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Designing Pathways for Net-Zero Greenhouse Gas Emission Plastics with Life Cycle Optimization - Dr Raoul Meys - Bog - Verlag G. Mainz - Plusbog.dk

Designing Pathways for Net-Zero Greenhouse Gas Emission Plastics with Life Cycle Optimization - Dr Raoul Meys - Bog - Verlag G. Mainz - Plusbog.dk

Plastics are on the rise to conquer every area of modern human life but lead to increased pollution of nature, enormous oil consumption, and large-scale greenhouse gas emissions. Thus, to avoid climate change above 1.5?C, net-zero greenhouse gas emission plastics are needed by the second half of this century. To reduce the greenhouse gas emissions associated with plastics, three circular technologies can be used: (1) chemical or mechanical recycling, (2) carbon capture and utilization, and (3) biomass utilization. However, current environmental assessments of these circular technologies focus solely on individual or partly combined circular technologies, are limited to regional scopes, and often apply inconsistent methodologies. Thus, it is currently unclear if net-zero emission plastics can actually be achieved with the current set of circular technologies. Furthermore, shifting from the linear to a circular economy is regarded as energy-intensive and costly, hindering strong policy implementation from fostering the transition to a circular economy. To assess if net-zero emission plastics can actually be achieved, this thesis builds and uses the first global, industry-wide and systematic bottom-up model for plastics production and waste treatment, representing the global life cycle greenhouse gas emissions of 90% of global plastic production. Using that model reveals that net-zero emission plastics can be achieved by combining biomass and CO2 utilization with an effective recycling rate of 70% while saving up to to 53% of energy and 288 billion USD compared to a fossil-based benchmark applying large-scale carbon capture and storage. Achieving the full potential of energy and cost savings while achieving netzero emissions requires the supply of biomass and CO2 at low cost, while cost of oil supply must be increased. To incentivize this shift, investment barriers for all available circular technologies have to be lowered by implementing consistent emission pricing schemes, using deposit systems for plastics to increase recyclability and stopping to subsidize fossil resources. Thus, this thesis shows that the greenhouse gas emission problem of plastics can be solved with technologies and solutions already available today.

DKK 415.00
1

Optimization Methods for Integrating Energy and Production Systems - Dr Ludger Leenders - Bog - Verlag G. Mainz - Plusbog.dk

Optimization Methods for Integrating Energy and Production Systems - Dr Ludger Leenders - Bog - Verlag G. Mainz - Plusbog.dk

The key measure to mitigate climate change is the reduction of greenhouse gas emissions. Hereby, energy-intensive industry plays a key role due to its substantial greenhouse gas emissions. A substantial share of these greenhouse gas emissions is caused by energy supply. Thus, energy supply needs to be more efficient in industry. In large industrial sites, on-site energy systems often supply production systems. Both systems thereby optimize their operation with respect to an objective such as operational cost or revenue. This thesis provides optimization methods for these large industrial sites. The optimization methods reflect two relationships between both systems: Both systems can either follow the same objective or system-specific objectives. The same objective exists, e.g., if both systems belong to one company. System-specific objectives exist, e.g., if both systems belong to different companies. For the case that both systems follow the same objective, a method is presented for the integrated synthesis of both systems. For the same case, a method is presented for integrated scheduling to provide control reserve. For the case that energy and production systems have system-specific objectives, two cases are distinguished: incomplete and complete information exchange. For incomplete information exchange, an optimization method is introduced for the coordination between a single energy and a single production system. This optimization method is then extended to multiple energy and multiple production systems. For complete information exchange between the systems, a bilevel problem is formulated. For solving the bilevel problem, an existing solution algorithm is adapted. All methods presented in this thesis are applied to case studies, and advantages and disadvantages are examined. The case studies show that no method provides the optimal solution for the production system in all identified relationships between the systems. Thus, depending on the case at hand, the respective optimization method has to be applied. Overall, this thesis presents optimization methods for all identified relationships between energy and production systems. Thus, this thesis enables the selection of a suitable optimization method for all kind of production systems with decentralized energy supply.

