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This study analyses the effect of fuel efficiency increase on travel demand in the city of Berlin. Vehicle technologies such as advanced driver assistance systems can help drivers to save fuel and thus lower exhaust emissions on a network level. In order to obtain high political endorsement among different stakeholders, the analysis of such effects which have an impact on overall fuel and emission savings are highly relevant. Recent testing of so called advanced driver assistance systems showed their ability to reduce fuel consumption and lower traffic emissions by giving driving recommendations to drivers.

Two effects on driving were simulated using a travel demand model: the increase in fuel prices which will take place in the coming years and a possible increase in vehicle fuel efficiency. Comparing these scenarios allowed us to calculate the effect of price change and the rebound effect of fuel efficiency gains using standard methods for transport elasticities. The simulation was run with the travel demand model TAPAS and the city of Berlin was the network used as a case study.

As fuel prices increase over time, driving tends to decrease. Driving increases, however, if vehicles become more fuel efficient and the result is the observed rebound effect. On a city network level, this also translates to lower emission savings than expected from the vehicle fuel efficiency gains. The rebound effect which we estimated matches similar findings in the literature, specifically in terms of their magnitude.

We used a simulation to compare scenarios of city travel demand. The result allowed us to estimate changes to the desired variables of fuel efficiency and fuel prices. For those interested in the effects of vehicle efficiency gains on city level these results are highly recommended for consideration.

The proposed framework for analysing rebound effects helped to assess the impacts of energy efficiency technologies on a city level.

Air carriers and aircraft manufacturers are investing in technologies and strategies to reduce fuel consumption and associated emissions. This chapter reviews related issues to assess airline fuel efficiency and offers various empirical evidences from our recent work that focuses on the U.S. domestic passenger air transportation system. We begin with a general presentation of four methods (ratio-based, deterministic frontier, stochastic frontier, and data envelopment analysis) and three perspectives for assessing airline fuel efficiencies, the latter covering consideration of only mainline carrier operations, mainline–subsidiary relations, and airline routing circuity. Airline fuel efficiency results in the short run, in particular the correlations of the results from using different methods and considering different perspectives, are discussed. For the long-term efficiency, we present the development of a stochastic frontier model to investigate individual airline fuel efficiency and system overall evolution between 1990 and 2012. Insight about the association of fuel efficiency with market entry, exit, and airline mergers is also obtained.

The purpose of this paper is to provide an assessment of the effects of fuel efficiency improvements on four‐wheeler ownership, fuel consumption, fuel imports and emissions for personal transportation in the context of India. The paper also aims to measure the rebound effect induced by this policy.

The paper relies on a system dynamics model to analyse the problem. A causal loop model was developed initially, which was transformed to a stock and flow diagram. Simulation was carried out to capture the effects of fuel efficiency improvements in the four‐wheeler sector of India.

The study has revealed that a policy of fuel efficiency improvements is favourable to the Indian four‐wheeler sector growth, but this policy could result in an increase in fuel consumption and therefore a corresponding increase in the fuel imports and emissions in the country. This policy also induces direct rebound effect that adds up to the already alarming fuel consumption levels.

The study is limited to four‐wheeler passenger cars in India and gasoline as the transport fuel.

The paper offers a system dynamics model that can aid the government, vehicle manufacturers, and environment protection groups to further analyse policies regarding fuel efficiency improvements, fuel price adjustments, four‐wheeler ownership, energy consumption and emission, and to obtain some useful policy insights before those policies are implemented.

The purpose of the conducted investigations is assessment of performance improvement of hybrid gas-turbine engine (HGTE) based on solid oxide fuel cell (SOFC) using cheaper and environmental alternative fuels (AF) such as liquid methane and propane – butane mixture (propane – butane). This paper also assessed the efficiency of mid-flight propulsion system (PS) based on HGTE for advanced short – medium hall aircrafts (SMHA) of 2025 (with level of parameters corresponding to technologies of 2025-2030 time period).

