Berlin (energate) - Water management must become an integral part of the national hydrogen strategy in the future, says Florencia Saravia, an engineer at the German Technical and Scientific Association for Gas and Water (DVGW). Water as a resource has so far received too little attention in Germany's hydrogen plans, Saravia said in an online seminar organised by the DVGW. In the future, the availability of water will be a major factor in the choice of location for an electrolysis plant, he said. "Water is often seen as an unlimited resource," said Saravia. She added that in the context of climate change, with increasing heat waves and droughts, this was a problem even in Germany
DVGW: No impairment for drinking water
"It takes 10 kilogrammes of water to produce 1 kilogramme of hydrogen," Saravia calculates. Against this background, too, there has recently been growing concern that the resource water could become the bottleneck of the German hydrogen plans. In a
recent study, the DVGW (Deutscher Verein des Gas- und Wasserfaches) therefore calculated how much water would be needed to produce green hydrogen with an electrolysis capacity of 40,000 MW. It concluded that, on balance, the drinking water supply in Germany would not be affected. According to the calculations, about seven million cubic metres of water would be needed, adding less than one per cent to Germany's total water demand.
Surface or groundwater is not available everywhere
Nevertheless, the DVGW points out that it is important to take regional conditions into account. For example, the availability and quality of local water resources should be taken into account when planning the capacity of electrolysers, as well as local impacts and long-term consequences. This is especially true for regions that have been particularly affected by drought and aridity, such as the German federal states of Brandenburg, Saxony-Anhalt and Lower Saxony.
Complex treatment of ultrapure water
Where there is not enough surface water or groundwater, other sources are possible, according to the DVGW. In coastal areas, this is mainly seawater. For Saravia, however, wastewater treatment plant effluent is the "best source" because it is available everywhere. It is important to know that so-called "ultrapure water" is needed for electrolysis. Depending on the quality of the water source, this water has to be processed in several steps, including various types of filtration and desalination processes. For example, only 10 kilogrammes of ultrapure water can be obtained from 30 kilogrammes of seawater.
For the future, the DVGW scientist would like to see more cooperation between electrolysis operators and the water industry. According to Saravia, there is still a lot of research to be done, for example on the extent to which the waste water from electrolysis needs to be treated. /ml
