The impact of disaggregated energy on productivity : A study of the US manufacturing sector, 1958–1985

The issue of the productivity slowdown of the 1970s and 1980s has received considerable analysis in the literature. However, the issue of the impact of energy on productivity is still debated. This study contributes to the debate, with the hope that some sight could be provided through disaggregating the factor input energy into two components; a petroleum component and a non-petroleum component. By analysing labour productivity growth, total factor productivity growth and labour intensity ratios, the disaggregated energy component can be viewed as a major influence in explaining the productivity decline.     

An econometric analysis of energy consumption in Nepal

Economic growth and energy demand are closely related. A clear understanding of the relation between energy and economic demand would help energy planners to understand the implications of changes in the exogenous variables when the underlying relationships are fairly stable. An understanding of broader impacts of energy use can be of great help in designing better energy policies, at least at the macro level. Therefore, in this paper, various econometric models have been proposed after studying the influence and significance of various independent variables with chosen dependent variables. The models are classified into fuel models and consumption sector models. These models have been used to provide medium-range energy demand projections till 2012. Policy implications of projections are also discussed.     

Thirty years of domestic solar hot water systems use in Greece – energy and environmental benefits – future perspectives

The effort to reduce the dependence on imported crude oil in Greece, after the oil crises in the '70s, has resulted, among others, in a total installed area of 3.57 million m² solar collectors in 2007, making Greece one of the pioneers in the use of domestic solar hot water system (DSHWS) worldwide.In the present work, the contribution of DSHWS to the reduction of conventional energy and greenhouse gases and other air pollutant emissions in Greece from its early years in mid '70s up to now is assessed. DSHWS market penetration, solar system technological changes and development and demographic changes in association with the climatic conditions in all regions of the country have been taken into account in order to calculate energy conservation and emissions reduction. The results show that the conserved energy ranges from 21.27 GW h_el (0.1% of the domestic sector energy use) in 1978 to 1513 GW h_el (2.4%) in 2007, resulting in an abatement of CO₂ emissions, which for the year 2000 was 1.67 Mt, exceeding by 76% the objectives of the Greek Program of “Climatic Change”, which indicated savings of 0.95 Mt CO₂ for 2000.Moreover DSHWS maximum technical potential is assessed to be about three times the current installed area, showing that they can play an important role in energy end environmental policy of the country.     

An econometric analysis of energy input–output in Turkish agriculture

This study analyzes energy use and investigates influences of energy inputs and energy forms on output levels in Turkish agriculture during the period 1975–2000. The output level was calculated in the form of annual grain equivalent at aggregate level for 104 agricultural commodities except livestock products. Output level was specified as a function of total physical, fertilizer and seed energy, and ordinary least squares was employed to estimate equation parameters. The results show that total energy input has increased from 19.6 GJ/ha in 1975 to 45.7 GJ/ha in 2000, whereas total output energy has risen from 27.1 GJ/ha to a level of 39.1 GJ/ha. Energy efficiency indicators, input–output ratio, energy productivity and net energy have declined over the examined period. Total physical and fertilizer energy, particularly nitrogen, significantly contributed to output level with elasticities of 0.24 and 0.14, respectively. The results also revealed that non-renewable, direct and indirect energy forms had a positive impact on output level. Moreover, Turkish agriculture has experienced a substantial increase in non-renewable energy use. This inefficient energy use pattern in the Turkish agriculture can create some environmental problems such as increase in global warming, CO₂ emissions, and non-sustainability. Thus, policy makers should undertake new policy tools to ensure sustainability and efficient energy use.     

Residential energy use and conservation in Denmark, 1965–1980

New data have been assembled to quantify patterns of residential energy use in Denmark from 1965 to 1980 by fuel and end use. Indicators of the structure and intensity of energy use are developed from basic data and reviewed. Changes since 1972 are quantified and compared with those observed in other countries. The reduction in oil use in oil-heated dwellings is shown to be the largest among OECD countries. Elements of past, present and future Danish conservation policies are reviewed. While many of these are unique and far reaching, the predominant cause of conservation up until 1980 has been short-term measures stimulated primarily by higher energy prices.     

