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Thermo-economically optimal design = optimal molecule + optimal process + optimal equipment.

National net zero emission targets could, if fully implemented, reduce best estimates of projected global average temperature increase to 2.0–2.4 °C by 2100, bringing the Paris Agreement temperature goal within reach. A total of 131 countries are discussing, have announced or have adopted net zero targets, covering 72% of global emissions. These targets could substantially lower projected warming as compared to currently implemented policies (2.9–3.2 °C) or pledges submitted to the Paris Agreement (2.4–2.9 °C). Current pledges for emissions cuts are insufficient to meet the Paris Agreement temperature goal. The wave of net zero targets being discussed and adopted could make the Paris goal possible if further countries follow suit.

The opportunities and challenges of applying micronutrients (MiNs) in full-scale anaerobic digestion (AD) plants has been reviewed. The review discusses the underlying mechanisms and the role of different micronutrients (Fe, Ni, Co, Mo, Zn, Cu, Se) in the enhancement of AD performance, as well as their environmental and economic implications in full-scale AD systems. Bioavailability is a key factor affecting the effectiveness of micronutrients application on the biochemical aspects of AD. Accordingly, the technical aspects of AD with a direct impact on bioavailability have been identified and critically addressed. Mono-supplementation is not the most favorable strategy to increase micronutrient bioavailability due to limited solubility, formation of insoluble compounds, interaction with other compounds, and specific microbial requirements. Nonetheless, co-supplementation can increase the bioavailability due to the simultaneous synergetic effects of co-micronutrients supplementation on the biochemical aspects of AD. However, the inconsistency of reported lab-scale results and the lack of protocols or guidelines for analyzing the bioavailability of micronutrients limit results interpretation and full-scale application. The environmental and economic implications of these micronutrients are other critical factors that need further research. The economic results showed that the mono-supplementation can be economically favorable when a methane enhancement of 20% is achieved. Co-supplementation of micronutrients is the most economically feasible option since this strategy allows reducing the total dosage of micronutrients when compared with mono-supplementation. The authors are grateful for the scholarship from the TUM SEED Center of the Technical University of Munich, which is part of the DAAD (German Academic Exchange Service) program “exceed” supported by DAAD as well as the German Federal Ministry for Economic Cooperation and Development (BMZ) and in cooperation with the hosting Chair of Urban Water System Engineering of TUM. Sergi Astals is thankful to the Spanish Ministry of Science, Innovation and Universities for his Ramon y Cajal. Peer Reviewed

We try to understand the role of technological change and diffusion of energy efficient technologies in order to explain the trend of energy intensity developments in the German steel industry. We selected six key energy efficient technologies and collected data to derive their diffusion since their introduction in Germany. Since all technologies have been applied in Germany for more than 30 years we would expect complete diffusion. We found complete diffusion only for basic oxygen furnaces and continuous casting. Newer technologies (i.e. basic oxygen furnace gas recovery, top pressure recovery turbine, coke dry quenching and pulverized coal injection) diffused quicker in the initial phase but then diffusion slowed down. Key improvements in energy efficiency are due to electric arc furnaces (24%), basic oxygen furnaces (12%), and continuous casting (6%) between 1958 and 2012. The contribution of top pressure recovery turbines, pulverized coal injection and basic oxygen furnaces gas recovery accounts in total of about 3%. If the selected technologies were diffused completely, the future energy consumption could be reduced by 4.5% compared to 2012. Our findings suggest that our selection of six technologies is the key driver for energy intensity developments within the German steel industry between 1958 and 2012.

