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District heating and cooling systems have been present on the European market for more than a century, constantly evolving into more efficient energy infrastructures important for decarbonization of the heating and cooling sectors. With roughly 17,000 operational district heating systems, serving over 70 million citizens, currently, the final energy consumption attributed to district heating in Europe is estimated at over 450 TWh. As the European district heating and cooling sector varies extensively in every analyzed aspect, there are vast differences between European countries regarding technical preferences, technological development, market structure and regulatory frameworks of these systems. The main purpose of this paper is to provide a comprehensive overview of the present status of the district heating and cooling systems in Europe with insight(s) and suggestions into future trends. In addition, the provided data serves as a valuable baseline for future research. Finally, this paper draws attention to the new socio-demographic approach, observed when analyzing the district heating and cooling systems, that has been recently introduced into the scientific community. This new approach also reveals the opportunity for creating new indicators that will influence the modeling of existing and future district heating and cooling systems. • Provides a review on ongoing trends in European district heating and cooling sector. • Analyses European DHC systems from technological, market, and regulatory aspect. • Provides an overview on commonly used performance indicators and energy models. • Discusses the possibility of creating new DHC indicators. • Discusses the trends in future DHC development. [ABSTRACT FROM AUTHOR]

This paper inaugurates the study of the energy-sustainable economic growth for Europe. It is novel both because it calculates an Index for Sustainable Economic Welfare (ISEW) index for European countries, but foremost because it compares the conventional energy-growth nexus with the newly appeared energy-sustainable growth nexus. Also, it goes further by suggesting ways to overcome the limitations pointed out to the use of the conventional GDP. The paper uses the road sector energy consumption, which is in accordance with the enormous discussion about the high energy intensity of the road transport sector and about the huge dependence from fossil sources of this sector. The dynamic Driscoll-Kraay estimator is also used, which allows decomposing the effects in the short- and long-run and is also robust in the presence of cross-sectional dependence. Results show that economic growth and sustainable economic welfare are not perfect substitute variables. In the long-run, the feedback hypothesis is verified only for sustainable growth. [ABSTRACT FROM AUTHOR]

By 2020 Europe has to increase its energy efficiency and share of renewables in 20%. However, even accomplishing these challenging objectives Europe will be effectively wasting energy as we demonstrate in this paper. In our way towards a fully renewable scenario, we need at least to stop wasting energy in order to guarantee the energy supply needed for growth and comfort. We waste energy when we employ more primary energy than the final energy we ultimately use and this excess cannot be reutilized. In this paper we propose the WE (wasted energy) as a novel metric to measure the performance of energy systems and set up appropriate targets. The WE incorporates information about energy efficiency and renewable sources. Unlike European legislation, the WE considers them in an integrated way. This approach will help Member States to exploit their intrinsic capabilities and design their optimum strategy to reach their objectives. Using the information in Eurostat, we calculate the WE of Member States in EU-28 and their evolution. We also analyze illustrative examples to highlight strategies to reduce the WE, study the connection between economic development and WE, and provide a tool to diagnose the potential of improvement of an energy system. [ABSTRACT FROM AUTHOR]

Industrial furnace is one of the most energy intensive processes in Europe and it has been the focus of multiple researches to address improvements in the competitiveness energy, environmental and cost performance. One of the alternatives is the reduction of fossil fuel consumption, such as natural gas, promoting its substitution by an alternative fuel (Co-firing). This paper gathers a wide evaluation of the possibilities of substitution of natural gas. A revision of the types of syngas with potential for use has been carried out, as well as the evaluation of the physical properties of the mixtures from the combustion operation point of view. Three types of syngas from biomass gasification (BSG) and three from process off-gases (POG) have been considered. The feasibility study has taken into consideration parameters such as the lower heating value, the Woobe index, adiabatic flame temperature, air preheating temperature, total flue flow and laminar flame velocity. Regardless of the type of syngas, significant increase in volumetric fuel flow occurs in all cases. This behaviour is directly related to the LHV of the syngas, so that using syngases with lower LHV than the NG will always produce an increase of the fuel flow. A weigh matrix has been obtained in order to evaluate the viability of burners use with the syngas/natural gas mixture. It has been considered a burner commonly used in ceramic sector and it has been concluded that relevant modifications are necessary in order to consider the combustion of syngas/natural gas. The modifications have been evaluated using CFD simulations to stablish the proper design of the mix zone to ensure the mixture between the air, syngas and natural gas. This evaluation has been carried out following the fuel to air ratio. • Woobe Index is the best theoretical parameter to evaluate fuel replacement. • AFT, LHV and LFV should be also taken into account in the evaluation. • Deep burner modifications should be carried out for NG substitution by syngas. • Fuel to air ratio is a proper parameter to evaluate combustion performance. • Swirl plate is required to achieve a suitable mixture between NG-SG-combustible. [ABSTRACT FROM AUTHOR]