DKK 445.00
1

Optimization of Low-Carbon Energy Systems from Industrial to National Scale - Dr Nils Julius Baumgartner - Bog - Verlag G. Mainz - Plusbog.dk

Optimization of Low-Carbon Energy Systems from Industrial to National Scale - Dr Nils Julius Baumgartner - Bog - Verlag G. Mainz - Plusbog.dk

Climate change mitigation requires a reduction of greenhouse gas (GHG) emissions. The main emitter of GHG emissions is the energy sector, which today is based on fossil fuels. To mitigate climate change, we need to transform the energy systems to low-carbon technologies. For this purpose, new energy system designs are required along with appropriate operational strategies. In principle, these new designs and operational strategies can be identified best using mathematical optimization. However, low-carbon technologies impose challenges in solving and assessing the resulting optimization problems. Low-carbon technologies are volatile, which increase the complexity of optimal synthesis and operation. To cope with the complexity of operational optimization, we develop a time-series decomposition method. The method decomposes the complex, time-coupled operational problem into smaller subproblems, while still providing feasible, near-optimal solutions. For the increased complexity in synthesis problems, we propose a method based on time-series aggregation. The method divides the original synthesis problem into two separate problems: one aggregated relaxed problem and another aggregated restricted problem, leading to feasible, near-optimal solutions. In addition, the transformation process requires a rigorous assessment of greenhouse gas emissions and potential burden-shifting. In particular, the assessment of emissions due to electricity usage on the industrial scale is difficult, as the underlying national electricity system is not modeled. Therefore, we propose methods to compute industrial greenhouse gas emission factors for electricity. By exploiting these emission factors, industrial energy systems can significantly reduce their emissions. On the national scale, burden-shifting towards environmental impacts besides climate change needs to be prevented in the transformation. Hence, we develop a national energy system model and extend the optimization with life-cycle assessment considering 15 further environmental impacts. With the model, we compute a cost-optimal transformation pathway to a low-carbon energy system. The transformation leads to many co-benefits, but also to severe burden-shifting, which needs to be considered during the transformation process and in the development of new low-carbon technologies. Overall, the methods and models in this thesis facilitate the integration of low-carbon technologies in energy systems.

DKK 445.00
1

Optimization-Based Synthesis of Large-Scale Energy Systems by Time-Series Aggregation - Dr Bjorn Bahl - Bog - Verlag G. Mainz - Plusbog.dk

Optimization-Based Synthesis of Large-Scale Energy Systems by Time-Series Aggregation - Dr Bjorn Bahl - Bog - Verlag G. Mainz - Plusbog.dk

Global greenhouse gas emissions significantly accelerate climate change and adversely affect life on earth. To mitigate these effects, greenhouse gas emissions need to be cut-down by significant reductions in primary energy consumption. Primary energy consumption can be reduced by increasing the efficiency of energy supply, which is mainly fixed during the synthesis of energy systems. Optimal synthesis of energy systems can be realized by mathematical optimization, however the solvable problem complexity is limited. In contrast, energy systems encompass highly complex energy conversion technologies and an increasing number of time-varying operation conditions. Thus, the synthesis of real-world energy systems usually result in large-scale optimization problems, which are computationally prohibitive. In this thesis, a solution framework is proposed to enable large-scale synthesis of energy systems. The framework exploits the two-stage character of synthesis problems: the decision stage of optimal investment for technologies and the operation stage. Thus, the framework solves two consecutive subproblems with reduced complexity by applying time-series aggregation methods. Time-series aggregation is performed by systematic clustering methods. Using these clustering methods, the framework simultaneously identifies the appropriate period length, required number of aggregated periods and number of aggregated time steps per period for accurate synthesis. Based on aggregated synthesis problems, the proposed framework calculates feasible solutions with known accuracy. In addition, the framework measures the accuracy as error of the objective function and iteratively refines the aggregation until an accuracy criterion is satisfied. The proposed solution framework for synthesis of energy systems is applied to two case studies motivated by real-world applications from industry. All results indicate that few time steps and few typical periods are sufficient to identify feasible near-optimal solutions of large-scale synthesis problems. Moreover, results show that intuitive aggregation methods (e.g., monthly averages) are not beneficial - only sophisticated clustering methods allow a strong time-series aggregation with high accuracy for synthesis of energy systems. Overall, the proposed framework outperforms available solution software in both solution time and solution quality.

