Seasonal energy balancing in Switzerland: What trade scenarios justify power-to-gas and gas-to-power?

By Behnam Akbari and Jared Garrison

Behnam Akbari is a postdoctoral researcher and former PhD candidate at the Reliability and Risk Engineering Lab at ETH Zurich. Specializing in power systems engineering and sustainable energy optimization, his current research focuses on flexibility assessment in integrated power and gas networks.

Jared Garrison is a senior research assistant at the Research Center for Energy Networks (FEN) focusing on transmission and market dispatch models of the electric power system. During his years at FEN, he has worked to develop modeling tools that merge the disciplines of electricity markets and electricity networks as well as to link energy models with unique capabilities together to investigate future possibilities for the Swiss and Central European net-zero energy system transition.

To achieve carbon neutrality by 2050, Switzerland anticipates significantly expanding solar photovoltaics and electrifying heating and transport, coinciding with the country’s  aimed nuclear phase-out. However, this development creates a seasonal imbalance, with high summer electricity generation but peak demand in winter. Our study investigates the role of power-to-gas technology as a potential solution, which converts surplus renewable electricity into hydrogen or methane. The findings suggest that these domestically produced gases can support a carbon-neutral gas supply, particularly under restricted energy trade conditions, but they remain cost-prohibitive for power generation.

By 2050, Switzerland anticipates a significant expansion of solar photovoltaics (PV) and increased electrification of heating and mobility, coinciding with the aimed phase-out of nuclear power plants. This transition, however, introduces a seasonal imbalance: solar PV generates the most electricity in summer, while power demand peaks in winter, particularly for heating.

Power-to-gas technology offers one possible solution to this imbalance by converting surplus renewable energy into hydrogen or methane. These electricity-based gases (e-gases) can be produced domestically or imported and have two key applications: they can decarbonize hard-to-abate sectors (e.g., industry and heavy-duty transport) or be burned in gas-to-power  (i.e., hydrogen or methane-fueled turbines) to generate electricity during winter months.

Our recent study investigates how Switzerland’s integrated energy system could use power-to-gas, gas-to-power, and other flexible resources to balance seasonal mismatches while complying with national energy policies for sustainability and energy security. We explore cost-effective energy system expansion and operation using spatiotemporally resolved models. Our analysis relies on EP2050+ for final power and gas demands.

This study has two main findings. Firstly, power-to-gas can partially absorb excess summer power generation to meet hydrogen and methane needs in Switzerland’s hard-to-abate sectors, especially under restricted energy trades. Secondly, while domestically produced e-gases appear too costly for power generation, imported gases can possibly be cost-effective contributors to winter power supply.

In the remainder of this blog post, we present the seasonal power balance for a reference scenario in 2050. Next, we delve into power-to-gas and gas-to-power operations for variations in Swiss energy trade conditions. 

The big picture: Seasonal flexibility needs and providers

In our reference scenario for 2050, we assume a power trade capacity of 10.6 GW (similar to current levels) and e-gas import prices of 120-160 €/MWh (three to four times current fossil gas prices).

Figure 1 shows the contrasting seasonality between power demand and generation from solar PV and run-of-river plants. Our results for the reference scenario indicate that power trades (in gray) play a crucial part in seasonal balancing, while domestic resources, including power-to-gas and gas-to-power, play complementary roles. On the supply side, reservoir hydro mainly contributes to winter power generation, and gas-to-power turbines make a modest contribution to bridging the winter supply gap. On the demand side, technologies such as pumped hydro and power-to-gas absorb cheap electricity generated in the summer. Our findings agree with other research at ETH Zurich, which also highlights the role of power trades and gas-to-power generation in winter power supply.

Figure 1: Monthly power supply and demand in 2050 under reference energy trades.

Trade restrictions amplify the seasonal role of power-to-gas and gas-to-power

The previous section examined the seasonal power balance in the reference scenario, emphasizing the critical roles of energy trades and the complementary contributions of power-to-gas and gas-to-power technologies. Given uncertainties surrounding Switzerland’s integration into the European power market and the future development of a European hydrogen market, we now analyze how changes in energy trade conditions affect the deployment of power-to-gas and gas-to-power technologies. Specifically, Figure 2 visualizes the seasonal operation of power-to-gas and gas-to-power technologies under various power trade capacities and e-gas import prices.

