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Cogeneration of heat and electricity is an important pillar of energy and climate policy. To plan the production and distribution system of combined heat and power (CHP) systems for residential heating, suitable methods for decision support are needed. For a comprehensive feasibility analysis, the integration of the location and capacity planning of the power plants, the choice of customers, and the network planning of the heating network into one optimization model are necessary. Thus, we develop an optimization model for electricity generation and heat supply. This mixed integer linear program (MILP) is based on graph theory for network flow problems. We apply the network location model for the optimization of district heating systems in the City of Osorno in Chile, which exhibits the “checkerboard layout” typically found in many South American cities. The network location model can support the strategic planning of investments in renewable energy projects because it permits the analysis of changing energy prices, calculation of break-even prices for heat and electricity, and estimation of greenhouse gas emission savings.

Small decentralized power generation units (DG) are politically promoted because of their potential to reduce GHG-emissions and the existing dependency on fossil fuels. A long term goal of this promotion should be the creation of a level playing field for DG and conventional power generation. Due to the impact of DG on the electricity grid infrastructure, future regulation should consider the costs and benefits of the integration of decentralized energy generation units. Without an adequate consideration, the overall costs of the electricity generation system will be unnecessarily high. The present paper analyses, based on detailed modelling of decentralized demand and supply as well as of the overall system, the marginal costs or savings resulting from decentralized production. Thereby particular focus is laid on taking adequately into account the stochasticity both of energy demand and energy supply. An efficient grid pricing system should then remunerate long-term grid cost savings to operators of decentralized energy production or/and charge long-term additional grid costs to these operators. With detailed models of decentralized demand and supply as well as the overall system, the marginal costs or savings resulting from decentralized production are determined and their dependency on characteristics of the grid and of the decentralized supply are discussed.

Purpose In Italy, composting olive mill waste has become a common practice, since it mitigates the environmental problems associated with spreading the waste on land. Compost can be used to prepare growth media for plant nursery cultivation as a substitute for peat, a non-renewable resource whose extraction has long raised environmental concerns. Here, we investigate two common composting procedures--open windrow and static-pile in gas-permeable bags--and compare them to evaluate their environmental impact. Methods We perform a cradle-to-grave life cycle assessment (LCA) in accordance with ISO 14040 and 14044. The LCA considers carbon storage in the soil after 100 years, fugitive greenhouse gas (GHG) emissions, and the impacts avoided by substituting for peat. We use cumulative energy demand, global warming potential (GWP), acidification potential, and eutrophication potential indicators in a contribution analysis and explore how the re-use of olive pits for energy production and reduction of commercial fertilizers improves the environmental balance. We also present a scenario analysis that indicates how parameter fluctuations affect the results. Results and discussion Our study shows that peat's impacts can be significantly reduced from 1162.3 to 96.3 kg CO2-eq/Mg for open windrow compost or 43.1 kg CO2-eq/Mg for static-pile compost in gas-permeable bags. For static-pile composting, the lack of volatile organic compound and ammonia emissions and the detection of oxygen concentrations above 12% vol. suggest fully aerobic conditions. Fugitive greenhouse gas emissions were the most important contributions to the GWP. In the contribution analysis for static-pile composting, the avoidance of compost spreading and the carbon storage effect (due to compost usage) contributed 54% of the overall impacts to GWP and between 21 and 45% to the other indicators. Conclusions This LCA study illustrates how horticulturists can improve their resource management practices by recycling olive mill waste materials. Proper management of composting unit aeration can reduce fugitive GHG emissions.

