Fuel Cost Reduction Research Articles

Energy Saving and GHG Emission Reduction in a Micro-CCHP System by Use of Solar Energy

Abstract In this work, the reduction of greenhouse gas emission, and the energy saving by integrating solar collectors and photovoltaic panels in a Stirling engine based microcombined cooling, heating and power (mCCHP) system are studied. The mCCHP system consists of a natural gas Stirling CHP and an adsorber chiller. When the thermal outputs of the Stirling CHP and solar collectors are not sufficient to cover the heat demand for domestic hot water (DHW), heating/cooling, an auxiliary heating boiler starts to operate. The energy saving by using solar energy varies from 13.35% in December to 59.62% in April, in the case of solar collectors usage and from 7.47% in December to 28.27% in July, in the case of photovoltaic panels usage. By using solar energy the annual GHG emission decreases by 31.98% and the fuel cost reduction varies from 12.73% in December to 49.78% in June.

Optimal Operation Scheduling of Pumped Storage Hydro Power Plant and Thermal Power Plants in Power System with a Large Penetration of Photovoltaic Generations

In recent years, a substantial amount of photovoltaic (PV) generations have been installed in power systems. However, the power output from the PV is random and intermittent in nature. Therefore, the PV generation poses many challenges to the power system operation. To evaluate the impact of the behavior of PV on power supply reliability, we have developed a power supply reliability evaluation model considering a large integration of PV generation into power system. As a result, the power supply reliability is getting worse as the PV penetration level increases. To solve this issue, we have proposed that pumped storage hydro power plant (PSHPP) is used effectively to improve the reliability. In this paper a cooperative scheduling method for the PSHPP and thermal power plants that makes it possible to improve both reliability and economy is presented. being considered as a solution in most situations. This paper proposes an effective use of Pumped Storage Hydro Power Plant (PSHPP). PSHPP is installed originally for hot reserve of the power system and load leveling. The energy is stored in the form of water pumped up from a lower reservoir to an upper reservoir. The PSHPP is usually operated as a generator in the daytime and a pump in the nighttime. A new operation scheduling of PSHPP is proposed to solve the problem in this paper. It will be operated with the proposed pattern solving the surplus power problem caused by the PV generation. The authors have already proposed how the PSHPP operation pattern is changed effectively to improve the power system reliability in case of a large integration of PV into the power system (1). However, the scheduling method for obtaining the optimal PSHPP operation pattern that makes it possible to improve both reliability and economy has not been developed yet. In this paper, we propose a new method for planning PSHPP operation pattern considering the surplus power problem, power supply reliability and fuel cost reduction, which is represented by pareto optimal solutions. The power supply reliability and the fuel cost are estimated for each PSHPP operation plan by using Monte Carlo simulation.

Direct Injection of Diesel-Butane Blends in a Heavy Duty Engine

Increasing fuel prices keep bringing attention to alternative, cheaper fuels. Liquefied Petroleum Gas (LPG) has been well known for decades as an alternative fuel for spark ignition (SI) passenger cars. More recently, aftermarket LPG systems were also introduced to Heavy Duty transport vehicles. These (port fuel) systems either vaporize the liquid fuel and then mix it with intake air, or inject fuel into the engine's intake ports. While this concept offers significant fuel cost reductions, for aftermarket certification and large-scale original equipment manufacturer (OEM) use some concerns are present. Unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions are known to be high because of premixed charge getting trapped into crevices and possibly being blown through during valve-overlap. Apart from the higher emission levels, this also limits fuel efficiency and therefore cost savings. Direct injection of LPG offers a solution to the aforementioned concerns by directing the fuel to the desired areas of the combustion chamber. To investigate the potential of this concept, diesel has been blended with liquid butane, in different ratios. These blends were directly injected into a heavy duty test engine, using a standard common rail injector. Results show that even at low loads, a butane mass fraction of one-third can be used without negatively affecting emissions. For direct injected butane, hydrocarbon emissions were found to be an order of magnitude lower than when port fuel injected butane is used. At this butane fraction, smoke emissions decrease by 50%. Because a high combustion efficiency is retained, fuel cost savings can be significant. At higher loads, an even higher butane mass fraction can be used, further enhancing the fuel cost saving potential.

