“Green” hydrogen, produced using renewable energies, is seen as the energy source of the future, replacing fossil fuels and thus paving the way to a greenhouse gas-free economy. Experts from the Industry business unit of the TÜV NORD GROUP support the industry in the energy transition.
“Hydrogen is not a new topic in the industrial sector or for our experts,” Dana Nowak says by way of preface to the conversation. The 17-strong team under TÜV NORD’s Head of Plant Safety North includes experts in explosion protection as well as specialists who are notified experts in accordance with Section 29b of the Federal Immission Control Act (BImSchG). They are particularly in demand whenever this potentially hazardous energy source is used in industrial plants, for example in the desulphurisation of fuels, the hardening of vegetable oil into margarine or metal production.
Hydrogen as a beacon of hope
Industry has been using hydrogen since the early 20th century, when it was still obtained from coal. As a result of the oil crisis of the 1970s, initial concepts were developed to convert the entire economy to run on gas as an energy source. The idea was to use solar power to drive the electrolysers that split water into oxygen and hydrogen. Fifty years later, this vision is becoming reality, but the drivers behind the transition have changed over time. Today, hydrogen is attractive because when it is combusted, it releases water instead of carbon dioxide, which contributes to global warming. Germany aims to become carbon-neutral by 2045, and the National Hydrogen Strategy is a central component of the energy transition. Plants are being built all over the country to produce, store and use hydrogen – and this means a lot of work for TÜV NORD’s plant safety teams.
“Customers approach us early on, especially when it comes to approval procedures,” says Ms. Nowak. Whenever industrial plants are to be converted to accommodate the additional or exclusive future use of hydrogen, the authorities always get involved. Their requirements include distance assessments to determine the effects of an incident on the surroundings.
In addition to its expert work, TÜV NORD also acts as an intermediary between authorities and plant operators. The experts who have been notified in accordance with Section 29b of the Federal Immission Control Act bear a special responsibility in this regard. They have acquired outstanding expertise in their fields courtesy of additional training, and their public appointment means that they are independent and non-partisan. Gregor Latzko is one of them. The process engineer talks about two projects in which TÜV NORD supported Aurubis AG. These are representative of the many projects in which the plant safety teams accompany widely differing companies as they navigate the energy transition.
Wire rod is the starting material for copper cables of all kinds.
Dana Nowak, Head of Plant Safety North, and Gregor Latzko, notified expert, both at TÜV NORD
Customers approach us early on, especially when it comes to approval procedures.
Dana Nowak
Head of Plant Safety North at TÜV NORD
Aurubis is Europe’s largest copper producer and also extracts other metals such as gold, silver, tin, and lead from metal concentrates and recycled raw materials. The company produces more than one million tonnes of high-purity copper cathodes annually, most of which are processed into wire rod. Aurubis is pursuing ambitious sustainability goals and wants to increasingly replace natural gas with hydrogen, provided that it is available at competitive prices. The company has been calling on the knowledge of TÜV NORD’s experts for several years.
In the summer of 2024, to reduce its future carbon emissions, Aurubis brought in two anode furnaces, in which liquid copper is cleaned and then poured into square plates that are further processed in a hydro-metallurgic process. The cylindrical anode furnaces are almost ten metres long, with a diameter of five metres. Mr. Latzko outlines the process that takes place in the plant: Once the copper has been decanted into the furnaces, air or oxygen is blown into the melt. This drives impurities to the surface of the vessel, which are removed as slag and reused. Natural gas is then injected to reduce unwanted oxides. With the new furnaces, Aurubis will one day be able to use hydrogen instead of natural gas. Pilot tests in 2021 showed that this was technically feasible.
Conversion with a focus on safety
The planning phase began a good six months before the conversion, Mr. Latzko explains: “We were involved from the very beginning, working with Aurubis to analyse the risks and supporting the approval processes.” Key issues at the top of the agenda were explosion protection and pressure, alongside functional safety. Also developed were implementation proposals for the new hydrogen supply. As soon as the infrastructure for the new energy source is in place, Aurubis will have the option of converting the process from natural gas to hydrogen. Dana Nowak describes the work of her department in more detail: “From a safety point of view, we assess whether certain plant components or materials are suitable for use with hydrogen, for example, and which measures can minimise possible hazards. This will help the plant’s operator with their decision-making.”
Before the anode furnaces went into operation, everything was carefully checked. As part of the tests that are legally required before commissioning, for example, experts from several departments verified that the planned parts had actually been installed. They tested the safety features and made sure that all lines and connections were tight and that all the necessary documents were complete and plausible. Mr. Latzko emphasises the objective and independent nature of the test: “Work for which our department has provided Aurubis with safety-related advice is of course assessed by experts from other operational units.”
Liquid copper solidifies in the square moulds of the casting wheel.
We were involved from the very beginning, working with Aurubis to analyse the risks and supporting the approval processes.
Gregor Latzko
notified expert at TÜV NORD
The technology of the new furnaces is more efficient than before and consumes up to 30 percent less natural gas. This corresponds to a savings potential of almost 1,200 tonnes of carbon dioxide per year, which could rise to 5,000 tonnes if hydrogen were to be used as the sole energy source.
From copper ingots to wire
The cleaned copper flows from the anode furnaces into square casting moulds at a temperature of 1,200 degrees Celsius. When the plates have cooled, they are electrolytically refined to a copper content of at least 99.99 percent before being transferred to another smelting furnace. A natural gas flame liquefies the copper, which then solidifies into an endless ingot in the channels of the casting machine. 16 rolling stages then form this ingot into wire. Rolled up into coils, which weigh between three and eight tonnes, the wire rod is then ready for shipment all over the world. It is used to make cables for electric cars and wind turbines as well as for household sockets.
Ammonia as an alternative to hydrogen
With the support of Dana Nowak’s team, Aurubis tested whether the smelting furnace could be heated using a mixture of natural gas and ammonia. This compound of nitrogen and hydrogen burns without releasing carbon dioxide. When dissolved in water, the gas is known as ammonia spirit and is popular as a cleaning agent. In the hydrogen economy, ammonia serves as a storage medium because it is cheaper to produce and easier to liquefy than pure hydrogen.
Due to its properties, pure ammonia can only be used subject to appropriate occupational safety requirements. Among other things, Gregor Latzko and his colleagues calculated how the gas would spread in the event of a breakdown-related release and designed a suitable safety concept. Dana Nowak sums the project up thus: “At TÜV NORD, we’re H₂-ready and will be happy to support our customers as they make their own transitions.”
Aurubis exports copper coils all over the world. The liquid copper has a temperature of 1,200 degrees Celsius.