Rail transportation by hydrogen vs. electrification – Case study for Ontario Canada,I: Propulsion and storage

Cities around the world are expanding their passenger train operations to address concerns with GHG pollution, noise and high costs of commuter transportation. Locomotives offer an attractive mode of transportation in terms of energy consumption per passenger kilometre of travel. This paper compares hydrogen against electrification as cleaner alternatives to power diesel locomotives. Disadvantages of electrification include the capital investment to install electrical substations and catenaries, together with a lack of flexibility for locomotives to move into other service areas not covered by electrification. This paper specifically analyzes the implementation and operation of hydrogen passenger locomotives in the GO Transit Lakeshore corridor, through Toronto, between Oshawa and Hamilton, Ontario. A sensitivity analysis is performed over a range of operational costs for a hydrogen train, with variability of feedstock prices, fuel cell power density and expected return on capital investment. Various methods of propulsion and storage are compared against electrification. The installation and operational costs in dollars per train-km are analyzed for various train scenarios and results are presented.     

Thermodynamic analysis of a parabolic trough solar power plant integrated with a biomass-based hydrogen production system

In the current study, a solar energy power plant integrated with a biomass-based hydrogen production system is investigated. The proposed plant is designed to supply the required energy for the hydrogen production process along with the electrical energy generation. Thermochemical processes are used to obtain high-purity hydrogen from biomass-based syngas. For this purpose, the simulation of the plant is performed using Aspen HYSYS software. Thermodynamic performance evaluation of the hybrid system is conducted with exergy analysis. Based on the obtained results, the exergy efficiencies of the hydrogen production process and power generation systems are 55.8% and 39.6%, respectively. The net power output of the system is obtained to be 38.89 MWe. Furthermore, the amount of produced hydrogen in the integrated system is 7912.5 tons/year with a flow rate of 10.8 tons/h synthesis gas for 7500 h/year operation. Results show that designing and operating a hybrid high-performance energy system using two different renewable sources is an encouraging approach to reduce the environmental impact of energy conversion processes and the effective use of energy resources.     

Assessment of pico hydro as an option for off-grid electrification in Kenya

This paper discusses off-grid electrification options for low-income households in rural Kenya, where less than 2% are grid connected. The paper outlines the electrical load priorities of rural households and describes how these are supplied at present through centrally charged automotive batteries and solar home systems. The recent introduction of pico hydro schemes (<5 kW) to Kenya is discussed, including details of the implementation of the two community schemes and the costs involved. A comparison is made between pico hydro and solar home systems and conclusions are presented on the way forward for off-grid electrification in Kenya.     

Sustainable energy future via grid interactive operation of spv system at isolated remote island

This paper has analyzed the case of Moushuni Island at Sundarban of 24 Parganas South of West Bengal, India. The proposition is to find out the possibility of grid-connectivity of Isolated Remote Island which is under rural electrification scheme by hybrid renewable energies under Jawaharlal Nehru National Solar Mission of India. In these rural electrification program, grid extension can be the best option if the grid is reliable, the rural community rather big and in proximity to the grid. In many circumstances, a strong case for mini-grids based on hybrid systems can be made. Scattered communities and isolated houses are well served by solar and small hydro (where available) or small wind energy systems. By feeding renewable electricity to the utility grid through the grid-connected hybrid renewable energy system, during time of peak demand, sufficient electrical loads can be shed to prevent turning on a coal or natural gas-fired plant and therefore save CO₂ emissions and potentially energy import costs, replacing fossil fuels. The Social, Economic, and Environmental Benefits can be achieved through this proposition. Also, the Grid Interactive Operation of SPV System at Moushuni Island is tested. Malda district of West Bengal, India is a vision towards smart-grid city towards sustainable future, where rural consumers can upgrade their quality of life through solar energy resource.     

