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Abstract In this paper, we analyze the rationale for an energy policy mix when the European Emissions Trading Scheme (ETS) is considered from a public choice perspective. That is, we argue that the economic textbook model of the ETS implausibly assumes (1) efficient policy design and (2) climate protection as the single objective of policy intervention. Contrary to these assumptions, we propose that the ETS originates from a political bargaining game within a context of multiple policy objectives. In particular, the emissions cap is negotiated between regulators and emitters with the emitters' abatement costs as crucial bargaining variable. This public choice view yields striking implications for an optimal policy mix comprising RES supporting policies. Whereas the textbook model implies that the ETS alone provides sufficient climate protection, our analysis suggests that support for renewable energies (1) contributes to a more effective ETS-design and (2) may even increase the overall efficiency of climate and energy policy if other externalities and policy objectives besides climate protection are considered. Thus, our analysis also shows that a public choice view not necessarily entails negative evaluations concerning efficiency and effectiveness of a policy mix.

Given the global energy and environmental situation, the European Union has been issuing directives with increasingly demanding requirements in term of the energy efficiency in buildings. The international competition of sustainable houses, Solar Decathlon Europe (SDE), is aligned with these European objectives. SDE houses are low energy solar buildings that must reach the near to zero energy houses’ goal. In the 2012 edition, in order to emphasize its significance, the Energy Efficiency Contest was added. SDE houses’ interior comfort, functioning and energy performance is monitored. The monitoring data can give an idea about the efficiency of the houses. However, a jury comprised by international experts is responsible for carrying out the houses energy efficiency evaluation. Passive strategies and houses services are analyzed. Additionally, the jury's assessment has been compared with the behavior of the houses during the monitoring period. Comparative studies make emphasis on the energy aspects, houses functioning and their interior comfort. Conclusions include thoughts related with the evaluation process, the results of the comparative studies and suggestions for the next competitions.

The successful electricity grid integration of solar energy into day-ahead markets requires at least hourly resolved 48 h forecasts. Technologies as photovoltaics and non-concentrating solar thermal technologies make use of global horizontal irradiance (GHI) forecasts, while all concentrating technologies both from the photovoltaic and the thermal sector require direct normal irradiances (DNI). The European Centre for Medium-Range Weather Forecasts (ECMWF) has recently changed towards providing direct as well as global irradiances. Additionally, the MACC (Monitoring Atmospheric Composition & Climate) near-real time services provide daily analysis and forecasts of aerosol properties in preparation of the upcoming European Copernicus programme. The operational ECMWF/IFS (Integrated Forecast System) forecast system will in the medium term profit from the Copernicus service aerosol forecasts. Therefore, within the MACC‑II project specific experiment runs were performed allowing for the assessment of the performance gain of these potential future capabilities. Also the potential impact of providing forecasts with hourly output resolution compared to three-hourly resolved forecasts is investigated. The inclusion of the new aerosol climatology in October 2003 improved both the GHI and DNI forecasts remarkably, while the change towards a new radiation scheme in 2007 only had minor and partly even unfavourable impacts on the performance indicators. For GHI, larger RMSE (root mean square error) values are found for broken/overcast conditions than for scattered cloud fields. For DNI, the findings are opposite with larger RMSE values for scattered clouds compared to overcast/broken cloud situations. The introduction of direct irradiances as an output parameter in the operational IFS version has not resulted in a general performance improvement with respect to biases and RMSE compared to the widely used Skartveit et al. (1998) global to direct irradiance conversion scheme. Cloudy situations and especially thin ice cloud cases are forecasted much better with respect to biases and RMSE, but large biases are introduced in clear sky cases. When applying the MACC aerosol scheme to include aerosol direct effects, an improvement especially in DNI biases is found for cloud free cases as expected. However, a performance decrease is found for water cloud cases. It is assumed that this is caused by the lack of an explicit modelling of cloud-aerosol interactions, while other meteorological forcings for cloud processes like the temperature field are modified by the aerosols.

Abstract Hybrid energy storage is a multi-modal approach to store and supply different forms of energy (electricity, heat, cold) simultaneously. This is an important sector coupling approach and enables large scale flexibility for a deep decarbonization of energy systems. Two different proposed energy storages – power-to-heat-to-X energy storage (PHXES) and pumped thermal energy storage (PTES) – are investigated in detail in this work towards their potential towards a hybrid deployment. The techno-economic analysis includes thermodynamic flowsheet simulations and unified cost estimations based on the used equipment. It is shown that the main input data set (e.g. working fluid selection, turbomachinery efficiency, pinch temperatures) has a strong influence on storage roundtrip efficiency in the thermodynamic simulations, but also on storage costs. Cost decrease and performance increase can be conflicting development targets, and it is not clear if future energy systems rather require technologies with the highest storage efficiencies or if low cost is an important prerequisite. PHXES and three variants of PTES are implemented into a simplified energy system model of the city of Hamburg that comprises the electric load and heat demand of the district heating system. Two scenarios (fossil benchmark and 80% decarbonization) are used to select the technologies and their capacities that allow the most cost-effective energy supply solution by a linear-programming optimization procedure. Large scale renewable power generation and hybrid energy storage play the major roles in the decarbonization scenario. PHXES with a storage capacity of 69 GWh, hot water storage (3.6 GWh) and a battery system (430 MWh) are part of the cost-optimal solution. A cost sensitivity analysis shows that a total cost reduction of 60–80% is required for PTES to become competitive in this model scenario.

