“One man’s trash is another man’s treasure,” goes the popular saying. This is certainly true of the burgeoning waste-to-energy sector in Europe. New reports from the Institute for Ecological Economy Research (IÖW) in Berlin propose how Germany’s cities could reuse wastewater from sewage treatment and industry to produce sustainable fuels, replacing part of their natural gas demand.
The UMAS research project led by the power company Berliner Erdgasspeicher and funded by the Federal Ministry for Economic Affairs and Climate Action outlines how this might be achieved in Germany’s capital city. The researchers focused on the city’s sewage treatment plants which could be transformed into green hydrogen (H2) plants using wastewater plasma lysis in a process developed by the tech company Graforce.
Here, the ammonium present in sewage water is split to produce green H2 using renewable electricity. The clear advantage of this approach is it’s cheaper and requires less electricity than hydrogen electrolysis. "The process is a great opportunity to reduce climate-damaging nitrous oxide emissions from sewage treatment plants and produce cheap hydrogen at the same time," explains Elisa Dunkelberg, IÖW’s energy expert, in a .
The same principle could be applied to certain industrial processes that produce wastewater including paper recycling, flue gas cleaning and biogas plants. All considered, the reports estimate that wastewater plasma lysis can cover up to 5 percent of Berlin’s expected H2 demand in the coming years, as well as boosting heat supply.
Broadly speaking, power-to-gas makes more economic sense for cities than buffering large amounts of renewable electricity for “dark lulls” when wind and solar is not directly available. "Cities should tap their local potentials for both wastewater plasma lysis and electrolysis," Dunkelberg concludes. “We have to make the jump from natural gas... where gas cannot be replaced, green hydrogen and synthetic methane should be used in the future.”