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AbstractOwing to the increasing challenges of climate change and limited resources, a bundle of requirements for bioenergy are given, such as securing the energy supply, linking with the material use of biomass, or producing negative emissions. Smart bioenergy generation and utilization can fulfil those requirements by the sustainable, efficient, and flexible provision of renewable energy. This study aims to thoroughly define and structure all contributions bioenergy can make to the energy system, in the form of a comprehensive multilevel goal and indicator system. The built system includes several levels of subgoals associated with biomass, with technology, and its integration. The goal system was verified by research project leaders and further experts and can be applied to any bioenergy concept worldwide.

Abstract The paper investigates the technical feasibility of an air gasification process of a Solid Recovered Fuel (SRF) obtained from municipal solid waste. A pilot scale bubbling fluidized bed gasifier, having a feedstock capacity of about 70 kg/h and a maximum thermal output of about 400 kW, provided the experimental data: the complete composition of the syngas (including the tar, particulate and acid/basic gas contents), the chemical and physical characterization of the bed material and that of entrained fines collected at the cyclone. The experimental runs were carried out by reaching a condition of thermal and chemical steady state under values of equivalence ratio ranging from 0.25 to 0.33. The results indicate that the selected SRF can be conveniently gasified, yielding a syngas of valuable quality for energy applications. The rather high content of tar in the syngas indicates that the more appropriate plant configuration should be that of a “thermal gasifier”, with the direct combustion of the syngas in a burner ad hoc designed, coupled with an adequate energy-conversion device.

Lacking recyclability of multilayer packaging can be overcome by using a thermoreversible crosslinking adhesive consisting of maleimide- and furan-functionalized polyurethane-(PU-)prepolymers, reacting in a Diels–Alder-reaction. Here, the furan-functionalized PU-prepolymer carries furan-side-chains to avoid the usage of an additional crosslinking agent. Thus, N‑(2‑hydroxyethyl)maleimide and furfurylamine are the only two chemicals contained in the adhesive that are not listed in the appendix of EU Regulation 10/2011. Using migration modelling, it could be shown that, at 23 °C, both chemicals have lag-times of only a few minutes if 45 µm PE is used as a barrier. However, if the residual content is below 30 mg/kg, the legally specified maximum amount of 0.01 mg/kg food is not reached. After determining the diffusion coefficients and the activation energy of diffusion through ethylene-vinyl alcohol copolymer (EVOH), it could be determined that the lag-time of the migrants can be extended to at least 9 years by the use of 3 µm EVOH. From a food law point of view, the use of the described adhesive is possible if the above‑mentioned measures are complied.

Recently, the European Commission identified the goal to achieve a double transition—ecological and digital—as one of the greatest challenges on the areas of the planet across various sectors of the society [...]

This paper presents an assessment and evaluation of the costs of operation and maintenance (O&M) in a real PV rural electrification (PVRE) programme, with the aim of characterizing its costs structure. Based on the extracted data of the 5-years operational costs of a private operator, the programme has been analyzed to take out the most relevant costs involved in the O&M phase as well as the comparative appraisal between the 3 main activities: installation, O&M and management. Through this study we try to answer to the new challenge of decentralized rural electrification based on larger programmes (with tens of thousands of SHSs) and longer maintenance and operation periods (at least 10 years).

The campus of the Karlsruhe Institute of Technology (KIT) contains several waste heat streams. In an effort to reduce greenhouse gas emissions by optimizing thermal power consumption on the campus, researchers at the KIT are proposing a ‘DeepStor’ project, which will sequester waste heat from these streams in an underground reservoir during the summer months, when the heat is not required. The stored heat will then be reproduced in the winter, when the campus’s thermal power demand is much higher. This paper contains a preliminary geochemical risk assessment for the operation of this subsurface, seasonal geothermal energy storage system. We used equilibrium thermodynamics to determine the potential phases and extent of mineral scale formation in the plant’s surface infrastructure, and to identify possible precipitation, dissolution, and ion exchange reactions that may lead to formation damage in the reservoir. The reservoir in question is the Meletta Beds of the Upper Rhein Graben’s Froidefontaine Formation. We modeled scale- and formation damage-causing reactions during six months of injecting 140 °C fluid into the reservoir during the summer thermal storage season and six months of injecting 80 °C fluid during the winter thermal consumption season. Overall, we ran the models for 5 years. Anhydrite and calcite are expected mineral scales during the thermal storage season (summer). Quartz is the predicted scale-forming mineral during the thermal consumption period (winter). Within ~20 m of the wellbores, magnesium and iron are leached from biotite; calcium and magnesium are leached from dolomite; and sodium, aluminum, and silica are leached from albite. These reactions lead to a net increase in both porosity and permeability in the wellbore adjacent region. At a distance of ~20–75 m from the wellbores, the leached ions recombine with the reservoir rocks to form a variety of clays, i.e., saponite, minnesotaite, and daphnite. These alteration products lead to a net loss in porosity and permeability in this zone. After each thermal storage and production cycle, the reservoir shows a net retention of heat, suggesting that the operation of the proposed DeepStor project could successfully store heat, if the geochemical risks described in this paper can managed.

Five different pre-treatments were investigated to enhance the solubilisation and anaerobic biodegradability of kitchen waste (KW) in thermophilic batch and continuous tests. In the batch solubilisation tests, the highest and the lowest solubilisation efficiency were achieved with the thermo-acid and the pressure-depressure pre-treatments, respectively. However, in the batch biodegradability tests, the highest cumulative biogas production was obtained with the pressure-depressure method. In the continuous tests, the best performance in terms of an acceptable biogas production efficiency of 60% and stable in-reactor CODs and VFA concentrations corresponded to the pressure-depressure reactor, followed by freeze-thaw, acid, thermo-acid, thermo and control. The maximum OLR (5 g COD L(-1) d(-1)) applied in the pressure-depressure and freeze-thaw reactors almost doubled the control reactor. From the overall analysis, the freeze-thaw pre-treatment was the most profitable process with a net potential profit of around 11.5 € ton(-1) KW.

The main objective of this research is to contribute to the economic literature on cooperative entrepreneurship as a model for sustainable development, taking into account the special alignment of the cooperative principles (ICA) with the UN Sustainable Development Goals (SDGs). It offers new empirical evidence from Spain, based on Stakeholder Theory, about the differences between cooperatives (Coops) and Capitalist Firms (CFs) in relation to the distribution of economic value between the different stakeholders. For this purpose, panel data was analysed using the Correlated Random Effects approach. The results reveal that cooperative firms generate value for some of the stakeholders analysed, specifically for their partners and creditors, but no significant differences have been found with CFs in terms of workers and the state. In both cases, it can be inferred that the period analysed has influenced the results, since it has been found that, first, cooperatives adjust wages downward rather than dismiss workers during a recession, which is in line with previous research, and second, that their tax contribution to the state is lower because they are subject to a more favourable tax system in Spain.