Operating cost control strategies for airlines

The purpose of this study is to explore the ranking of international airlines operating cost control strategies based on empirical studies of an international full-service airlines operation in Taiwan. Cost control has become more and more important for airlines in recent years, especially after the dramatic increases in crude oil prices that began in 2008, as well as the on-going global financial crisis that started in the same year. In this study, the ranking policies and cost control strategies were extracted from questionnaires answered by airline industry experts and evaluated using the fuzzy Delphi method. The cost control strategies were then ranked using the analytic hierarchy process. The findings of this study can provide international full-service airlines with five key policies for operating cost control, including a fuel cost reduction policy, employee productivity improvement, flight operations, aircraft maintenance cost reduction, and operating procedure simplification. By ranking these potential cost reduction strategies, we identified the ten most significant ones out of twenty-one that branched out of the upper five criteria. These were as follows: (1) optimizing aircraft fleet dispatch, (2) conducting fuel hedging strategies, (3) improving aircraft fuel saving performance, (4) reducing the dead weight of an aircraft, (5) optimizing flight speeds using the efficient cost index, (6) scheduling reasonable flight hours for flight crew, (7) correcting en route flight plans and alternate airports, (8) increasing direct ticket sales, (9) encouraging employees to provide cost-control strategies, and (10) replacing old aircraft. The results of this study could be used to establish guidelines for international airlines with regard to the possibly best distribution of operational resources. We expect that the total operating costs of airlines can be reduced significantly through the use of these cost control strategies. Key words: Airline, operating cost control, fuzzy Delphi, analytical hierarchy process.

A Power-Management Strategy for Multiple-Unit Railroad Vehicles

Improved fuel consumption and lower emissions are two of the key objectives for future transportation. Hybrid electric vehicles (HEVs), in which two or more power systems are combined, can meet these objectives through the capture and reuse of regenerated braking energy and through optimized use of the prime mover. However, more complicated power-management strategies are required for such vehicles. This paper explores the potential of applying to advanced power-management strategies for a diesel multiple-unit (DMU) train. These types of vehicles have multiple diesel engines that are commonly operated in a homogenous manner. This paper analyzes the potential energy savings that may be obtained through the independent operation of the engines. Two widely investigated power-management strategies that have been developed for HEVs have been applied to a typical DMU railroad vehicle. Dynamic programming (DP) strategies have been applied to the results produced by a single-train motion simulator to identify the optimal instant power distribution between the engines. An adaptive rule-based online strategy based on the optimization results from the DP solution is then proposed and realized using a nonlinear programming optimization algorithm. Both strategies indicate acceptable agreement and show a fuel cost reduction of around 7%, in comparison with the evenly split engine operation.

An improved model and its applied adaptive control for power turbine generator

PurposeThe purpose of this paper is to present an improved model and its applied adaptive controller for a waste heat recovery generation system using a power turbine generator (PTG) with an accurate model on shipboard that is employed by an identification method on the basis of an overall system model.Design/methodology/approachThe PTG system has been developed as a waste heat recovery type generation system making use of exhaust gas from the main shipboard diesel engines. Conventionally, control of a plant is exercised using the proportional‐integral‐derivative (PID)‐based controller. The PID controller, however, is difficult to keep in place because of fouling conditions and variations across time. Thus, the load bank controller is proposed using a PID‐based controller. The controller should take into account both the fouling conditions and variations across time because the exhaust gas contains considerable amounts of ash and soot. Hence, an accurate model needs to improve the dynamic characteristics of the PTG system. The identification method clarifies the PTG system. The unknown parameters of the PTG speed model can be estimated using the prediction error method after the mathematical model is transferred to the state‐space model.FindingsSimulation results are verified with measured data of a prototype. In the transient response of the PTG speed, all the errors are within 0.23 percent. The proposed model using the identification method shows the error between the accurate model and the standard to be less than 10 percent. The proposed controller is evaluated by comparing it with the conventional controller. As a result of using the proposed controller, limit speed overshooting is improved by more than 25 percent. Hence, the proposed model is confirmed to have excellent property.Originality/valueThe PTG is an extremely effective system for fuel cost reduction in the face of rising fuel prices, and systems capable of providing several thousand kilowatts are being considered.

