Sustainable development of energy systems for western China

The distribution of energy and industry in China is extremely uneven. The western region is rich in energy resources but relatively economically backward, while the eastern region, particularly, the southeast coastal area, is an industrially-developed area but is short of energy resources. On the basis of such a situation, this paper recommends the sustainable development of energy systems for the western region. The specific innovative energy systems adopted here can convert the western region's fossil fuels to alternative fuels and electricity with higher efficiency, lower investment cost, and less impact upon the environment. As one of such innovative energy systems, the MES (multi-functional energy system) can achieve 10–14% in the energy conservation ratio, 4–8% reduction of investment cost, and a 10–37% decrease of main pollutants. Moreover, its adoption will increase the income and accelerate the development of the energy industry in the western region, as well as meet the energy demand of the eastern region. The analysis in this paper presents a feasible energy road map for the rapid yet sustainable development of China's western region.     

EnerGis: A geographical information based system for the evaluation of integrated energy conversion systems in urban areas

A geographical information system has been developed to model the energy requirements of an urban area. The purpose of the platform is to model with sufficient detail the energy services requirements of a given geographical area in order to allow the evaluation of the integration of advanced integrated energy conversion systems. This tool is used to study the emergence of more efficient cities that realize energy efficiency measures, integrate energy efficient conversion technologies and promote the use of endogenous renewable energy. The model is illustrated with case studies for the energetic planning of the Geneva district (Switzerland).     

Reimagining future energy systems: Overview of the US program to maximize energy utilization via integrated nuclear-renewable energy systems

A sustainable, balanced energy portfolio is necessary for a country's continued economic growth. This portfolio must collectively be able to provide reliable, resilient electricity at stable, affordable prices. Nuclear energy is an important contributor to global clean energy supply, both as a primary source and by complementing and enabling other clean energy sources. As we look to the design and operation of future energy systems, we see an increasing need to think differently about how we utilize our energy resources to meet all of our energy needs—not just electricity but also industrial and transportation demands. Resource utilization in light of a broader desire to reduce environmental impacts leads us to consider transforming how we use nuclear energy, which currently provides more than half of the nonemitting electricity generated in the United States. A paradigm shift is required to develop optimal energy generation and use configurations that embrace novel approaches to system integration and process design. The US Department of Energy (DOE) Office of Nuclear Energy (NE) program on Integrated Energy Systems (IES)—formerly the Nuclear-Renewable Hybrid Energy Systems (N-R HES) program—was established to evaluate potential options for the coordinated use of nuclear and renewable energy generators to meet energy demands across the electricity, industrial, and transportation sectors. These formerly independent sectors are becoming increasingly linked through technology advances in data acquisition, communications, demand response approaches, and control technologies. Advanced modeling and simulation tools can be employed to design systems that better coordinate across these sectors. Implementation of integrated multi-input, multi-output energy systems will allow for expanded use of nuclear energy beyond the grid in a manner that complements the increased build-out of variable renewable energy generation. These integrated systems would provide enhanced flexibility while also providing energy services and supporting the production of additional, nonelectric commodities (eg, potable water, hydrogen, and liquid fuels) via excess thermal and electrical energy from the nuclear system. Increased flexibility of traditionally baseload nuclear systems will support energy security, grid reliability, and grid resilience while maximizing the use of clean energy technologies. This paper provides an overview of current efforts in the United States that assess the potential to increase utilization of nuclear energy systems, in concert with renewable energy generation, via the IES program. Analysis tools and approaches and preliminary analysis results are summarized, and planned experimental activities to demonstrate integrated system performance are introduced.     

