Water efficiency and hydrogen Interview with Stephan Jakobs, OSMO Membrane Systems GmbH

Electrolysis requires a lot of energy and water. But many regions of Germany are already suffering from water stress. Our interview with Stephan Jakobs discusses which other water sources are available and how electrolysis firms can cut back on operating costs.

REH: Mr Jakobs, you are an expert in water treatment. Can you give us a brief description of your company?

"OSMO Membrane Systems GmbH is a supplier of water treatment systems with over 40 years of experience. A highly specialised company in the GAW Group, OSMO Membrane Systems GmbH develops and implements industrial filtration and membrane separation processes for sophisticated and custom separation tasks. As part of this portfolio, OSMO Membrane Systems GmbH's processes include a variety of workflows for the treatment of water and process fluids. Process development at OSMO Membrane Systems GmbH produces four simple steps to create high-performance separation technology. From process and membrane screening in our in-house laboratory and industrial piloting in partial streams to large-scale industrial plants and their optimisation and maintenance. Established in 1980 , the company draws on a wide variety of applications in the industrial segments of pulp & paper, chemicals & polymers, power & water, surface & coating, metals & recycling, biotech and cosmetic & sugar. One important area for us is to optimise CAPEX and OPEX for our individual customers."

REH: Discussions on the ramp-up of the hydrogen economy tend to focus on the use of (green) energy, while neglecting the issue of water. Which risks do you see here?

"The issue is indeed largely ignored. If I look at the tenders for large-scale electrolysis projects, they are often centred on the use of drinking water. This is not especially sustainable and is expensive for the companies, but investigations of alternatives are lacking. It is lamentable that few alternative water sources such as rivers, wells, the sea and treated wastewater are taken into account, especially in large projects. I believe that we really need to ask ourselves the following question: how green is hydrogen if its production uses electricity from renewable energies, but also consumes valuable drinking water? We also need to scrutinise what the water is used for and distinguish between actual water consumption and water utilisation. The water is removed from the local cycle when it is consumed. But if it is utilised, the water is returned to the local cycle in a controlled manner. Often it is easier and cheaper to extract process water from rivers for cooling, but also for the electrolysis process itself. Not only does this make sense from an ecological perspective, it also has economic benefits, as hydrogen will only find buyers if it is produced and provided at low cost."

REH: Could you give us a model calculation?

"Producing just one kilogramme of hydrogen requires approximately ten times the amount of high-purity water, so around 10 litres. Added to this is the what we need for cooling, which is another 9 litres. Let’s remain with drinking water for now: as an H2 producer, you pay not only for water extraction, but also for disposal of the wastewater. Considerable quantities of waste water also accumulate during electrolysis, as a portion will always flow back out of the electrolyser and is sometimes contaminated with heavy metals from the stacks. The amounts they pay differ from region to region, but let's say an average of €2.35/m3 for drinking water and another €2.85/m3 for wastewater disposal. Drinking water also requires treatment to reach high purity status and avoid damaging the electrolyser.

Where available, you can extract river water for a few cents per cubic metre and, depending on local conditions, return it without any disposal costs. Admittedly, this must be considered on a case-by-case basis and there is no guarantee. But there is a rule of thumb: Extracting surface water or groundwater for the purpose of hydrogen production requires authorisation in accordance with the Water Resources Act (WHG). The same applies to the discharge of water used. During the process of granting these authorisations, the impacts of water extraction and its discharge after use are scrutinised to ensure there are no adverse changes to the water. In particular, this requires compliance with the requirements of the Surface Waters Ordinance (OGewV) and compatibility with the management objectives under the Water Framework Directive. The requirements of nature conservation and species protection must be met as well. In recent years, we have already worked with our customers to get numerous systems up and running that use river water instead of well or drinking water. A major advantage of our treatment technology is that it operates almost without chemicals, so that the resulting wastewater has minimal or even no environmental impact.

The initial investment is initially higher due to the more complex treatment, as the process steps of a drinking water plant have to be installed upstream. But the running costs are at most half compared to drinking water. Water-conservation levels should be used, regardless of where the water is extracted. They enable yields of 90-95 percent instead of the usual 60-70 percent. Saving water cuts costs and is more sustainable.