This paper contributes insights on differences in observed rates of substitution for fossil fuels across countries as measured by changes in the energy mix. If some countries are relatively slower in substituting for fossil fuels, climate change will be addressed less successfully. This paper specifically investigates the role of industrialisation and state-related institutions in the speed of energy substitution in 19 European countries from years 2011–2018 using panel data econometric methods, and has three main results. This paper finds evidence that (1) higher industrialisation levels in the economy increase the speed of energy substitution; (2) that changes in industrialisation levels, not the levels themselves, decrease the speed of energy substitution, but state-related institutions in support of green energy policy weaken this effect; and that (3) higher degrees of state control of the electricity sector slows down energy substitution, but state-related institutions in support of green energy policy likewise weaken this effect. These findings imply that higher industrialisation levels require more energy in absolute terms, implying greater energy portfolio diversification in order to satisfy such energy demand, and that a faster energy substitution can result from a more liberalised electricity sector. • A study on 19 European countries from years 2011–2018 using panel data. • Changes in industrialisation levels decelerates energy substitution. • More state control of the electricity sector decelerates energy substitution. • State-related institutions supporting green energy policies weaken these effects. • Higher industrialisation levels themselves however accelerate energy substitution. [ABSTRACT FROM AUTHOR]

The energy retrofitting of residential stock is not always straightforward where heritage protected housing is concerned. In southern Europe, many examples built under the Modern Movement codes are now obsolete in terms of energy efficiency. The aim of this paper is to assess the potential for improvement of comfort conditions and energy efficiency in Mediterranean heritage residential buildings, through the incorporation of passive strategies in keeping with preserving heritage values. Long-term monitoring and field tests in representative flats of the case-study building were carried out and, focusing on a single example, adaptive comfort equations were used to assess results. The passive strategies considered are the thermal isolation of the air cavities of walls, changing window frames, optimizing window glazing, and setting up regular mechanical ventilation rates for indoor air changes. Although simulation results generally predict a better energy performance after testing retrofit strategies, the potential decrease in energy demand is more noticeable than the potential improvement in comfort conditions. • The improvement of comfort and energy efficiency in a heritage building is assessed. • Long-term monitoring and field tests were carried out in representative flats. • Passive strategies in keeping with preserving heritage values were examined. • Adaptive comfort equations were used to assess results focusing on one flat. • Energy efficiency improvements are more noticeable than those of comfort conditions. [ABSTRACT FROM AUTHOR]

Abstract: Building energy use accounts for almost 50% of the total CO2 emissions in the UK. Most of the research has focused on reducing the operational impact of buildings, however in recent years many studies have indicated the significance of embodied energy in different building types. This paper primarily focuses on illustrating the relative importance of operational and embodied energy in a flexible use light distribution warehouse. The building is chosen for the study as it is relatively easy to model and represents many distribution centres and industrial warehouses in Europe. A carbon footprinting study was carried out by conducting an inventory of the major installed materials with potentially significant carbon impact and material substitutions covering the building structure. Ecotect computer simulation program was used to determine the energy consumption for the 25 years design life of the building. This paper evaluates alternative design strategies for the envelope of the building and their effects on the whole life emissions by investigating both embodied and operational implications of changing the envelope characteristics. The results provide an insight to quantify the total amount of CO2 emissions saved through design optimisation by modeling embodied and operational energy. [Copyright &y& Elsevier]

