Academic literature on the topic 'Mini-hydro system'

The interest of those involved in hydroelectricity has been attracted by mini-hydro projects due to their minimal environmental impact and low installation cost. Besides, mini hydros can cooperate with an impressively wide extent of water-related infrastructure, offering a broad potential for investment. In the present chapter, the integrated solution of hydro implementation in water supply systems is presented. Thus, the benefits of a water-supply installation (with constant Q) are extended to energy production. However, defining the optimum operation of such a project is a complicated task, which may involve environmental, hydraulic, technical, and economical parameters. In the present chapter a novel approach is presented, the optimum management of mini hydros in a water supply system with the use of an optimization algorithm (i.e. Harmony Search Algorithm [HAS]). This approach is applied at a site in Northern Greece and is used as a case study of the present chapter.

Energy is one of the most important inputs in the process of development for a nation. With the growth of industrialization, there is increase in the demand of energy in every sector. The total electricity generating capacity of India stands at 205.34 GW with 19.1% from hydro power. Power sector is facing problem of increasing electricity demand as well as regulation on greenhouse gas emissions. It is crucial to exploit sustainable energy generation sources with high efficiency and low cost. Hydro power stations have inherent ability for instantaneous starting, stopping and load variations which help in improving the reliability of power system. Hydropower is a renewable source of energy, which is economical, non-polluting and environmentally benign among all renewable sources of energy. For efficient operation of hydropower plants, in order to meet the electricity demand, the hydro energy is stored either in reservoirs for dam based schemes or settling basins for run-of-river scheme. Hydro potential India is endowed with economically exploitable and viable hydro potential assessed to be about 84,000 MW at 60% load factor. In addition, 6,780 MW in terms of installed capacity from Small, Mini, and Micro Hydel schemes have been assessed. Also, 56 sites for pumped storage schemes with an aggregate installed capacity of 94,000 MW have been identified. It is the most widely used form of renewable energy. India is blessed with immense amount of hydroelectric potential and ranks 5th in terms of exploitable hydro-potential on global scenario. Thus hydro power stations are the best choice for meeting the peak demand.

The target application of this study is hydraulic excavators, which are one of the most common machines found at construction sites across the world. Road constructions and improvements, laying operation of cables or pipes and building can be seen in urban areas and digging and dumping operations of natural resource are done in country regions. For the construction site in urban areas, mini hydraulic excavators with operating weights up to 6 tons are often used and they make up more than 60% of the total hydraulic excavators market [1]. In recent years, a number of new system architectures for mobile hydraulic systems have been proposed. Examples of such improved architectures are displacement control, transformer systems and valve controlled systems with multiple pressure rails. For these systems, electronic controls are always used. Although these new methods are promising, they cannot be applied to mini-excavators, because today’s mini-hydraulic excavators do not use electronic controls as this would increase costs and make the system complex. Therefore, the goal of this study is to propose a fully hydro-mechanical valve controlled constant pressure system, which can be applied to mini-excavators in the future. This paper begins by introducing the details of this novel hydraulic system and shows its advantages. Using a simulation model of an 18 ton excavator, it is confirmed that the novel system functions well and the energy efficiency is compared to a conventional Load Sensing system. The simulation results show that the novel system can save 22% and 24% of fuel in leveling and 90° dig-dump cycles respectively.

An adsorption system driven by solar heat or waste heat can help to eliminate the use of ozone depletion substances, such as chlorofluorocarbons (CFCs) and hydro-chlorofluorocarbons (HCFCs). In recent years, adsorption system has witnessed an increasing interest in many fields due to the fact that this system is quiet, long lasting, cheap to maintain and environmentally benign. Although adsorption system is not commonly used for automobile air conditioning, adsorption-cooled mini-refrigerators have been marketed for recreational transports (motor homes, boats, etc). Hence, there exists a need for a creative design and innovation to allow adsorption technology to be practical for air conditioning in automobile. The objective of this paper is to present a comprehensive review on the past efforts in the field of solar adsorption refrigeration systems and also the feasibility study of this technology for automobile airconditioning purpose. It is a particularly an attractive application for solar energy because of the near coincidence of peak cooling loads with the available of solar power.