BACKGROUND There is ample evidence for human alteration of Europe’s regional seas, particularly the enclosed or partly enclosed Baltic, Black, Mediterranean, and North Seas. Accounts of habitat and biodiversity loss, pollution, and the decline of fish stocks in these economically, socially, and ecologically important seas demonstrate unsustainable use of the marine environment. At the same time, there is an insufficient quantity and quality of information to enable purely evidence-based management of Europe’s seas despite this being a declared goal of many decisionmakers; for example, less than 10% of the deep sea has been systematically explored (UNEP 2006). Evidence-based management alone is rarely possible in situations with complex value-laden policy options (Greenhalgh and Russell 2009), and unfortunately, many of the most pervasive problems in the marine environment are “wicked” second-order problems (Jentoft and Chuenpagdee 2009): they are complex in nature and their management will often involve both winners and losers. Solutions to these problems involve less politically attractive, valuebased choices and may require long time lags before tangible results are observed. Fisheries management, habitat and species protection, competition for marine space, and invasive species are all examples of “wicked” problems. These are some of the biggest issues facing Europe’s seas and are the major focus of this article and Special Feature. For the first time in European history, most countries have adopted a common maritime policy (the 2007 Integrated Maritime Policy) and a legally binding environmental directive (the 2008 Marine Strategy Framework Directive [MSFD]). These comprehensive policy vehicles encompass, or closely interface with, more specific measures, such as the recently reformed Common Fisheries Policy, the Water Framework Directive, the Habitats and Birds Directive, and a number of targeted policy instruments that deal with aspects of pollution control and coastal zone management. The overall array of measures has the potential to ensure the sustainable use of Europe’s seas and the restoration of marine environments, but the pathway between the current situation and the implementation of an ecosystem approach to management (the aspiration of the European Commission; see Our Approach to Research) is fraught with “wicked” problems. Science can help society resolve these problems, but in many cases this requires the broad and integrative vision of Odum’s (1971) “macroscope” rather than trying to piece together an ill-fitting jigsaw puzzle of discipline-focused information. This paper and the others in this Special Feature employ a systems approach. We describe the approach, how it can be applied practically, and some of the challenges in making it work. Though the work is based on research on Europe’s seas, it has much wider implications for regional seas throughout the world. OUR APPROACH TO RESEARCH ON MARINE SOCIALECOLOGICAL SYSTEMS The research described in this paper (and Special Feature) was conducted in the framework of the EU-FP7 funded project Knowledge-based Sustainable Management of Europe’s Seas (KnowSeas). The interdisciplinary research spanned 4 years and involved 33 institutions from 16 European countries (KnowSeas 2013). Its primary objective was to develop “a comprehensive scientific knowledge base and practical guidance for the application of the ecosystem approach to the sustainable development of Europe’s regional seas.” Given the knowledge gaps and uncertainties in the way Europe’s marine social-ecological systems function (e.g., unresolved causal links, poorly mapped habitats, nonlinear dynamics), an iterative approach to inquiry was adopted, based partly on the reasoning behind soft systems analysis (e.g., Checkland 2000).

A fuel levy is one of the market-based measures (MBMs) currently under consideration at the International Maritime Organization. MBMs have been proposed to improve the energy efficiency of the shipping sector and reduce its emissions. This paper analyses the economic and environmental implications of two types of levy on shipping bunker fuels by means of an analytical model built on the cobweb theorem. A unit-tax per ton of fuel and an ad-valorem tax, enforced as a percentage of fuel prices, are examined. In both cases, a speed and fuel-consumption reduction equivalent to an improvement in the energy efficiency of the sector would be expected as a result of the regulation enforcement. The speed reduction in the unit-tax case depends on fuel prices and the tax amount, whereas in the ad-valorem case it relies upon the enforced tax percentage.Both schemes lead to industry profit decline, the extent of which depend on the structure of the levy and market conditions. Since there is concern that the costs resulting from the policy will be passed from shipping companies to their customers along the supply chain, the paper dwells on how the costs arising from the enforcement of the levy will be actually allocated between ship-owners and operators, and cargo-owners. In a market characterised by high freight rates and with no or limited excess capacity, a higher percentage of the total tax amount is transferred from ship-owners to shippers. In case of a recession the opposite happens.

Digitalization is a transformation process which has already affected many parts of industry and society and is expected to yet increase its transformative speed and impact. In the energy sector, many digital applications have already been implemented. However, a more drastic change is expected during the next decades. Good understanding of which digital applications are possible and what are the associated benefits as well as risks from the different perspectives of the impacted stakeholders is of high importance. On the one hand, it is the basis for a broad societal and political discussion about general targets and guidelines of digitalization. On the other hand, it is an important piece of information for companies in order to develop and sustainably implement digital applications. This article provides a structured overview of potential digital applications in the German energy (electricity) sector, including the associated benefits and the impacted stakeholders on the basis of a literature review. Furthermore, as an outlook, a methodology to holistically analyze digital applications is suggested. The intended purpose of the suggested methodology is to provide a complexity-reduced fact base as input for societal and political discussions and for the development of new digital products, services, or business models. While the methodology is outlined in this article, in a follow-up article the application of the methodology will be presented and the use of the approach reflected.

Virtual field trips (VFTs) are a way to overcome travel restrictions and continue to explore distant spaces, foreign issues, and learning opportunities. The intent of this article is to show how VFTs are used in learning geography in the context of education for sustainable development (ESD). The goal is to develop a didactic approach to the use of virtual fieldwork in ESD with geography teachers in pre-service and in-service teacher training at two universities. This article has the following aims. The first is to explain what a VFT is from a theoretical and technical perspective, which raises questions about forms and tools. The second is to explain how a remote intercultural seminar was conceived and implemented to create virtual fieldwork. The third is to present the methodology on which this experimentation is based and to explore the opportunities and limitations of VFTs. The last is to present and discuss the results.