Promotion of grid-connected photovoltaic systems in Spain: Performance analysis of the period 1998–2008

This paper contributes a critical view of the development of grid-connected photovoltaic systems (GCPVS) in Spain during the period 1998–2008 by looking into the different actions that were intended to promote this technology. The Spanish photovoltaic (PV) sector has undergone bullish development in the recent years, but its underlying factors still lack systematic identification and analysis. Accordingly, this paper collects and presents detailed data for describing this evolution. It also makes a special case of the particular promotion of PV systems on roof and goes further to analyze how these actions have affected GCPVS evolution as well as the magnitude of their impact on its performance. The exponential growth of installed cumulative PV power at the end of this period, which largely exceeded the target set for 2008, is canvassed by building an analogy with feedback control systems. In this approach, market response or the PV power attained is considered as the system output, while the different regulation changes are regarded as control actions aimed at enabling GCPVS to hit the energy target. Such an analysis allows determining the most significant delays and control actions that explain the system's performance. Hence, this study suggests an alternative framework to support the formulation and assessment of energy policy as it puts the emphasis not only on the evolution of the system per se but rather on the performance of the system against the energy target. In this regard, it might contribute to enhance the promotion mechanisms of green technologies.     

Energy consumption in iodine section of I–S: Effect of operating parameters of electro-electrodialysis on overall efficiency of cycle

Reducing heat demand for increasing concentration of HI in the HI_x solution of the iodine circuit of the Iodine–Sulphur cycle is considered the most effective way of increasing efficiency of the cycle. Electro-electrodialysis has emerged as an energy efficient way of increasing the HI_x concentration above azeotropic value. Simulation of the iodine circuit consisting of an EED, a flash and a decomposer was carried out in Aspen Plus™ simulation platform to study the effect of EED current density and outlet HI concentration on the efficiency of the cycle. Efficiency reduced strongly with increase in current density. For EED current density of 5 A/dm², maximum efficiency was ∼35.9% and the optimal range of EED catholyte's exit HI concentration, iodine-free, mole fraction was 0.19–0.21. Simulation results showed that reducing EED resistance was most effective, among all EED parameters, in increasing the cycle's thermal efficiency and if the EED resistance is completely eliminated the thermal efficiency value would increase to 39.4%.     

LMDI decomposition analysis of energy consumption in Andalusia (Spain) during 2003–2012: the energy efficiency policy implications

The aim of this paper is to analyse the changes in final energy consumption in Andalusia through logarithmic mean Divisia index (LMDI) decomposition analysis during the period 2003–2012. The results lead us to conclude that a reduction of final energy (FE) consumption of 1 % took place as a result of a diminishing in structural effect by 11 % and an increase in the activity effect and intensity effect by 7.4 and 3.5 %, respectively. Chain-linked LMDI decomposition shows the existence of two sub-periods, with a turning point in 2008. The first period, coinciding to a great extent with the Andalusian Energy Plan 2003–2006 (PLEAN), showed an increase in final energy consumption, mostly due to the activity effect but also to the intensity effect. The second period, coinciding with the implementation of the Andalusian Sustainable Energy Plan 2007–2013 (PASENER), shows a reduction in the activity, structure and intensity effects. The results allow us to conclude that many of the energy efficiency measures, implemented through the PASENER, are related to sectors that experienced a decline in energy consumption due to the intensity effect, such as transport, primary and service sectors. Additionally, although they were included in PASENER, more policy attention should be given to the energy transformation, residential and industrial sectors which increased the demand for energy due to the intensity effect during this period. Finally, the energy-saving behaviour of economic agents due to the economic downturn should also be considered as an explanation for the diminishing in energy consumption during this sub-period.     

