The wind and solar energy are omnipresent, freely available, and environmental friendly. The wind energy systems may not be technically viable at all sites because of low wind speeds and being more unpredictable than solar energy. The combined utilization of these renewable energy sources are therefore becoming increasingly attractive and are being widely used as alternative of oil-produced energy. Economic aspects of these renewable energy technologies are sufficiently promising to include them for rising power generation capability in developing countries. A renewable hybrid energy system consists of two or more energy sources, a power conditioning equipment, a controller and an optional energy storage system. These hybrid energy systems are becoming popular in remote area power generation applications due to advancements in renewable energy technologies and substantial rise in prices of petroleum products. Research and development efforts in solar, wind, and other renewable energy technologies are required to continue for, improving their performance, establishing techniques for accurately predicting their output and reliably integrating them with other conventional generating sources. The aim of this paper is to review the current state of the design, operation and control requirement of the stand-alone PV solar–wind hybrid energy systems with conventional backup source i.e. diesel or grid. This Paper also highlights the future developments, which have the potential to increase the economic attractiveness of such systems and their acceptance by the user.

A current and future state of art development of hybrid energy system using wind and PV-solar: A review

Although desalination technologies have been widely adopted as a means to produce freshwater, many of them require large installations and access to advanced infrastructure. Recently, floating structures for solar evaporation have been proposed, employing the concept of interfacial solar heat localization as a high-efficiency approach to desalination. However, the challenge remains to prevent salt accumulation while simultaneously maintaining heat localization. This paper presents an experimental demonstration of a salt-rejecting evaporation structure that can operate continuously under sunlight to generate clean vapor while floating in a saline body of water such as an ocean. The evaporation structure is coupled with a low-cost polymer film condensation cover to produce freshwater at a rate of 2.5 L m−2 day−1, enough to satisfy individual drinking needs. The entire system's material cost is $3 m−2 – over an order of magnitude lower than conventional solar stills, does not require energy infrastructure, and can provide cheap drinking water to water-stressed and disaster-stricken communities.

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A salt-rejecting floating solar still for low-cost desalination

Water plays an important role in all our day to day activities and its consumption is increasing day by day because of increased living standards of mankind. Some regions of the globe are under severe stress due to water scarcity and pollution. The fresh water needs of mankind can be only satisfied if saline water which is available in plenty is converted to potable water by desalination. Desalination industry has shown increased threats of CO2 emissions and severe environmental impacts. Desalination industry can be made sustainable if they are integrated with renewable energy and if proper brine disposal methods are followed. In this review different desalination units integrated with renewable energy with special emphasis given to solar energy is discussed. The problems associated with desalination units and their remedies have been presented. Apart from this some novel methods of desalination process has also been explained. This review will allow the researchers to choose appropriate desalination technology for further development.

A review of solar energy driven desalination technologies

Performance study on basin type double slope solar still with different wick materials and minimum mass of water

Single basin double slope solar still with minimum basin depth and energy storing materials

The performance of Stirling engines meets the demands of the efficient use of energy and environmental security and therefore they are the subject of much current interest. Hence, the development and investigation of Stirling engine have come to the attention of many scientific institutes and commercial companies. The Stirling engine is both practically and theoretically a significant device, its practical virtue is simple, reliable and safe which was recognized for a full century following its invention by Robert Stirling in 1816. The engine operates on a closed thermodynamic cycle, which is reversible. Today Stirling cycle-based systems are in commercial use as a heat pump, cryogenic refrigeration and air liquefaction. As a prime mover, Stirling cycles remain the subject of research and development efforts. The objective of this paper is to provide fundamental information and present a detailed review of the past efforts taken for the development of the Stirling cycle engine and techniques used for engine analysis. A number of attempts have been made by researches to build and improve the performance of Stirling engines. It is seen that for successful operation of engine system with good efficiency a careful design of heat exchangers, proper selection of drive mechanism and engine configuration is essential. The study indicates that a Stirling cycle engine working with relatively low temperature with air of helium as working fluid is potentially attractive engines of the future, especially solar-powered low-temperature differential Stirling engines with vertical, double acting, and gamma configuration.

Technological development in the stirling cycle engines

Influence of water depth on internal heat and mass transfer in a plastic solar still

The intention of this work was to study the effect of cover materials on heat and mass transfer coefficient and hence productivity of the still. Two plastic stills having similar geometrical features were constructed to maintain the comparison under the same weather conditions. The condensing surface of one still was an acrylic (plastic) cover (3 mm thick) while of the other still it was a glass cover (3 mm thick), both fixed in an aluminum frame. It was found that for water depth of 10 cm the plastic solar still with the glass cover produced 30–35% more output than the plastic solar still with Plexiglas cover. The evaporative heat transfer coefficient for the glass cover still was 57% more than that for the still with the plastic cover which resulted in a higher output. Plastic can be used as the structural material for solar stills but increased costs do not always increase the distillate output.

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Effect of cover materials on heat and mass transfer coefficients in a plastic solar still

A new geometry of roughness in the sinusoidal form has been investigated computationally using Computational Fluid Dynamics (CFD) software for examining the influence of roughness on heat transfer ...

Suresh Kant Verma

Papers

Technological development in the stirling cycle engines

Influence of water depth on internal heat and mass transfer in a plastic solar still

Effect of cover materials on heat and mass transfer coefficients in a plastic solar still

Three-dimensional simulation and experimental validation of solar air heater having sinusoidal rib

Heat transfer and fluid flow analysis of sinusoidal protrusion rib in solar air heater