DKK 460.00
1

Assessment of Adsorbents for Drying by Experiments and Dynamic Simulations - Dr Meltem Erdogan - Bog - Verlag G. Mainz - Plusbog.dk

Assessment of Adsorbents for Drying by Experiments and Dynamic Simulations - Dr Meltem Erdogan - Bog - Verlag G. Mainz - Plusbog.dk

In order to slow down global warming, greenhouse gas emissions must be reduced. Human-caused greenhouse gas emissions come primarily from consumption of fossil energy. In order to reduce the consumption of fossil energy, the demand is rising for energy-efficient technologies. One promising energy-efficient technology is the adsorption dishwasher that was commercialized recently. The use of adsorbents enabled the adsorption dishwasher to save 25% of energy compared to a conventional dishwasher. To increase the savings and to further enhance the entire process, the adsorption dishwasher should be improved. The improvement should foremost focus on the adsorbents, since adsorbents are the key of this energy-efficient technology. This thesis therefore assesses adsorbents for the application in an adsorption dishwasher. The assessment is carried out both experimentally and theoretically. Theoretical investigations are divided in 3 stages of complexity: Stage 1 is a static analysis that is used to determine the required minimum mass of adsorbent. Stage 2 is a simple dynamic model that is used to determine the drying times. This simple 2-stage theoretical investigation method is applicable for any drying process in order to estimate the suitability of adsorbents. As a parameter study, adsorbents out of 3 material classes are evaluated regarding drying time and adsorbent mass required for the application in an adsorption dishwasher . The trade-off between drying time and adsorbent mass is discussed by employing the Pareto-frontier. Based on the results of the simple 2-stage theoretical investigations, suitable commercially available adsorbents are investigated experimentally. Evaluation criteria of the experimental investigations are working capacity, pressure drop over the adsorbent bed and dehumidification rate. Based on these 3 criteria, the most suitable commercially available adsorbents are identified. Finally, to assess adsorbents considering all dynamic interactions within the adsorption dishwasher, a theoretical investigation is conducted as Stage 3. Stage 3 is a complex dynamic model of the adsorption dishwasher including all its components. The tradeoff between drying time, adsorbent mass and energy consumption is discussed by employing the resulting Pareto-frontiers. In summary, this thesis presents methods for characterisation of desiccants. By using these methods, more suitable adsorbents are found for use in the dishwasher application.

DKK 445.00
1

Comparative Life Cycle Assessment of Industrial Multi-Product Processes - Dr Johannes Jung - Bog - Verlag G. Mainz - Plusbog.dk

Comparative Life Cycle Assessment of Industrial Multi-Product Processes - Dr Johannes Jung - Bog - Verlag G. Mainz - Plusbog.dk

Smoking chimneys are a symbol for environmental impacts of industrial processes. Indeed, industrial processes are major contributors to environmental problems such as global warming. Beyond emission-related problems, industrial processes deplete limited resources because they require raw materials. Raw materials are directly linked to costs, emission-related impacts cause indirect expenditures, e.g., through the European emissions trading scheme (EU-ETS) for greenhouse gas emissions. Therefore, industrial enterprises seek to reduce costs by reducing environmental impacts of their processes. Two well-known strategies for reducing environmental impacts of industrial processes are process integration and recycling. Process integration establishes interconnections between formerly separate processes by utilizing co-products. Process integration thereby relies on unit processes with multiple products, so-called multi-product processes. Similarly, recycling uses waste as raw material for new products. But neither process integration for recycling guarantee reduced environmental impacts. E.g., recycling may cause more impacts than waste disposal. Decision makers thus need a holistic method for comparing environmental impacts from multi-product processes. This work investigates methods for comparisons of industrial multi-product processes. The environmental impacts of multi-product processes can be analyzed using life cycle assessment (LCA). LCA studies all environmental impacts of all processes involved in a procuct’s entire life cycle. Due to ist holistic approach, LCA identifies shifting of environmental problems between processes and between different types of environmental impacts. Results of LCA-studies can thus help avoiding such problem shifting.