Tests for structural change in US oil consumption, 1967–1982

The purpose of this paper is to test US oil consumption for structural change over the period 1967–1982. A frequently used functional form is posited for total petroleum consumption as well as for gasoline, distillate, and residual fuel. Tests for abrupt change (Chow) and gradual or conservation-like change (Durbin, Brown, Evans and Farley, Hinnich, McGuire) are employed at special break points (1973 embargo, 1979 Iranian crisis, 1980 recession) to check for abrupt changes and across years in general to detect gradual shifts. Both abrupt and gradual changes are found, although the last five years may be the beginning of a new non-changing period.     

Energy efficiency developments in the Dutch energy-intensive manufacturing industry, 1980–2003

We studied energy efficiency trends in the Dutch manufacturing industry between 1995 and 2003 using indicators based on publicly available physical production and specific energy consumption data. We estimated annual primary energy efficiency improvements in this period at 1.3% on average, with the individual sub-sectors ranging between −0.1% and 1.5%. Energy efficiency developments with respect to electricity, fuels/heat and non-energy use have been monitored separately and are shown to differ significantly (for the sum of the sectors studied: 1.9% for electricity, 2.6% for fuels/heat and −0.1% for non-energy use). We combined our results with those from a previous, similar study for 1980–1995 and show that over the full time period, efficiency improvements of 1% per year have been achieved on average. Based on comparison with other sources and a detailed uncertainty analysis, we conclude that we developed a reliable top-down monitoring framework for studying energy efficiency trends of the manufacturing industry that can also be applied in other countries where similar data are available. We also showed that substantial differences exist between energy consumption data available from energy statistics and according to the Long Term Agreement monitoring reports, stressing the need for ongoing independent checks of available energy consumption data to avoid problems in future evaluations of energy efficiency policies.     

Validation of short and medium term operational solar radiation forecasts in the US

This paper presents a validation of the short and medium term global irradiance forecasts that are produced as part of the US SolarAnywhere (2010) data set. The short term forecasts that extend up to 6-h ahead are based upon cloud motion derived from consecutive geostationary satellite images. The medium term forecasts extend up to 6-days-ahead and are modeled from gridded cloud cover forecasts from the US National Digital Forecast Database.The forecast algorithms are validated against ground measurements for seven climatically distinct locations in the United States for 1 year. An initial analysis of regional performance using satellite-derived irradiances as a benchmark reference is also presented.     

Characteristics of day‐ahead wind power forecast errors in Nordic countries and benefits of aggregation

The growing proportion of wind power in the Nordic power system increases day‐ahead forecasting errors, which have a link to the rising need for balancing power. However, having a large interconnected synchronous power system has its benefits, because it enables to aggregate imbalances from large geographical areas. In this paper, day‐ahead forecast errors from four Nordic countries and the impacts of wind power plant dispersion on forecast errors in areas of different sizes are studied. The forecast accuracy in different regions depends on the amount of the total wind power capacity in the region, how dispersed the capacity is and the forecast model applied. Further, there is a saturation effect involved, after which the reduction in the relative forecast error is not very large anymore. The correlations of day‐ahead forecast errors between areas decline rapidly when the distance increases. All error statistics show a strong decreasing trend up to the area sizes of 50,000 km². The average mean absolute error (MAE) in different regions is 5.7% of installed capacity. However, MAE of a smaller area can be over 8% of the capacity, but when all the Nordic regions are aggregated together, the capacity‐normalized MAE decreases to 2.5%. The average of the largest errors for different regions is 39.8% and when looking at the largest forecast errors for smaller areas, the largest errors can exceed 80% of the installed capacity, whereas at the Nordic level, the maximum forecast error is only 13.5% of the installed capacity. Copyright © 2016 John Wiley & Sons, Ltd.     

