Berlin-based Graforce Hydro GmbH, the developer of a plasma electrolyzer—the Plasmalyzer—is applying its technology for the highly efficient generation of hydrogen from industrial waste water.

Mixing in biogas produces hydrogen-enriched compressed natural gas (HCNG)—a cost-effective, environmentally friendly fuel for vehicles that also generates electricity and heat. The technology not only converts wastewater pollutants into valuable energy, but also reduces emissions (CO₂, CO, HC) by 30 to 60 percent. Nitrogen oxide emissions are also reduced by up to 60%. Graforce’s partners include carmaker Audi and Berliner Wasserbetriebe.

The technology we’ve developed is capable of cleaning wastewater and producing a low-cost, low-emission fuel from it. This lets us contribute to solving two pressing problems at once: air pollution and wastewater treatment.

—Graforce founder Dr. Jens Hanke

The new plasma electrolyzer technology is based on a change in the effect of radiation on matter. In a high-frequency plasma process, reactive species are produced as a result of electron-molecule interactions that initiate reactions at ambient temperatures that would otherwise only occur at significantly higher temperatures.

This allows both dissociative electron attraction and dissociative excitations of process gases and water, and also plasma-chemical synthesis processes. The combined use of different plasma inductors is leading to a new crossover technology in the form of plasma processing.

The current Plasmalyzer offers highly efficient water splitting. This means that hydrogen can be produced from water, in contrast to electrolysis processes currently on the market, at an affordable price using regenerative electricity for around €3/kg instead of €6-8/kg (assuming electricity costs of €0.08 per kWh).

Moreover, unlike other processes, it does not require the water to be purified; that means that non-purified water can also be used.

Graforce is producing hydrogen using the plasmalysis process in its demonstration plant in Berlin. The process uses electricity to split wastewater obtained from biogas, sewage treatment and industrial plants into oxygen and hydrogen. Mixing hydrogen with biogas produces HCNG, which can be used as fuel in natural gas vehicles and in block heating and gas power plants. Only purified water and oxygen remain as waste products.

German carmaker Audi has also been committed for many years to alternative, synthetic fuels. One of the biggest challenges to e-fuel production is the wastewater produced by biogas plants. It requires very expensive cleaning or disposal.

Integrating plasmalysis technology into Audi’s e-fuel plants repurposes the wastewater into hydrogen production while purifying it at the same time. This enables Audi’s systems to be used more efficiently.

Graforce’s plasmalysis is an important contribution to low-emission fuel production while boosting the economy and efficiency of biogas and power-to-gas plants.

—Dr. Hermann Pengg, Head of Project Management for Renewable Fuels at Audi and CEO of Audi Industriegas GmbH