Energy efficiency outlook in China’s urban buildings sector through 2030

This study uses bottom-up modeling framework in order to quantify potential energy savings and emission reduction impacts from the implementation of energy efficiency programs in the building sector in China. Policies considered include (1) accelerated building codes in residential and commercial buildings, (2) increased penetration of district heat metering and controls, (3) district heating efficiency improvement, (4) building energy efficiency labeling programs and (5) retrofits of existing commercial buildings.Among these programs, we found that the implementation of building codes provide by far the largest savings opportunity, leading to an overall 17% reduction in overall space heating and cooling demand relative to the baseline. Second are energy efficiency labels with 6%, followed by reductions of losses associated with district heating representing 4% reduction and finally, retrofits representing only about a 1% savings.     

Energy embodied in the international trade of China: An energy input–output analysis

Growing international trade has not only positively affected the People’s Republic of China’s (China’s) economic development, but also expanded the exportation of energy embodied in goods during their production. This energy flow out will pose risks to China’s rational utilization of natural resources as well as environmental protection. In this paper, we evaluate the energy embodied in goods produced in China during 1992–2005 and use input–output structural decomposition analysis to identify five key factors causing the changes of energy embodied in exports. (Direct primary energy efficiency, primary energy consumption structure, structure of intermediate inputs, structure of exports, and scale of exports.) For the three sub-periods of 1992–1997, 1997–2002, and 2002–2005, results show that China is a net exporter of energy, and the energy embodied in exports tends to increase over time. The expanding total volume of exports and increasing exports of energy-intensive goods tend to enlarge the energy embodied in exports within all three sub-periods, but these driving forces were offset by a considerable improvement of energy efficiency and changes in primary energy consumption structure from 1992 to 2002 and the effects of structure of intermediate input only in the sub-period from 1992 to 1997. From 2002 to 2005, the sharp augmentation of energy embodied in exports was driven by all the five factors. Our research has practical implications for the Chinese economy. Results of this study suggest that the energy embodied in trade should receive special attentions in energy policies design to limit the energy resource out-flow and pollution generation.     

Woodfuel consumption in Scotland 2005–8

Three surveys were done in 2004–5 to assess the use of wood for energy in Scotland. Businesses using more than 10,000 odt y^?1 dominated the sector, accounting for 131 thousand odt (k odt) which was used mainly for co-firing and heat production in the wood-processing industry. Within the category using 1000–10,000 odt y^?1 there were four developments using a total of 6 k odt y^?1. In the smallest category 33 projects used a total of 4 k odt y^?1. Of 4000 adults surveyed 4.8% used woodfuel at home. Data from a subset of users were combined with survey information to estimate domestic woodfuel usage (52 k odt y^?1). The total 2004–2005 woodfuel use in Scotland was therefore estimated as 193 k odt y^?1.Industrial and commercial usage was resurveyed in 2006, 2007, and 2008. Total woodfuel usage increased to 306 and 324 k odt in 2006 and 2007 due to an increase in the use of pellets for co-firing and also the number of projects in the two smaller size classes. The following year saw the commissioning of a dedicated biomass power plant, increasing use of recycled wood and decreasing use of pellets. The net effect within the industrial and commercial sector was an increase in demand to 413 k odt y^?1 by spring 2008. Domestic usage was reestimated in 2007. The number of households using woodfuel was static or decreasing slightly; we estimate an annual usage of 50 k odt. Total woodfuel usage in Scotland was estimated as 463 k odt y^?1 by spring 2008.     

Energy–exergy optimization of comminution

The comminution process has exceedingly low efficiency because it is highly irreversible. An outline of energy analysis for comminution is presented. The application refers to an ore-processing plant, which consists of a series of crushers feeding a traditional ball mill that delivers products to a downstream metallurgical process. For optimization, the design characteristics are fixed, i.e. decision variables can only be operational parameters. The chosen decision variable is the size of the feed (F) to the mill. In practice, the mill operator may control the feed granulometry and keep the product size constant by using a constant ball charge. The objective cost function is the sum of energy costs at the crusher and mill, which depend only on F. The exergy consumption of the crusher and mill are evaluated using the Bond correlation, including pertinent correction factors. Optimization leads to a 10% saving in overall energy costs.     

