Abstract: ECEMP / > 1000 words

# Energy Imports and Infrastructure in a Climate-Neutral European Energy System

Fabian Neumann (TU Berlin), Johannes Hampp (JLU Giessen), Tom Brown (TU Berlin)

The transformation of the European energy system towards climate-neutrality demands for unrivalled technological change. Whereas the development of renewables energy sources in Europe and supporting measures like reinforcing the electricity grid do not always meet the level of acceptance required for a swift transition, other parts of the world have cheap and abundant renewable energy supply potentials to offer to global energy markets. They could become key partners for a cost-effective and socially accepted energy transition in Europe.

However, even if they are economically attractive, a strong dependence on energy imports can be a double-edged sword, as Europe currently experiences owing to its heavy reliance on Russian fossil energy. On one side, energy imports can increase energy security by offering a way to mitigate weather-induced energy droughts. On the other hand, energy imports might tie European energy supply to few exporters or markets outside the control of European actors.

In this contribution, we explore the dipole between full self-sufficiency and wide-ranging energy imports. We investiage how the infrastructure requirements of a self-sufficent European energy system that exclusively leverages continental resources may differ from a system that relies on energy imports. For our analysis, we use a spatially and temporally resolved European energy system model, PyPSA-Eur-Sec to investigate the impact of imports on European energy infrastructure needs. We evaluate potential import locations and carriers, the economic impetus for such imports, and how their inclusion affects deployed infrastructure.

## European infrastructure needs depend on import choices

What infrastructure is needed to support the system depends on the levels of clean energy imported. This relates to the geographic distribution of energy resources tapped as well as directions and magnitudes of energy flows which have to be supported.

Today, European energy infrastructure is built around the heavy imports of fossil oil and gas. The transition to a system that exploits the best wind and solar sites across the continent would offer manifold opportunities to develop a self-sufficient system without imports (Pickering et al., 2022). Developing transmission infrastructure, like reinforcing the power grid and building a hydrogen network that partially repurposes an increasingly unused gas network is consistently beneficial in such scenarios (Neumann et al., 2022; Gils et al., 2022). A *European Hydrogen Backbone* was also recently envisioned by a consortium of the European gas industry (EHB, 2022). However, a hydrogen backbone may not be needed if imports of renewable energy carriers are considered.

Since most hydrogen is used to produce synthetic fuels and ammonia, if these were imported at scale, much of the hydrogen demand would fall away. This would reduce the need for hydrogen transport infrastructure. Even if there is high demand for direct hydrogen imports, the optimised topology of a hydrogen network might differ significantly as new import locations need to be connected rather than domestic production. The network's role changes from distributing energy from North Sea hydrogen production hubs to incorporating inbound hydrogen pipelines from North-Africa.

In this contribution, we investigate the potential benefit of importing energy into the European energy system in scenarios with high shares of wind and solar electricity and net-zero carbon emissions. In our analysis, we explore what level of energy imports would lead to the lowest system costs, which types of energy carriers are preferred, how import choices affect European infrastructure requirements, and how much more expensive a fully self-sufficient energy system would be. For this purpose, we perform sensitivity analyses interpolating between cost-optimal levels of imports and no imports at all.

## Characteristics of energy carriers create advantages and challenges

As possible import options we consider imports of electricity, hydrogen, methane, ammonia and Fischer-Tropsch fuels. Each carrier has different characteristics which leads to trade-offs regarding how, where and under which circumstances they may be imported.

Electricity, the most versatile carrier, is challenging to store and requires variability management if directly sourced from renewable sources. Hydrogen is easier to store and transport in large quantities than electricity but at the expense of being less versatile. Hydrogen has attracted significant interest with plans of the European Commission under REPowerEU to import 10 Mt hydrogen and derivatives by 2030. Furthermore, hydrogen from electrolysis and climate-neutral electricity is considered a replacement for hydrogen from fossil sources as a chemical feedstock in the future. Synthetic, carbon-neutral methane could benefit from existing infrastructure but requires a sustainable carbon source and leakage prevention. Ammonia does not require a carbon source and is simple and cheap to store and transport over long distances. However, it suffers from acceptance problems due to its toxicity and lower energy density. Lastly, Fischer-Tropsch fuels are easy to store, transport and reuse existing infrastructure, but the synthesis is energy-intensive due to high conversion losses. Like methane, a sustainable carbon source is required.

For each energy carrier we identify locations with existing or planned import infrastructure where the respective carrier may enter the European energy system. We consider import options for electricity by transmission line, hydrogen as gas by pipeline and liquid by ship, methane as gas by pipeline and liquid by ship, ammonia as liquid by ship, and Fischer-Tropsch fuels by ship.
Moreover, we compute scenarios where import volumes are limited and only a subset of carriers can be imported to probe the flatness of the near-optimal solution space and assess how the carrier choice affects intra-European import infrastructure.

## Sector-coupling in the European energy system with PyPSA-Eur-Sec

To model the European energy system, we use the open-source energy system optimisation model [PyPSA-Eur-Sec](https://www.github.com/pypsa/pypsa-eur-sec), which combines a fully sector-coupled approach with high spatial and temporal resolution and detailed transmission infrastructure representation. The model co-optimises the investment and operation of generation, storage, conversion and transmission infrastructures in a single linear optimisation problem. It covers 181 regions and uses a 3-hourly time resolution for a full year. With these settings, the model is detailed enough to capture existing grid bottlenecks and the variability of renewables and requirements for seasonal storage. The model includes regional demands from the electricity, industry, buildings, agriculture and transport sectors, including shipping and aviation as well as non-energy feedstock demands in the chemicals industry. Furthermore, the model covers transmission infrastructure for electricity, gas and hydrogen as well as candidate entry points for energy imports like existing and prospective LNG terminals and cross-continental pipelines.

## Energy import options and costs are modelled for each entry-point

Import costs seen by our energy system model are based on recent research by [Hampp et al. (2021)](https://arxiv.org/abs/2107.01092), who assessed the cost importing energy across different energy supply chains for the afromentioned energy carriers from various regions of the world. Based on this research we determine for each energy carrier and model entry point the regional-specific lowest import cost, thus, incoporating the potential trade-off between import cost and import location.

## Impact

Our analysis offers insights into how energy imports might interact with European energy infrastructures and what economic benefit they can bring. We seek to stimulate further discussions about trade-offs between public acceptance, system cost, and energy security pertaining to the import of low-carbon fuels and sensitise to what extent infrastructure policy decisions depend on the path taken on energy imports.

## References

Pickering

RepowerEU

PyPSA-Eur-Sec

Hampp, J., Düren, M., and Brown, T. (2021). Import options for chemical energy carriers from renewable sources to Germany. ArXiv:2107.01092 [Physics].

EHB (2022): https://ehb.eu/ .

Gils (Remix)

Neumann et al. "Benefits of a Hydrogen Network in Europe"

## Figures

[One plot of clustered map with electricity and gas network, entry-points (colored by type), final energy demand on region shapes]()