• Energy Research
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One of the key concerns raised by the developers of mini grids is "what will become of my mini grid when the main grid arrives?" This report presents detailed case studies of what happened to isolated mini grids in Cambodia, Sri Lanka, and Indonesia when the main grid reached their villages. Six possible outcomes are described: 1) conversion to a small power producer (SPP), 2) conversion to a small power distributor (SPD), 3) conversion to a combined SPP and SPD, 4) side-by-side operation of the mini grid and main grid without any physical connection between the two systems, 5) compensation and exit, and 6) abandonment. Each case study describes the regulatory, commercial, and technical characteristics that affected the observed outcomes for the community-owned hydro mini grids in Sri Lanka and Indonesia and the privately-owned diesel mini grids in Cambodia

46th Workshop on Geothermal Reservoir Engineering 2021 ISBN:978-1-7138-2907-2

Measures for limiting environmental pollution by power plants using fossil fuel sources and for efficient use of local energy sources can cause significant changes in the structure of the electricity distribution networks through the development of micro-grids that can operate practically isolated or connected to the public electricity network, which ensures bilateral exchanges of energy. The microgrid requires a detailed analysis of the level of quality of electricity supplied to the microgrid. The detailed analysis of technical solutions is needed to ensure a necessary level of electric energy quality in practically isolated microgrid. Some of the specific conditions of microgrid operation are analyzed, which will ensure operation of the system at the action of disturbances.

This chapter gives an overview of the different technologies available for energy recovery and power generation from membrane-based desalination processes. In addition to introducing current desalination technologies, the basic principle of salinity gradient energy and technologies such as pressure-retarded osmosis and reverse electrodialysis are presented. This chapter also summarizes state-of-the-art devices for energy recovery used in reverse osmosis desalination as well as promising, novel alternative techniques for power production with membranes.

Direct comparisons of microbial fuel cells based on maximum power densities are hindered by different reactor and electrode sizes, solution conductivities, and materials. We propose an alternative method here, the electrode potential slope (EPS) analysis, to enable quantitative comparisons based on anode and cathode area-based resistances and operating potentials. Using EPS analysis, the brush anode resistance ( RAn = 10.6 ± 0.5 mΩ m2) was shown to be 28% lower than the resistance of a 70% porosity diffusion layer (70% DL) cathode ( RCat = 14.8 ± 0.9 mΩ m2) and 24% lower than the solution resistance ( RΩ = 14 mΩ m2) (acetate in a 50 mM phosphate buffer solution). Using a less porous cathode (30% DL) did not impact the cathode resistance but did reduce the cathode performance due to a lower operating potential. With low-conductivity domestic wastewater ( RΩ = 87 mΩ m2), both electrodes had higher resistances [ RAn = 75 ± 9 mΩ m2, and RCat = 54 ± 7 mΩ m2 (70% DL)]. Our analysis of the literature using EPS analysis shows how electrode resistances can easily be quantified to compare system performance when the electrode distances are changed or the sizes of the electrodes are different.

The basic circuits of multifunctional solar systems of drainage of air, heating (hot water supply and heating), cooling and air conditioning are developed on the basis of open absorption cycle with direct absorbent regeneration. The basic solutions for new generation of gas-liquid solar collectors are developed.

Experiments were performed at a private garden in Al-Qaddbah, Al-Gharbia Governorate, Egypt. The latitude and longitude of the experiment site are 30°56'37''N and 30°47'01'' E, respectively, and the altitude equals 30 m, at the 2019 season, the total landscape area (13.5m x 9m) was divided into 6 treatments each of an area (20.25 m2), three plots were operated using solar system while the other three plots were operated using electric system. The irrigation systems were similar, 4 multi-stream sprayers, (90◦) and the distance between the sprayers was (4.5*4.5 m), different operating times were applied on each plot, under local climatic and working conditions. All the plots were planted with turfgrass (Passpalm10). The obtained results show, at solar energy powered system, uniformity coefficient increased from (65% - 75%) at operating time (10 –30 min), then it decreased during operating time (40 - 60 min), while at electric energy powered system the averages of the uniformity coefficient were (76% - 80%), at operating time (10 –40 min), while at operating time (45 - 60 min) the uniformity coefficient decreased to (75%), due to the silt clogging in the sprayers' filters. The energy saving reached (63%) with solar energy operation rather than electric energy operation in the summer season. The least total cost was (351 L.E/m2/year) at the landscape area (A3 60.75m2), which was irrigated on 3 cycles per day to give the highest uniformity coefficient (75%). When operating the solar batteries at full charge 3 - 4 times for a plot area of (20.25 m2). The hydraulic power obtained was (17.86 –26.74 W), the sprayer radius was (5.3 –5.8 m), at an average pressure of (1.9 -2.5 bar) which gave the best uniformity coefficient. The turf quality index was higher using electric motor rather than solar motor.

As reliance on wind and solar power for electricity generation increases, so does the importance of understanding how variability in these resources affects the feasible, cost-effective ways of supplying energy services. We use hourly weather data over multiple decades and historical electricity demand data to analyze the gaps between wind and solar supply and electricity demand for California (CA) and the Western Interconnect (WECC). We quantify the occurrence of resource droughts when the daily power from each resource was less than half of the 39-year daily mean for that day of the year. Averaged over 39 years, CA experienced 6.6 days of solar and 48 days of wind drought per year, compared to 0.41 and 19 for WECC. Using a macro-scale electricity model, we evaluate the potential for both long-term storage and more geographically diverse generation resources to minimize system costs. For wind-solar-battery electricity systems, meeting California demand with WECC generation resources reduces the cost by 9% compared to constraining resources entirely to California. Adding long-duration storage lowers system costs by 21% when treating California as an island. This data-driven analysis quantifies rare weather-related events and provides an understanding that can be used to inform stakeholders in future electricity systems.