Near-optimal solutions for carbon capture, conversion, storage, and removal strategies

TL;DR

This paper explores various near-optimal configurations for carbon management in a European energy system, demonstrating multiple solutions can achieve net-zero emissions with minimal cost increases, highlighting the flexibility in deploying CDR options and synthetic fuels.

Contribution

It integrates diverse carbon removal strategies into a sector-coupled energy model and uses MGA to identify multiple near-optimal solutions within a small cost margin.

Findings

Multiple configurations can achieve net-zero emissions with only 5% cost increase.

Full deployment of CDR options is feasible within a marginal cost increase.

Reliance on CDR does not significantly reduce costs compared to synthetic fuels.

Abstract

Achieving climate neutrality in Europe requires rapid electrification alongside carbon management strategies for residual emissions. Existing analyses of the European energy system often focus on collocated carbon capture and geological sequestration, with limited attention to the interactions among carbon capture and utilization, transport, sequestration, and diverse carbon dioxide removal (CDR) options. Moreover, existing literature focuses on discussing the optimal, neglecting that near-optimal solutions might provide very different system configurations at a marginal higher cost. Here, we integrate afforestation, biochar, enhanced rock weathering, and perennialization into a sector-coupled European energy system model (PyPSA-Eur) clustered to 39 nodes with 750 aggregated time steps. We explore their contributions using a Modelling to Generate Alternatives (MGA) approach. The approach combines minimization, maximization, and random vectors to explore the near-optimal solution space for up to 5% increased total system costs. Our results show that, in a carbon-neutral system, multiple configurations of carbon management options can achieve net-zero emissions with only marginal cost increases. We find that a 5% total system cost increase is sufficient to accommodate the full spectrum from zero to full deployment of the individual CDR options, as well as a wide range of synthetic fuel use across different fuel types. Increased reliance on CDR options offers no clear cost advantage compared to greater utilization of synthetic fuels.