Results 1 - 10 of 1875
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[en] The techno-economics of biomass gasification systems for the production of Fischer-Tropsch (FT) based liquid fuels are analysed by estimating the overall mass and energy conversion of biomass to liquid (BTL) fuel. The investigation of BTL systems for 1000 kg/h biomass gasification system and an expected liquid hydrocarbon output of 1500 tonnes are estimated. The cost analysis, based on the annualized life cycle of the systems, includes a steam-oxygen based biomass gasification plant paired with the FT unit. The gasifier considered in this analysis is the downdraft reactor design, operating on oxygen-steam gasifying medium at an equivalence ratio of 0.1 and a steam-to-biomass ratio in the range of 0.8–1.2 to generate syngas with H2/CO ratio of 2.1:1, ideally suitable for the cobalt based fixed bed FT reactor. The mass and energy balance reveal that for a once-through FT reactor configuration, substantial energy exists in the gas phase, which includes C1-C5 hydrocarbons and unconverted syngas. The study suggests that the product gas be utilized in an IC engine and converted to electricity, for in-house power demands and for the sale of excess electricity to the grid. The analysis indicates a market competitive liquid fuel production with CO conversion greater than 60%, at a cost ranging from INR 35–40/litre (0.5–0.6 USD/litre) alongside electricity as a major co-product in the BTL system. This study examines the economics of building economically affordable and environmentally favourable BTL systems of smaller throughputs with particular reference to India. - Highlights: • Investigation on 1000 kg/h, O2-steam biomass gasifier & cobalt catalyzed FT system. • ALC based cost analysis of FT-BTL system to estimate its economic sustainability. • CO conversion should be >60% for market competitive liquid fuel production. • Liquid fuel produced at INR 39.1/l & INR 35.9/l with CO conversion of 65.6% and 73.1%. • Electricity generated as co-product from product gases of once-through FT reactor.
[en] The Korean government has given efforts to reduce green-house gas emissions. In order to avoid the monolithic system that only focuses on reducing the emission without considering operational environments of firms, the government should encourage respective firms to improve their energy efficiency which wastes less energy but produces maximum economic revenue. This paper employed a DEA (Data Envelopment Analysis) model to measure energy efficiency of energy intensive manufacturing firms in Korea. Identifying and comparing the difference in efficiency score by using the simplified single-stage DEA model is not sufficient to give governments and firms meaningful policy implications related to energy efficiency improvement. To compensate for this insufficiency, this study extended the single-stage model into a two-stage model that includes two efficiency measures: pure energy efficiency which is only for energy-related process and economy efficiency which is for the pursuit of profit, to reach the improvement of total energy efficiency. By using the two-stage DEA model, it has identified that the difference from overall energy efficiency is not caused by pure energy efficiency but rather by economy efficiency. In addition, this paper statistically analyzed the effects of environmental variables such as firm size, possession of certified management systems and emission type. - Highlights: • We develop DEA mathematical models for measuring energy efficiency. • The two-stage DEA model includes pure energy efficiency and economy efficiency. • We statistically validates the effects of environmental variables on efficiency. • Overall energy efficiency is more sensitive to pure energy efficiency. • A firm in different conditions has different possibilities to improve its efficiency.
[en] This paper presents an optimal planning and scheduling on energy storage systems (ESSs) for congestion management in electric power systems including renewable energy resources. The proposed problem finds optimal capacity and charging-discharging regime of ESSs. The storage units are optimally charged and discharged to tackle the uncertainty related to wind-solar units as well as relief congestion in the lines. Output power of solar and wind units is modeled by Gaussian probability distribution function (PDF) and Monte-Carlo simulation (MCS) is applied to tackle the uncertainty. Simulation results demonstrate that the proposed planning can manage congestion of the network efficiently while dealing with wind and solar resources uncertainties. - Highlights: • Congestion management is addressed through energy storage planning. • Uncertainty of wind and solar units is considered. • Monte-Carlo simulation is carried out to deal with the uncertainty. • Scenario based stochastic planning is applied to solve the problem. • The planning can tackle the uncertainties and manage congestion of the network.
