Optimum size of thermal power stations

It is well known that the price per unit of generated electrical energy decreases with increasing size of the generator, which implies longer transmission lines and hence larger transmission losses. Considering both these facts, the optimum size of a thermal power station has been obtained by using life-cycle costing analysis; the demand is proposed to be met by a base load generator and a peak load generator. The dependence of the investment ratio (the ratio of present worth of net income to the capital investment) on relevant parameters has been studied. It is seen that there exist optimum sizes of base load generator and peak load generator of a power station, for a given load density. The effect of electricity price, coal price and escalation rates on the optimum sizes has also been investigated. The analysis has been made for constant demand as well as for growing demand. The effect of the ratio of base load to peak load on the economics has also been investigated. The cost data from a recent study in India have been used.     

Technology parameter for thermal power stations

The technology parameter which represents the ratio of fractional change of an investment to fractional change in cost of electrical energy has been computed for thermal power stations. The value lies below ten which signifies that the is good scope for additional investment (bigger power stations).     

Optimum fuel combination for MHD power generators

Various combinations of commercially available gaseous and liquid fuels, burnt with air and preheated (1400K) air, and seeded with K₂CO₃, have been investigated analytically to arrive at an optimum combination that gives a reasonable electrical conductivity (10 mho/m) at minimum cost. This analysis has been carried out for gaseous and liquid fuels, separately, under Indian conditions. Variation of the electrical conductivity with the ratio of the mass of the fuels has also been obtained to make them usable in the cost structure of any country. Further, it has been shown that it is not only the C/H ratio but also the calorific value of the fuel that determines the electrical conductivity of the working fluid.     

Optimum placement/distribution of insulation/concrete in a heavily insulated multilayered roof/wall for best load levelling

In this paper we investigate the optimum placement/distribution of insulation/concrete in a double hollow multilayered wall/roof for achieving the best load levelling in the thermal flux through the slab. It is seen that, of six possible configurations, for a given total thickness of insulation and given total thickness of concrete, the best load levelling is achieved when equal thicknesses of insulation are placed on outside and inside. Better load levelling is achieved in the insulation-air gap-concrete-air gap-concrete configuration when the thickness of the inner layer of concrete (facing room) is least, consistent with structural considerations. No, or the worst, load levelling is achieved in the concrete-air gap-insulation-air gap-insulation and insulation-air gap-insulation-air gap-concrete configurations.     

基于最小网损的风电场无功优化分配策略

针对含双馈式风电机组的风电场接入系统维持接入点电压稳定性问题,通过分析通辽某风电场的实测数据,分析其无功补偿特点,提出了基于有功最小的无功优化分配策略;构建了以风力发电机、箱式变压器和集电线路有功损耗最小的无功优化分配目标函数,利用等微增率法对其求解;在考虑风电场有功损耗的前提下,充分利用双馈式风电机组无功调节能力,制定了该风电场无功分配方案。仿真结果表明该策略的可行性,对风电系统的经济运行具有一定的参考价值。     

Techno-economic analysis of PEM fuel cells role in photovoltaic-based systems for the remote base stations

Expansion of telecommunication networks even to the most remote areas where connection to the utility grid could never be justified, especially in touristic regions, has led to the increasing need for stand-alone power systems. In Adriatic coastal area employment of hybrid photovoltaic-based systems is straightforward due to high sun potential. Inherent intermittent nature of renewable sources is especially not compatible with telecommunication system who require uninterrupted power supply. This leads to the need of not only energy storage, but also a “back up” solution in the case of primary system failure. Emphasis is put on the system reliability and simplicity while system price is not necessarily top priority. Usual approach of using diesel generators as a “back up” has been challenged by the introduction of PEM fuel cells. Even with hydrogen technologies market development still lagging behind some comparable advantages such as high energy conversion efficiency, silent operation and no emissions make PEM fuel cells a legitimate candidate for replacing traditional oil burning generators. Techno-economic analysis of various stand-alone power systems for the remote base station on an Adriatic island is made. At the moment, levelized cost of electricity point of view still gives slight advantage to the diesel generators. Though, uncertain petroleum market and fast developing hydrogen technology market could reverse this trend in the near future. Long term reliability of PEM fuel cells system still needs to be examined in practice, as this combined with pro-environmental characteristics of fuel cells can make the difference especially in pristine and protected areas.     

A review of integration strategies for solid oxide fuel cells

Due to increasing oil and gas demand, the depletion of fossil resources, serious global warming, efficient energy systems and new energy conversion processes are urgently needed. Fuel cells and hybrid systems have emerged as advanced thermodynamic systems with great promise in achieving high energy/power efficiency with reduced environmental loads. In particular, due to the synergistic effect of using integrated solid oxide fuel cell (SOFC) and classical thermodynamic cycle technologies, the efficiency of the integrated system can be significantly improved. This paper reviews different concepts/strategies for SOFC-based integration systems, which are timely transformational energy-related technologies available to overcome the threats posed by climate change and energy security.