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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]

Energy harnessing from renewable energy sources has become more flexible with power electronic technologies. Recent advancements in power electronic technologies achieve converter efficiency higher than 98%. Today, reliable power electronic devices are needed to design a PV-based energy converter (inverter) to reduce the risk of failure and maintenance costs during operation. Wide-bandgap SiC devices are becoming more common in power electronic converters. These devices are designed to reduce switching loss and improve the efficiency of the system. Nevertheless, the cost of SiC devices is a major concern. Hence, to improve the reliability of the PV inverter while considering the economic aspects, this paper develops a highly reliable PV inverter with a hybrid Si/SiC power module that consists of a Si-IGBT with a SiC anti-parallel diode. A test case of a 3 kW PV inverter is considered for reliability analysis. The loading of the PV inverter is done under uncertain environmental conditions by considering the yearly Mission Profile (MP) data related to Ambient Temperature (AT) and Solar Irradiance (SI) at the India and Denmark locations. The effectiveness of the proposed hybrid Si/SiC power module is tested by comparing it with a conventional IGBT power module. The results showcase the marked improvement in PV inverter reliability with the proposed hybrid power module. [ABSTRACT FROM AUTHOR]

Hydropower development on gravity-based drinking water supply pipelines in India has not been widely practiced, even at the micro-hydropower (MHP) scale. Site visits including measurements of pipeline flow and pressure were conducted at 12 schemes in Uttarakhand, and 3 were chosen for detailed analysis. Due to a complete lack of existing pressure control, the available drinking water flow would have to be reduced to enable retrofitting with MHP turbines. Technical and economic calculations were performed for a hypothetical 20% flow reduction, but showed electric power yields between just 1.2 and 3.9 kW and long payback periods between 8 and 24 years. The favoured alternative proposal is to incorporate the planning of MHP facilities into the inevitably necessary renovation and/or expansion of pipelines to both (1) meet future water demand and (2) enable the development of MHP. This hypothetical improved case showed an increase in electric power yield by a factor of 5 over the retrofitting case, and was recommended to the state water utility Uttarakhand Jal Sansthan. [ABSTRACT FROM AUTHOR]

Highlights • We quantified the impact of climate-change on hydropower in Italian Alps. • We provided the first country scale perspectives of run-of-the-river plants. • We employed a semi-distributed hydrological model and nine climate scenarios. • Median hydropower production is expected to reduce by 3% by 2065. • Glacier retreat is the major driver of this reduction in hydropower production. Abstract We assess the impacts of nine climate-change scenarios on the hydrological regime and on hydropower production of forty-two glacierized basins across the Italian Alps, assumed exemplary of similar systems in other glacierized contexts. Each of these basins includes one (or more) hydropower plant, here treated as a run-of-the-river system. We implemented a semi-distributed hydrologic model that divides each basin in elevation bands and reconstructs orographic effects on both precipitation and temperature. The nine climate-change scenarios quantify the individual and combined effects of an increase in temperature and a change in liquid-solid phase partition. The simulation horizon is 2016–2065. Thus, we avoided long-term scenarios and worked at short-medium range to maximize the relevance of this work for decision makers. Our results predict a decline of about −30% in average summer runoff across all basins compared to present. Because most of this decrease in runoff occurs during high-flow periods when the run-of-the-river capacity of these plants is exceeded, this result translates into a median decrease of about −3% in hydropower production for run-of-the-river systems through 2065, across all the basins and all scenarios. The predominant cause of this decline is glacier shrinkage, whereas different temperature or precipitation trends plays a marginal role. Run-of-the-river hydropower production in basins where the current glacier coverage is less than 10% of total area is particularly robust to climate change. [ABSTRACT FROM AUTHOR]

Contrary to conventional fossil fuel-based electricity generation technologies, renewable energy centered technologies, specifically small hydropower, release a lesser amount of anthropogenic greenhouse gases but are normally more expensive. A major segment of the capital investment in the current small hydropower scenario accounts for equipment and construction process costs. The construction and cost administration process are generally limited to analysis of the capital cost of civil constructions, electro-mechanical equipment works, neglecting the costs related to operating and maintaining the plant, replacement or refurbishment, certified emission reductions, among others. Contemporary studies indicate that these costs form a substantial fraction of the total capital investment. Consequently, for cost management and investment decision making, small hydropower plant developers are drawing increased attention in recent years towards conducting life cycle costing studies that take into account the ignored costs. In addition, small hydropower plants in developing nations can become more competitive by trading the emission reductions achieved under the provision of the Clean Development Mechanism, an outcome of the Kyoto Protocol proposed at the United Nations Framework Convention on Climate Change. In this paper, a modest attempt has been made to determine the Levelized cost of electricity generation using life cycle costing methodology, which accounts for all the costs over operating lifetime on a range of small hydropower plants and the results are analyzed. [ABSTRACT FROM AUTHOR]

In terms of fuel resource, hydropower possesses a prominent advantage over any other large power plants which burn fossil fuels to generate electricity. Moreover, due to the abundance in resource availability (as a domestic source in small streams and rivers), small hydropower (SHP) plants are showing prominence all over the world. SHP plants have led to improved access to electricity usage in under-developed and developing nations, thereby contributing to sustainable development goals and social empowerment. SHP, as a technology, is regarded as the largest density renewable resource with high adaptability, and low investment costs. The primary objective of the paper is to study and analyze recent developments in SHP technologies with reporting statistical figures in terms of installed capacity and MW potential in several parts of the world. Methodologies adopted by researchers to conduct techno-economic analysis of SHP projects are reviewed. Various costs involved in conducting pre-feasibility studies—such as constructing, maintaining, and sustainably operating SHP projects—are studied. The results of the study indicate cost and regulatory issues are the major factors affecting the growth of the small hydropower sector in many nations. Major impediments to construction, development and deployment of SHP projects, mutually existing among the nations worldwide, are also reported. Technical hindrances include non-availability of the grid and very limited accessibility to SHP sites, emissions due to storage of water, disruptive technologies with limited manpower and non-technical hindrances include discouragement from local bodies and groups, lack of suitable and precise pathways to accomplish SHP goals of a nation, lack of incentives for encouraging private players to invest in SHP projects, complex approval processes, and many more. [ABSTRACT FROM AUTHOR]