Small hydropower technology has gained traction in the Nigerian energy and power ecosystem owing to incentives and reforms aimed at increasing Nigeria’s energy mix for sustainable development. Utilizing these opportunities through harnessing SHP potentials has not made it to the front burner during policy formulations and implementations in South-Eastern Nigeria despite the availability of water bodies and waterlines in the region. This paper focuses on the potentials of small hydropower in Abia state and utilized ArcGIS software to conduct spatial analysis using map data overlayed by shapefiles of water bodies, waterlines, road networks and Land use, Land Cover data (LULC). Multiple ring buffers were created for various proximities around the waterbodies and waterlines and Normalized Difference Vegetation Index calculations were done to determine suitability areas for small hydropower schemes after reclassification of the data. The analysis revealed suitability areas in Osisioma Ngwa and Obingwa Local Government areas with suitable elevations and hydraulics data for run off the river schemes and siting of hydropower plants within a multiple ring buffer distance between 200m to 5km from the waterlines and roads, having a weighted score between 33-66 with NDVI range of -0.018 –0.015 indicating the presence of water bodies and built-up areas around the water bodies with NDVI range of 0.015 – 0.14 and a weighted score within the range of 11-16 This revelation also encourages the hybridization of renewable energy technology using pumped hydro storage to improve the reliability and affordability of mini-grid solutions in Abia State and Nigeria at large.

The left tributaries of the Middle Dnipro - Psel, Vorskla, Sula, Trubyzh, Supii, Zolotonoshka, Kryva Ruda, Kobelyachok, Kagamlyk, Irkliy, Kovray and Kovalivka belong to the category of medium and small rivers. These rivers are important for the left-bank forest-steppe of Ukraine, where they flow. They are used for irrigation of agricultural land and for hydropower. Global climate change in the region and the introduction of green electricity in Ukraine, these two aspects are currently very important for two reasons. The total flow volume of the rivers of the left bank of the Middle Dnipro subbasin is similar to the flow volume of the Southern Bug, and the catchment area is even larger. The three largest rivers of the region, Psel, Vorskla and Sula, are particularly promising in this aspect. Today, small hydroelectric power plants only operate on the Psel and Vorskla rivers. All hydroelectric power plants are located in the middle course of the river: on the Psel - within the boundaries of Sumy and Poltava regions, and on Vorskla - within the boundaries of the Poltava region. The left bank of the Middle Dnipro has 15 small hydros operating today, with 10 of them on the Psel and 5 on the Vorskla. River Psel, from the village of Nyzy in the Sumy region to the village Sukhorabivka fish of Poltava region, fully regulated. The following small hydropower plants operate on Psel: Nyizivska, Vorozhblyanska, Mykhailivska, Bobrivska, Knyshivska, Veliko-Sorochynska, Shishatska, Velika Bagachka, Ostapievska and Sukhorabivska. The total annual electricity generated is 4.78 MW. Upon the completion of its planned operation by 2025 as planned in the plan for the development of hydroelectric power plants, the Malobudyshchanska hydroelectric power plant is scheduled to be functional. 5 small hydroelectric power stations operate within the Vorskla riverbed and its left tributary – the Vilshanka – Opishnyanska, Vakulynska mini hydro, Poltava Hydro mini hydro, Nizhnyomlinska and Kuntsivska. The Vorskla river from the village of Kuzemin in southern Sumy Oblast to the village of Kunzevo in Poltava Oblast is regulated by regulating locks and small hydrographic locks. These locks are located in the villages of Kuzemin (Sumy Region) and Derevky (Poltava Region). Both systems are included in the development plans of their regions until 2025, within which 2 small hydroelectric power plants will operate. A total of 1.72 MW of small hydropower is generated within the Vorskla Basin. The power of hydroelectric power stations on both rivers ranges from 0.19 MW to 1.04 MW - Shyshatska small hydroelectric power station. Global climate changes also affected the Left Bank-Dnipro hydrological region. Over the past 30 years, the average annual air temperature has increased by 1.5-2 0C and the annual precipitation has decreased by 20-30 mm. The most significant changes are seen in the southern, southwestern, and eastern parts of the left bank of the Middle Dnipro, especially in the small river basins of the Dnipro Lowlands and the lower reaches of the Sula, Psel and Vorskla rivers. Therefore, these regions need irrigation systems functioning within their river basins. The left bank of the middle Dnipro River basin has a total of 26 irrigation systems covering a total area of 65,000 hectares. The largest number of irrigation systems is in the Dnipro Lowland river basin:13 irrigation systems (12,000 ha) on the left bankin Cherkasy Oblast,11 irrigation systems (50,000 ha) in Poltava Oblast, and 2 irrigation systems (up to 3,000 ha) in Kharkov Oblast. Thus, the left bank of the middle Dnipro river has great potential for hydropower and water quality improvement. The total capacity of small hydropower plants in the Psel and Vorskla river basins is 6.5 MW, which is about 6.37% of the total capacity of small hydropower plants in Ukraine (in 2019: 102 MW for Ukraine). The use of small hydroelectric power stations on Vorskla and Psel is quite promising for Poltava and Sumy regions for local consumption and the growth of the share of green energy in these regions. As for irrigation systems, in general, 32% of the total irrigated area in the Dnipro basin (196,000 ha) is concentrated on the left bank of the middle Dnipro river.

