Chemical production is set to become the single largest driver of global oil consumption by 2030. To reduce oil consumption and resulting greenhouse gas (GHG) emissions, carbon dioxide can be ...captured from stacks or air and utilized as alternative carbon source for chemicals. Here, we show that carbon capture and utilization (CCU) has the technical potential to decouple chemical production from fossil resources, reducing annual GHG emissions by up to 3.5 Gt CO₂-eq in 2030. Exploiting this potential, however, requires more than 18.1 PWh of low-carbon electricity, corresponding to 55% of the projected global electricity production in 2030. Most large-scale CCU technologies are found to be less efficient in reducing GHG emissions per unit low-carbon electricity when benchmarked to power-to-X efficiencies reported for other large-scale applications including electro-mobility (e-mobility) and heat pumps. Once and where these other demands are satisfied, CCU in the chemical industry could efficiently contribute to climate change mitigation.
National energy models provide decarbonization strategies. Most national energy models focus on costs and greenhouse gas emissions only. However, this focus carries the risk that burdens shift to ...other environmental impacts. Energy models have therefore been extended by life-cycle assessment (LCA). Furthermore, deep decarbonization is only possible by targeting all high-emission sectors. Thus, we present a holistic national energy model that includes high-emission sectors and LCA. The model provides detailed environmental impacts for electricity, heat, and transport processes in Germany for meeting the climate targets up to 2050. Our results show that renewable energies and storage are key technologies for decarbonized energy systems. Furthermore, sector coupling is crucial and doubles electricity demand. Our LCA shows that environmental impacts shift from operation to infrastructure highlighting the importance of an impact assessment over the full life cycle. Decarbonization leads to many environmental cobenefits; however, it also increases freshwater ecotoxicity and depletion of metal and mineral resources. Thus, holistic planning of decarbonization strategies should also consider other environmental impacts.
Optimization models can support decision-makers in the synthesis and operation of multi-sector energy systems. To identify the optimal design and operation of a low-carbon system, we need to consider ...high temporal and spatial variability in the electricity supply, sector coupling, and environmental impacts over the whole life cycle. Incorporating such aspects in optimization models is demanding. To avoid redundant research efforts and enhance transparency, the developed models and used data sets should be shared openly. In this work, we present the SecMOD framework for multi-sector energy system optimization incorporating life-cycle assessment (LCA). The framework allows optimizing multiple sectors jointly, ranging from industrial production and their linked energy supply systems to sector-coupled national energy systems. The framework incorporates LCA to account for environmental impacts. We hence provide the first open-source framework to consistently include a holistic life-cycle perspective in multi-sector optimization by a full integration of LCA. We apply the framework to a case-study of the German sector-coupled energy system. Starting with few base technologies, we demonstrate the modular capabilities of SecMOD by the stepwise addition of technologies, sectors and existing infrastructure. Our modular open-source framework SecMOD aims to accelerate research for sustainable energy systems by combining multi-sector energy system optimization and life-cycle assessment.
Carbon capture and storage can both reduce greenhouse gas emissions and provide negative emissions to contribute to the transition to a net-zero society. The contribution of carbon capture and ...storage has been investigated within cross-sectorial energy system models. However, such models commonly focus on cost and greenhouse gas emissions, while broader environmental impacts are investigated for individual technologies only. Here, we analyze economic and environmental impacts of the transition to net-zero emissions by combining energy system modeling with life-cycle assessment. We focus on the system-wide implications of carbon dioxide storage on economic or environmental impacts. In our investigation of the transition of the German energy system until 2045, net-zero emissions require a minimal amount of carbon capture and storage. However, increasing carbon dioxide storage beyond the minimum amount significantly lowers cost and environmental impacts in up to 13 out of 16 impact categories by avoiding investments into material-intensive technologies, such as power-to-methane or renewable power plants in areas with low generation potential. In scenarios without electricity imports, carbon dioxide storage ranges between 118Mt to 379Mt in 2045 with cost increasing by 105% when carbon dioxide storage is minimized. 84% of the cost increase is incurred for eliminating the final 23Mt of carbon dioxide stored.
