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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.

Biomethane is a flexible energy vector that can be used as a renewable fuel for both the heat and transport sectors. Recent EU legislation encourages the production and use of advanced, third generation biofuels with improved sustainability for future energy systems. The integration of technologies such as anaerobic digestion, gasification, and power to gas, along with advanced feedstocks such as algae will be at the forefront in meeting future sustainability criteria and achieving a green gas supply for the gas grid. This paper explores the relevant pathways in which an integrated biomethane industry could potentially materialise and identifies and discusses the latest biotechnological advances in the production of renewable gas. Three scenarios of cascading biomethane systems are developed.

Buildings in private and domestic use are responsible for about 30% of the global greenhouse gas emissions attributable mainly to their need for heating and cooling energy. This corresponds to about 40% of the global final energy consumption. Therefore, a viable implementation of building energy efficiency policies is inevitable to realize a transformation of the energy system to mitigate climate change. Within the building sector lies a huge potential for emission reduction consisting in the renovation of the existing building stock and climate-friendly building guidelines applicable to new constructions, both adapting CO2-neutral technology solutions. However, as there are several different pathways leading to a decarbonized energy system, there is always the question which political and technological solutions are most efficient, effective, and feasible. This paper aims to analyze building efficiency policy measures and instruments and the related technological solutions in two front-runner countries of the energy transition, possessing different structural conditions: Germany and Norway. We hence apply a comparative approach which allows us to present and assess the policies in place. The paper answers three research questions: (1) Which policies prevail in Germany and Norway to foster the deployment of energy efficient and decarbonized solutions for residential buildings? (2) How do these policies respond to country-specific barriers to the energy transition in the building sector, and (3) What effects do they have on the actual implementation of technological and societal solutions? This research provides a new insight to the highly relevant topic of energy efficiency in buildings in the context of international Intended Nationally Determined Contribution benchmarking and discusses some unsolved trade-offs in the translation of the global climate governance into the national building sector.

The design and assessment of net-zero buildings commonly focus exclusively on the operational phase, ignoring the embodied environmental impacts over the building life cycle. An analysis is presented on the consequences of integrating embodied impacts into the assessment of the environmental advantageousness of net-zero concepts. Fundamental issues needing consideration in the design process - based on the evaluation of primary energy use and related greenhouse gas emissions - are examined by comparing three net-zero building design and assessment cases: (1) no embodied impacts included, net balance limited to the operation stage only; (2) embodied impacts included but evaluated separately from the operation stage; and (3) embodied impacts included with the operation stage in a life cycle approach. A review of recent developments in research, standardization activities and design practice and the presentation of a case study of a residential building in Norway highlight the critical importance of performance indicator definitions and system boundaries. A practical checklist is presented to guide the process of incorporating embodied impacts across the building life cycle phases in net-zero design. Its implications are considered on overall environmental impact assessment of buildings. Research and development challenges, as well as recommendations for designers and other stakeholders, are identified.

Common ragweed (Ambrosia artemisiifolia L.) is a highly allergenic annual ruderal plant and native to Northern America, but now also spreading across Europe. Air pollution and climate change will not only affect plant growth, pollen production and duration of the whole pollen season, but also the amount of allergenic encoding transcripts and proteins of the pollen. The objective of this study was to get a better understanding of transcriptional changes in ragweed pollen upon NO2 and O3 fumigation. This will also contribute to a systems biology approach to understand the reaction of the allergenic pollen to air pollution and climate change. Ragweed plants were grown in climate chambers under controlled conditions and fumigated with enhanced levels of NO2 and O3. Illumina sequencing and de novo assembly revealed significant differentially expressed transcripts, belonging to different gene ontology (GO) terms that were grouped into biological process and molecular function. Transcript levels of the known Amb a ragweed encoding allergens were clearly up-regulated under elevated NO2, whereas the amount of allergen encoding transcripts was more variable under elevated O3 conditions. Moreover transcripts encoding allergen known from other plants could be identified. The transcriptional changes in ragweed pollen upon elevated NO2 fumigation indicates that air pollution will alter the transcriptome of the pollen. The changed levels of allergenic encoding transcripts may have an influence on the total allergenic potential of ragweed pollen.

Building facades are under permanent environmental influences, such as sun and acid rain, which age and can ultimately destroy them. Living wall systems can protect facades and offer similar benefits to those gained from installing a green roof. A view back in history shows that vegetated facades are not new technology but can offer multiple benefits as a component of current urban design. In the 19th century, in many European and some North American cities, woody climbers were frequently used as a cover for simple facades. In Central Europe in the 1980s a growing interest in environmental issues resulted in the vision to bring nature into cities. In many German cities incentive programmes were developed, including some that supported tenant initiatives for planting and maintaining climbers in their backyards and facades. Since the 1980s, research has been conducted on issues such as the insulating effects of plants on facades, the ability of plants to mitigate dust, plants’ evaporative cooling effects, and habitat creation for urban wildlife, including birds, spiders and beetles. The aim of this paper is to review research activities on the green wall and facade technology with a focus on Germany. The potential of green facades to improve urban microclimate and buildings’ ecological footprint is high, but they have not developed a widespread presence outside of Germany because they are not as well known as green roofs and there is a lack of implementation guidelines and incentive programs in other countries.

We analyze how countries with different institutional settings use natural resources for economic growth. For a panel of 159 countries over the period 1992–2010, we estimate how the effect of a permanent increase in the growth rate of GDP on the growth rate of resource use depends on political institutional quality. We study this relationship for total resource use and for its subclasses fossil fuels, biomass, non-metallic minerals, and metal ores. Our results show that the effect of an increase of economic growth on total resource use growth is higher for countries with higher political institutional quality. This result holds for the subclasses biomass and non-metallic minerals and in most specifications for metal ores. In contrast, we find no positive association for fossil fuels. We reconcile our results with endogenous growth theory and suggest technology and input prices as transmission channels. In this interpretation, our results highlight that institutions provide important framework conditions, but they are no general panacea to further decrease the resource dependency of economic growth.

This paper discusses the influence of time horizon on dynamic optimization of small-size wastewater treatment plants alternating aerobic and anoxic processes. The optimization problem consists in determining the aeration policy (air-on and air-off periods) that minimizes the energy dissipated by the aeration system subject to both effluent and operating constraints. Optimization over short time horizons is first considered and reductions of the energy consumption up to 30% are obtained with respect to the usual operating mode of the process. But the application of such aeration strategies eventually results in a biomass wash-out when applied over long time periods. Here, it is shown that long time horizon optimized policies guarantee a durable functioning of the treatment plant. The resulting energy consumption savings are however lower (up to 15%), but are still important.

Abstract This study investigates the drivers of energy consumption in Sub-Saharan African countries. It applies the bounds testing approach to cointegration to time series data at individual country levels over the period from 1970 to 2011. The study finds that energy consumption is cointegrated with real GDP per capita, industrial output, imports, foreign direct investment, credit to private sector, urbanization and population. Furthermore, the sign and magnitude of long-run estimates vary significantly for a single country and across countries depending on the energy consumption variable used. Overall, the findings confirm the leading role of economic growth, industrial output, population and urbanization. Economic growth, industrial output and population have positive effects on energy consumption in the majority of countries. Given the urgent need to address climate change, African countries should adopt policies to improve energy efficiency and accelerate transition toward renewable energy. The African Renewable Energy Initiative launched at the 21st session of the United Nations Conference of the Parties (COP21) is an opportunity for African countries to provide and maintain widespread access to reliable and affordable environmentally cleaner energy to meet the requirements of rapid economic growth and improved living standards.