DKK 460.00
1

Technology Choice Model for Consequential Life Cycle Assessment - Dr Cornelius Arne Katelhon - Bog - Verlag G. Mainz - Plusbog.dk

Technology Choice Model for Consequential Life Cycle Assessment - Dr Cornelius Arne Katelhon - Bog - Verlag G. Mainz - Plusbog.dk

Consequential Life Cycle Assessment (CLCA) aims at capturing the environmental consequences of decisions such as the introduction of a new technology, the implementation of a policy, or the purchase of a product. CLCA combines technical and economic modeling approaches to track the consequences of decisions throughout the economy, considering both technical relationships within industrial production systems and market-mediated effects. However, although CLCA is well defined at a conceptual level, a commonly accepted modeling framework for CLCA is still missing, leading to wide differences in CLCA practice. To promote the systematization of the CLCA approach, this thesis proposes a comprehensive modeling framework for CLCA: the Technology Choice Model (TCM). Compared to existing approaches, TCM captures market-mediated effects in multiple markets at a substantially higher level of technical detail, while systematically considering constraints in factor availability, uncertainty, and suboptimal decisions. Due to its higher level of technical detail, TCM can model changes in technology mixes through both capacity adaptions and substitution effects among competing technologies. These changes in technology mixes are shown to substantially affect the CLCA results in two illustrative case studies on the introduction of new technologies and climate policy. Furthermore, the consideration of uncertainties and suboptimal decisions provides the basis for a first comprehensive uncertainty assessment in CLCA. The practical application of TCM is demonstrated in a large-scale industrial case study on novel Carbon Capture and Utilization (CCU) technologies in the chemical industry. These technologies use carbon dioxide from industrial point sources or ambient air as alternative carbon feedstock for chemical production. The case study shows that CCU in the chemical industry can reduce up to 3.5 Gt CO2-eq greenhouse gas emissions per year by 2030 and highlights potential barriers for CCU implementation. The results provide a strong scientific basis for the integration of CCU into international policy frameworks and research agendas. The application of TCM in this case study demonstrates the ability of CLCA to provide sound environmental decision support.

DKK 459.00
1

Life-Cycle Assessment of Low-Carbon Technologies from Screening to Integrated Energy System Design - Dr Sarah Deutz - Bog - Verlag G. Mainz -

Life-Cycle Assessment of Low-Carbon Technologies from Screening to Integrated Energy System Design - Dr Sarah Deutz - Bog - Verlag G. Mainz -

Climate change mitigation requires a massive reduction of greenhouse gas (GHG) emissions and even negative emissions in the near future. To achieve GHG mitigation, low-carbon technologies are developed. However, environmental benefits are not generally proven since most technologies require significant amounts of low-carbon energy and interact in complex energy systems. Moreover, low-carbon technologies comprise a wide range of maturity and varying data availability. Assessing the full range of low-carbon technologies requires life-cycle assessment (LCA), from screening to an integrated energy system design at the concept, process, plant to system level. At the concept level, we demonstrate handling of limited data availability and apply an LCA-based short-cut method enabling a best-case ranking of CO2-based chemicals. Half of these products have the potential to provide environmental benefits already today through shortened synthetic pathways and low H2 demand. In contrast, the other products could only achieve environmental benefits when sufficient low-carbon electricity is available. Using a process from the best-case ranking, we expand the LCA model scope to the process level providing a more detailed environmental assessment for the example of CO2-based oxymethylene ethers (OME) fuels. Our well-to-wheel analysis shows a significant potential to decrease local pollutants, whereas climate impacts are only reduced if large amounts of low-carbon energy are available. Subsequently, we extend the LCA model scope to the plant level exemplary for direct air capture (DAC). We demonstrate that climate benefits strongly depend on the electricity supply and the subsequent application of CO2: permanent storage leads to negative emissions, whereas using CO2 as feedstock for fuels could reach carbon neutrality at best. Furthermore, large-scale deployment of DAC, e. g., capturing 1% of global annual CO2 emissions, will not be limited by energy and materials requirements and will increase other environmental impacts by much less than 1%. Our analyses emphasize the environmental potential of low-carbon technologies and their dependence on low-carbon energy; however, neglecting their cross-sectoral interconnectivity in the energy system. Therefore, we extend the scope of LCA to the system level by developing an energy system model with integrated LCA. The computed low-carbon transition pathways lead to many co-benefits in other environmental impact categories but also cause burden-shifting, which needs to be considered when developing climate mitigation strategies.