According to purposes of this paper, following are conducted: Analysis of properties of conventional and advanced aviation fuels, updating of architectures and parameters of energy system of HGTE based on SOFC using different fuels (kerosene, methane and propane – butane). Examination of rational architectures and updating of possible design parameters of HGTE using different types of fuel. Assessment of efficiency of PS with HGTE using different fuels under aircraft criteria. Assessment of emission of harmful substances and acoustical efficiency of SMHA with HGTE using different fuels.

Improvement of technical and environmental performances of SMHA with HGTE based on SOFC using AF in comparison with turbofan is shown.

Accuracy of research results is defined by a number of the adopted aircraft and engine restrictions, as well as accuracy of prediction concerning to the improvement of integral characteristics of elements SMHA and PS with HGTE for 2025.

Advantages of HGTE based on SOFC create good preconditions for initiation of works on development of new-generation aircrafts using AF after 2025.

Development of SOFC technologies result in evolution of new high-economic and environmental friendly hybrid gas-turbine PS for aircrafts using AF, Improvement of an environmental situation around the airport, decrease of CO₂ emission for full-flight cycle, creation of scientific and technological base for transition to electric PS of full electric aircraft.

Research results show that application of AF increases efficiency of electrochemical generator (ECG) based on SOFC and fuel efficiency of whole engine, which enable to use HGTE for PS of advanced aircrafts more effectively than turbofan. As distinct from storage battery (Bradley et al., 2010) and ECG based on Polymer Electrolyte Membrane Fuel Cell (Horyson Energy Systems, 2010), specific characteristics of ECG based on SOFC using methane allow to design PS for SMHA of 2025.

Concern about increasing fuel prices and levels of environmental pollution is forcing firms to improve the fuel efficiency of their transport operations. Assesses the extent to which British road hauliers have implemented a range of fuel‐saving measures and examines their general attitudes to fuel utilization. Good vehicle maintenance and driver training are believed to offer the greatest potential, with improved aerodynamics and vehicle replacement policy also considered important. Operators are sceptical, however, about the value of speed limiters and driver incentive schemes. Outlines the experience of a distribution contractor who has implemented a broadly‐based fuel conservation programme. Overall, the research highlights the importance of managerial initiatives, particularly in the areas of driver monitoring and training, and the need to develop a well co‐ordinated package of fuel efficiency measures.

The purpose of this study is to assess the influence of institutional quality (IQ), fossil fuel efficiency, structural change and renewable energy (RE) consumption on carbon efficiency.

This research uses an econometric approach, more specifically the Autoregressive Distributed Lag model, to examine the relationship between structural change, RE consumption, IQ, fossil fuel efficiency and carbon efficiency in India from 1996 to 2019.

This study finds the positive contributions of variables like fossil fuel efficiency, technological advancement, structural transformation, IQ and increased RE consumption in fostering environmental development through enhanced carbon efficiency. Conversely, this study emphasises the negative contribution of trade openness on carbon efficiency. These findings provide concise insights into the dynamics of factors impacting carbon efficiency in India.

This study's exclusive focus on India limits the generalizability of findings. Future studies should include a broader range of variables impacting various nations' carbon efficiency. Furthermore, it is worth noting that this study examines renewable and fossil fuel efficiency aggregated. Future research endeavours could yield more specific policy insights by conducting analyses at a disaggregated level, considering individual energy sources such as wind, solar, coal and oil. Understanding how the efficiency of each energy source influences carbon efficiency could lead to more targeted and practical policy recommendations.

To the best of the authors’ knowledge, this study addresses a significant gap in the existing literature by being the first empirical investigation into the effects of IQ, fossil fuel efficiency, structural change and RE consumption on carbon efficiency. Unlike prior research, the authors consider a comprehensive IQ index, providing a more holistic perspective. The use of a comprehensive composite index for IQ, coupled with the focus on fossil fuel efficiency and structural change, distinguishes this study from previous research, contributing valuable insights into the intricate dynamics shaping India's path towards enhanced carbon efficiency, an area relatively underexplored in the existing literature.