Adaptive post‐processing of short‐term wind forecasts for energy applications

We present a new method of reducing the error in predicted wind speed, thus enabling better management of wind energy facilities. A numerical weather prediction model, COSMO, was used to produce 48 h forecast data every day in 2008 at horizontal resolutions of 10 and 3 km. A new adaptive statistical method was applied to the model output to improve the forecast skill. The method applied corrective weights to a set of forecasts generated using several post‐processing methods. The weights were calculated based on the recent skill of the different forecasts. The resulting forecast data were compared with observed data, and skill scores were calculated to allow comparison between different post‐processing methods. The total root mean square error performance of the composite forecast is superior to that of any of the individual methods. Copyright © 2010 John Wiley & Sons, Ltd.     

Convergence of energy productivity in Australian states and territories: Determinants and forecasts

The Australian government has recently launched a National Energy Productivity Plan that calls for a 40% increase in energy productivity (economic output divided by energy use) before 2030. Improving energy productivity would help boost economic competitiveness, reduce energy costs, and reduce carbon dioxide emissions in Australia. Understanding energy productivity dynamics at the state level is essential for the success of this program. This research analyses the convergence path of energy productivity in Australian states and territories. Club convergence analysis applied to data over the period 1990–2015 reveals two converging energy productivity clubs. Initial energy productivity, industry structure, and automobile fuel prices are important determinants of higher energy productivity. Based on Australian state energy productivity forecasts to 2030, New South Wales and Victoria will be the forerunners in maintaining higher energy productivity in 2030. Australia will not achieve a 40% increase in energy productivity before 2030 without significant changes to its fuel mix and industry structure.     

Electric buses – An energy efficient urban transportation means

Bus transit systems with electric traction are an important contribution to the post fossil fuel mobility. Most renewable energy sources provide energy in the form of electricity. Electric motors thus have promise in the development of the way “beyond oil”. The reactivation of trolley bus systems – grid bounded but also catenary free for short distances – paves this way. The design of modern trolley bus operations overcomes the existing disadvantages of conventional buses using fossil fuel. Germany has an efficient industry in this field, that offers braking energy recuperation and energy storage in modern supercapacitors as well as technical and organisational innovations for a local emission free and a low noise transit system. Gentle but powerful when starting and braking, the trolley bus is cost effective and easy to integrate into an existing infrastructure. Such an electric bus system is ecological, customer-friendly and suitable for cities. It has a high economic efficiency and it also expands the traffic planning field towards an ecological future technology. This paper shows examples at home and abroad how electric buses achieve an energy solving modern urban traffic. It gives insights into technical developments of electric vehicle equipment, cateneries with fast driving handling characteristics and the use of plain electric and hybrid powertrains.     

Thermal utilisation of solar energy : Croatian National Energy Program SUNEN, 1998 – 2010

In the paper, thermal use of solar energy as well as prospects and problems of its utilisation in Croatia have been given. The National Solar Energy Program, SUNEN, has been established to stimulate the usage of solar energy. The main goals of the program are the assessment of technical and economically viable solar potential in order to define real objectives and tasks to provide use of exploitable indigenous clean and renewable energy potential. The Program addresses benefits, the most promising solar applications and solar potential. Much attention has been given to identification of obstacles and barriers in the process of solar technology dissemination. SUNEN is an initiative to increase solar energy use and to become more compatible with the present renewable energy sources policy in EU and Mediterranean countries. The program proposes twelve different types of thermal solar energy systems, which could be multiplied up to 28 000 installations until the year 2010 with annual heat recovery of approximately 1,5 TWh (5,4 PJ).     

US states and energy efficiency: North Carolina's ‘quango’

This paper argues that energy efficiency remains an abstraction until actions produce significant results in the ways in which energy is produced and used. In the USA, such actions have depended historically on the private sector, with government taking an increasingly prominent role since the first energy crisis of the 1970s. Experience has shown that neither acting alone has been fully successful at realizing the economically and societally rational rate of implementation made possible by either the needs or the opportunities in energy. Recent developments in various states have begun to explore hybrid organizations - quasi-public and quasi-private - as ways to focus resources in productive applications. Four examples merit attention, with particular emphasis on the North Carolina Alternative Energy Corporation.     