Optimizing the energy and exergy of building integrated photovoltaic thermal (BIPVT) systems under cold climatic conditions

Building integrated photovoltaic thermal (BIPVT) system has the potential to become a major source of renewable energy in the urban environment. In this paper, the system has been used as the roof top of a building to generate higher electrical energy per unit area and to produce necessary thermal energy required for space heating. One-dimensional transient model has been developed using basic heat transfer equations. On the basis of this model, an analysis has been carried in order to select an appropriate BIPVT system suitable for the cold climatic conditions of India. The PV performances, net energy gain and exergy of the building are determined. The results show that for a constant mass flow rate of air the system connected in series gives a better performance whereas for a constant velocity of air flow the system connected in parallel gives a better performance. The BIPVT system, fitted on the rooftop in an effective area of 65 m², is capable of annually producing the net electrical and thermal exergies of 16,209 kW h and 1531 kW h, respectively, at an overall thermal efficiency of 53.7%.     

Extended-power pinch analysis (EPoPA) for integration of renewable energy systems with battery/hydrogen storages

An extended-power pinch analysis (EPoPA) is proposed as a means of extending the power pinch analysis (PoPA) for optimal design of renewable energy systems with battery and hydrogen storage (RES-BH). The EPoPA concept is based on the storage of wasted electricity that cannot be stored by the battery bank designed by PoPA. This energy is stored in the form of hydrogen and is discharged in the form of electricity when the external electricity source is needed. EPoPA graphical and numerical tools are introduced to determine the minimum required external electricity source, wasted electricity sources, and appropriate hydrogen storage system capacity of the RES-BH system during first and normal operation years. Furthermore, the integration of the RES-BH system with a diesel generator as a high reliable system is investigated in view point of economic. The optimal sizes of diesel generator and hydrogen storage system components, such as electrolyzer, fuel cell and hydrogen tank are obtained with the minimization of the total annual cost (TAC) of the system. The implementation results of the EPoPA tools on three possible case studies indicate that EPoPA, unlike other process integration methodologies such as PoPA, is able to optimally design RES-BH systems.     

山西省煤基石油替代燃料中长期发展战略

山西是我国重要的煤炭基地，实施煤基石油替代燃料战略是保障国家能源安全，建设国家新型能源基地，培育煤炭接续产业的必然选择。根据国家能源替代能源中长期发展战略和山西省的省情，提出了山西“以市场为导向，以企业为主体，以技术进步为支撑，立足于丰富的劣质煤、焦炉煤气、煤层气等资源优势，把发展煤基醇醚燃料作为战略重点，加快推进包括煤基醇醚燃料、煤制油、水煤浆等替代能源的多元化发展”战略思路和目标，并提出了相应的政策建议。     

State-of-art review of the optimization methods to design the configuration of hybrid renewable energy systems (HRESs)

The current research aims to present an inclusive review of latest research works performed with the aim of improving the efficiency of the hybrid renewable energy systems (HRESs) by employing diverse ranges of the optimization techniques, which aid the designers to achieve the minimum expected total cost, while satisfying the power demand and the reliability. For this purpose, a detailed analysis of the different classification drivers considering the design factors such as the optimization goals, utilized optimization methods, grid type as well as the investigated technology has been conducted. Initial results have indicated that among all optimization goals, load demand parameters including loss of power supply probability (LPSP) and loss of load probability (LLP), cost, sizing (configuration), energy production, and environmental emissions are the most frequent design variables which have been cited the most. Another result of this paper indicates that almost 70% of the research projects have been dedicated towards the optimization of the off-grid applications of the HRESs. Furthermore, it has been demonstrated that, integration of the PV, wind and battery is the most frequent configuration. In the next stage of the paper, a review concerning the sizing methods is also carried out to outline the most common techniques which are used to configure the components of the HRESs. In this regard, an analysis covering the optimized indicators such as the cost drivers, energy index parameters, load indicators, battery’s state of charge, PV generator area, design parameters such as the LPSP, and the wind power generation to load ratio, is also performed.     