Power-to-gas in summer: Power-to-gas primarily uses surplus renewable power in summer, as indicated by the darker cells in Figure 2b compared to Figure 2a. Power-to-gas conversion grows as the power export potential diminishes with lower power trade capacity (i.e., moving left within panels). Moreover, power-to-gas becomes more competitive for hydrogen and methane supply as e-gas import prices rise (i.e., moving down within panels). The annual power-to-gas consumption (summing the values in Figure 2a and 2b) reaches 15% of the final power demand in the scenario with the most restricted power trades and the highest e-gas import prices (represented by the bottom-left cells of the power-to-gas panels in Figure 2).

Gas-to-power in winter: Figure 2c and 2d show power generation from domestic and imported e-gases (i.e., electricity-based hydrogen and methane). Imported e-gases are used for power generation if import prices are 60% below reference levels. However, domestically produced e-gases are prohibitively expensive for power generation, as shown by the minimal contribution of e-gases to power generation under higher e-gas import prices. Figure 2e and 2f show that under these higher e-gas import prices, imported fossil gas becomes a more viable option, even justifying additional costs for carbon capture and storage. Overall, gas-to-power mainly supports winter power supply, especially under restricted power imports, as indicated in Figure 2c and 2e. Notably, all scenarios still project a decline in overall fossil gas consumption compared to current levels even when using fossil gas for power generation largely thanks to the electrification of residential and commercial heating.

Figure 2: Total power-to-gas and gas-to-power energy conversion in winter and summer half-years under various energy trade scenarios for 2050. The colors correspond to the electric energy consumption (for power-to-gas) or electric energy production (for gas-to-power), with the darkest color corresponding to 10.3% of the annual final electricity consumption of Switzerland.

Seasonal gas storage: The seasonal dynamics of gas supply and demand make a case for gas storage to serve the final gas demand in winter. Specifically, storing domestically produced hydrogen in summer can reduce reliance on costly winter hydrogen imports, and methane storage can leverage the seasonal spread of methane prices. However, the choice of gas storage technology presents challenges. Innovative solutions, such as lined rock caverns, still require thorough technical assessments in Switzerland, while large-scale tank storage remains cost-prohibitive. If lined rock caverns prove feasible, Switzerland can benefit from a combined capacity of up to 1.9 TWh for hydrogen and methane storage, particularly in the absence of cheap e-gas imports (Figure 3). To put this in context, this potential gas storage capacity is around one-sixth of the electricity storage capacity of Switzerland’s hydropower reservoirs.

Figure 3: Installed gas storage capacity under various energy trade scenarios for 2050.

In conclusion, power-to-gas and gas-to-power are promising components of the solution to Switzerland’s seasonal energy imbalance, but they are not the complete answer. These technologies become particularly relevant when power trade restrictions reduce the ability to export surplus electricity in summer or import electricity in winter. Absorbing the surplus summer electricity, power-to-gas contributes to the gas supply, but imported gases are still needed especially in winter. Similarly, while gas-to-power contributes to winter power supply, this conversion relies on cost-effective gas imports. These factors highlight the crucial role of both power and fuel trades in shaping a cost-efficient future energy system, underscoring the need for proactive policies to secure Switzerland’s access to European energy markets.

Cover image: generated by Freepik

This blog post is based on the work presented in Akbari, B., Garrison, J., Raycheva, E., & Sansavini, G. (2024). Flexibility provision in the Swiss integrated power, hydrogen, and methane infrastructure. Energy Conversion and Management, 319, 118911.

This blog post is supported by the Swiss Federal Office of Energy as part of the SWEET consortium PATHFNDR.

Keep up with the Energy Blog @ ETH Zurich on Twitter @eth_energy_blog.

Suggested citation: Behnam Akbari, Jared Garrison. “Seasonal energy balancing in Switzerland: What trade scenarios justify power-to-gas and gas-to-power?”, Energy Blog @ ETH Zurich, ETH Zurich, December 5th, 2024, https://blogs.ethz.ch/energy/power-to-gas/

 

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