• Energy Research
• 12. Responsible consumption close
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• RWTH Aachen University close

AbstractThe future European energy supply system will have a high share of renewable energy sources (RES) to meet the greenhouse gas emission policy of the European Commission. Such a system is characterized by the need for a strongly interconnected energy transport grid as well as a high demand of energy storage capacities to compensate the time fluctuating characteristic of most RE generation technologies. With the RE generators at the location of high harvest potential, the appropriate dimension of storage and transmission system between different regions, a cost efficient system can be achieved. To find the preferred target system, the optimization tool GENESYS (Genetic Optimization of a European Energy System) was developed. The example calculations under the assumption of 100% self-supply, show a need of about 2,500 GW RES in total, a storage capacity of about 240,000 GWh, corresponding to 6% of the annual energy demand, and a HVDC transmission grid of 375,000 GWkm. The combined cost for generation, storage and transmission excluding distribution, was estimated to be 6.87 ct/kWh.

Due to climate change and current efforts to reduce emissions in the construction sector, this study evaluates and discusses the results of a comparative cradle-to-grave Life Cycle Assessment (LCA), with a main focus on Global Warming Potential for functionally equivalent carbon-reinforced concrete (CRC) and steel-reinforced concrete (SRC) façade panels for the first time. The novelty of this study is the focus on construction waste and, in particular, the worst-case application of non-recycled construction waste. The use of CRC requires a lower concrete thickness than SRC because the carbon fiber reinforcement does not corrode, in contrast to steel reinforcement. Façade panels of the same geometrical dimensions and structural performance were defined as functional units (FU). Assuming an End-of-Life (EoL) scenario of 50% landfill and 50% recycling, the Global Warming Potential (GWP, given in CO2 equivalent (CO2e)) of the CRC façade (411–496 kg CO2e) is shown to perform better than or equal to the SRC façade (492 kg CO2e). Changing the assumption of CRC to a worst-case scenario, going fully to landfill and not being recycled (single life cycle), turns the GWP results in favor of the SRC façade. Assuming a 50-year service life for the SRC façade panel and relativizing the emissions to the years, the more durable CRC façade performs much better. Finally, depending on the system boundary, the assumed EoL and lifetime, CRC can represent a lower-emission alternative to a functionally equivalent component made of SRC. The most important and “novel” result in this study, which also leads to future research opportunities, is that delicate adjustments (especially concerning EoL scenarios and expected service life) can lead to completely different recommendations for decision-makers. Only by combining the knowledge of LCA experts, structural engineers, and builders optimal decisions can be made regarding sustainable materials and building components.

AbstractWorld-wide coal reserves can supply the global demand for primary energy for several centuries. However, low thickness and structural complexity may constrain the economic exploitation of many coal deposits. Taking into account these circumstances, underground coal gasification (UCG) can offer an economical and sustainable approach for coal exploitation and subsequent feedstock generation from the syngas. The UCG process produces a high-calorific synthesis gas mainly consisting of methane, hydrogen and carbon dioxide, which can be used for electricity generation or feedstock production at the surface. Considering the latter, the Urea process can be applied to establish the nitrogen based fertilizer carbamide (CH4N2O). The required feedstock for carbamide production in the Urea process can be supplied by UCG syngas. The aim of the present study was the development of an integrated carbon utilisation concept based on the coupled UCG-Urea process. A significant amount of carbon dioxide from the UCG synthesis gas is required for carbamide production in the Urea process, while the excessive carbon dioxide can be re-injected into the cavities resulting in the coal seams and surrounding strata after the gasification process. Thus, a new approach for utilisation of carbon dioxide resulting from coal combustion was developed to provide a coupled technology also comprising geological storage of excessive carbon dioxide. A theoretical feasibility study considering UCG-Urea process economics and potentials of UCG and carbon dioxide storage in the gasified strata was conducted for a selected study area in northern Bangladesh revealing the high competitiveness of the combined technology on the international feedstock markets.

In this study, we explore synergetic effects between biomass and CO2 utilization to reduce both GHG emissions and renewable resource use.