Evaluation of electricity generation and energy cost of wind energy conversion systems (WECSs) in Central Turkey

The negative effects of non-renewable fossil fuels have forced scientists to draw attention to clean energy sources which are both environmentally more suitable and renewable. Although Turkey enjoys fairly high wind energy potential, an investigation and exploitation of this source is still below the desired level. In this study which is a preliminary study on wind energy cost in Central Anatolian-Turkey, the wind energy production using time-series approach and the economic evaluation of various wind energy conversion systems (WECSs) enjoying the 2.5, 5, 10, 20, 30, 50, 100 and 150 kW rated power size using the levelised cost of electricity (LCOE) method for the seven different locations in Central Turkey were estimated. In addition, effects of escalation ratio of operation and maintenance cost and annual mean speed on LCOE are taken into account. The wind speed data for a period between 2000 and 2006 years were taken from Turkish State Meteorological Service (TSMS). According to the result of the calculations, it is shown that the WECS of capacity 150 kW produce the energy output 120,978 kWh per year in the Case-A (Pinarbasi) for hub height 30 m and also the LCOE varies in the range of 0.29–30.0 $/kWh for all WECS considered.     

DSP based inverter control for alternate energy systems

This paper presents a DSP based algorithm to control inverters used in interfacing alternate energy systems with the electric utility. Since a constant and ripple free dc bus voltage is not ensured at the output of alternate energy sources, the main aim of the proposed algorithm is to make the output of the inverter immune to the fluctuations in the dc input voltage. In this paper a modified space vector pulse width modulation (SVPWM) technique is proposed which will maintain the quality of the ac output of the inverter, regardless of the ripple present at the inverter input. The principle is explained qualitatively and extensive experiments have been carried out to verify and validate the proposed algorithm. A 16-bit fixed-point C2000 family DSP from Texas Instruments was used as the controller to implement the proposed control algorithm.     

Chance-constrained energy-reserve co-optimization scheduling of wind-photovoltaic-hydrogen integrated energy systems

An optimal energy-reserve scheduling model of wind-photovoltaic-hydrogen integrated energy systems (WPH-IES) with multi-type energy storage devices including electric, thermal and hydrogen is presented in this paper. The chance-constrained programming (CCP) theory is utilized to model the impact of renewable and load uncertainties on reserve constraints. Considering the non-convex of proposed CCP model, an improved discretized step transformation (DST) method is proposed to transform the CCP problem into a solvable mixed integer linear programming (MILP) formulation. In addition, a critical threshold value selection approach is developed to reduce the number of constraints and improve solution efficiency. Case studies demonstrate that the proposed energy-reserve model can reduce the total operating cost on the premise of ensuring the safety of system operation. The combined improved DST and critical threshold value selection method can reduce computational burden and improve the accuracy of scheduling results.     

Integrated energy systems based on cascade utilization of energy

Focusing on the traditional principle of physical energy utilization, new integration concepts for combined cooling, heating and power (CCHP) system were identified, and corresponding systems were investigated. Furthermore, the principle of cascade utilization of both chemical and physical energy in energy systems with the integration of chemical processes and thermal cycles was introduced, along with a general equation describing the interrelationship among energy levels of substance, Gibbs free energy of chemical reaction and physical energy. On the basis of this principle, a polygeneration system for power and liquid fuel (methanol) production has been presented and investigated. This system innovatively integrates a fresh gas preparation subsystem without composition adjustment process (NA) and a methanol synthesis subsystem with partial-recycle scheme (PR). Meanwhile, a multi-functional energy system (MES) that consumes coal and natural gas as fuels simultaneously, and co-generates methanol and power, has been presented. In the MES, coal and natural gas are utilized synthetically based on the method of dual-fuel reforming, which integrates methane/steam reforming and coal combustion. Compared with conventional energy systems that do not consider cascade utilization of chemical energy, both of these systems provide superior performance, whose energy saving ratio can be as high as 10%–15%. With special attention paid to chemical energy utilization, the integration features of these two systems have been revealed, and the important role that the principle of cascade utilization of both chemical and physical energy plays in system integration has been identified.     