A new control method in startup progress for power turbine generators as waste heat recovery system using an overall shipboard system model

PurposeThe purpose of this paper is to present a new control method for a power turbine generator (PTG) as a waste heat recovery system using an overall shipboard system model that ascertains startup characteristics.Design/methodology/approachThe PTG system is a waste heat recovery‐type generation system making use of exhaust gas from the main shipboard diesel engines. With the PTG systems, control during startup is not entirely clear. Startup characteristics from power turbine startup through synchronization to the system bus are ascertained using an overall shipboard system model.FindingsA startup sequence control is clarified for a combination of gas valve operation and load bank. A prototype constructed on the basis of the simulation. As a result, in the startup process, so as to limit speed overshooting that is 0.83 p.u. at 100 percent output from main diesel engine as the severest condition. The synchronization to the system bus is attained, and highly satisfactory results are achieved.Originality/valueThe PTG is an extremely effective system for fuel cost reduction in the face of rising fuel prices, and systems capable of providing several thousand kilowatts are being considered.

The actual effect of wind power on overall electricity generation costs and CO 2 emissions

To correctly investigate the effects of wind power, it is necessary to embed wind turbines in a wider power system and to take a look at the overall picture. It is not possible to isolate wind turbines and their impact from the rest of the power system; they interact with the electricity generation of the entire power system. This paper presents a simulation tool that models wind power and its unpredictability properly, and allows determining the effects wind power has on the cost of electricity generation and on CO 2 emissions. The simulation model uses mixed integer linear programming (MILP) and has the characteristics of an advanced unit commitment (UC) model. The model takes into account a wide set of technical constraints of power plants. To take wind power and its limited unpredictable character into account properly, a specific algorithm has been developed. In a first step, a regular day-ahead UC optimization is performed, applying with a certain forecast of wind power. In a second step, the real-time dispatch is executed. Each hour of the day, the activated plants are dispatched, now taking the actual wind power output into account. Spinning reserves can be used to overcome incorrect wind power forecasts. The method is applied to a case study for Belgium (having an interesting diverse generation mix). High detailed technical information of power plants, demand profiles and empirical data of several wind sites is used in the simulations. Accurate estimates are made concerning the beneficial impact of wind power on a yearly basis. Fuel cost reductions are situated around 56 k EUR per MW of installed wind power capacity per year, while CO 2 emission reduction would reach a level of 1.26 kton of CO 2 avoided, again per MW of installed wind power capacity per year. Wind speed forecast errors do not seem to have a significant effect on this cost and CO 2 reduction.

Research on Variable Cylinders of the Tandem 4-Cylinder Gasoline Engine for Fuel Economy

With progress in internal combustion engine fuel economy, variable cylinder systems have attracted attention. We measured fuel consumption in cylinder cutoff by stopping the injector alone, collected data changing the location and number of cutoff cylinders and when varying the cutoff cylinder, and compared the difference in fuel cost reduction. A transistor is inserted serially into the injector control circuit of the electronic control unit (ECU). By controlling the transistor via microcomputer, the injector is turned on or off independently from ECU control in obtain cylinder cutoff. The amount of fuel consumption is measured using enhancement mode of a failure diagnostic device based on the OBD II standard to collect injection time and rotational speed of the injector for a predetermined time and calculated based on this data. We confirmed that by stopping the injector alone, fuel consumption was reduced 6 to 22% and is reduced when the cutoff cylinder is varied.

Fuel and emissions properties of Stirling engine operated with wood powder

From viewpoints of the environment and fuel cost reduction, small-scale biomass combined heat and power (CHP) plants are in demand, especially wood-waste fueled system, which are simple to operate and maintenance-free with high thermal efficiency similar to oil fired units. These are requested by wood and other industries located in mountainous region. To meet these requirements, a Stirling engine CHP system combined with simplified biomass combustion process with pulverized wood powder was developed. In an R&D project started in 2004 considering wood powder properties as a fuel, combustion performance and emissions in combustion flue gas were tested using combustion test apparatus with commercial size units. The wood powder combustion system was modified and optimized during the combustion test results, and the design of the demonstration plant combined with 55 kW e Stirling engine power unit was considered. The demonstration plant was finally completed in March of 2006, and test operation has been progressed for the future commercial CHP system. In the wood powder combustion test, wood powder of less than 500 μm is mainly used, and a combustion chamber length of 3 m is applied. In these conditions, the air ratio can be reduced to 1.1 without increasing CO emission of less than 10 ppm and combustion efficiency of 99.9%. In the same conditions, NO x emission is estimated to be less than 120 ppm (6% O 2 basis). Wood powder was confirmed to have excellent properties as a fuel for Stirling engine CHP system. This paper summarizes the wood powder combustion test, and presents the evaluation of the burner design parameters for the biomass Stirling engine system.

