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There is a significant energy transition in progress globally. This is mainly driven by the insertion of variable sources of energy, such as wind and solar power. To guarantee that the supply of energy meets its demand, energy storage technologies will play an important role in integrating these intermittent energy sources. Daily energy storage can be provided by batteries. However, there is still no technology that can provide weekly, monthly and seasonal energy storage services where pumped hydro storage is not a viable solution. Herein, we introduce an innovative energy storage proposal based on isothermal air compression/decompression and storage of the compressed air in the deep sea. Isothermal deep ocean compressed air energy storage (IDO-CAES) is estimated to cost from 1500 to 3000 USD/kW for installed capacity and 1 to 10 USD/kWh for energy storage. IDO-CAES should complement batteries, providing weekly, monthly and seasonal energy storage cycles in future sustainable energy grids, particularly in coastal areas, islands and offshore and floating wind power plants, as well as deep-sea mining activities. [ABSTRACT FROM AUTHOR]

Low-carbon energy transitions taking place worldwide are primarily driven by the integration of renewable energy sources such as wind and solar power. These variable renewable energy (VRE) sources require energy storage options to match energy demand reliably at different time scales. This article suggests using a gravitational-based energy storage method by making use of decommissioned underground mines as storage reservoirs, using a vertical shaft and electric motor/generators for lifting and dumping large volumes of sand. The proposed technology, called Underground Gravity Energy Storage (UGES), can discharge electricity by lowering large volumes of sand into an underground mine through the mine shaft. When there is excess electrical energy in the grid, UGES can store electricity by elevating sand from the mine and depositing it in upper storage sites on top of the mine. Unlike battery energy storage, the energy storage medium of UGES is sand, which means the self-discharge rate of the system is zero, enabling ultra-long energy storage times. Furthermore, the use of sand as storage media alleviates any risk for contaminating underground water resources as opposed to an underground pumped hydro storage alternative. UGES offers weekly to pluriannual energy storage cycles with energy storage investment costs of about 1 to 10 USD/kWh. The technology is estimated to have a global energy storage potential of 7 to 70 TWh and can support sustainable development, mainly by providing seasonal energy storage services. [ABSTRACT FROM AUTHOR]

Inappropriate food conservation practices along with insufficient and inefficient storage systems are often responsible for the deterioration in food quality of agricultural products leading to food insecurity and economic loss. Open sun drying is a well-known traditional food preservation technique but is limited in use due to its low efficiency and long drying times. Solar drying is considered the most effective, economical, green and sustainable technology available to preserve farm produce. In this regard, an attempt has been made in this study, to review the solar dryer technologies, natural energy materials and storage systems available for persevering food products and reported in detail. An extensive classification and comparative analysis of solar dryers have been presented. Evolutionary classification and performance assessment using various indicators has been carried out for solar dryers employing natural energy materials for energy storage. Polices, challenges, risks and recommendations for the improvement of existing solar dryers as well as the development of new technologies impacting the quality, economic, social and environmental aspects of solar dried products have been discussed in detail. The study concluded that solar drying processes with thermal energy storage devices based on natural materials are most preferred for delivering extended shelf life for farm produce in an energy-efficient and sustainable manner. [Display omitted] [ABSTRACT FROM AUTHOR]