H$_2$ and CO$_2$ Network Strategies for the European Energy System

TL;DR

The paper investigates how hydrogen and carbon dioxide transport networks interact within a climate-neutral European energy system, using a high-resolution PyPSA-Eur model that explicitly represents CO2 capture, utilization, and sequestration (CU/CC/CS) alongside hydrogen transport. It examines four scenarios—Baseline, CO2 Grid, H2 Grid, and Hybrid—and analyzes outcomes under net-zero and net-negative emission targets to reveal competition and synergy between networks. Key findings show that hydrogen networks generally offer greater cost savings in isolation, while integrating both networks yields the largest cost reductions (up to about 5.3% or ~41 billion €/a) and robust layouts under tightened targets, with DAC reliance decreasing and CCS sources shifting toward biomass and offshore sequestration. The study highlights the need for coordinated cross-sector planning across hydrogen, carbon, and synthetic-fuel pathways to unlock system-wide cost efficiencies and resilience, while noting limitations such as autarky assumptions and limited imports that warrant further investigation.

Abstract

Hydrogen and carbon dioxide transport can both play an essential role in climate-neutral energy systems. Hydrogen networks help serve regions with high energy demand, while excess emissions are transported away in carbon dioxide networks. For the synthesis of carbonaceous fuels, it is less clear which input should be transported: hydrogen to carbon point sources or carbon to low-cost hydrogen. We explore both networks' potential synergies and competition in a cost-optimal carbon-neutral European energy system. In a direct comparison, a hydrogen network is more cost-effective than a carbon network, as it serves to transport hydrogen to demand and to point source of carbon for utilization. However, in a hybrid scenario where both networks are present, the carbon network effectively complements the hydrogen network, promoting carbon capture from distributed biomass and reducing reliance on direct air capture. The layouts of the hydrogen and carbon dioxide networks are robust if the climate target is tightened to be net-negative.

Figures (23)

• Figure 1: Assumptions on exogenous demand, derived from piamanzGeoreferencedIndustrialSites2018muehlenpfordtTimeSeries2019mantzosJRCIDEES20152018NationalEmissionsReported2023EurostatCompleteEnergyBalanceuwekrienDemandlib2023. The figure shows total annual energy demands for each energy source, which determine the model's endogenous investments and operation. Endogenous processes can lead to higher total production volumes of some energy carriers, e.g., the demand for methanol requires more hydrogen and carbon as secondary (energy) inputs, which are not considered here. In the model, demands are defined per region and time stamp.
• Figure 2: Total annual system cost, subdivided into groups of technologies for the different models of the European energy system with a net-zero emission target. While in the Baseline scenario, the model has neither a carbon nor a hydrogen network, it can expand both in the Hybrid scenario. "Gas Infrastructure" combines gas facilities for transport, power and heat production, "CO$_2$ Infrastructure" and "H$_2$ Infrastructure" combine transport and storage for each carrier. "Carbon Capture at Point Sources" combines all technologies with integrated carbon capture, including the cost of the main facility (e.g., Combined Heat and Power units) and the carbon capture application.
• Figure 3: Balance of captured carbon for all scenarios assuming net CO$_2$ neutrality. Positive values indicate carbon capture and negative values indicate carbon consumption. By integrating hydrogen and carbon networks, the predominant method for carbon removal shifts from Direct Air Capture (DAC) to bio-energetic processes with capture. At the same time, the reliance on methanation decreases.
• Figure 4: Average production, consumption, flows and prices of the carbon (top line) and hydrogen (bottom line) sectors in the CO$_2$/̄Grid (left) and the H$_2$/̄Grid scenario (right). For each region, upper semicircles show the average production per technology, lower semicircles the consumption, and colors the average marginal prices. Lines and arrows show the interregional transportation. Carbon sequestration offshore is drawn in full circles.
• Figure 5: Average operation, flows and prices of the carbon (left) and hydrogen (right) sectors in the Hybrid scenario assuming net CO$_2$ neutrality. For each region, upper semicircles show the average production per technology, lower semicircles the consumption, and colors the average marginal prices. Carbon Sequestration offshore is drawn in full circles. Lines and arrows show interregional transportation volume. Carbon from point-source in the inland either supplies local CU with imported hydrogen or facilitates sequestration in nearby offshore regions.