Interphase heat transfer during bulk condensation in the flow of vapor–gas mixture

The investigation of heat transfer between a single droplet and a vapor–gas mixture at different Knudsen numbers of growing droplet is presented. The influence of the interphase heat transfer on the behavior of macroparameters and the distribution function of droplets was studied using the results obtained for bulk condensation of vapor–gas mixture flow in a nozzle. A comparison of results obtained within the frames of general formulation and ones following from the certain simplifying assumptions on the droplets temperature was carried out for the free molecular regime of droplets growth.     

The Peak of the Oil Age – Analyzing the world oil production Reference Scenario in World Energy Outlook 2008

The assessment of future global oil production presented in the IEA’s World Energy Outlook 2008 (WEO 2008) is divided into 6 fractions; four relate to crude oil, one to non-conventional oil, and the final fraction is natural-gas-liquids (NGL). Using the production parameter, depletion-rate-of-recoverable-resources, we have analyzed the four crude oil fractions and found that the 75 Mb/d of crude oil production forecast for year 2030 appears significantly overstated, and is more likely to be in the region of 55 Mb/d. Moreover, analysis of the other fractions strongly suggests lower than expected production levels. In total, our analysis points to a world oil supply in 2030 of 75 Mb/d, some 26 Mb/d lower than the IEA predicts.     

Energy requirements of output of the New Zealand economy, 1976–1977

This paper describes the methodology, data sources and results of an input-output energy analysis of the 1976–1977 inter-industry survey of the New Zealand economy. Results are tabulated (at 29-sector and 178-sector levels of detail) as the total energy intensities of output, for the following energy supply industries: coal mining and natural gas production; petroleum refining, oil and coal products; electricity, state supply; electricity, local body supply; and gas manufacture and distribution. The disposition of energy embodied in outputs to final demand sectors of the economy is discussed.     

Risk Analysis in Renewable Energy： Assessment of the Vulnerability of the Environment and Community

As a result of recent accidents, society is becoming more conscious and concerned about the risk that are under to the environment and communities. A proposal of assessment of the vulnerability of the environment and community is presented here under a holistic perspective using fuzzy logic as a formal tool. An internal factor of the risk of a system under a given threat is assessed. Risk is considered as the union between the threat and the vulnerability of the environment and community. This approach shows that the reduction in either or both of them makes a reduction in the risk content as well. The main purpose of this proposal is not to obtain a single value as output; in fact the result is a map which can contribute to the different areas of the community in decision making.     

Experimental analysis of propagation regimes during the autoignition of a fully premixed methane–air mixture in the presence of temperature inhomogeneities

The present work is devoted to the study of the combustion processes of a homogeneous methane–air mixture subject to thermal stratification within a rapid compression machine (RCM). Temperature fields obtained in nonreactive conditions have been documented in a previous study and the present work aims at correlating these data with the combustion process. The analysis of chemiluminescence images enables the delineation of two propagation regimes, namely spontaneous ignition fronts and deflagrations. The first is observed for short ignition delays, as the fluid features a fairly large and homogeneous hot core zone. The second dominates the combustion process for longer ignition delays. Indeed, despite global homogenization of the temperature fields, the hottest zones are fairly narrow and surrounded by non-negligible thermal gradients, which favors the formation of deflagration. The results thus clearly show a strong correlation between the preignition temperature field and the subsequent combustion process. They are commented on in the light of recent literature. In a second part, quantitative predictions of the occurrence of autoignition fronts and deflagrations are performed by employing a criterion derived from the analysis of direct numerical simulation data (Sankaran et al., 2005). The results are in good agreement with others previously obtained through chemiluminescence imaging for early and intermediate stages of combustion. It is more difficult to reach definitive conclusions for later instants. The present work highlights the relevance but also suggests some limitations of the corresponding criterion for the analysis of homogeneous charge compression ignition (HCCI) combustion processes at the cylinder scale. Furthermore, the quantitative data gathered within the RCM demonstrate the relevance of this device for further investigation of these fundamental issues.     

