Energy-intensive industries still produce high amounts of non-renewable CO₂ emissions. These emissions cannot easily be fully omitted in the short- and mid-term by electrification or switching to renewable energy carriers, as they either are of inevitable origin (e.g., mineral carbon in cement production) or require a long-term transition of well-established process chains (e.g., metal ore reduction). Therefore, carbon capture and utilization (CCU) has been widely discussed as an option to reduce net CO₂ emissions. In this context, the production of synthetic natural gas (SNG) through power-to-methane (PtM) process is expected to possess considerable value in future energy systems. Considering current low-temperature electrolysis technologies that exhibit electric efficiencies of 60–70%_{el, LHV} and methanation with a caloric efficiency of 82.5%_LHV, the conventional PtM route is inefficient. However, overall efficiencies of >80%_{el, LHV} could be achieved using co-electrolysis of steam and CO₂ in combination with thermal integration of waste heat from methanation. The present study investigates the techno-economic performance of such a thermally integrated system in the context of different application scenarios that allow for the establishment of a closed carbon cycle. Considering potential technological learning and scaling effects, the assessments reveal that compared to that of decoupled low-temperature systems, SNG generation cost of <10 c€/kWh could be achieved. Additional benefits arise from the direct utilization of by-products oxygen in the investigated processes. With the ability to integrate renewable electricity sources such as wind or solar power in addition to grid supply, the system can also provide grid balancing services while minimizing operational costs. Therefore, the implementation of highly-efficient power-to-gas systems for CCU applications is identified as a valuable option to reduce net carbon emissions for hard-to-abate sectors. However, for mid-term economic viability over fossils intensifying of regulatory measures (e.g., CO₂ prices) and the intense use of synergies is considered mandatory.

Efforts towards climate neutrality in Europe must prioritise manufacturing industries, particularly the energy-intensive industry (EII) subsectors. This work proposes a novel approach to assessing transformation options for EII subsectors. At the center of this approach we position a potential analysis of technologies’ impact on subsector decarbonisation—an approach only known so far from the investigation of renewable energy potentials. These so-called technical climate neutrality potentials, supplemented by a set of indicators taking into account energy consumption, capital and operational expenditures, and GHG taxation programs per technology and subsector, enable cross-sector comparisons. The indicators allow the reader to compare the impact on GHG emission mitigation, energy demand, and cost for every considered technology. At the same time, we keep an open mind regarding combinations of technological solutions in the overall energy system. This ensures that the technology pathways with the greatest climate neutrality potential are easily identified. These focal points can subsequently serve in, e.g., narrative-driven scenario analyses to define comprehensive guides for action for policymakers. A case study of Austria for the proposed potential analysis demonstrates that bio-CH₄ and electrolysis-derived H₂ are the most economical green gases, but GHG certificate costs will be necessary for cost-competitiveness in high-temperature applications. Electrification offers advantages over conventional technologies and CO₂-neutral gas alternatives in low-to-mid temperature ranges. Under the given assumptions, including GHG emission certificate costs of 250 EUR/t CO₂, alternative technologies in the identified climate neutrality pathways can operate at total annual costs comparable to conventional fossil-based equivalents.

This analysis estimates the technically available potentials of renewable gases from anaerobic conversion and biomass gasification of organic waste materials, as well as power-to-gas (H2 and synthetic natural gas based on renewable electricity) for Austria, as well as their approximate energy production costs. Furthermore, it outlines a theoretical expansion scenario for plant erection aimed at fully using all technical potentials by 2050. The overall result, illustrated as a theoretical merit order, is a ranking of technologies and resources by their potential and cost, starting with the least expensive and ending with the most expensive. The findings point to a renewable methane potential of about 58 TWh per year by 2050. The highest potential originates from biomass gasification (~49 TWh per year), while anaerobic digestion (~6 TWh per year) and the power-to-gas of green CO2 from biogas upgrading (~3 TWh per year) demonstrate a much lower technical potential. To fully use these potentials, 870 biomass gasification plants, 259 anaerobic digesters, and 163 power-to-gas plants to be built by 2050 in the full expansion scenario. From the cost perspective, all technologies are expected to experience decreasing specific energy costs in the expansion scenario. This cost decrease is not significant for biomass gasification, at only about 0.1 €-cent/kWh, resulting in a cost range between 10.7 and 9.0 €-cent/kWh depending on the year and fuel. However, for anaerobic digestion, the cost decrease is significant, with a reduction from 7.9 to 5.6 €-cent/kWh. It is even more significant for power-to-gas, with a reduction from 10.8 to 5.1 €-cent/kWh between 2030 and 2050.

Corrigendum: Techno-Economic Assessment of Thermally Integrated Co-Electrolysis and Methanation for Industrial Closed Carbon Cycles

In the effort to limit global warming to below 2 °C and implement EU climate targets, Austria has set itself the goal of achieving climate ne