ABSTRACT: Accurate assessment and prediction of the in-situ horizontal stress is essential for ensuring the integrity of subsurface storage systems. Fluid injection and extraction affect the in-situ stresses. Changes of effective vertical stress are well constrained. However, changes of effective horizontal stress are not well characterized, particularly in the caprock where undrained loading and locked-in stresses can change the response significantly from drained linear poroelasticity predictions. In this study, we introduce a high-stress experimental setup designed to accurately measure horizontal stress during the consolidation process and subsequent unloading of clay-rich resedimented samples. Horizontal stress is determined by accurately measuring the tangential strain around the oedometer cell, while ensuring that this lateral strain is minimal enough to justify uniaxial strain condition. The results indicate that the K0 (ratio of horizontal to vertical effective stress) values converge to a constant value during loading (normally consolidated) as expected, but the unloading phase (over consolidated) presents a significant increase of K0 up to ∼2, increasing under undrained conditions. These results help calibrate advanced constitutive models to predict in-situ and change of effective vertical stresses in subsurface systems subjected to thermos-hydro-mechanical loadings. 1. INTRODUCTION Geo-energy projects, such as geologic carbon storage, hydrogen storage, and geothermal energy, alter the in-situ stress state by fluid injection or extraction. While the vertical stress is mostly affected by the overburden and can be calculated from depth and mass density, predicting horizontal stress requires an accurate constitutive model and knowledge of the loading history. In the case of mudrocks, characterizing the horizontal stress requires knowledge of the stress history, pore pressure and mineral composition (Casey et al. 2016). Mudrocks serve as sealing layers in many subsurface storage systems. Thus, properly assessing the horizontal stress is essential to ensure seal mechanical integrity (Guiltinan et al. 2018, Kim and Makhnenko 2020, Zheng et al. 2022). The coefficient of earth pressure at rest K0 is defined as the ratio between the horizontal and vertical effective stresses. (equation) Assuming zero lateral strain εlat = 0 is often referred to as the "K0-condition". K0 can be expressed as a function of the Poisson's ratio ν, where K0 = ν/(1-ν), under the assumption of linear isotropic poroelasticity. However, geomaterials including mudrocks generally exhibit responses that deviate siginificantly from this simplification (Prioul et al. 2004). Previous studies have developed empirical relationships from field experiments to estimate the K0 values, employing mini-frac or leak-off tests, and finding the relationship with overburden stress gradient (Brudy et al. 1997, Haimson and Chang 2002). However, fracture measurements are usually spare and difficult to obtain. Most importantly, field experiments do not capture the stress history or permit predicting changes, which is a critical factor for the evolution of horizontal stresses in mudrocks.