To provide for the use of airlines and other civil aviation organizations a practical definition of operational efficiency and to show how it can be determined.

A brief account of air transport economics is used to demonstrate how bom load factors and aircraft utilization need to be considered in assessing operational efficiency. Then other efficiencies are treated briefly before an example is given of how the better of two fictitious aircraft can be chosen for a particular route. A second example involving the calculation of the operational efficiency achieved by an imaginary airline is also given to show that the typical value is lower than might be expected, particularly in view of the relatively high load factors involved.

Provides performance values and economic figures which are typical of current airline operations.

Use of the proposed definition will allow the consistent assessment of the economic performance of airlines.

At present there is no definition of operational efficiency in general use although it is greatly needed by airlines. The definition proposed in this paper is practical and easy to use.

This chapter examines the impact of recent airline consolidations in the United States on the technical efficiencies of the airlines involved. Data envelopment analysis (DEA) is used to assess the efficiencies, and the consolidations examined are those that occurred among major network carriers between 2005 and 2013. The airline production process is conceptualized as the transformation of labor, fuel, and fleet-wide seating capacity into available seat-miles, or, under an alternative model specification, into user value, as measured by the airline’s operating revenue. Efficiency is conceptualized in terms of minimizing the airline’s usage of the three inputs, given its output level. The analysis seeks to determine whether the airlines that consolidated were more efficient, post-consolidation, than they were prior to consolidation, compared to airlines that did not enter into consolidations. Although there are limitations owing to the small number of airlines in the dataset, the chapter finds no evidence that the consolidations enhanced the efficiencies of the airlines involved, relative to the efficiencies of the airlines that did not enter into consolidations.

The purpose of this paper is to analyze the performance of the gas turbine cycle integrated with solid oxide fuel cell technology. In the present work, intermediate temperature solid oxide fuel cell has been considered, as it is economical, can attain an activation temperature in a quick time, and also have a longer life compared to a high-temperature solid oxide fuel cell, which helps in the commercialization and can generate two ways of electricity as a hybrid configuration.

The conceptualized cycle has been analyzed with the help of computer code developed in MATLAB with the help of governing equations. In this work, the focus is on the performance investigation of a Gas turbine intermediate temperature solid oxide fuel cell hybrid cycle. The work also analyzes the performance behavior of the proposed cycle with various design and operating parameters.

It is found that the power generation efficiency of the IT-SOFC-GT hybrid system reaches up to 60% (LHV) for specific design and operating conditions. The cycle calculations of an IT-SOFC-GT hybrid system and its conceptual design have been presented in this work.

The unique feature of this work is that IT-SOFC has been adopted for integration instead of HT-SOFC, and this work also provides the performance behavior of the hybrid system with varying design and operating parameters, which is the novelty of this work. This work has significant scientific merit, as the cost involved for the commercialization of IT-SOFC is comparatively lower than HT-SOFC and provides a good option to energy manufacturers for generating clean energy at a low cost.

This study aims to investigate the aviation, energetic, exergetic, environmental, sustainability and exergoeconomic performances of a micro turbojet engine used in unmanned aerial vehicles at four different modes.

The engine data were collected from engine test cell. The engine performance calculations were performed for four different operation modes.

According to the results, maximum energy and exergy efficiency were acquired as 19.19% and 18.079% at Mode 4. Total cost rate was calculated as 6.757 $/h at Mode-1, which varied to 10.131 $/h at Mode-4. Exergy cost of engine power was observed as 0.249 $/MJ at Mode-1, which decreased to 0.088 $/MJ at Mode-4 after a careful exergoeconomic analysis.

The novelty of this work is the capability to serve as a guide for similar systems with a detailed approach in the thermodynamic, thermoeconomic and environmental assessments by prioritizing efficiency, fuel consumption and cost formation. This investigation intends to establish a design of the opportunities and benefits that the thermodynamic approach provides to turbojet engine systems.