DKK 460.00
1

A Design Approach for Adsorption Energy Systems Integrating Dynamic Modeling with Small-Scale Experiments - Dr Stefan Wilhelm Graf - Bog - Verlag G.

A Design Approach for Adsorption Energy Systems Integrating Dynamic Modeling with Small-Scale Experiments - Dr Stefan Wilhelm Graf - Bog - Verlag G.

Adsorption energy systems can be driven by thermal energy from waste heat or the sun and thereby allow reducing fossil energy consumption and thus reduce global greenhouse gas emissions. Adsorption heat pumps and chillers can provide heating or cooling, adsorption thermal energy storage allows storing thermal energy. However, adsorption energy systems suffer from high investment costs due to low performance. Performance of adsorption energy systems strongly depends on the equilibrium properties of the working pair as well as heat and mass transfer mechanisms of the adsorption material in the adsorption energy system (adsorbent configuration). Evaluating new working pairs and adsorbent configurations is rather challenging: While the working pair''s equilibrium properties can be determined with standardized measurement equipment, heat and mass transfer mechanisms cannot easily be determined, since they strongly depend on the full-scale adsorption energy system. Construction and operation of full-scale experiments requires high effort. Besides, often only small amounts of an adsorbent configuration are available, which are insufficient for full-scale experiments. To resolve these drawbacks, this thesis provides and validates a comprehensive method to determine the performance of working pairs and adsorbent configurations in adsorption energy systems from simple small-scale experiments. As a representative class of adsorption energy systems, adsorption chillers are investigated in this thesis. A small-scale Large-Temperature-Jump experiment is combined with dynamic modeling of the transient heat and mass transfer processes. Additionally, the experiment is extended by an infrared camera. The additional temperature information allows to distinguish and to determine the time-resolved effective heat transfer coefficient and diffusion coefficient in the heat and mass transfer model. The heat transfer and diffusion coefficients are inserted into a full-scale adsorption chiller model to predict the performance. Exemplarily, a commercial available silica gel and the adsorbent class of metal-organic frameworks (MOFs) are evaluated for an adsorption chiller application. The method is validated with experimental data of a full-scale prototype adsorption chiller and shows high accuracy. Furthermore, the method allows optimizing the adsorption chiller for a given working pair or adsorbent configuration and allows identifying bottlenecks and potential for improvement of the working pairs. In summary, this thesis bridges the gap between small-scale experiments and modeling of full-scale adsorption energy systems. The method allows for a comprehensive and reliable evaluation of working pairs and adsorbent configurations for adsorption energy systems.

DKK 460.00
1

Decarbonization of Copper Production by Optimal Demand Response and Power-to-Hydrogen - Dr Fritz Thomas Carl Roben - Bog - Verlag G. Mainz -

Decarbonization of Copper Production by Optimal Demand Response and Power-to-Hydrogen - Dr Fritz Thomas Carl Roben - Bog - Verlag G. Mainz -