REH: How do you explain that the topic of water is often neglected?

"Many of the project stakeholders are essentially novices to this new topic. What’s more, water planning is often outsourced to the local water supplier instead of the organisations developing their own concept or putting it out to tender. My appeal, especially to regions that are already struggling with water stress, is that they should look in particular at other sources such as wastewater from sewage treatment plants."

REH: Can you explain in more detail how water is returned during electrolysis?

"One hundred percent separation of water into hydrogen and oxygen is technically impossible, so residual water will inevitably accumulate in every electrolyser. The return depends on the electrolyser type and the production conditions, so it would be impossible for me to give you any precise information about the quantities and composition. But what I can say is that various institutes are currently researching what exactly has accumulated in the wastewater – probably heavy metal erosion and transformation products. Alkaline electrolysis is likely to be somewhat more complex due to the high pH value. The magnitude is also unclear at this time. Disposal is certainly a cost factor in projects. As water purifiers, we therefore see potential in the treatment and “neutralisation” of this wastewater, although it is currently difficult to define. At present, the legal regulation for ongoing projects stipulates that they dispose of their wastewater in the municipal wastewater network or neutralise the pollutants locally prior to treatment."

REH: In Germany, we experienced a nationwide water problem in the record summer of 2022, when rivers ran dry and the forests and fields withered. Do we still have a water problem, and will the hydrogen economy exacerbate the situation?

"Even if all currently announced electrolysis projects were put into practice, on-site production would cover no more than 30 percent of domestic demand. This does not consume water on a scale that would result in a general worsening of the water situation in Germany – overall, it is a small percentage of total domestic annual consumption. According to the Federal Statistical Office (Destasis), 176 billion cubic metres of water are available in Germany every year. In 2022, the German economy used 12.75 billion m3. Assuming 10 GW of electrolysis capacity, water consumption for the production of hydrogen would increase total water consumption in Germany by only around one third of the amount that is currently used.
But it can be problematic in regions that are already dry. Water stress will be many times higher in these places if several hundred cubic metres are extracted per day."

REH: Which regional consumption levels should be expected?

"Let's look at a large-scale project like the 100 MW electrolyser by the Hamburg Green Hydrogen Hub – its water consumption will be equivalent to that of a small town. I estimate that at full load, the PEM electrolyser there requires 19 m3 per hour – so for electrolysis plus cooling – in order to produce 1.9 tonnes of hydrogen per hour. Another 5 m³ of water per hour is required – in addition to the 19 m³ of process water – when using fresh water, in this case from the Elbe. This additional water absorbs the residual substances removed from the process water, which is then returned to the local water cycle in a controlled manner. The water treatment system from the old Moorburg coal-fired power station is used in this project – a step in the right direction for Hamburg. There are different variants for cooling, depending on whether, for example, the heat is decoupled and used downstream. Here, the GetH2 initiative has prepared a valuable Water Balance Fact Sheet for Electrolysis.

REH: In terms of water consumption, how does hydrogen production compare with other sectors such as the extraction and processing of conventional energy carriers?

"If we take the process chain for coal-fired power generation as a benchmark, consumption there is significantly higher. Vast quantities are needed just to cool the power stations. But there is no power station that uses drinking water for this process, so why should it be the case in hydrogen production? What can be done to reconcile economic concerns and ecological sustainability in water planning? It needs to be optimised to suit locally available water sources. Electrolysis can be used to treat any kind of water. The technologies are established and used also in other sectors, such as for medical devices or in semiconductor production. Small plants under 100 MW are often planned with a classic configuration, which is very expensive. For example, the issue of whether softening is inserted before or after reverse osmosis makes a big difference in regard to costs. Very significant cost savings are possible with the necessary expertise in system design. With all this in mind, can we implement major projects across the country with a clear conscience? Germany will need a hydrogen economy in the medium term, as it is important for decarbonisation and industry. The demand for ‘green’ steel is likely to rise going forward. When it comes to water, we must take into account the quantities for consumption and utilisation and return as much as possible to the local cycles."

Thank you vey much for the talk!