Advanced vehicles: Costs, energy use, and macroeconomic impacts

Advanced vehicles and alternative fuels could play an important role in reducing oil use and changing the economy structure. We developed the Costs for Advanced Vehicles and Energy (CAVE) model to investigate a vehicle portfolio scenario in California during 2010-2030. Then we employed a computable general equilibrium model to estimate macroeconomic impacts of the advanced vehicle scenario on the economy of California. Results indicate that, due to slow fleet turnover, conventional vehicles are expected to continue to dominate the on-road fleet and gasoline is the major transportation fuel over the next two decades. However, alternative fuels could play an increasingly important role in gasoline displacement. Advanced vehicle costs are expected to decrease dramatically with production volume and technological progress; e.g., incremental costs for fuel cell vehicles and hydrogen could break even with gasoline savings in 2028. Overall, the vehicle portfolio scenario is estimated to have a slightly negative influence on California's economy, because advanced vehicles are very costly and, therefore, the resulting gasoline savings generally cannot offset the high incremental expenditure on vehicles and alternative fuels. Sensitivity analysis shows that an increase in gasoline price or a drop in alternative fuel prices could offset a portion of the negative impact.     

Energy system aspects of hydrogen as an alternative fuel in transport

Considering the enormous ecological and economic importance of the transport sector the introduction of alternative fuels—together with drastic energy efficiency gains—will be a key to sustainable mobility, nationally as well as globally. However, the future role of alternative fuels cannot be examined from the isolated perspective of the transport sector. Interactions with the energy system as a whole have to be taken into account. This holds both for the issue of availability of energy sources as well as for allocation effects, resulting from the shift of renewable energy from the stationary sector to mobile applications. With emphasis on hydrogen as a transport fuel for private passenger cars, this paper discusses the energy systems impacts of various scenarios introducing hydrogen fueled vehicles in Germany. It identifies clear restrictions to an enhanced growth of clean hydrogen production from renewable energy sources (RES). Furthermore, it points at systems interdependencies that call for a priority use of RES electricity in stationary applications. Whereas hydrogen can play an increasing role in transport after 2030 the most important challenge is to exploit short–mid-term potentials of boosting car efficiency.     

A new perspective in optimum sizing of hybrid renewable energy systems: Consideration of component performance degradation issue

The ever increasing demand for energy and the concerns on the environmental sustainability issue all around the world lead to more interest in alternative sources for energy production. However, as the current costs of the alternative sources such as solar, wind energy conversion systems etc. are relatively higher as compared to the conventional means of energy production, an optimum sizing approach is quite necessary in order to avoid over-sizing of such systems without lowering the reliability of load demand supply in all possible conditions including the variability of meteorological conditions or the changing power demand of load. There are many research papers available in the literature dealing with this optimum sizing issue. Even the mentioned papers significantly contribute to the wider penetration of such sources, none of them consider the power output degradation of alternative energy sources due to aging during their pre-defined operating life time. Besides, there are a few studies utilizing detailed dynamic models of energy sources apart from first-degree linear equations based models that may fall short in presenting the exact dynamics of the related system. Thus, an “observe and focus” algorithm based optimization of a hybrid alternative energy system considering the power output degradation and detailed models of each hybrid system component is performed in this study. Related details presented within the paper can provide a new perspective in optimum sizing of such hybrid systems and may further be considered in future updates of famous sizing software programs commercially or freely available in websites of several laboratories or universities.     

Integrated modelling of material flows and energy systems (MIMES)

A comprehensive nonlinear programming model, MIMES, for the optimization of linked material and energy flow systems is presented. The model is generic, intended for systems that can be described by materials and energy balances but where the details of phase transitions and chemical reactions can be omitted. It fills a niche between energy systems engineering and process flowsheeting models. Issues suitable for analysis by the model range from energy conservation in industrial plants, specific industries or industrial subsectors to municipal waste management and fuels and materials life cycle analysis. MIMES is implemented on PC (386/486). The model is demonstrated for a paper production line in a paper mill. This example shows how the model can be used for joint analysis of energy and water conservation, substitution of energy carriers, and utilization of waste heat outside the system.     

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.     