考虑光热电站参与的新能源热电联供型微网运行优化

针对传统热电联供型微网运行存在的问题,文章引入光热电站,并结合风力发电、光伏发电、电加热器、储能系统构成热电联供型微网,提出了一种计及微网运行成本的新能源热电联供型微网运行优化策略。该优化策略综合考虑与外部电网交互成本、各设备维护成本、储能老化成本及热电功率平衡约束等因素,建立了热电联供型微网运行优化模型,并采用YALMIP工具箱进行求解。结果表明:该模型运行成本降低了6.2%,电加热器配合光热电站可以提高微网的运行灵活性,实现电-热能量的双向流动,光热电站在一定范围内增大了发电规模,可有效降低微网运行成本。     

Possibilities for biomass-based power plant and wind system integration

In this paper, the integration of a biomass-based diesel–wind system is investigated. The system consists of a pitch controlled wind turbine, which is equipped with an induction generator. The induction generator is connected to an ac bus-bar in parallel with a diesel-generator set consisting of a diesel engine driving a synchronous generator. A power plant can generate electric power using biomass from the olive tree in Spain. A gasifier is capable of converting tons of wood chips per day into a gaseous fuel that is fed into a diesel engine. While there are significant systems whose models may be exactly obtained from physical laws and whose states are measured, it is much less realistic to assume that all the parameters, such as the higher heating value of the biogas or wind speed, are exactly known. It is then natural to investigate what happens to control systems involving unknown, or not precisely known, parameters. In this paper, the derived model of biomass-based wind–diesel systems is quite valid for robust control studies.     

Combined cycle versus one thousand diesel power plants: pollutant emissions,ecological efficiency and economic analysis

The increase in the use of natural gas in Brazil has stimulated public and private sectors to analyse the possibility of using combined cycle systems for generation of electrical energy. Gas turbine combined cycle power plants are becoming increasingly common due to their high efficiency, short lead times, and ability to meet environmental standards. Power is produced in a generator linked directly to the gas turbine. The gas turbine exhaust gases are sent to a heat recovery steam generator to produce superheated steam that can be used in a steam turbine to produce additional power. In this paper a comparative study between a 1000 MW combined cycle power plant and 1000 kW diesel power plant is presented. In first step, the energetic situation in Brazil, the needs of the electric sector modification and the needs of demand management and integrated means planning are clarified. In another step the characteristics of large and small thermoelectric power plants that use natural gas and diesel fuel, respectively, are presented. The ecological efficiency levels of each type of power plant is considered in the discussion, presenting the emissions of particulate material, sulphur dioxide (SO₂), carbon dioxide (CO₂) and nitrogen oxides (NO_x).     

Modelling the promotion of biomass use: A case study of Thailand

This study develops a computable general equilibrium model of the Thailand economy which features several energy-specific enhancements. The model is used to simulate a number of potential policies to achieve the Thai government’s biomass-generated electricity targets contained in its 15-year renewable energy development plan. Examples of simulations conducted with the model include increasing biomass-based electricity purchased from small and very small power producers and increasing other agricultural residue use in electricity generation. The results indicate that implementation of all of the biomass-based electricity promotion policies is likely to achieve the short-run target and reduce somewhat the importation of fuels. However, the policy causes a huge increase in prices of biomass. The sugarcane-based sectors are big winners, while the cassava-based sectors are big losers. The losses can, however, be partly mitigated by promoting other agricultural residue use in electricity generation.     

Exergy-based method for analyzing the composition of the electricity cost generated in gas-fired combined cycle plants

The proposed method to analyze the composition of the cost of electricity is based on the energy conversion processes and the destruction of the exergy through the several thermodynamic processes that comprise a combined cycle power plant. The method uses thermoeconomics to evaluate and allocate the cost of exergy throughout the processes, considering costs related to inputs and investment in equipment. Although the concept may be applied to any combined cycle or cogeneration plant, this work develops only the mathematical modeling for three-pressure heat recovery steam generator (HRSG) configurations and total condensation of the produced steam. It is possible to study any n×1 plant configuration (n sets of gas turbine and HRSGs associated to one steam turbine generator and condenser) with the developed model, assuming that every train operates identically and in steady state. The presented model was conceived from a complex configuration of a real power plant, over which variations may be applied in order to adapt it to a defined configuration under study [Borelli SJS. Method for the analysis of the composition of electricity costs in combined cycle thermoelectric power plants. Master in Energy Dissertation, Interdisciplinary Program of Energy, Institute of Eletro-technical and Energy, University of São Paulo, São Paulo, Brazil, 2005 (in Portuguese)]. The variations and adaptations include, for instance, use of reheat, supplementary firing and partial load operation. It is also possible to undertake sensitivity analysis on geometrical equipment parameters.     

