Energy transition

Final Report Summary - HELMETH (Integrated High-Temperature Electrolysis and Methanation for Effective Power to Gas Conversion), 25 July 2018

A highly efficient Power-to-Gas process has been realized by the European research project HELMETH. It has the potential to be the most efficient storage solution for renewable energy utilizing the existing natural gas grid without capacity limitations and to be a source for “green” Substitute Natural Gas (SNG) to avoid fossil carbon dioxide emissions.

The objective of the HELMETH project is the proof of concept of a highly efficient Power-to-Gas process by realizing the first prototype that combines a pressurized high temperature steam electrolysis with a CO2-methanation module.

The demonstration plant was assembled at the sunfire facility in Dresden. The methanation unit, developed and built by KIT in Karlsruhe, was set up inside a container and transported to sunfire to perform combined operational tests.

The steam outlet from the methanation cooling circuit is fed to the electrolyser and the hydrogen output from the electrolyser is fed to the methanation unit. The steam is converted to hydrogen in the electrolyser.

Coupled Power-to-Gas plant (left container: methanation; right container: electrolyser)

The efficiency is significantly increased by using the heat of reaction from the exothermic methanation reaction to produce steam for the high temperature electrolysis.

Since the produced SNG is fully compatible with the existing natural gas grid and storage infrastructure, practically no capacity limitations apply to store energy from fluctuating renewable energy sources.

Steam Hydrogasification

By replacing the CO2 methanation module in the Power-to-Gas process realized by the HELMETH research project with a lignite methanation module, Australia can manufacture 50% renewable methane. That is, synthetic natural gas containing 50% renewable energy (as hydrogen) and 50% fossil fuel (from low-cost wet lignite).

This can fuel dispatchable generators in conjunction with renewable intermittent generators to provide 100% reliable electricity generation: the intermittent renewable generators supplying 50% of electricity and dispatchable generators powered by 50% renewable methane providing the other 50%.

The lignite methanation module has been developed in the U.S.

Making synthetic natural gas from hydrogen and a variety of waste streams and coal has been researched for some time.

For example:

UC Riverside researchers receive two grants to advance steam hydrogasification reaction for waste-to-fuels, 15 September 2011

Researchers at the University of California, Riverside’s Center for Environmental Research and Technology (CERT) at the Bourns College of Engineering have received two grants to further explore a steam hydrogasification process they developed...

A $650,000 grant from the California Energy Commission (CEC) extends its commitment to $2 million to CERT for the patented steam hydrogasification reaction (SHR), which can turn any carbonaceous material into transportation fuels or natural gas. The CEC grant will allow for the completion of a process demonstration unit at CERT that will provide data needed before a proposed pilot plant is built at the city of Riverside’s waste water treatment facility.

Synthetic natural gas made from wet carbonaceous feedstock such as lignite