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Power-to-gas on the go

2012-11-21

New gas technologies allows further use of renewable energies

A schematic representation of power-to-gas, yellow arrows, and gas-to-power, red arrows, in between the power grid and the gas grid (image: St├ęphane Walspurger) A schematic representation of power-to-gas, yellow arrows, and gas-to-power, red arrows, in between the power grid and the gas grid (image: St├ęphane Walspurger)

“Gas-to-power” and “power-to-gas” have nothing to do with super-heroes skills. They belong to a new class of technologies that facilitate the storage and transportation of a large quantity of energy. Combined together, they provide the decentralization of energy production, as well as a better coordination between electricity and gas grids.

Power-to-gas transforms electrical power into gas through the electrolysis of water. Gas-to-power is the other way around: a power plant burns that gas, which is mixed with natural gas, to generate electricity. For Stéphane Walspurger, a project leader at ECN, there are some key advantages to use these technologies, according to what he presented at the conference Back to the Future of Gas, in Groningen, on 21 November.

These technologies solve part of the trouble that comes from the intermittency of renewable energies. Indeed, they can be used to store energy in the period of excess production of renewable energies. Gas can be converted later on into power. With to the convergence of gas and electricity grid, network operators can manage power flows smoothly.

The electrolysis process

Mr Walspurger and his team work on power-to-gas technologies that produce synthetic methane through electrolysis. They aim at identifying and develop promising efficient and cost effective key technologies in the conversion process chain from electricity to gas. They explore the process through which methane is produced, by considering, for example, the quality of the feedstock while taking intermittency into account. Moreover, they are working on the design and optimization of the production chain, from both technical and economic point of views.

The electrolysis process remains one of the critical components. Dimosthenis Trimis, a professor at the Freiberg University of Mining and Technology, and his research team have compared the efficiency chains for energy storage with power-to-gas technologies, according to a presentation made at the same conference.

Electrolysis can be based on the alkaline, proton exchange membrane or high temperature solid oxide based technologies. Whatever the technology into questions, future research will remain constrained by the physical law of thermodynamics, which provide the framework in what is possible to achieve in the matter of efficient technologies.

Power-to-gas technologies have the potential of changing the energy landscape. The challenge consists of finding the best conversion technologies between gas and electricity. According to Mr Walspurger:  “There will be a business case for power-to-gas in which it pays off to turn excess renewable electricity into synthetic natural gas.”

By Jean-François Auger