Abstract: During the project Clean Urban Transport for Europe (CUTE), which ended in May 2006, 27 fuel cell buses were operated in nine European cities. In this paper key performance parameters from the operation of the fuel cell buses in the project are reported, the energy system of the bus is analysed and drive cycle tests in five cities are presented and analysed. The focus of the paper is on fuel consumption and optimisation potential but experiences of, and recommendations for, evaluation in large demonstration projects are also presented. The results show that although the total fuel cell system efficiency was found to be high (36–41%), the fuel consumption was higher for the fuel cell buses than for diesel buses. Since the CUTE buses were a pre-commercial generation of fuel cell buses, with standard auxiliaries and extensive reliability measures, large fuel consumption reduction is possible. Suggestions on how to increase the efficiency is presented in this paper. Minimising the reliability measures would decrease fuel consumption by about 20% and lowering the weight by 2 tonnes would decrease fuel consumption by another 10%. Hybridisation in combination with using electrical auxiliaries could save an additional 5–10% or more. [Copyright &y& Elsevier]

This paper proposes an overarching review of national municipal waste management systems and waste-to-energy as an important part of it in the context of circular economy in the selected countries in Europe. The growth of population and rising standards of living means that the consumption of goods and energy is increasing. On the one hand, consumption leads to an increase in the generation of waste. On the other hand, the correlation between increased wealth and increased energy consumption is very strong as well. Given that the average heating value of municipal solid waste (MSW) is approximately 10 MJ/kg, it seems logical to use waste as a source of energy. Traditionally, waste-to-energy (WtE) has been associated with incineration. Yet, the term is much broader, embracing various waste treatment processes generating energy (for instance, in the form of electricity and/or heat or producing a waste-derived fuel). Turning waste into energy can be one key to a circular economy enabling the value of products, materials, and resources to be maintained on the market for as long as possible, minimising waste and resource use. As the circular economy is at the top of the EU agenda, all Member States of the EU (including the EEA countries) should move away from the old-fashioned disposal of waste to a more intelligent waste treatment encompassing the circular economy approach in their waste policies. Therefore, the article examines how these EU policies are implemented in practice. Given that WtE traditionally is attached to the MSW management and organisation, the focus of this article is twofold. Firstly, it aims to identify the different practices of municipal waste management employed in selected countries and their approaches in embracing the circular economy and, secondly, the extent to which WtE technologies play any role in this context. The following countries, Estonia, Greece, Italy, Latvia, Lithuania, Norway, Poland, Slovenia, Spain, and the UK were chosen to depict a broad European context. [ABSTRACT FROM AUTHOR]

This paper compares the electricity, heating, and cooling sectors at national level for various European countries. Annual energy demands are compared for all 28 EU countries, while peak hourly demands are compared for four countries that vary significantly. The results indicate that the heat demand is currently the largest of the three demand types considered in terms of both annual and peak demands: it is the largest annual demand in 25 of the 28 EU countries, and it represents the largest peak demand in all four countries analysed. Electricity, heating, and cooling demands are all likely to change significantly in the future with increasing electrification, energy efficiency (e.g. building insulation), and improved comfort (especially for cooling). Some extreme scenarios are presented here to quantify the potential impact of these changes on the electricity sector, with results revealing that the demand for electricity could double compared to today, depending on how these changes occur. Considering the scale of additional electricity required to electrify future heating and cooling demands, heat pumps should be prioritised over electric heating and other alternatives, such as district heating and cooling, will likely be required to minimise the strain on the electricity grid in the future. [ABSTRACT FROM AUTHOR]

Forest biomass is one of the few non-fossil and non-weather-dependent energy sources available in the Nordic countries. The future role of forest-based bioenergy is, however, unclear as biomass is a limited resource and has many alternative applications. This study analyses how fossil emissions and land-use is affected by forest bioenergy in the North-European heat and power sector, using an energy system model with endogenous capacity investments. The novelty of this paper lies in the detailed description of the substitution factors for different bioenergy levels toward a fully decarbonised energy system. The main results show that forest biomass remains important for heat production in the Nordic countries towards 2050 in a cost-optimal scenario. According to our model results, less use of forest biomass for heating will increase the use of fossil fuel, wind power, and power-to-heat in 2030, while in 2050 also solar PV will be used as a substitute for forest biomass. Implying that less use of forest biomass will increase the land use from wind and solar PV installation and increase and prolong the fossil carbon emission in the Nordic countries. • 1 TWh biomass reduces the emission with 0.10 mill ton of CO 2 in 2030 in North Europe. • The land-use substitution factor in North Europe is 18–47 km2/TWh biomass in 2050. • Forest biomass remains important for heat production towards 2050. • Excluding forest biomass from the energy sector increases emissions and land use. • Less use of biomass implies more use of land for wind installations. [ABSTRACT FROM AUTHOR]