Energy saving mechanism analysis of the absorption–compression hybrid refrigeration cycle

Focusing on the effective use of low-grade solar heat as heat source to provide refrigeration for residential and commercial space cooling, an absorption-compression hybrid refrigeration cycle has been studied on the basis of available data of working pair 1,1,1,2-tetrafluoroethane (R134a) and dimethylformamide (DMF). In order to investigate their performance, the energy saving mechanism of the hybrid cycle was analyzed, by means of thermodynamic diagrams of log p–T, log p–h and T–s. The results show that the hybrid refrigeration cycle has a relatively high thermodynamic perfectibility and can use low-grade heat to replace parts of mechanical work for obtaining lower temperature refrigeration effect owing to its energy complement and cascade refrigerating configuration between the internal sub-cycles. Moreover, on the basis of two new criteria, the heat powered coefficient of performance and the electricity saving rate, the competition behavior between the sub-cycles of the hybrid cycle, i.e. the trade-off effects of compressor pressure on the low-grade heat utilization performance were also investigated. It was found that the sub-cycles compete in their contribution to the hybrid refrigeration system and the cycle preferences depend on the dominance which one achieves. In other words, there is an optimum compressor outlet pressure region under specified working conditions, where the hybrid refrigeration cycle has the maximum heat powered coefficient of performance and electricity saving rate.     

Carbonization Index and Energy Intensity in the Formation of Worldwide CO2 Emissions, 1971–2000

This study uses three methods to explore the roles of the carbonization index and energy intensity in the formation of CO ₂ emissions throughout the world based on statistics from 1971 to 2000. The finding is that the role of both the carbonization index and energy intensity is the same in the formation of CO ₂ emissions. That is, they decreased CO ₂ emissions. However, the decrease of CO ₂ emissions caused by energy intensity is larger than the decrease of CO ₂ emissions caused by the decarbonization index. The estimated rates of the former to the latter are four times larger.     

An ex-post assessment of the regulation on the energy performance of buildings in Greece and the Netherlands—a cross-country comparison

Hastening the energy saving rate in the built environment is a common goal of both the Dutch and the Greek government within the context of EU2020 strategy. In view of the recast Directive on the Energy Performance of Buildings (EPBD) (2010/31/EC), considered to be an important route towards exploiting the energy saving potential of the building stock, this paper conducted an ex-post assessment of the national Regulations on Energy Performance of Buildings (REPB) including energy performance certificates (EPCs), as transposed and implemented in Greece and the Netherlands. Results suggest that the implementation of the new EPBD requirements is still at an early stage for both countries. Similarities in the design of the two national schemes are demonstrated regarding quality assurance systems, while enforcement regimes show contrasting approaches with the Dutch EPCs operating at a voluntary basis. Both Dutch and the Greek scheme present a similar case regarding their low implementability, attributed though to dissimilar causes and external influences. Policy incoherence is another common characteristic traced between the two national yet different administration styles across governance levels, lacking of policy integration and coordination. The evaluation framework sheds some light on the understanding of the policy outcomes and design characteristics of the transposed REPB schemes in relation to the theory behind their implementation, while dealing with regulatory elements verified by observations and experiences, which need to be considered.     

Climatic considerations in school building design in the hot–humid climate for reducing energy consumption

Energy-conscious design of school buildings can contribute to significant energy savings and improve the students’ learning environment. The purpose of this research is to formulate design recommendations for school buildings in the hot–humid climatic zone and assess the influence of different design variables on their energy consumption. A base-case classroom was constructed by taking commonly used values for each design variable. Using computer simulation techniques, these variables were modified one by one to find the value that minimized energy consumption, while keeping thermal and visual comfort in the room. Based on these tests, the recommended value for each design variable to achieve a high performance classroom, was determined. Comparative tests were done to determine which variables have greatest impact on the energy consumption and thermal comfort in the classroom, and how their absolute influence depends on the order of implementation of each improvement. A complex interdependence among the design variables was found, but strong conclusions for energy savings could still be reached.     

Evaluating the impact of the administrative procedure and the landscape policy on grid connected PV systems (GCPVS) on-floor in Spain in the period 2004–2008: To which extent a limiting factor?