Bioplastics are alternatives of conventional petroleum-based plastics. Bioplastics are polymers processed from renewable sources and are biodegradable. This study aims at conducting an environmental impact assessment of the bioprocessing of agricultural wastes into bioplastics compared to petro-plastics using an LCA approach. Bioplastics were produced from potato peels in laboratory. In a biochemical reaction under heating, starch was extracted from peels and glycerin, vinegar and water were added with a range of different ratios, which resulted in producing different samples of bio-based plastics. Nevertheless, the environmental impact of the bioplastics production process was evaluated and compared to petro-plastics. A life cycle analysis of bioplastics produced in laboratory and petro-plastics was conducted. The results are presented in the form of global warming potential, and other environmental impacts including acidification potential, eutrophication potential, freshwater ecotoxicity potential, human toxicity potential, and ozone layer depletion of producing bioplastics are compared to petro-plastics. The results show that the greenhouse gases (GHG) emissions, through the different experiments to produce bioplastics, range between 0.354 and 0.623 kg CO2 eq. per kg bioplastic compared to 2.37 kg CO2 eq. per kg polypropylene as a petro-plastic. The results also showed that there are no significant potential effects for the bioplastics produced from potato peels on different environmental impacts in comparison with poly-β-hydroxybutyric acid and polypropylene. Thus, the bioplastics produced from agricultural wastes can be manufactured in industrial scale to reduce the dependence on petroleum-based plastics. This in turn will mitigate GHG emissions and reduce the negative environmental impacts on climate change.

AbstractAlthough the road-map of the oxy-fuel process seems to be very advanced, there are still plenty of open questions. One of the significant ones is the corrosive behaviour of the heat exchanger surfaces. The Institute of Combustion and Power Plant Technology, University of Stuttgart, performs research on the fireside corrosion under oxy-fuel and conventional combustion conditions for the current and supercritical power plants considering the influence of combustion modus, gas atmosphere and fly ash deposits on the waterwall and superheater surfaces. Since the oxy-fuel-combustion atmosphere is composed of recirculated flue gases and pure oxygen, significantly higher concentrations of CO2, SO2 and H2O are present compared to the conventional combustion of coal with air as an oxidizer. In the here presented study the influence of an oxy-fuel combustion of a hard-coal on the surface of selected superheater materials is discussed and compared to the results obtained for lignite. Especially the interactions between the flue gas atmosphere, ash deposits and heat exchanger materials are studied in detail. The investigation encompassed in this paper has been focused on impacts of oxide-scale growth, carbon enrichment of the materials and sulphur-induced corrosion.Increased sulphur-induced corrosion has been observed in samples exposed to the oxy-combustion atmosphere. The noticed higher depth of corrosive attack of the oxy-fuel samples might be explained by a higher partial pressure of SO2 which is characteristic for oxy-fuel process. Moreover in certain cases the sulphur might be released by the deposits. Beside that, the oxy-fuel samples were exposed to much higher partial pressures of carbon dioxide comparing to the air-case leading apparently to rapid and massive internal carbon enrichment in the oxide scale. Moreover dependence between the chromium content and oxidation ability of the austenitic materials surfaces was noticed under oxy-fuel conditions.

Climate change affects the timing of phenological events, such as the start, end, and length of the growing season of vegetation. A better understanding of how the phenology responded to climatic determinants is important in order to better anticipate future climate-ecosystem interactions. We examined the changes of three phenological events for the Mongolian Plateau and their climatic determinants. To do so, we derived three phenological metrics from remotely sensed vegetation indices and associated these with climate data for the period of 1982 to 2011. The results suggested that the start of the growing season advanced by 0.10 days yr-1, the end was delayed by 0.11 days yr-1, and the length of the growing season expanded by 6.3 days during the period from 1982 to 2011. The delayed end and extended length of the growing season were observed consistently in grassland, forest, and shrubland, while the earlier start was only observed in grassland. Partial correlation analysis between the phenological events and the climate variables revealed that higher temperature was associated with an earlier start of the growing season, and both temperature and precipitation contributed to the later ending. Overall, our findings suggest that climate change will substantially alter the vegetation phenology in the grasslands of the Mongolian Plateau, and likely also in biomes with similar environmental conditions, such as other semi-arid steppe regions.

Abstract Alternative fuel vehicles (AFV) may help to reduce global CO2 emissions from the transport sector. One obstacle for AFV market diffusion is the lack of refueling infrastructure which prevents potential users from buying AFVs. Meanwhile infrastructure suppliers await market developments before investing in an extensive infrastructure roll-out. This mutual interaction has been a field of research for several years and a variety of modeling approaches have been applied. This paper aims at reviewing models of combined AFV and refueling infrastructure market diffusion and pointing out research gaps. We retrieve stylized facts which models should account for from empirical studies on natural gas vehicles, user acceptance analyses on AFVs and technical restraints of plug-in electric vehicles (PEVs) and fuel cell electric vehicles (FCEVs). Ten interaction models are evaluated with respect to the identified aspects. We find that simulation is the most common approach for an interaction model. Besides, the majority of the examined stylized facts is covered by the models. However, models for FCEVs could be improved by reflecting the transport of fuel to refueling infrastructure while new models on PEVs should include charging duration, frequency and charging station ownership.