To avoid greenhouse gas (GHG) emissions and mitigate climate change, low-carbon technologies must be used to provide renewable energy and replace fossil fuels. However, this system transition is very material-intensive and leads to high demand for critical materials. Copper is such a material that is essential for electrical applications and many low-carbon technologies. The production of copper itself is an energyintensive process. Thus, two challenges arise that are addressed in this thesis: the flexible process operation in a fluctuating renewable energy system and the avoidance of process-based GHG emissions. The flexible operation of electricity-intensive processes can support the power grid and provide economic benefits. Demand response (DR) describes operational adjustments based on an economic incentive, such as fluctuating electricity prices. Our initial analysis shows a large DR potential of two electricity-intensive process steps in copper production. To consider the DR potential of the entire production process and to capture the dependencies of the many process steps, we formulate a detailed scheduling model of a representative copper production process. The developed mixed-integer linear program (MILP) allows minimizing the electricity costs without reducing the production volume. This process-wide scheduling enables significant DR potential, reducing annual electricity costs by up to 14.2% and shifting large parts of the electricity demand. Avoiding process-based GHG emissions is challenging because fossil fuels are hard to substitute in some processes. These processes use fossil fuels as high-temperature process heat and as chemical reducing agents. A promising alternative for these use cases is hydrogen (H2), when H2 is produced from renewable electricity using water electrolysis (Power-to-H2). The oxygen produced as a by-product offers further benefits as it can be utilized in copper production. To optimally design a power-to-H2 system, we formulate a MILP that minimizes the total annualized cost. The resulting CO2 abatement costs are 201EUR/t CO2-eq, which exceeds the current prices of EU allowances. However, a sensitivity analysis shows great potential through further development of water electrolysis. Decarbonization through Power-to-H2 offers additional DR potential. Our scheduling model of the decarbonized copper production shows that DR strongly contributes to low CO2 abatement costs. Consequently, this work identifies the potential of decarbonized copper production that provides a critical material for low-carbon technologies and supports the power grid through DR.

DKK 445.00
1

Reaction Models from Reactive Molecular Dynamics and High-Level Kinetics Predictions - Dr Malte Dontgen - Bog - Verlag G. Mainz - Plusbog.dk

Reaction Models from Reactive Molecular Dynamics and High-Level Kinetics Predictions - Dr Malte Dontgen - Bog - Verlag G. Mainz - Plusbog.dk

The design and optimization of complex chemical processes is a key challenge in chemical engineering and requires knowledge of the underlying kinetic model. This information can be obtained from experiments by inverting the reaction mechanism, which needs to be known therefore. Solving this inverse problem, however, is mathematically challenging, if not impossible, and the reaction mechanism is mostly unknown for novel compounds. Both of these challenges are addressed in the present thesis by proposing a novel methodology for forward reaction model development, which is based on exploring chemical space without the need for prior knowledge. The presently proposed methodology makes use of reactive molecular dynamics simulations to explore the chemistry of gas-phase compounds. In these dynamic simulations the chemical systems are allowed to evolve naturally, based on the atomistic interactions. During this evolution, bond formation and cleavage are traced based on the atomic connectivities and used to detect reaction events. For each reaction, molecular structures are extracted and high-level quantum mechanical calculations are used to predict reliable thermochemistry and kinetics. This novel chemistry exploration scheme is used to generate an ab initio reaction model for the well-studied high-temperature methane oxidation, which is used as a reference. The ab initio reaction model and a novel reaction pathway observed during simulation are validated against this reference and against high-level quantum mechanics. The comparison of the present ab initio reaction model obtained for high temperature methane oxidation to well-established literature reaction model shows striking agreement. This validation case demonstrates the potential of forward reaction model development using the present purely predictive methodology. Moreover, a reaction pathway previously not considered in kinetic modeling is discovered using the present chemistry exploration scheme and successfully validated in a detailed kinetic study. Potential extensions to the presented chemistry exploration scheme are derived, discussed, and implementations are outline. These extensions focus on the inclusion of effects resulting from microscopic balancing: Pressuredependence and reactions involving non-thermal intermediates. Conversion of high-pressure limit reaction models to pressure-dependent models is intended to be described by microcanonical properties obtained via transformation of canonical properties. A similar transformation is used to obtain information about hot reactions, i.e. the kinetics of non-thermal intermediates. Ultimately, these extensions will be implemented in the presently proposed chemistry exploration scheme to obtain even more accurate ab initio reaction models. In conclusion, the present thesis addresses the increasing need for reaction model development of novel chemical compounds by proposing a novel chemistry exploration scheme. The agreement of reaction pathways and rate constants with literature data reveals the potential of trajectory-based chemistry exploration for developing quantitative reaction models.