[en] With the limiting supply of fossil fuel and the beneficial impact of technological innovation on renewable energy costs, PV power generation is increasingly considered a promising way to generate renewable power. Under the support of the national emerging industry, China's PV industry has experienced a dramatic development over recent years, catapulting into a vital position in the world PV market. The newly installed PV capacity has led to cost reductions. This paper chooses the methodology of techno-economic evaluation to analyze current market application of residential PV power generation, including grid-connected and off-grid systems. One of the main innovations is choosing five Chinese cities in different areas of solar radiation as research objects, which enables regional differentiation in calculating levelized cost of energy (LCOE). The results show that grid-connected PV systems with 3 kW PV modules can meet the electric demand of a 60–90 m2 residential building. The capacity of off-grid systems are 5–10 kW, which is determined by local solar radiation. By incorporating a learning curve, we forecast that off-grid PV systems for each of the five cities will reach grid parity over the next several decades. The estimation is used to offer policy recommendations for PV market diffusion in China. - Highlights: • Grid-connected and off-grid PV systems are examined by techno-economic evaluation. • The levelized cost of energy (LCOE) of PV systems is calculated for five regions. • The grid parity of PV power generation in China is estimated using learning curves. • Grid parity varies across regions based on solar radiation and electricity prices. • Policy implications are given to promote market deployment of China's PV industry.
[en] In this study, an inexact two-stage stochastic fuzzy programming (ITSFP) is developed for regional power generation planning with considering the intermittency and fuzziness of renewable energy power output. ITSFP incorporates interval-parameter programming (IPP), two-stage stochastic programming (TSP), and fuzzy credibility constrained programming (FCCP) within a general optimization framework which can tackle uncertainties expressed as intervals, probability distributions, and fuzzy sets. The developed method is applied to a regional electric power system over a one-day optimization horizon coupled with air pollution control. The power generation schemes, imported electricity, and system cost under various environmental goals and risk preferences are analyzed. The obtained results indicate that the model can provide a linkage between predefined electric power generation schedule and the relevant economic implications, as well as more reasonable decision alternatives for decision makers by loosening system constraints at specified confidence level. Besides, the fuzziness of forecast error corresponding to the variability of renewable energy resources could be effectively reflected. Moreover, the results are useful for addressing the trade-off between system economy and system risk. - Highlights: • An inexact stochastic-fuzzy programming is proposed for generation scheduling. • Uncertainties are expressed as intervals, probability distributions and fuzzy sets. • Power generation schemes, imported electricity, and system cost are analyzed. • Alternative solutions associated with different confidence levels are obtained. • Tradeoffs between system economic and reliability risk could be evaluated.
[en] This paper analyses practical procedures for the virtual recognition of CHP (Combined Heat and Power) and non-CHP parts of the plant, and for determining their efficiencies and other parameters required by the regulator. The division of the plant into CHP and non-CHP parts is done on the basis of standard measurements carried out in practice, and the correct thermodynamic energy balance. The Energy efficiency of the CHP part is equal to a pre-set value and that of the non-CHP part is lower than this value. Instead of the Primary Energy Saving (PES) indicator, which compares the efficiency of a CHP plant with a classical plant for the production of heat energy and electricity, here we are analyzing a method that recognizes only the part of the CHP plant that fulfills the preset value of high-efficiency cogeneration. This value is prescribed by the national regulator and depends on the type and age of the plant, operating conditions, etc. Practical calculation procedures rely primarily on rules that are used in the EU (European Union). The impact of a changeable practical operating mode and the sensitivity of the referred efficiency to the attractiveness of cogeneration is particularly evaluated. - Highlights: • Calculation procedures for complex cogeneration schemes are demonstrated. • Power loss coefficient is calculated simply based on standard industrial measurements. • Adjusting thresholds in EU Directives can be a powerful tool for creating energy policy. • The calculation is demonstrated for real CCGT plant calculation.