An analytical approach for optimising a set of α and ε values for solar energy applications

An analytical method for optimising a set of α and ε values for specified set of operating conditions (plate temperature, ambient temperature, number of glass covers, wind velocity, solar flux etc.) has been proposed. The absorptivity (α)-emissivity (ε) curves obtained suggest the existence of an optimum (α, ε) set, which would maximise the useful energy from a collector.     

An integrated model for performance simulation of hybrid wind–diesel systems

Stand-alone hybrid systems have turned into one of the most promising ways to handle the electrification requirements of numerous isolated consumers worldwide. The proposed wind–diesel–battery hybrid system consists of a micro-wind converter, a small diesel-electric generator—basically operating as a back up energy production system—and a lead-acid battery bank that stores the wind energy surplus during high wind speed periods. In this context the present work is focused on presenting a detailed mathematical model describing the operational behavior of the basic hybrid system components, along with the representative calculation results based on the developed mathematical model. Accordingly, an integrated numerical algorithm is built to estimate the energy autonomy configuration of the hybrid system under investigation. Using the proposed numerical algorithm, the optimum configuration selection procedure is verified by carrying out an appropriate sensitivity analysis. The proposed methodology may equally well be applied to any other remote consumer and wind potential type, in order to estimate the optimum wind–diesel hybrid system configuration that guarantees long-term energy autonomy.     

Economical – environmental evaluation of natural gas and renewable energy systems

Although the energy crisis has been slightly abated in the recent times, the possibility of a crisis caused by extremely high oil prices is still imminent. Simultaneously, the environmental crisis represented by climate change is further the major concern which requires an immediate solution. Hence, in this research, economical and environmental assessment of utilizing renewable energies in comparison with natural gas have been investigated which resulted to choose the best economically–environmentally alternative for power generation. Equivalent uniform annual value and scaling‐weighting check list with experts' comments through analytical hierarchy process have been applied for economical and environmental assessment, respectively. Afterward, the results of normalized economical and environmental assessment have been coalesced to gain a combined economical–environmental perspective. As economical surveys, four scenarios have been considered. The results reveal that the best choices are conventional steam cycle, combined cycle, and biogas if power is sold to consumer (other technologies have negative net present value in this scenario), respectively, without considering the social costs and the emission reduction. If power is sold to government, biogas, conventional steam cycle, combined cycle, and wind are technological priorities. In case of considering social costs and emission reduction incomes, the best choices are biogas, combined cycle, and conventional steam cycle, respectively, if power is sold to consumers. If not, the priorities are biogas and wind. Furthermore, environmental surveys have indicated that wind is the most applicable environmentally friendly energy to produce electricity with negative impact magnitude (NIM) of 1.3 (out of 10). In addition, photovoltaic, biogas, and hydropower remain at the next levels with NIM of 1.6, 1.7, and 3.2 (out of 10), respectively. While conventional steam cycle has 6.2 of NIM. Eventually, the combination of economical and environmental evaluation reveals that wind farms and biogas plants with normalized weight of 3.10 (310%) and 2.34 (234%) are the best choices of electricity generation method, respectively. Moreover, the least applicable one is conventional steam cycle with normalized weight of 0.63 (63%). To sum it up, wind farms and biogas plants are about five and four times more economical–environmental beneficial than conventional steam cycle power generation. Copyright © 2012 John Wiley & Sons, Ltd.     

Optimized electrolyzer operation: Employing forecasts of wind energy availability,hydrogen demand,and electricity prices

One of the main advantages of fuel cell based mobility over other sustainable mobility concepts is the flexible production of hydrogen via electrolysis. To date, it is unclear how electrolysis at hydrogen refueling stations should be operated in order to achieve the lowest possible costs despite the constraints of hydrogen demand. This study proposes and evaluates an intelligent operating strategy for electrolysis capable of exploiting times of low electricity prices while participating in the spot market and maximizing wind energy utilization when combined with a wind farm. This strategy is based on a simulation model considering imperfect forecasts (e.g. of wind availability or energy prices) and non-linear electrolyzer behavior. Results show that this approach reduces hydrogen production costs by up to 9.2% and increases wind energy utilization by up to 19%, respectively.