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Increase in demand for drinking water due to growth in world population and industrialization has lead route for innovating new technologies for purifying sea water. Desalination by conventional energy source increases the emission of greenhouse gases and leads to global warming. As a solution for pollution and water scarcity, solar desalination techniques are incorporated worldwide for converting brackish water into portable water using solar power. Solar power helps water purification via solar thermal systems and also using solar photovoltaic panels which provide electric supply. This review article consolidate the solar thermal energy based small, medium and large scale solar desalination plants for extracting pure water. The environmental benefits and the futuristic challenges of utilizing solar thermal system for purification of water is also highlighted.

Processing of banana results in a huge amount of waste generation, leaves, stems and peels etc. Indiscriminate disposal of these wastes when decomposed produces noxious gases such as hydrogen sulphide and ammonia, which pose serious environmental hazards. Thus turning them into biomass feedstock offers a better waste management option and also source of energy production. For the past 30 years, there has been only biogas plants which are developed for treating cow dung as feed material. In those plants only other organic wastes are used as feed material. As banana wastes contain high moisture, they can be treated by the way of solid state digestion. The paper describes the design of solid state digester of 1 m3 capacity of biogas production, exclusively for treating banana wastes by the method of solid state anaerobic digestion. The reactor was designed based on the hydraulic retention time and the total solid content of the banana feedstock in order to complete digest and produce biogas at a faster rate with optimum quantity and methane content. The digester was designed for a feed capacity of 30 kg with 30 days retention time with a gas holder volume of 1 m3. The diameter and height of the digester are 1.09 m and 2.1 m and for gas holder the diameter and height are 1.01 m and 0.9 m respectively. The developed digester was found to convert 90% of the solid content in feed to bioenergy.

Sun is the most promising renewable resource available to mankind for extracting maximum useful energy. One of the best ways to trap solar energy is to install photovoltaic thermal (PVT) systems whose main novelty is to produce power by photovoltaic conversion and also dissipate the heat evolved to recover thermal energy thereby enhancing the overall efficiency of the system. Implementing this approach in practical application system lags mainly due to the requirement of economic investment. This paper reviews on the economics involved in the installation, operation and maintenance of solar PVT systems. The economic viability of solar PVT systems is evaluated by considering five criteria (energy costs, life cycle costs, profit ratio, cost savings and pay-back period). Furthermore the performances of many PVT systems were compared and the economic evaluation has proved that the PVT system is economically feasible and has greater potential for incorporating in residential/commercial buildings especially for tropical countries like India.

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There is a lot of scope for fuel production from the unexploited potential of wastes generated from agro processing industries. In the case of palm oil processing industries, four different wastes are produced from various unit operations of palm oil production viz., empty fruit bunches, palm fiber, palm kernel and decanted cake. Among these oil palm empty fruit bunches (OPEFB) was found to be abundantly available. In order to recover energy from this waste, preliminary studies like proximate analysis and thermo-gravimetric analysis were conducted to analyze its characteristics to use it as a bioenergy feedstock. The proximate analysis reveals that the moisture content of OPEFB is relatively higher. The thermal behavior was analyzed in TG Analyzer (TGA) at different heating rates of 20, 30, 40, and 50˚C/min. There were three peaks appeared in all the thermo-grams and temperature ranges for maximum weight loss of the selected biomass sample was also reported. From the study, OPEFB was found to be well suitable for fuel production through thermochemical conversion route.

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