Life cycle sustainability assessment (LCSA) is one of the most relevant tools delving in sustainability science, based currently on the triple bottom line idea that is defined as the contemporary implementation of the three tools of life cycle assessment (LCA), life cycle costing (LCC) and social life cycle assessment (S-LCA). The methodology is currently being applied to a wide set of products and systems. However, as per in the large interest towards energy-related products, the sustainability assessment of energy systems—in particular those where fluid streams are used—could be more effective if some further stages could be included in the analysis, i.e. a process level analysis with regard to energy quality and exergy, and a more thorough energy analysis of the fluid flows available to achieve an optimal design of the system. This paper proposes an extended framework for LCSA introducing two additional stages to the methodology: Constructal law (CL) inspired analysis of the energy design of the system and exergy analysis (EA) of the system and its life cycle. A fully developed case study (a biomass boiler) is proposed, described the extended life cycle energy and sustainability assessment (LCESA: LCA, LCC, S-LCA, CL, EA), highlighting both the quantitative results related to each section together with the strengths and limits of the methodology, while stressing the potential applications as, e.g., decision support tool and support to the design of energy system. The results highlight different and optimized designs for the boiler through a constructal law–based analysis and several hot-spots throughout different stages of the life cycle, ranging from the production stage of steel for most environmental indicators in LCA to the cooking stage for the exergy analysis. Relevant positive impacts are traced also in the S-LCA point of view during both the use and production step. The methodology could represent a potential advancement towards the LCSA application to energy technologies as it highlights some limits and proposes specific advancements.

Space heating accounts for a large fraction of the primary energy consumption and CO2 emissions of residential buildings in Germany. Besides targeting the insulation standard, innovative (i.e. renewable energies-based and/or energy-efficient) residential heating systems (RHS) offer the potential to reduce CO2 emissions from space heating. Therefore, understanding the determinants of the RHS adoption decision becomes increasingly important. In this paper, we analyze the influence of preferences about RHS-specific attributes on the homeowners' adoption decision. Moreover, we control for the influence of socio-demographic, home and spatial characteristics. To this end, we specify the discrete appliance choice by a multinomial logit model and apply it to representative survey data for Germany. Our findings show that there are different drivers for the adoption of innovative RHS (partly) based on renewable energies in newly built and existing 1- and 2-family homes, and that the importance of key drivers also differs across groups of homeowners and RHS, respectively. First, we find that adopters of a gas- and oil-fired condensing boiler with solar thermal support have a strong preference for energy savings, while adopters of a heat pump or wood pellet-fired boiler prefer being more independent from fossil fuels. Second, we find that owners of existing homes have less scope for preferences in the RHS adoption decision. The decision to replace a RHS in an existing home is rather driven by socio-demographic, home and spatial characteristics. Third, our findings are quite contrary for newly built homes. Here, preferences about RHS specific attributes are found to be highly relevant, while there is less evidence for an influence of socio-demographic, home and spatial characteristics on the adoption decision.

This paper presents an adapted agent-based model for the diffusion of new aircraft model series. Expanding on the classical economic decision framework, where investment decision-making is entirely based on profitability, our holistic modeling approach takes into account profitability, flexibility, as well as the environmental impact of new aircraft model series in the adoption decision process. Technical parameters such as the range and maximum take-off weight of an aircraft model series, various emissions of the aircraft engine, as well as daily operational data, are used to calibrate the model. In validation, our model produces results that are comparable to data on the market diffusion of an existing aircraft model series, the Boeing 737-500. This result shows the applicability of our model, which can also subsequently be used on aircraft with new generations of technologies. Our simulation shows that a price reduction or a decrease in emissions could lead to more adoption and faster diffusion. Furthermore, our modeling approach demonstrates that a holistic framework to include not only profitability but also flexibility and environmental impact can be helpful when modeling the investment decision-making process.

Abstract While Germany is striving to move away from internal combustion engines towards alternative propulsion systems in the wake of the “Verkehrswende” (sustainable mobility transition), a diametrical protest movement has been rising since the beginning of 2019. “Pro-diesel protesters” are demonstrating against impending diesel driving bans and expressing doubts on threshold values and nitric oxide (NOx) measurements in the affected cities. In this paper, we describe the pro-diesel protest movement in Germany against the background of the diesel crisis. To assess the social embedding of the pro-diesel protest movement, we report on the findings of an empirical survey with 926 German drivers. Empirical data shows that German diesel drivers do not have a specific profile or “DNA”, as they do not differ from gasoline drivers in their perceptions of alternative fuels. The analysis of the pro-diesel protest phenomenon, its manifestations and argumentation lines reveals a multifactorial bundle of causes, and it is - at least at the current time - temporally, locally and thematically confined. However, a considerable anti-decarbonization protest potential can be expected from upcoming far-reaching climate-protecting measures (e.g., gasoline driving bans, CO2 taxation) affecting the entire German population. Implications and research needs for a socially acceptable implementation and communication of sustainable transitions are derived.