DKK 445.00
1

From Life-Cycle Assessment towards Life-Cycle Design of Carbon Dioxide Capture and Utilization - Dr Niklas Vincenz Von Der Aßen - Bog - Verlag G.

From Life-Cycle Assessment towards Life-Cycle Design of Carbon Dioxide Capture and Utilization - Dr Niklas Vincenz Von Der Aßen - Bog - Verlag G.

Ever since humans have existed, they have impacted the earth in many different ways (Redman, 1999). Currently, important impacts are associated with the excessive use of non-renewable fossil fuels such as coal, oil and natural gas. Most fossil fuels are used for electricity generation, heating and mobility (eia, 2011), and as feedstock in the chemical industry (IEA et al., 2013). Moreover, the use of fossil fuels is associated with carbon dioxide emissions (CO2) (IEA, 2014; Leimk¨uhler, 2010). Emitting CO2 into the atmosphere leads to global warming and disrupts the natural carbon cycle (Stocker et al., 2013). To close the disrupted carbon cycle, CO2 can be captured and re-utilized, thereby mitigating global warming and saving fossil resources (Styring et al., 2014). CO2 can be captured from current anthropogenic CO2 sources or directly from the atmosphere. Captured CO2 can then be utilized as valuable physical product “as such”or as alternative carbon feedstock for fuels, chemicals and materials. The general concept of CO2 Capture and Utilization (CCU) can be considered established: already today, CO2 is captured and utilized in processes in the chemical industry (Aresta et al., 2014). However, the scope of CO2 utilization is limited. Despite the existing industrial implementations as well as continuous progress and current efforts in CCU research, most CCU technologies are still in early stages of development. Besides the limited technological readiness, CCU is intrinsically challenging since both capture and utilization of CCU typically require substantial amounts of energy (Sakakura et al., 2007). If the provision of energy relies on fossil resources, indirect CO2 emissions are caused. Therefore, the intuitively expected environmental benefits from using CO2 are not given by default (Peters et al., 2011b). In fact, it cannot be ruled out that a tediously accomplished CCU process is finally environmentally less sustainable than a conventional fossil-based route. Therefore, it is desirable to know whether a specific CCU process is environmentally favorable. For this purpose, a reliable environmental assessment of CCU is required. As indicators for the environmental performance of CCU, a large variety of approaches are proposed ranging from qualitative design principles (Anastas andWarner, 1998) and metrics for ‘green’ chemistry (Constable et al., 2002) to CCU-specific ad-hoc criteria (Peters et al., 2011b; M¨uller and Arlt, 2014). These approaches are rather intended to guide the development towards ‘sustainable’ CCU processes than to systematically quantify the actual environmental impacts. In contrast to these approaches, Life-Cycle Assessment (LCA) is a systematic and standardized methodology to analyze the actual environmental impacts of products and processes (ISO 14040, 2009). Although LCA is frequently advocated for the environmental assessment of CCU (Aresta and Dibenedetto, 2007b; Peters et al., 2011b; Quadrelli et al., 2011), it is not yet standard practice (Sch¨affner et al., 2014). The reasons for this are the complexity of LCA as well as the limited data availability of many CCU processes at early design stages (Quadrelli et al., 2011). In this context, this thesis pursues two major goals: First, the thesis enables and supports the reliable environmental assessment for CCU processes using LCA. To overcome the complexity of LCA and to enable LCA novices to apply LCA to CCU, a jargon-free introduction is presented for LCA in the context of CCU. Furthermore, a framework for LCA of CCU is derived to avoid severe pitfalls in LCA of CCU. A case study for CO2-based polymers illustrates the application of LCA as well as the size and origin of environmental benefits of CCU. The second goal of this thesis is to provide an LCA-based approach to support the design of environmentally beneficial CCU processes at early stages. In summary, the thesis is intended to facilitate the utilization of LCA for CCU from early design stages to industrial implementation.

DKK 285.00
1