State of the Art on Small-Scale Concentrated Solar Power Plants☆

AbstractMany efforts have been spent in the design and development of Concentrated Solar Power (CSP) Plants worldwide. Most of them are for on-grid electricity generation and they are medium or large plants (in the order of MWs) which can benefit from the economies of scale.Nevertheless, several potential applications for Small-Scale CSP plants (< 1 MW) can be relevant in the industrial sector as well as for off-grid purposes (i.e. in rural contexts).This paper presents the technologies suitable for off-grid applications, for electricity or cogenerated production. Major characteristics are illustrated and advantages and drawbacks for each configuration identified and discussed

Light source selection for a solar simulator for thermal applications: A review

Solar simulators are used to test components and systems under controlled and repeatable conditions, often in locations with unsuitable insolation for outdoor testing. The growth in renewable energy generation has led to an increased need to develop, manufacture and test components and subsystems for solar thermal, photovoltaic (PV), and concentrating optics for both thermal and electrical solar applications. At the heart of any solar simulator is the light source itself. This paper reviews the light sources available for both low and high-flux solar simulators used for thermal applications. Criteria considered include a comparison of the lamp wavelength spectrum with the solar spectrum, lamp intensity, cost, stability, durability, and any hazards associated with use. Four main lamp types are discussed in detail, namely argon arc, the metal halide, tungsten halogen lamp, and xenon arc lamps. In addition to describing the characteristics of each lamp type, the popularity of usage of each type over time is also indicated. This is followed by guidelines for selecting a suitable lamp, depending on the requirements of the user and the criteria applied for selection. The appropriate international standards are also addressed and discussed. The review shows that metal halide and xenon arc lamps predominate, since both provide a good spectral match to the solar output. The xenon lamp provides a more intense and stable output, but has the disadvantages of being a high-pressure component, requiring infrared filtering, and the need of a more complex and expensive power supply. As a result, many new solar simulators prefer metal halide lamps

The atmospheric steam engine as energy converter for low and medium temperature thermal energy

Many industrial processes and renewable energy sources produce thermal energy with temperatures below 100 °C. The cost-effective generation of mechanical energy from this thermal energy still constitutes an engineering problem. The atmospheric steam engine is a very simple machine which employs the steam generated by boiling water at atmospheric pressures. Its main disadvantage is the low theoretical efficiency of 0.064. In this article, first the theory of the atmospheric steam engine is extended to show that operation for temperatures between 60 °C and 100 °C is possible although efficiencies are further reduced. Second, the addition of a forced expansion stroke, where the steam volume is increased using external energy, is shown to lead to significantly increased overall efficiencies ranging from 0.084 for a boiler temperature of T0 = 60 °C to 0.25 for T0 = 100 °C. The simplicity of the machine indicates cost-effectiveness. The theoretical work shows that the atmospheric steam engine still has development potential.<br/

A review of solar-powered Stirling engines and low temperature differential Stirling engines

This article provides a literature review on solar-powered Stirling engines and low temperature differential Stirling engines technology. A number of research works on the development of Stirling engines, solar-powered Stirling engines, and low temperature differential Stirling engines is discussed. The aim of this review is to find a feasible solution which may lead to a preliminary conceptual design of a workable solar-powered low temperature differential Stirling engine. Results from the study indicate that Stirling engines working with relatively low temperature air are potentially attractive engines of the future, especially solar-powered low temperature differential Stirling engines with vertical, double-acting, gamma-configuration.Stirling engine Hot-air engine Solar-powered heat engine