Green hydrogen also requires the resource water

02/24/2023

Source: Energy & Management Powernews

Green hydrogen requires not only regeneratively generated electricity. Also the resource water is necessary. How it is about it in Germany, examined the Engler Bunte Institute.

Worldwide, climate change has an impact on the availability of the raw material water. To what extent the concern is justified, the resource water develops into the bottleneck in the hydrogen production on German soil, occupied the research center of the German Gas and Water Association (DVGW) at the Engler Bunte Institute. Dr. Florencia Saravia presented the results of the investigations at a digital event hosted by the DVGW on Feb. 22.

In previous investigations, water as a resource would not have played a major role, the department head for water chemistry and water technology indicated. Only hydrogen production technologies and the availability of electricity from renewable energy plants had been in focus, she said. However, she said, the electrolysis process also requires ultrapure water as well as water for cooling.

Saravia drew on the German government's target of 10,000 MW of electrolysis capacity at German production sites by 2030 for the amount of water needed in Germany. The amount of water would be around seven million cubic meters of ultrapure water, which corresponds to a maximum of nine million cubic meters of fresh water. To the explanation: By pure water one understands fresh water and/or groundwater prepared for the electrolysis.

In the comparison to other uses this is "a small quantity", as the DVGW confirms also in a communication. For the irrigation of agricultural land alone, almost 450 million cubic meters of raw water were used in 2019. The comparison with the energy industry is also exemplary: here, at least 300 million cubic meters of water escaped from the cooling towers of power plants through evaporation alone in the same year. That is more than thirty times what would be needed for electrolysis in 2030.

Water demand in Germany does not increase significantly

Even with a long-term electrolysis capacity of 40,000 MW, the total water demand in Germany would only increase by less than one percent as a result of the production of green hydrogen by electrolysis. According to the DVGW, drinking water supplies in Germany will not be affected. He concludes that concerns about the availability of drinking water resources are understandable in light of increasing periods of heat and drought, but are rather unconcerned with regard to hydrogen production. "The results of our calculations provide clarity to the effect that the electrolysis capacities currently planned by politicians do not represent a significant increase in Germany-wide water demand," DVGW Board Member, Dr. Wolf Merkel, was quoted as saying in a statement issued by the industry association.

Both Merkel and Saravia, however, emphasize the importance of taking regional conditions into account when choosing an electrolyzer location. For example, the availability and quality of water resources at the respective site should be factored into capacity planning - especially in regions that have been affected by dryness and drought in recent years. Here, the DVGW cites regions in Brandenburg, Saxony-Anhalt and Lower Saxony as examples. In addition, the association also draws attention to other water sources, should surface or groundwater only be available to a limited extent. At coastal locations or for offshore electrolysis, desalinated seawater is also a possibility. The DVGW refers to a study by the Offshore Wind Energy Foundation, according to which the expansion plans envisage one third of the electrolysis capacities being installed directly at the wind farms in the North Sea and two thirds on land. This would reduce the need for freshwater. In addition, an alternative source of raw water for offshore regions would be the use of wastewater from sewage treatment plants, which could be purified and treated.

A factsheet with detailed facts and figures on the water requirements of electrolysis can be downloaded from the DVGW website.

Author: Davina Spohn