Sliding mode control for low-thrust Earth-orbiting spacecraft formation maneuvering

This paper considers the control of entire-formation maneuvering in low-thrust Earth-orbiting spacecraft formation flying (SFF). A coordinated control scheme based on the leader-follower approach is developed to achieve formation maneuvers while keeping the internal formation intact. To implement the control scheme, a low-level sliding mode control (SMC) based on nonlinear dynamics is provided. Using a Lyapunov-based control design and stability analysis technique, we prove that the closed-loop system is globally asymptotically stable. Numerical simulations show the advantage of the controller for fuel cost reductions, tracking accuracy, and effectiveness in ensuring entire-formation maneuvering. An exact nonlinear model with modeled disturbances ( J 2 disturbance and bounded uncertainties) is used for dynamic simulation.

Avaliação de parâmetros de consumo de combustível do Tritrem no transporte de madeira

Analisou-se o efeito dos parâmetros marcha lenta, excesso de rotação do motor para valores superiores a 2.000 rpm, pontos neutros e velocidades superiores a 80 km/h, com o objetivo de monitorar o consumo de combustível de veículos de transporte rodoviário de duas transportadoras de madeira (A e B), com base nas informações obtidas de um computador de bordo instalado no cavalo-mecânico LS 2638 da Mercedes-Benz. A marcha lenta foi responsável pelo maior desperdiço de combustível; as transportadoras A e B consumiram 20.122,33 e 18.321,72 L/mês, respectivamente. Ela induziu a um consumo mensal de combustível na ordem de R$ 19.164,50 (91,32%) e R$ 17.449,61 (99,09%), pois, em média, os motores dos veículos funcionaram 24,47 e 25,79% do tempo de operação para as transportadoras A e B, respectivamente. O excesso de rotação do motor dos veículos também induziu ao consumo mensal de combustível de R$ 69,45 (0,33%) para a transportadora A e de R$155,62 (0,88%) para a transportadora B. O ponto neutro contribuiu com o consumo de combustível em R$ 1.751,73 (8,35%) e R$ 4,80 (0,03%), respectivamente, para as transportadoras A e B. Não foi calculado o consumo relativo ao excesso de velocidade, por não serem conhecidos a faixa de potência, a rotação e o consumo específico associado a cada velocidade. A metodologia usada é específica para o motor OM 457 LA, podendo ser adotada em outros estudos, desde que adaptada às especificações dos motores utilizados; a marcha lenta foi responsável pelo maior consumo de combustível no transporte de madeira, seguida do ponto neutro e do excesso de rotação. No transporte de madeira é possível reduzir significativamente o consumo de combustível em relação à marcha lenta, em virtude do elevado tempo de espera (carregamento, descarregamento, filas e paradas obrigatórias). O uso do ponto neutro e o excesso de velocidade não economizam combustível e comprometem a segurança. As rotações superiores a 2.000 rpm implicam desperdício de combustível. O ponto de rotação máxima ideal para o motor dos veículos nas condições estudadas está na faixa de 1.700 rpm. Um pequeno número de equipes foi responsável pelo elevado número de infrações cometidas. A falta de treinamento dos motoristas contribui para o aumento de consumo de combustível. O cumprimento das normas sobre condução econômica ajuda a reduzir os custos com combustível.

CONSUMER THEORY, HOME PRODUCTION, AND ENERGY EFFICIENCY

Arguments about the existence of the so‐called energy efficiency gap are typically based on evaluations of efficiency measures as investments whose end result is to reduce the cost of providing a given level of energy services. This article demonstrates that the investment approach tends to undervalue energy efficiency improvements because it omits the increase in utility that results from the consumer's substitution of energy services for other goods. The substitution occurs because the efficiency measure reduces the marginal cost (implicit price) of energy services. Sample calculations based on a Cobb‐Douglas utility function are used to illustrate the potential size of the undervaluation of efficiency investments.

FUEL MIXING WITH CLAY1

The question of fuel cost reduction is very pertinent. Mixing cinders with clay produced a granular structure which stimulated drying and reduced firing expense. Other methods tried are mentioned.