In all European countries the energy and building related legislature stand for energy refurbishment of existing building stock. Depending on the economical situation of countries there are different national programs that help owners to invest in energy related refurbishments of their houses or flats. The financial support is given only in case of a certain payback time, which should be obtained by the proposed project. The payback time for heating related investments in Hungary is calculated based on the theoretical degree day curve, which can lead to inaccurate results. Thus in this paper a long-term analysis of heating degree day, done for Debrecen (the second largest city of Hungary), is presented. We focused our analysis on residential buildings. It was found that the degree day has important variations during the analysed decades, which can lead to deviations of energy consumption up to 15–18%. Furthermore, taking into account the heat island effects in Debrecen, it was proven that differences of about 22% can be obtained between real degree day values in different zones of the city. The interrelation between specific heat gains and balance point temperature, respectively the effects of glazed area of the facades on the balance point temperature was discussed. It was found that for buildings with similar thermal characteristics of the envelope and the same values of specific heat gains, the balance point temperature can be even double for a detached house compared with a block of flats. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen has a wide range of applications. In view of the environmental benefits, hydrogen can be produced by decarbonized means. When alkaline electrolysis is the selected process, extra value is offered by flexible operation that could bring both; an opportunity to reduce the cost of hydrogen produced (by consuming electricity during off-peak hours, and stopping the process during peak hours) and also a complementary tool to help balancing of the electric system. This paper assesses the profitability of market-driven operation for three different markets: France, Germany and Spain, with an analysis on the spot market. The market that exhibits the biggest potential in terms of profitability thanks to flexible operation is the French one, for each studied year. France is also the country that has the smallest installed renewable capacity amongst three considered countries. The gain on the hydrogen production cost allowed by the optimization is less than 3%. Hence, market-driven operation does not seem highly favourable to valorize fluctuating hydrogen production, when only the market price opportunities are considered. The balancing tool provided by the electrolysis system needs to be specifically valorized, in order to make flexible operation profitable. [Copyright &y& Elsevier]

Abstract: In transmission and distribution systems, the high number of installed transformers, a loss source in networks, suggests a good potential for energy savings. This paper presents how the Spanish Distribution regulation policy, Royal Decree 222/2008, affects the overall energy efficiency in distribution transformers. The objective of a utility is the maximization of the benefit, and in case of failures, to install a chosen transformer in order to maximize the profit. Here, a novel method to optimize energy efficiency, considering the constraints set by the Spanish Distribution regulation policy, is presented; its aim is to achieve the objectives of the utility when installing new transformers. The overall energy efficiency increase is a clear result that can help in meeting the requirements of European environmental plans, such as the ‘20–20–20’ action plan. [ABSTRACT FROM AUTHOR]

Abstract: Over the last few years, load growth, increases in intermittent generation, declining technology costs and increasing recognition of the importance of customer behaviour in energy markets have brought about a change in the focus of Demand Response (DR) in Europe. The long standing programmes involving large industries, through interruptible tariffs and time of day pricing, have been increasingly complemented by programmes aimed at commercial and residential customer groups. Developments in DR vary substantially across Europe reflecting national conditions and triggered by different sets of policies, programmes and implementation schemes. This paper examines experiences within European countries as well as at European Union (EU) level, with the aim of understanding which factors have facilitated or impeded advances in DR. It describes initiatives, studies and policies of various European countries, with in-depth case studies of the UK, Italy and Spain. It is concluded that while business programmes, technical and economic potentials vary across Europe, there are common reasons as to why coordinated DR policies have been slow to emerge. This is because of the limited knowledge on DR energy saving capacities; high cost estimates for DR technologies and infrastructures; and policies focused on creating the conditions for liberalising the EU energy markets. [Copyright &y& Elsevier]

