Elsevier

Renewable Energy

Volume 85, January 2016, Pages 1371-1390
Renewable Energy

Review
Renewable Power-to-Gas: A technological and economic review

https://doi.org/10.1016/j.renene.2015.07.066Get rights and content
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Highlights

  • Electrolysis and methanation technologies are compared with respect to the PtG chain.

  • Efficiencies and economics of several PtG chains are presented.

  • Hydrogen production costs dominate the whole process costs.

  • Dynamics of biological and catalytic methanation mainly depend on the peripheral equipment.

  • The dynamic behaviour of the methanation determines the size of the H2 storage.

Abstract

The Power-to-Gas (PtG) process chain could play a significant role in the future energy system. Renewable electric energy can be transformed into storable methane via electrolysis and subsequent methanation.

This article compares the available electrolysis and methanation technologies with respect to the stringent requirements of the PtG chain such as low CAPEX, high efficiency, and high flexibility.

Three water electrolysis technologies are considered: alkaline electrolysis, PEM electrolysis, and solid oxide electrolysis. Alkaline electrolysis is currently the cheapest technology; however, in the future PEM electrolysis could be better suited for the PtG process chain. Solid oxide electrolysis could also be an option in future, especially if heat sources are available.

Several different reactor concepts can be used for the methanation reaction. For catalytic methanation, typically fixed-bed reactors are used; however, novel reactor concepts such as three-phase methanation and micro reactors are currently under development. Another approach is the biochemical conversion. The bioprocess takes place in aqueous solutions and close to ambient temperatures.

Finally, the whole process chain is discussed. Critical aspects of the PtG process are the availability of CO2 sources, the dynamic behaviour of the individual process steps, and especially the economics as well as the efficiency.

Keywords

Power-to-Gas
Electrolysis
Methanation
SNG
Renewable energy

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