The development of renewable clean energy such as hydropower can not only ensure energy security, but also help achieve the United Nation's Sustainable Development Goals. This paper uses the annual data of 30 provinces in China from 2000 to 2017, and constructs a dynamic spatial Durbin model and a geographically weighted regression model to empirically test the dynamic impact of hydropower on haze pollution and economic growth at the national and provincial levels. The empirical results show that the promoting effect of hydropower on economic growth in Western China is less than that in Eastern China, which further aggravates the economic development gap between the eastern and western regions. In addition, the suppression effect of hydropower on the haze pollution in the western region is greater than that in the eastern region, where the haze pollution is serious. From the national level, hydropower can promote regional economic growth and inhibit haze pollution, and the spatial spillover effects of these two effects are greater than the local effects, and the long-term impact is greater than the short-term impact. The research conclusions of this paper will help China realize the sustainable development goals of energy saving and emission reduction. [ABSTRACT FROM AUTHOR]

The article investigates nature–culture interrelation over the case studies of hydroelectric plants of the 20th century. In many cases, construction of these structures has evidently resulted in irreversible changes in natural and cultural environments. However, they have also supplied energy for the industrialization of civilizations. After approximately 100 years of existence, it is crucial to determine the future of these hydroelectric facilities, which are artifacts of industrial heritage approaching the end of their productive life spans. The article proposes an analytical approach aiming to sustain the integrity of nature and culture in the conservation of hydroelectric plants, presenting these energy facilities as cultural properties of industrial heritage, and discussing the impact of hydroelectric dams on natural and cultural environments, along with the effects of nature in the deterioration of these structures in order to pave the way to an optimized and sustainable future for the heritage of energy. [ABSTRACT FROM AUTHOR]

Climate change has repercussions on the management of water resources. Particularly, changes in precipitation and temperature impact hydropower generation and revenue by affecting seasonal electricity prices and streamflow. This issue exemplifies the impact of climate change on the water-energy-nexus, which has raised serious concern. This paper investigates the impact of climate change on hydropower with a multidisciplinary approach. A holistic perspective should be favored as the issue is complex, consequently, we chose to investigate a specific case study in Italy. It allows grasping the details, which matters in mountainous area. We integrated a hydrological model, hydropower management model, nine climate scenarios, and five electricity scenarios for a specific storage hydropower plant. Independently from the scenarios, the results show a glacier volume shrinkage upward of 40% by 2031 and minimum of 50% by 2046. The reservoir mitigates losses of revenue that reach 8% in the worst case, however, are lower compared with run-of-the-river configuration. Changes in price seasonality amplitude also determine modifications in revenues, while temporal shifts appear to be ineffective. For run-of-the-river, any variation in hydrological cycle immediately translates into revenue. Comparing the results of all future scenarios with the base scenario, it can be concluded that an increase in temperature will slightly improve the performances of hydropower. [ABSTRACT FROM AUTHOR]

Climate change jeopardizes the future of hydropower across the world. Precipitation patterns evolve, glacier retreat affects sedimentation, and rising temperatures perturb both the water cycle and the energy-price seasonality. The energy sector also faces an energy turnaround. The growing penetration of intermittent wind and solar energy increases supply variability, thus price volatility. These trends raise concerns about the future profitability of traditional hydropower. This work quantifies these impacts with an integrated, transferable, and parsimonious model. It integrates a semi-distributed hydrological with hydropower management models to translate climate change and energy scenarios into future energy generation and revenue. We simulated nine future streamflow scenarios for an Italian and a Swiss case study. These inputs fueled a hydropower management model, which maximizes revenue accordingly to five Italian and twenty-eight Swiss electricity prices scenarios. The simulations couple both types of scenario for the period 2016-2045. This time horizon especially matters for current decisions in climate and energy policy. Results show that variations of climate regime adversely influence the hydroelectric production. Climate change will modify the seasonality of inflows and volumes that are exploitable for hydropower generation. However, smart hydropower management could mitigate revenue losses. This research represents a toolkit for dam operators and decision makers to assess future generation capacity in a warming climate. Key words: Climate Change, Hydropower, Electricity Market, Water-Energy Nexus, Modelling [ABSTRACT FROM AUTHOR]

Hydropower represents an interesting technology: affordable, renewable, and flexible. However, it must cope with climate changes and new energy policies that jeopardize its future. A smooth transition to sustainability requires decision makers to assess the future perspectives of hydropower: about its future revenue and related uncertainty. This investigation requires a multidisciplinary approach as both streamflow and energy mix will evolve. We simulated future streamflow based on eight climate scenarios using a semi-distributed hydrological model for our case study, the Tremorgio hydropower plant located in southern Switzerland. Next, using a hydropower management model we generated income according to these streamflows and twenty-eight electricity price scenarios. Our results indicate that climate change will modify the seasonality of inflows and volumes exploitable for hydropower generation. However, adaptive strategies in the management of reservoirs could minimize revenue losses/maximize revenue gains. In addition, most market scenarios project an increase in revenues, except in the case of high wind and solar energy penetration. Markets do not provide the right incentive, since the deployment of intermittent energy would benefit from more flexible hydropower. [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]