[en] This analysis contributes to recent efforts to better understand the evolution of energy security in a low-carbon world. Our objective was to assess how energy security may change over the course of the century, and to what extent these changes depend on the uncertainty of the factors that drive the evolution of energy systems, including future technologies, improved energy efficiency, fossil fuel resources and markets, and economic growth. To this end, we focused on Europe and on a set of energy security indicators based on three perspectives: sovereignty, robustness and resilience. A database of scenarios allowed us to account for the large uncertainties surrounding the determinants of future energy systems. We then analyzed the way energy security indicators evolve over time, and how their trajectories vary across scenarios. We identified the indicators that vary the most between scenarios, i.e., the indicators whose future evolution is the most uncertain. For these indicators, we performed an analysis of variance to estimate the contribution of each driver to the uncertainty of the indicators. The paper shows that the European double target of significantly decreasing CO2 emissions and increasing the security of the supply of energy may be difficult to reach. Nevertheless, some levers could facilitate the transition to a low-carbon society while improving energy security, or by limiting its degradation. The results emphasize not only the importance of policies in favor of low or zero carbon technologies in power generation but also the differences in their contributions to the complete uncertainty of the indicators. Policies promoting energy efficiency also play a role but only in the resilience of TPES. These policies are thus important levers for mitigating the negative impacts of climate policies on energy security.
[en] The market-based Perform Achieve and Trade scheme was introduced in India to enhance the energy efficiency of energy-intensive sectors, and for thermal power plants by reducing their specific energy consumption within the framework of a tradable certificate scheme. International experience suggests that effectiveness of such schemes is greatly influenced by the assigned targets of the obligated units. Setting rational targets is thus, a key aspect of successful implementation of the scheme. In the present study, we examine the rationality of the targets set for the power sector of India, based on comparing it with energy saving potential of the plants, and the targets assigned to the respective plants. Data envelopment analysis models are used to determine relative efficiency and energy saving potential. The study results indicate that in most cases, (i) The targets are much less than the actual potentials of the thermal power sector, (ii) There exist substantial inefficiencies within the system in both energy use and managerial dexterity; and (iii) If the sector realizes its full potential, then the Energy Saving Certificate market may witness a surplus of 4.7 million certificates on account of thermal power sector alone. - Highlights: • Rationality of setting target for coal-based thermal power plants, under the Perform, Achieve and Trade (PAT) is examined. • Data Envelopment Analysis is used as the main analysis tool. • The results indicate that the PAT targets for ENERGY SAVINGS are much less than the sector’s potential • The scheme undermines the potential of improved managerial practice accounting for 24% of the sector’s potential • At full potential, 4.7 million additional Energy Saving Certificates are expected to be generated.
[en] In a new environment marked by the growing importance of Green House Gas emissions, fuel poverty, and energy efficiency in the different national agendas, the comprehension of energy demand factors appears to be crucial for the effectiveness of energy policies. We consider the latter could be improved by targeting specific household groups rather than looking to follow a single energy consumption level target. This article explores the scope of having a disaggregated energy consumption market to design policies aimed at curbing residential energy consumption or lowering its carbon intensity. Using a clustering method based on the CHAID (Chi Square Automatic Interaction Detection) methodology, we find that the different levels of energy consumption in the French residential sector are related to socio-economic, dwelling and regional characteristics. Then, we build a typology of energy-consuming households where targeted groups (fuel poor, high income and high consuming households) are clearly and separately identified through a simple and transparent set of characteristics. This classification represents an efficient tool for energy efficiency programs and energy poverty policies, but also for potential investors, which could provide specific and tailor made financial tools for the different consumer groups. Furthermore, our approach helps designing some energy efficiency score that could reduce the rebound effect uncertainty for each identified household group. - Highlights: • We question the heterogeneity of households’ energy consumption in the French residential sector. • We identify the key drivers of households’ energy consumption using a clustering method. • We build an efficient typology of energy-consuming households. • We identify vulnerable households as well as potential target investors for energy efficiency programs.
[en] Stand-alone single-family dwellings are the dominant housing type in several countries. The floor-area of the average stand-alone dwelling has been increasing faster than the floor-area of the average apartment/flat/row-house in England, Australia, Canada, the USA and New Zealand. Standalone dwellings have a greater external heat transfer area than multiple family dwellings, for the same floor-area. Larger dwellings require more energy to heat than smaller dwellings insulated to the same level. Although insulation requirements have been increasing, the heating required to maintain newer larger stand-alone dwellings to a constant temperature can be similar to that required to heat older smaller stand-alone dwellings. Building regulations should be future-proofed by considering trends in dwelling size. - Highlights: • Stand-alone dwellings are still the dominant new dwelling type in many countries. • Stand-alone dwelling sizes have been increasing in many countries. • Larger dwellings require more energy to heat. • Increased dwelling size can cancel out energy savings from increased insulation.