Review and comparison study of hybrid diesel/solar/hydro/fuel cell energy schemes for a rural ICT Telecenter

In this paper, the rural electrification study of an ICT Telecenter in particular reference to the Kelabit Highland of Sarawak is presented. The use of diesel generator and its associated environmental implications is first discussed. The cost-effectiveness of the present solar PV system and the solar/hydro schemes for rural electrification of the rural ICT are evaluated employing the HOMER simulation software, considering sustainability factors such as system efficiency, weather, fuel costs, operating and maintaining costs. Subsequently, simple novel Hybrid Energy Performance Equations and the associated Energy Performance Curves are derived and introduced, respectively, which provide a visualization model, simplifying hybrid system analysis. Results obtained in this study have shown that combined power schemes is more sustainable in terms of supplying electricity to the Telecenter compared to a stand-alone PV system due to prolong cloudy and dense haze periods. The hybrid systems can have efficiency range of ∼15%–75% compared to PV stand-alone of only ∼10%, indicating hybrid systems are more reliable and sustainable – in minimizing both energy losses and excess energy.     

Gas turbines in district heating combined heat and power systems: influence of performance on heating costs and emissions

Much work is currently focussed on identifying economically and environmentally optimal strategies for increasing gas turbine based combined heat and power (CHP). In many such studies, only a few fixed parameters are used to describe the CHP plant. These are typically total and electrical efficiencies, investment and running costs, minimum and maximum acceptable size, and minimum acceptable part-load. However, for gas turbine based systems these characteristics are clearly functions of the operating conditions, especially for part-load operation. This study examines the effects of varying performance of the gas turbine on the overall heat production costs and CO₂ emissions of a medium sized community district heating plant. Both single and double-shaft engines are considered in the study. The results show that the assumption of constant efficiencies for all operating conditions leads to an overestimation of the optimal CHP plant size, thereby underestimating the heat production costs and overestimating the CO₂ emissions of the plant. The results also show marked differences according to the type of gas turbine used and part-load operating strategy adopted. In particular, the paper discusses the part-load operating difficulties for CHP plants running gas turbines equipped with low emissions burners.     

北疆电厂脱硫系统经济运行的研究与实践

介绍了北疆电厂脱硫系统节能管理过程中,围绕如何降低脱硫系统厂用电、系统优化等方面进行了相关的分析与试验,对脱硫系统的经济运行进行了探讨和实践。     

Optimised model for community-based hybrid energy system

Hybrid energy system is an excellent solution for electrification of remote rural areas where the grid extension is difficult and not economical. Such system incorporates a combination of one or several renewable energy sources such as solar photovoltaic, wind energy, micro-hydro and may be conventional generators for backup. This paper discusses different system components of hybrid energy system and develops a general model to find an optimal combination of energy components for a typical rural community minimizing the life cycle cost.The developed model will help in sizing hybrid energy system hardware and in selecting the operating options. Micro-hydro-wind systems are found to be the optimal combination for the electrification of the rural villages in Western Ghats (Kerala) India, based on the case study. The optimal operation shows a unit cost of Rs. 6.5/kW h with the selected hybrid energy system with 100% renewable energy contribution eliminating the need for conventional diesel generator.     

Assessing wood-based synthetic natural gas technologies using the SWISS-MARKAL model

In future, new biomass technologies can gain significant importance in the Swiss energy sector. Therefore, this paper assesses the economic conditions under which new biomass technologies become competitive. The focus of this assessment is on the production of synthetic natural gas (bio-SNG) from wood in a methanation plant. The assessment is conducted with the cost-optimization model SWISS-MARKAL (MARKet ALlocation). SWISS-MARKAL projects future technology investments and provides an integrated analysis of primary, secondary, final and end-use energy in Switzerland. In addition to a reference scenario, the effects of increasing oil and gas prices, the effects of allocating subsidies to the methanation plant and the effects of competition between the methanation plant and a biomass-based Fischer–Tropsch (FT) synthesis are evaluated. Moreover, a sensitivity analysis is performed by varying investment costs of the methanation plant. The results are in favour of bio-SNG in the transportation sector where the synergetic use of bio-SNG and natural gas reduces the dependence on oil imports and the level of CO₂ emissions.     

