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Using treated wastewater in Power-to-X

Pure water is critical for Power-to-X and green fuel production. In Esbjerg, the new large-scale facility 'Høst' aims at using treated wastewater to make the future production more sustainable.


HØST PtX Esbjerg is a leading, Danish Power-to-X project under development, deploying large-scale industrial use of electrolysis technology on gigawatt level to produce ammonia. Powered entirely by renewables, HØST PtX Esbjerg will produce green ammonia for use in fertilizers and in fuels, contributing to the long-term sustainability of agriculture and shipping

It is expected that at least two large Power-to-X plants will be established in the area of Esbjerg within the next five years. As Power-to-X requires large volumes of water, Esbjerg’s local utility DIN Forsyning is now investigating whether treated wastewater can be used in the process, instead of using groundwater, which is the main source of drinking water in Denmark.

This will be an immensely beneficial solution both environmentally, and financially as well as play a significant sustainable contribution to the development of Power-to-X in Denmark.  

Denmark is privileged to have clean, drinkable water in the ground. However, clean water is a scarce resource that must be used wisely. In situations where large volumes of water are required, it is therefore important to consider alternatives. This applies to the case of the Power-to-X facilities that have been announced in Denmark, including Esbjerg.  

“Power-to-X requires large volumes of water. Copenhagen Infrastructure Partners’ expected facility in Esbjerg, Høst PtX, anticipates using approx. 1.3 mil. m3 annually with current production methods. As the water used in PtX must be ultra-clean, Danish drinking water is not the best fit. In drinking water, there are a variety of natural salts and minerals that must be removed before the water can be used. This means, that even if DIN Forsyning delivered water with the quality of drinking water, the water would still need further purification. This made DIN Forsyning think of new ideas, as we have plenty of water in Esbjerg. Yet, it is the resource of drinking water that is scarce,” says Business Development Manager at DIN Forsyning, Claus A. Nielsen.

The most obvious solution is that DIN Forsyning supplies technical water, which can be groundwater that is unsuitable for drinking water. But treated wastewater can be another alternative. And if realized, it will be an important contribution to making the power-to-x production of the future, more sustainable.

White paper on groundwater-based water supply

This is not the first time DIN Forsyning find ways to save groundwater use and find reuse purposes in the water below drinking quality. Learn more in our white paper on groundwater-based water supply. 

No lack of treated wastewater 

“We have plenty of treated wastewater. And we never run out. In Esbjerg alone, we annually discharge 15 mil m3 in the sea. Additionally, treated wastewater does not have to be pumped up from the ground, but is already found in our circuits. Another advantage of using treated wastewater is that we avoid pumping groundwater with salts and minerals up from the subsoil, then purify it and direct the residual water with increased concentration of salts through the treatment plant for treatment,” says Claus A. Nielsen.

Therefore, DIN Forsyning has initiated a collaboration with NIRAS, which, among others, are specialists in advanced water treatment. The purpose of the collaboration is to examine whether large amounts of wastewater can be utilized in power-to-x production.

We see great potential in contributing to the development of the technology in terms of using treated wastewater in Power-to-X. Water, along with authority permits and access to sufficient quantities of green power, is critical to unleashing the potential of Power-to-X. Thus, our collaboration with DIN Forsyning is of great importance,” says Jens Brandt Bering, Director of Supply at NIRAS.

A sustainable contribution to the energy solutions of the future 

Esbjerg Municipality is very positive about the new opportunities:

“Our groundwater is very valuable but is also a vulnerable resource, which we in Esbjerg Municipality have a lot of focus on protecting. Therefore, it means a lot that we have actors who focus on using other resources via innovative solutions, that save water and protect nature. This innovative way of thinking emphasizes that Esbjerg’s status as a sustainable energy hub, also entails developing new sustainable energy solutions,” says Jørgen Ahlquist, Chairman of the Climate & Environment Committee.

DIN Forsyning constantly strives to create new, customized solutions that support the green transition:

“If successful, it is a great way to safeguard our precious resources and minimize waste. We want to make an innovative contribution by making the energy solutions of the future as sustainable as possible. Here, we hope to be able to offer a customized solution that supports the power-to-X development in a sustainable way,” emphasises Claus A. Nielsen from DIN Forsyning.

The thrill of further developments at Høst 

The potential end-user of the treated wastewater is very pleased with the new initiative, which only supports the visions and ambitions that are already hallmarks in the development of the new power-to-X plant.

“The entire project is based on sustainability. Anytime we can take steps to further that, it is considered positive action. We are very attentive to the protection of nature’s resources, and if it is technically possible to use treated wastewater in the production phase, we have achieved another breakthrough. We are constantly looking for the technological solutions that lower impact on nature and the environment – locally and globally, so if we, with our facilities, can contribute to minimizing wastewater discharge locally, then we are very satisfied,” states David Dupont-Mouritzen, project director

“We want to contribute to the development in Esbjerg with local jobs and CO2 reductions while also ensuring Denmark is a global driver in a new green industry. Again, this is a new technology that not only can be used in this region but potentially also encourage sustainability elsewhere in the world,” concludes David Dupont-Mouritzen, Copenhagen Infrastructure Service Co.

Høst PtX is expected to be ready in 2026.

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