An international research team analyzed the effects of installing floating photovoltaics (FPV) on Egypt's Aswan High Dam Reservoir (AHDR). Using numerical analysis, they have accounted for the possible power generation of the FPV plant, in addition to the evaporation reduction provided.
“This study investigates the benefits of an FPV system over 12 years, from 2005 to 2016, on the AHDR,” they said. “We also investigate different scenarios for complementing Aswan High Dam's (AHD's) hydropower with FPV and using additional water for reservoir management or irrigation.”
The AHD was constructed in the 1960s, supplying annual hydropower generation of 10,000 GWh. Effectively, the dam also created the AHDR, one of the largest manmade reservoirs in the world. The entire reservoir stretches for about 500 km along the Nile River; 330 km of it is in Egypt, where it is called Lake Nasser, and 170 km is in Sudan, where it is named Lake Nubia. Its total surface area is 6,000 km2 and it has a storage capacity of 169 billion cubic meters (BCM). However, evaporation rates are high due to the region's very hot and dry climate.
For their investigation, the scientists assumed to build an FPV plant on the reservoir with panel coverage of 0%, 10%, 45%, and 90% of the lake. “According to the International Energy Agency (2020), the annual electricity consumption of the African continent is 715.6 TWh. To cover this by FPV on the AHDR, a 45% FPV occupancy would be sufficient. The investment costs (CAPEX) of such a project would amount to approximately $ 14.6 billion,” they highlighted.
To model the installations, the academics used the hydrodynamic General Lake Model, a vertical 1D model that represents the hydrodynamic processes of standing water bodies. They assumed tilt angles of either 12 degrees or 30 degrees, using LONGi LR4 modules, with a row distance of 1.44 m. In the case of 90% FPV coverage, the installed capacity calculated was 735 GW.
“To estimate the contribution of an FPV system on the AHDR to Egypt's energy supply, we calculated the electrical yield using the simulation software Zenit,” explained the group. “The simulations were evaluated in terms of the power plant's electrical yield and the performance ratio.”
The results of the simulation showed that, in the case of 0% panel coverage, that being the situation today, the cumulative annual water loss to evaporation ranged from 10.65 to 13.17 BCM. The total evaporation loss over 2005–2016 was 141.6 BCM, while the mean yearly loss was 11.8 BCM, and the mean evaporation rate per day was 6.5 mm.
If 10% of the lake were covered by FPV, a total of 7.2 BCM would have been saved over the 12 years, while if 45% were covered, 33.7 BCM would have been saved. “The maximum cumulative water savings for a 90% FPV occupancy over the 12-year study period reached 70.4 BCM, amounting to annual water savings of 5.9 BCM and a reduction of evaporation loss by 49.7%,” added the research group.
Furthermore, the academics found that, at 90% coverage and a tilt angle of 30 degrees, the maximum annual yield of the FPV system would be 1,431 TWh, with a performance ratio of 78.7%. That would rise slightly to 1,459 TWh and a performance ratio of 80.8% in the case of a 12-degree tilt angle.
Following those calculations, the group analyzed three scenarios for using the water saved from evaporation. In the first scenario, it would be used to generate additional hydropower at the existing plant; in the second, it was assumed to assist in the filling of the Toshka Lakes; and in the last scenario, the additional water was used by the Mubarak Pumping Station for irrigation of the fields in the New Valley, an area that stretches between the Toshka Lakes and the AHDR.
“A constant water withdrawal for irrigation during FPV coverage was regarded as most favorable. Depending on FPV occupancy, between 7.35 and 8.07 BCM of irrigation water could be supplied annually, with a maximum of 16 BCM spilled into the Toshka Lakes,” concluded the researchers.
The analysis was presented in the study “Evaporation reduction and energy generation potential using floating photovoltaic power plants on the Aswan High Dam Reservoir,” which was published in the Hydrological Sciences Journal. The research group was formed by scientists from Germany's Fraunhofer Institute for Solar Energy Systems (ISE) and the University of Freiburg, as well as the United States' University of Wisconsin-Madison.
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What was the effect on animal bio diversity in case of 45% coverage.
If fishing is done on those lakes as an economic activity what effect would such measure would have on fishing activity and environmental impact of loss of bio diversity
The only one costed is the 45% coverage,
So CAPEX 14.6 billion = 367 GW and about 700TWh/year
Covers 45% x 6000km2 = 2700km2. .
That seem like dense packed solar.
The CAPEX comes out at $40 per KW, which is about 1/3 the costs of modules.
The real costs though is distribution.
Note annual generation of Aswan dam = 10 TWh, and it has a capacity of 2.1GW.
When doing the study, did they consider what would happen to the surrounding ecosystem with the lack of evaporation? In such a dry, hot climate, I would imagine that the evaporation that currently happens has a benefit somewhere, such as additional cloud cover or rain in a different region. Do they know the effects of the evaporation that currently happen?