Hydrogen as Inter-seasonal Large-scale Storage: Pathways Comparison for Southern Sweden

Abstract

The transition towards renewable energy technologies is essential to mitigate climate change. However, the intermittency of Variable Renewable Energy (VRE) such as wind and solar creates seasonal imbalances in the electricity supply. To address this, inter-seasonal energy storage solutions are needed. Produced via electrolysis from excess electricity, hydrogen offers a promising storage medium. However, its inter-seasonal large-scale storage remains a significant challenge in some locations. This work investigates the technical and economic performance of various hydrogen storage technologies for large-scale, inter-seasonal applications in Southern Sweden. Six pathways were evaluated after selection based on a literature survey. These pathways combine two electrolysis technologies, alkaline and Proton Exchange Membrane (PEM), with three storage methods: Synthetic Natural Gas (SNG), and two Liquid Organic Hydrogen Carriers (LOHCs), namely toluene and dibenzyltoluene. Process simulations were conducted using Aspen Plus and assessed through energy efficiency metrics, defined as electric efficiency and overall efficiency, as well as two economic indicators, Levelized Cost of Energy (LCOE) and Levelized Cost of Fuel (LCOF). Results show that SNG pathways achieved the highest total efficiency, particularly when coupled with a PEM electrolyser at 54.76%, while offering the most favourable economic performance. Economic analysis revealed high costs for systems operating solely on surplus summer electricity, though higher capacity factors improved viability. The study highlights SNG pathways as the most promising option under current assumptions while identifying key areas for further research, including consideration of carbon capture within the scope of the study, full-cycle power-to-power analysis, and sensitivity studies on technical and economic parameters.

Popular Abstract

Synthetic Natural Gas could be the backbone for inter-seasonal hydrogen storage in southern Sweden.

According to projections for an industrial case in southern Sweden, storing hydrogen by turning it into Synthetic Natural Gas results in an economical and energy-efficient chemical storage when compared to other technologies.
In a context where every ounce of clean energy matters to build a sustainable society, energy storage is of utmost importance to heavily reduce our reliance on fossil fuel extraction. Indeed, due to climate change, the current energy transition involves an increasing incorporation of renewable energies into energy systems worldwide. However, renewable energies such as wind and solar energy are not fully controllable, so they generate energy in excess at times when it is not needed, and there is a lack of energy produced when it is most needed, such as in the evening when everyone comes back home from work. To tackle this issue, hydrogen is investigated as a potential solution to store energy on both a long-term, such as an inter-seasonal scale, where batteries are not efficient, and for large energy quantities.
A suitable storage method is thus to be selected to store energy in the long term, since many of them currently exist. The focus of this thesis is to study the technical and economic aspects of energy storage through hydrogen. A summary of the main methods used to store hydrogen on a large scale for a long-term perspective has been put together. Then, the methods deemed the most suitable for the task at hand were modelled to retrieve both the main energy efficiency and the main costs associated with each technology.
The comparison conducted in this work possesses both economic and technical benefits. Choosing the most suitable technology for a given situation is important to make the most out of the money invested in an energy storage facility. On top of that, it is important to choose a technology that stores energy better. Why would we choose to use a leaking tank when a more sealed one could be preferred?
The considerations of this thesis are case-dependent, meaning that each storage method is chosen according to a specific location. For instance, the best storage method for both long-term and large-scale overall is to put hydrogen into an empty salt cavern, just like putting energy in a box underground, and retrieve it when energy is needed. However, this solution has not been considered in this analysis as the location chosen doesn't have this geological advantage. Different storage options were modelled to obtain their associated energy efficiency and costs. The first option studied is to create methane from hydrogen and carbon dioxide. This latter process creates methane, also called synthetic natural gas. The two other options studied are to store hydrogen in two different chemical pairs, known as Liquid Organic Hydrogen Carriers, to get hydrogen back later when needed. As a result of this thesis, converting hydrogen into methane has been observed to be the most economical, while outperforming other chemical storage options efficiency-wise as well.

• author: Falkenauer, Marion
• supervisor: Hesameddin Fatehi
• organization: Department of Energy Sciences
• course: MVKM01 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Hydrogen storage, Power-to-X, Inter-seasonal, Large-scale, Synthetic Natural Gas, Liquid Organic Hydrogen Carriers, Aspen Plus
• report number: ISRN LUTMDN/TMPH-25/5649-SE
• ISSN: 0282-1990
• language: English
• id: 9203952
• date added to LUP: 2025-06-23 09:12:00
• date last changed: 2025-06-23 09:12:00