The role of direct air capture in achieving climate-neutral aviation

Growing demand for air travel and limited scalable solutions pose significant challenges to the mitigation of aviation’s climate change impact. Direct air capture (DAC) may gain prominence due to its versatile applications for either carbon removal (direct air carbon capture and storage, DACCS) or synthetic fuel production (direct air carbon capture and utilization, DACCU). Through a comprehensive and time-dynamic techno-economic assessment, we explore the conditions for synthetic fuels from DACCU to become cost-competitive with an emit-and-remove strategy based on DACCS under 2050 CO2 and climate neutrality targets. We find that synthetic fuels could achieve climate neutrality at lower cost than an emit-and-remove strategy due to their ability to cost-effectively mitigate contrails. Under demand reductions, contrail avoidance, and CO2 neutrality targets the cost advantage of synthetic fuels weakens or disappears. Low electricity cost (€0.02 kWh-1) and high fossil kerosene prices (€0.9 l-1) can favor synthetic fuels’ cost-competitiveness even under these conditions. Strategic interventions, such as optimal siting and the elimination of fossil fuel subsidies, can thus favor a shift away from fossil-reliant aviation.

January 11, 2025

Decentralized ammonia production via electric Haber–Bosch (Haber–Bosch 2.0) could support shipping, chemical manufacturing, and local fertilizer supply chains. Unlike conventional Haber–Bosch systems, Haber–Bosch 2.0 technologies operate at lower pressures (∼30–60 bar) and temperatures (∼400 °C), enabling smaller, modular ammonia systems powered by low-carbon electricity. However, its economic viability and environmental performance under diverse conditions remain unclear. Here, we apply techno-economic and environmental life cycle assessment using a novel, open-source framework to optimally design ∼13 000 grid-connected, hybrid, and off-grid electric Haber–Bosch configurations worldwide. Our results demonstrate that decentralized ammonia production costs are between €740–4100 tNH3−1, which is substantially higher compared to centralized ammonia production (∼300 tNH3−1 historically with recent spikes up to ∼€800 tNH3−1). Hybrid configurations exhibit the lowest costs (€740–2090 tNH3−1), particularly in regions with low grid electricity prices, low capital costs, and/or abundant renewables. However, their GHG emissions vary widely depending on the GHG intensity of the local grid. Off-grid systems exhibit the lowest life cycle GHG emissions (on average 0.70 tCO2-eq. tNH3−1), but demonstrate high costs (more than €1100 tNH3−1), driven by oversized renewables and energy storage media to enable continuous Haber–Bosch operation. Cost parity may be achieved by 2050 through technology learning, especially for hybrid systems (€325 tNH3−1). To realize this potential and secure low-carbon fertilizer supply, policymakers should; (1) accelerate the decarbonization of national power grids, (2) provide early-stage deployment support for flexible, electric Haber–Bosch technologies, and (3) establish clear certification standards for low-carbon ammonia.

The role of direct air capture in achieving climate-neutral aviation

Latest findings from research

3rd Annual Conference of the SWEET Consortium reFuel.ch Highlights Implementation Pathways for Sustainable Fuels

Haber–Bosch 2.0 for low-carbon ammonia production: a global techno-economic and environmental assessment

Strong interest in FOCA Aviation and Climate Funding Programme