this, which is a perfect utilization of that electricity. The hydrogen obtained can be used in a variety of ways. Besides feeding it into the natural gas network, it is also possible for example to use it to drive trains. The power-to-gas concept therefore plays a central role in climate action, which is why it is currently undergoing extensive research.
Hydrogen in the gas network
In several regions in the world, up to ten percent hydrogen is currently being fed into the natural gas network. Scientists in Europe and Asia are investigating whether it would be possible in future to add up to 20 percent hydrogen to the natural gas. The added hydrogen affects the properties of the natural gas: It changes its density, viscosity, explosivity, flow rate and sound propagation speed. This presents completely new challenges for the pipes, compressors, seals, pipelines, valves, measurement technology etc., which affects, for example, the risk of leaks and explosions, and the determination of the calorific value. With this is mind, gas network operators and gas suppliers are wondering what impact this will have on the performance of their gas flow meters.
FLOWSIC600-XT reliably measures hydrogen
The FLOWSIC team at the Dresden location of SICK has the answer: “In conjunction with experts at the DNV SE classification organization, we tested the effect of the added hydrogen on the ultrasonic technology of our devices: The existing devices already measure hydrogen containing natural gas as reliably and stably as natural gas without hydrogen.” says Strategic Product Manager Daniel Heinig. “The device can compensate for any measurement uncertainty – even in mixtures containing up to 10 percent hydrogen.” It is nevertheless possible that certain applications will become borderline due to the addition of hydrogen. “We therefore offer to our customers to check their FLOWSIC devices in their specific application and to give them a recommendation on whether, and if so which conversions are required to equip them for a higher hydrogen content in the natural gas in future,” explains Daniel Heinig. SICK even has a solution for a higher hydrogen content of up to 30 percent: “We have developed a new ultrasonic probe which can already be optionally installed in the FLOWSIC600-XT product family. This probe is suitable for a wide range of applications and can measure very reliability and precisely over an even larger range”, says the product developer Thomas Hegewald. This has also been confirmed by the results of an independent public test performed by industry partners and in collaboration with the DNV SE. Already installed FLOWSIC devices can, by the way, also be retrofitted with the new probe.
Turnkey gas flow measurement
Developing the probe presented some challenges to the team, because hydrogen with its very low density changes the behavior of the sound wave in the gas mixture: “This results in a significant increase in the sound propagation speed, which makes the acoustic measurement more difficult because sound reflections can arise in the measurement device,” explains Thomas Hegewald. “We solved this with a substantially narrower sound beam, which can suppress reflections from the sides and ensures a reliable measurement even at small nominal diameters. The FLOWSIC600-XT gas flow meters are thereby prepared for high hydrogen contents, and are a future proof investment for our customers.”
Building on the FLOWSIC600-XT, SICK offers a turnkey gas flow measurement solution called FLOWSKID, and a turnkey flow metering solution called FLOWRUN, where all aspects from the initial project management, installation, and servicing after commissioning have been tailored.to one another.