The growth of the Spanish photovoltaic (PV) sector in the period 2004–2008 rendered Spain a prominent place among top worldwide countries. Yet, this growth was rather uneven across the different Spanish regions which raised the interest on the drivers ultimately effecting these disparities. Especially controversial were the arguments about the influence of the administrative procedure and the landscape policy on the development of GCPVS on-floor. This study therefore discloses both two elements and evaluates their impact in a group of PV prominent Spanish regions and Catalonia, the latter used as a benchmark because of its comprehensive and stringent regulation on landscape protection, which was accused by the PV industry of thwarting the development of the GCPVS on-floor. Both quantitative and qualitative analyses were carried out. In particular two indexes were elaborated to determine the consistency of the arguments pointing to the landscape protection policy as a decisive barrier to GCPVS growth. First, when the analysis is made in relative terms, the ranking of PV prominent regions changes and many of the differences vanish. Second, rather than the preeminence of a landscape protection policy what really matters for GCPVS on-floor growth is the administrative procedure and the processing enabling its implementation.     

Energy conservation measures in buildings heated by district heating – A local energy system perspective

The extensive energy use in the European building sector creates opportunities for implementing energy conservation measures (ECMs) in residential buildings. If ECM are implemented in buildings that are connected to a district heating (DH) system, the operation of DH plants may be affected, which in turn may change both revenue and electricity production in cogeneration plants. In this study a local energy system, containing a DH supplier and its customer, has been analysed when implementing three ECMs: heat load control, attic insulation and electricity savings. This study is unique since it analyses economic and CO₂ impacts of the ECMs in both a user and a supplier perspective in combination with a deregulated European electricity market. Results show that for the local energy system electricity savings should be prioritised over a reduction in DH use, both from an economic and a global CO₂ perspective. For the DH supplier attic insulation demonstrates unprofitable results, even though this measure affects the expensive peak load boilers most. Heat load control is however financially beneficial for both the DH supplier and the residences. Furthermore, the relation between the fixed and variable DH costs is highlighted as a key factor for the profitability of the ECMs.     

Winds of time: Lessons from Utö in the Stockholm Archipelago, 1990–2001

When investigating the success or failure of different wind power projects, it is essential to take into account how they were historically situated. This study focuses on attempts to develop wind power in an archipelago setting, at Utö in Sweden. It has been argued that the development of Swedish wind power slowed during the 1990s; by revisiting the early days of wind power, looking at resistance and support, and connecting success factors, this can be further investigated.Whereas earlier research pointed out institutional conditions and site-specific conditions as crucial for successful wind power development and acceptance, the picture can be made more complete by discussing how wind power projects are affected by time-specific historical conditions. In the case of Utö, these can partly be associated with a newly launched political support program that gave the project political legitimacy and added a “pioneering spirit” to the endeavor. Conversely, when wind power is not seen as “pioneering” or “experimental” any more, but as a mere industrial activity, other incentives may need to be offered to municipalities.     

Cooperation for climate-friendly developments—an analysis of the relationship between the energy and buildings sectors in Sweden

Buildings account for more than 40 % of the total energy demand in the European Union (EU). The energy sector is responsible for 80 % of the total greenhouse gas emissions in the EU, of which more than a third are emitted as a result of energy use in buildings. Given these numbers and the large potential for energy savings in buildings, the energy and buildings sectors emerged as key contributors to fulfilling the European climate targets. Effective cooperation between these two key sectors can contribute significantly to the efficacy of the European climate strategy. However, there may be factors that negatively impact the relationship between the energy and buildings sectors and put cooperation in climate-friendly developments at risk. Based on 23 semi-structured interviews and a web survey answered by key stakeholders, this paper provides a snapshot of the current level of cooperation between the energy and buildings sectors in Sweden and identifies factors that impact the interdependencies between the two sectors. The findings show that the current business models in energy supply and the regulations in place limit the development of mutually beneficial cases between the energy and buildings sectors. This paper contributes to improved knowledge for policymaking that affects both sectors and highlights issues for further study.