Holistic View on Synthetic Natural Gas Production: A Technical, Economic and Environmental Analysis

Estefania Vega Puga,Armin Ardone,Martin Roeb,Nicole Carina Neumann,Christian Sattler,Gkiokchan Moumin

doi:10.3390/en15051608

Estefania Vega Puga, Armin Ardone + Show 4 more

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https://doi.org/10.3390/en15051608

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Abstract

Synthetic Natural Gas (SNG) is the most researched option for a Power-to-Fuel pathway in Germany after hydrogen, having the advantage of being compatible with the existing infrastructure. However, it is not clear under which conditions SNG is economically and environmentally advantageous compared to natural gas usage, since this is determined by a complex interplay of many factors. This study analyzes the technical, economic and environmental aspects of a pilot SNG plant to determine the key parameters for profitable and sustainable operation. The SNG plant was simulated in Aspen Plus® with CO2 from biogas production as a feedstock and with hydrogen provided by a 1 MWel electrolyzer unit. A life cycle analysis (LCA) was undertaken considering several impact categories with a special focus on global warming potential (GWP). An SNG cost of 0.33–4.22 €/kWhth was calculated, depending on factors such as operational hours, electricity price and type of electrolyzer. It was found that the CO2 price has a negligible effect on the SNG cost, while the electricity is the main cost driver. This shows that significant cost reductions will be needed for SNG to be competitive with natural gas. For the investigated scenarios, a CO2 tax of at least 1442 €/t was determined, calling for more drastic measures. Considering the global warming potential, only an operation with an emission factor of electricity below 121 g CO2-eq/kWhel leads to a reduction in emissions. This demonstrates that unless renewable energies are implemented at a much higher rate than predicted, no sustainable SNG production before 2050 will be possible in Germany.

Highlights

In view of increased anthropogenic emissions and the imminent threat of climate change, Germany has committed to reduce its Greenhouse Gas (GHG) emissions by 2030 by at least 65% compared to 1990s levels, and achieve GHG neutrality by 2045 [1]
Power-to-Synthetic Natural Gas (SNG), known as Power-to-Gas (PtG) technology, generates methane via a two-step process: H2 production by water electrolysis and CH4 generation via H2 and CO2 conversion according to the Sabatier reaction [3]
The simulation yields around 34 kg/h of synthetic natural gas and shows a plant capacity of 0.46 MWSNG, considering SNG’s lower heating value (LHV)

Summary

Introduction

In view of increased anthropogenic emissions and the imminent threat of climate change, Germany has committed to reduce its Greenhouse Gas (GHG) emissions by 2030 by at least 65% compared to 1990s levels, and achieve GHG neutrality by 2045 [1] To meet these targets, different strategies, policies and instruments must be developed considering that, while the transformation towards renewable energy sources is already well advanced, concepts for extensive industry decarbonization exist mainly isolated. In the Power-to-Fuel (PtF) concept it is foreseen to produce chemical energy carriers by using electricity and CO2 , offering a way for storing fluctuating renewable electricity while utilizing CO2 that would otherwise be emitted into the atmosphere In such a system, CO2 can be separated from flue gas streams of industrial processes or power plants.

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