The benefits of applying carbon capture and storage are robust to variations in the amount of renewable electricity imports and residual emissions that require compensation. Hence, the results suggest that carbon capture and storage can offer economic and environmental benefits in the transition to net-zero energy systems beyond greenhouse gas emission mitigation.
•Life-cycle assessment of transition to net-zero energy system for Germany.•Analysis of system effects of integrating carbon capture and storage in energy system.•Carbon capture and storage reduces cost and many environmental impact categories.•Impact reductions persist when varying electricity imports and residual emissions.
The combustion of fossil fuels within the transportation sector is a key driver of global warming (GW) and leads to harmful emissions of nitrogen oxides (NOx) and particulates (soot). To reduce these ...negative impacts of the transportation sector, synthetic fuels are currently being developed, which are produced from renewable energy stored via catalytic conversion of hydrogen (H2) and carbon dioxide (CO2). A promising class of synthetic fuels are oxymethylene ethers (OMEs). This study conducts a prospective environmental assessment of an OME-based fuel using Life Cycle Assessment (LCA). We investigate an OME1-diesel-blend (OME1-blend), where OME1 replaces 24 mass% of diesel fuel. Such an OME1-blend could be a first step towards an OME transition. For the production of OME1 from CO2-based methanol, we consider both the established route via condensation with formaldehyde and a novel direct pathway based on catalytic combination with CO2 and hydrogen. To close the carbon loop, CO2 supply via biogas and direct air capture is considered. In a best-case scenario, hydrogen is produced by water electrolysis using electricity from wind power in the European Union as an input. The direct pathway reduces the required process steps from three to two and is shown to allow for an improved utilization of the energy provided by hydrogen: the exergy efficiency is increased from 74% to 86%. For combustion, we conducted experiments in a single cylinder engine to determine the full spectrum of engine-related emissions. The engine data provide the input for simulations of the cumulative raw emissions over the Worldwide Harmonized Light Vehicles Test Procedures (WLTP) cycle for a mid-size passenger vehicle. Our well-to-wheel LCA shows that OME1 has the potential to serve as an almost carbon-neutral blending component: replacing 24 mass% of diesel by OME1 could reduce the GW impact by 22% and the emissions of NOx and soot even by 43% and 75%, respectively. The key to achieving these benefits is the integration of renewable energy in hydrogen production. The cumulative energy demand (CED) over the life cycle is doubled compared to fossil diesel. With sufficient renewable electricity available, OME1-blends may serve as a promising first step towards a more sustainable transportation sector.
•Integration of dynamic Life Cycle Assessment into energy systems optimization.•Comparison between static and dynamic case for Germany till 2050.•Quantitative differences in both technology choices ...and environmental impacts.•Dynamic LCA leads to lower environmental impacts in most categories.•Dynamic: increase in ionizing radiation (25%) compared to the static case.
Mitigating climate change requires a fundamental transformation of our energy systems. This transformation should not shift burdens to other environmental impacts. Current energy models account for environmental impacts using Life Cycle Inventories (LCIs) that typically rely on historic processes. Thus, the LCIs are static and do not reflect improvements in underlying background processes, e.g., in the energy supply. Dynamic Life Cycle Assessment (LCA) incorporates changes in the LCI and allows for a consistent assessment of future energy systems. We integrate dynamic LCA in a national energy system optimization and discuss the differences between employing static and dynamic LCA in energy system optimization and assessment. Dynamic LCA leads to lower environmental impacts in most categories (e.g., climate change: -18%) and is required for a quantitative environmental assessment. However, our analysis shows that static LCA is sufficient to identify general trends in energy system optimization and assessment for Germany till 2050.