基于模糊隶属度的电力设备资产全寿命周期成本模型及评价体系研究

电网企业将LCC理论应用作为提高设备资产效率和质量的有效手段,亟需解决LCC应用中的模型计算和评价体系问题.本文通过构建电网企业资产全寿命周期管理机制,建立了电力设备的LCC的计算模型和方法,采用基于模糊数学中的模糊隶属度方法,改进了技改和大修项目分摊到多个设备资产分摊方法,提出了电力设备的LCC评价模型和评价体系,并...     

Electrification co-operatives bring new light to rural Tanzania

One possibility to accelerate the progress of rural electrification in developing countries could be to form independent electrification co-operatives that are allowed to generate and distribute electric power and set their own tariffs. This approach has been successfully tried in the village Urambo, located about 80 km west of Tabora in Tanzania. The co-operative was formed in 1993 and started regular operation in 1994 with 67 consumers. The co-operative received initial financial support for rehabilitation of a diesel power plant and some other investments. The national utility TANESCO has provided technical support and training for operators and an accountant. Despite a tariff more than 15 times higher than in the nearby town Tabora that is served by TANESCO, the number of consumers in Urambo has been growing and reached 241 in October 2002. About 70% of the supplied electricity in 2002 was used by households, 15% in businesses, 12% in institutions and public buildings and approximately 3% for street lighting. The reliability of the supply has improved from 80% in 1994, to 97% during 2002. The experiences must be considered as very promising. Several more electrification co-operatives have been formed in Tanzania and are looking for financing for the necessary initial investments.     

基于峰谷分时电价的虚拟电厂日前申报及运行优化

鉴于分布式能源的出力性质为间歇性和波动性,影响电网安全高效运行,而虚拟电厂可解决此问题。对虚拟电厂进行申报-调度两阶段建模,以包含分布式电源(光电、风电和燃气轮机)和储能系统(储能电池)两大类分布式能源的虚拟电厂为例,基于光照强度及风速等不确定因素,研究峰谷分时电价下日前市场虚拟电厂的出力申报和运行调度策略并利用风险价值模型进行风险管理。结果表明,申报出力时,当电价激励足够高时储能电池方会参与出力,成功起到削峰填谷的作用;运行调度时,平衡出力偏差方面,储能电池发挥主要作用,且虚拟电厂运行调度策略具有一定的经济效益。     

Assessment of using hydrogen in gas distribution grids

Substantial changes in the energy system are necessary to achieve greenhouse gas neutrality. Green hydrogen is a key to defossilisation. Politicians frequently mention the use of hydrogen in the building sector to supply decentrally produced heat as a potential field of application. An advantage repeatedly mentioned is that the existing gas distribution network infrastructure is an important asset that could still be used in the future. However, there is a lack of analyses of the conversion of gas distribution networks to hydrogen focussing on the economic implications on the costs of the distribution network infrastructure. The paper provides insights using a techno-economic model network analysis (MNA) tool called gas Distribution grId modelliNg tOol (DINO). The analysis is carried out for Germany and considers hydrogen use in all counties. The results are compared to a synthetic methane and electrification scenario. In the hydrogen scenario, the total need for distribution grids is decreasing until 2050 by at least 130,000 km. The network length of the synthetic methane scenario is slightly lower and that of the electrification scenario drops to zero. The annual operation costs are lower in all scenarios as gas demand and infrastructure are reduced. Nevertheless, the total annual cost in the hydrogen scenario is potentially two times higher than in the case of the synthetic methane scenario and more than four times higher than in the electrification scenario. Based on the present results, it is questionable whether an advantage of the continued use of the existing gas distribution grid infrastructure in case of synthetic gas or hydrogen scenarios exists.     

计及风光不确定性的新能源虚拟电厂多时间尺度优化调度

针对中国西北地区新能源消纳问题,该文聚合风力发电、光伏发电、光热电站、电储能装置组成虚拟电厂（VPP）,提出一种基于鲁棒随机优化理论的新能源虚拟电厂多时间尺度优化调度策略。首先对风力发电、光伏发电、光热电站与电储能装置进行数学描述,在此基础上建立VPP多时间尺度优化调度模型。在日前调度层中,以VPP运行效益最大为目标,依据风光日前预测出力建立日前优化调度模型;在时前调度层中,以VPP运行成本最小为目标,根据风光时前预测出力建立时前调度修正模型。同时,为了衡量风电、光伏发电出力不确定性对系统的运行影响,建立VPP随机优化调度模型。仿真结果验证该模型可提高运行效益与新能源消纳能力。