Abstract While it is generally accepted that our fossil fuel-dominated energy systems must undergo a sustainable transition, researchers have often neglected the potential impacts of this on water and land systems. However, if unintended environmental impacts from this process are to be avoided, understanding its implications for land use and water demand is of crucial importance. Moreover, developed countries may induce environmental stress beyond their own borders, for instance through extensive imports of bioenergy. In this paper, Germany serves as an example of a developed country with ambitious energy transformation targets. Results show that in particular, the politically-driven aspiration for more organic farming in Germany results in a higher import quota of biomass, especially biofuels. These imports translate into land demand, which will exceed the area available in Germany for bioenergy by a factor of 3–6.5 by 2050. As this will likely bring about land stress in the respective exporting countries, this effect of the German energy transformation ought to be limited as much as possible. In contrast, domestic water demand for the German energy system is expected to decrease by over 80% through 2050 due to declining numbers of fossil-fuelled power plants. However, possible future irrigation needs for bioenergy may reduce or even counterbalance this decreasing effect. In addition, energy policy targets specific to the transport sector show a high sensitivity to biomass imports. In particular, the sector-specific target for greenhouse gas reductions will seemingly promote biomass imports, leading to the above-described challenges in the pursuit of sustainability.

AbstractThis study describes the relationships between climate change and the concept of a circular economy, outlining the need for synergies within a company's context. It reports on a bibliometric analysis of the relations between climate change and circular economy, and it provides evidence and assessments based on a sample of 11 large companies in the chemical industry. The results show that there is a concern in the academic literature to discuss circular economy efforts to combat climate change, reduce carbon emissions, strengthen the supply chain, assess the life cycle of products, their environmental impact, and waste management, and identify barriers to implementing the circular economy. In addition, there is a close association between the CE concept and tackling climate change in how organisations report their practices to the stakeholders, in considering concepts of recycling, reusing, adopting renewable energy, seeking resource efficiency, and rethinking strategies. The study concludes by providing some suggestions that may assist companies in intensifying their efforts to reduce their carbon footprint, combining them with more circular business models. Efforts from interested stakeholders must focus on defining CE in a more detailed manner, as well as its implementation at the different stages of production and consumption, especially in operations for which no uniform approach or common practice can be established. In this context, implications for positive social and environmental impacts by promoting a faster and more proactive climate transition in the chemical sector are presented. The novelty of this paper relies on the fact that it advances knowledge on matters related to the circular economy under a climate change context, identifying current trends and suggesting some measures which may optimise current business practices of the chemical sector.

Abstract The rapid uptake of renewable energy sources requires new forms of flexibility in electricity systems, including a more responsive demand-side. The social acceptability, scale and economic value of flexible demand remain subjects of conjecture. In this paper we inform this debate with a multi-methods approach using three instruments: surveys, observations and modelling. This multi-method approach brings out similarities and differences between Germany and Great Britain in relation to demand-side flexibility. Participants in both countries express a high willingness to participate in time variant tariffs, but their implementation may need to be context specific. In Germany national peak demand occurs at midday, when PV generation results in lower emission factors. Conversely, British peak demand is in the early evening when emission factors are at their highest. The differences in responses allow us to explore important technical and cultural differences affecting the need for flexibility. Germany gains most from flexibility during the daytime in summer, while flexibility in Great Britain contributes most during winter evenings. We observe high degrees of acceptability of time-variant electricity tariffs (55%) and willingness to shift demand is high, resulting in peak demand reductions of up to 14.5%. However, the resulting cost and carbon savings of these efforts is less than 2% in both countries. We conclude that short term carbon or cost savings may be less powerful motivators for load shifting measures than long term system decarbonisation.

Abstract Behavior change towards sustainable lifestyles such as adoption of renewable energy technologies is a significant element in the fight against anthropogenic climate change. Increasingly, private households can be observed to take up different renewable energy technologies; however, the introduction of these technologies is not accompanied by a broader adoption of pro-environmental behaviors, as recent studies have shown. At the same time, group settings and social capital seem to promote the uptake of wide-ranging sustainability measures. Six case studies were conducted among different sustainable community projects in Germany to shed light on why and how broad sustainability transformation in such settings comes about. Findings suggest that successful implementation of wide-ranging sustainable measures and changes in behaviors in community settings result from motivations that originate from an interplay of social needs, social capital, social norms, and environmental concern. Strong environmental attitudes, not among all, but a critical mass of members and key individuals are necessary. The desire for community and other motives, along with social influence and social norms push individuals with low environmental concern to participate in sustainable endeavors.