Most CO
2
utilization technologies are at low technology readiness levels (TRLs). Given the large number of potential technologies, screening to identify the most promising ones should be conducted ...before allocating large R&D investment. As these technologies exhibit different levels of technical maturity, a systematic, TRL-dependent evaluation procedure is needed which can also account for the quality and availability of data. We propose such a systematic and comprehensive evaluation procedure. The procedure consists of three steps: primary data preparation, secondary data calculation, and performance indicator calculation. The procedure depends on the type of CO
2
utilization technology (thermochemical, electrochemical, or biological conversion) as well as the TRL (2-4). We suggest databases, methods, and computer-aided tools that support the procedure. Through four case studies, we demonstrate the proposed procedure on emerging CO
2
utilization technologies, which are of different types and at various TRLs: electrochemical CO
2
reduction for production of ten chemicals (TRL 2); co-electrolysis of CO
2
and water for ethylene production (TRL 2-4); direct oxidation of CO
2
-based methanol for oxymethylene dimethyl ether (OME
1
) production (TRL 4); and microalgal biomass co-firing for power generation (TRL 4).
Three-step procedure for early-stage evaluation of CO
2
utilization technologies based on TRLs.
Synthetic dimethoxymethane (DMM) is a promising fuel or blend component as it offers outstanding combustion characteristics. DMM production from hydrogen (H
2
) and carbon dioxide (CO
2
) is ...technically feasible with established technology but results in a low overall process efficiency. Recent research in catalyst development has increased DMM yield significantly and new reaction pathways have been proposed. Yet, it remains unknown how the achievements in catalyst development affect process performance. To close this gap, we analyze processes based on five reaction pathways regarding exergy efficiency, production cost, and climate impact. As the pathways have different technology readiness levels, we develop a methodology that ensures consistent boundary conditions and model detail between pathways. The methodology enables a hierarchical optimization-based process design and evaluation. The results show that the non-oxidative (
i.e.
, reductive, dehydrogenative, and transfer-hydrogenative) pathways consume stoichiometrically less H
2
not only than the established and oxidative pathway, but also less than most other electricity-based fuels (e-fuels). The higher resource efficiency of these pathways increases process exergy efficiency from 75% to 84%; production cost (2.1$ L
diesel-eq.
−1
) becomes competitive to other e-fuels; and the impact on climate change reduces by up to 92% compared to fossil diesel, if renewable electricity is utilized. Whereas the reductive pathway may already enable a sustainable production of DMM with only little catalyst improvements, the dehydrogenative and transfer-hydrogenative pathways still require a higher DMM selectivity and methanol conversion, respectively. With considerable catalyst improvements, a maximum exergy efficiency of 92% and minimum production cost of 2.0$ L
diesel-eq.
−1
are achievable. Our analyses show: With the non-oxidative pathways, the high potential of DMM is no longer restricted to its outstanding combustion characteristics but extended to its production.
A hierarchical methodology for process design and evaluation reveals how the remarkable achievements in catalyst development for dimethoxymethane (DMM) synthesis can make DMM a sustainable future e-fuel.
Most CO
2
utilization technologies are at low technology readiness levels (TRLs). Given the large number of potential technologies, screening to identify the most promising ones should be conducted ...before allocating large R&D investment. As these technologies exhibit different levels of technical maturity, a systematic, TRL-dependent evaluation procedure is needed which can also account for the quality and availability of data. We propose such a systematic and comprehensive evaluation procedure. The procedure consists of three steps: primary data preparation, secondary data calculation, and performance indicator calculation. The procedure depends on the type of CO
2
utilization technology (thermochemical, electrochemical, or biological conversion) as well as the TRL (2–4). We suggest databases, methods, and computer-aided tools that support the procedure. Through four case studies, we demonstrate the proposed procedure on emerging CO
2
utilization technologies, which are of different types and at various TRLs: electrochemical CO
2
reduction for production of ten chemicals (TRL 2); co-electrolysis of CO
2
and water for ethylene production (TRL 2–4); direct oxidation of CO
2
-based methanol for oxymethylene dimethyl ether (OME
1
) production (TRL 4); and microalgal biomass co-firing for power generation (TRL 4).
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