Life cycle assessment of alternative energy types – including hydrogen – for public city buses in Taiwan

Human activities have exacerbated the global greenhouse effect, resulting in extreme climate changes that have caused disasters and food and water shortages in recent years. Transportation is one of the main causes of global greenhouse gas (GHG) emission. Therefore, policy makers must develop feasible strategies to reduce GHG emission. One of Taiwan's policy is to replace traditional diesel fuel urban buses with alternative energy buses. This paper uses a case study of city bus route No. 2 in Tainan City following the international standard ISO/TS 14067:2013 to measure the carbon footprint of different energy buses. The bus carbon footprints measured from high to low as: LNG buses, 63.14 g CO2e/pkm; traditional diesel buses, 54.6 g CO2e/pkm; liquefied petroleum gas (LPG) buses, 47.4 g CO2e/pkm; plug-in electric buses, 37.82 g CO2e/pkm, and hydrogen fuel cell buses, 29.17 g CO2e/pkm. If all urban area public buses in Taiwan were switched to hydrogen fuel cell buses, this would reduce CO2e footprint by 227,832.39 t annually. This reduction is equivalent to planting 22.78 million trees.     

A smooth co-ordination control for a hybrid autonomous power system (HAPS) with battery energy storage (BES)

The standalone hybrid power system constitutes a synchronous generator driven by a diesel engine, renewable energy source (wind) apart from a battery energy storage system. A coherent control strategy to regulate the voltage and frequency of the standalone grid is proposed in this paper. The system is simulated using Matlab/Simulink for preliminary validation and further tested on a laboratory prototype which involves a TMS320LF2407A DSP controller to digitally implement the control strategy. The dynamic behavior of the system is perused through the direct connection of an induction machine. The control strategy is verified for step changes in load and variation in wind power.     

Solar photovoltaic (PV) energy; latest developments in the building integrated and hybrid PV systems

Environmental concerns are growing and interest in environmental issues is increasing and the idea of generating electricity with less pollution is becoming more and more attractive. Unlike conventional generation systems, fuel of the solar photovoltaic energy is available at no cost. And solar photovoltaic energy systems generate electricity pollution-free and can easily be installed on the roof of residential as well as on the wall of commercial buildings as grid-connected PV application. In addition to grid-connected rooftop PV systems, solar photovoltaic energy offers a solution for supplying electricity to remote located communities and facilities, those not accessible by electricity companies.The interest in solar photovoltaic energy is growing worldwide. Today, more than 3500 MW of photovoltaic systems have been installed all over the world. Since 1970, the PV price has continuously dropped [8]. This price drop has encouraged worldwide application of small-scale residential PV systems. These recent developments have led researchers concerned with the environment to undertake extensive research projects for harnessing renewable energy sources including solar energy. The usage of solar photovoltaic as a source of energy is considered more seriously making future of this technology looks promising.The objective of this contribution is to present the latest developments in the area of solar photovoltaic energy systems. A further objective of this contribution is to discuss the long-term prospect of the solar photovoltaic energy as a sustainable energy supply.     

Water desalination systems powered by renewable energy sources: Review

Water and energy are two of the most important topics on the international environment and development agenda. The social and economic health of the modern world depends on sustainable supply of both energy and water. Many areas worldwide that suffer from fresh water shortage are increasingly dependent on desalination as a highly reliable and non-conventional source of fresh water. So, desalination market has greatly expanded in recent decades and expected to continue in the coming years. The integration of renewable energy resources in desalination and water purification is becoming increasingly attractive. This is justified by the fact that areas of fresh water shortages have plenty of solar energy and these technologies have low operating and maintenance costs.The present paper presents a review for the work that has been achieved during the recent years in the field of desalination by renewable energies, with emphasis on technologies and economics. The review also includes water sources, demand, availability of potable water and purification methods. A comparative study between different renewable energy technologies powered desalination systems as well as performance and economics have been done. Finally, some general guidelines are given for selection of desalination and renewable energy systems and the parameters that need to be considered.