Abstract: This study begins with a review of energy consumption by end-use sector in Hawaii. Then, the energy generated from renewable energy sources is analyzed between 1991 and 2006. The results show that while geothermal is a considerable source of renewable energy on the Island of Hawaii (also known as Big Island), fossil fuel is the main energy source in the State of Hawaii. The energy intensity index for the State of Hawaii is then calculated by dividing energy consumption per capita by the income per capita. The calculated energy intensity index reveals that energy consumption is directly controlled by per capita income. The results also indicate that the energy intensity index increases over time despite positive developments in energy efficient technologies. In the second part of the paper, the effect of the tourism industry on energy usage in the State of Hawaii is analyzed. The results show that tourism volume, measured in terms of tourist arrival numbers, does not change the energy consumption directly. However, a change in tourism volume does affect per capita income within a few months to a year. In the last part of the study, the energy efficiency index of Hawaii is compared with consumption averages for the US, California and the most energy efficient country in Europe, Denmark. The comparison shows that Hawaii lags behind California and Denmark in terms of energy efficiency. The comparison also shows that an increase in energy efficiency corresponds to an increase in per capita income across the board, which is in agreement with a recent report published by the American Physical Society. [Copyright &y& Elsevier]

4th Generation District Heating (4GDH) systems can have a supply temperature lower than 50 °C to decrease losses and to favour the integration of renewable and waste heat. As the temperature requirement for space heating in new and retrofitted buildings is around 35 °C or lower, they would be suitable for 4GDH. However, Domestic Hot Water (DHW) is a significant barrier in district heating, because the temperature needs to be maintained above the standard Legionella growing range (25 °C–55 °C), even if 45 °C would be sufficient for comfort. Nonetheless, current regulations vary widely across countries in Europe, especially for small buildings. This paper aims to study the effect of different Legionella regulations on the DHW energy use, and on the substation cost of a Swiss single-family household connected to a 4GDH network. The Swiss standard is confronted with the requirements of the Danish regulation and the German "3-litre rule". Results demonstrated that a relaxation of the current Swiss regulation could present energy and economic savings. The "3-litre rule" resulted in an annual heat consumption reduction of 13% while the Danish standard achieved the lowest annual running cost and annualized total cost. • Impact of DHW regulations on a 4GDH substation energy and economic performance. • DHW regulations in Europe with different temperatures or specific exceptions. • Swiss DHW standard compared with Danish and German regulations. • Danish standard reduced the annualized system cost and the annual running cost. • German 3-litre rule with lowest investment cost but highest annual cost. [ABSTRACT FROM AUTHOR]

Many countries apply measures for the limitation of the conventional energy technologies and try to expand the use of renewables. As the building sector accounts for almost 40% of the energy consumption in Europe, building integrated photovoltaic (BIPV) systems gain peoples' interest lately concerning the replacement of the conventional construction materials of the buildings envelope with photovoltaic (PV) panels which can serve at the same time as construction material and energy producer. The aim of this study is to present an overview of the available published research on the BIPV systems and identify the barriers and risks associated with the application of BIPV and discuss the future perspectives and solutions through recommendations for future research and development. The most important barriers of the BIPV systems are the feed in tariff implementation, the public acceptance, the governmental economic support in terms of subsidies and technical aspects like the power losses and the architectural considerations. The future perspectives of the BIPV systems proposed are based on the barriers discussed. It is stated that new solutions in the PV industry are many and various and there is room for improvement regarding design, configuration, ventilation, positioning, guidelines, monitoring and performance prediction. In total, more than 100 articles have been identified and analysed since 2000. Many of these articles have a predominant focus on the investigation of the performance of the system, and the ventilation of the PV panels in BIPV applications for electricity production, due to the negative role of the temperature on PVs electrical efficiency, and the heat transfer behavior of the system. This paper shows that although research in the adoption of BIPV systems in terms of their performance and optimization is fairly new, it has gained attention in the last decades. However, their practical applications have been slow in comparison with the conventional rack-mounted PV panels. • Status of the BIPV systems applications and configurations. • Technical barriers of the BIPV systems. • Future perspectives and recommendations to increase the usage of BIPV systems. [ABSTRACT FROM AUTHOR]