The role of floating PV in the retrofitting of existing hydropower plants and evaporation reduction

Abstract

Introduction Hydropower development is a key renewable source to reach the European climate targets (2030 climate and energy framework, the 2050 long-term strategy) and it is encouraged by the Renewable Energy Directive 2009/28/EC (and its recast 2018 /2001/EU also known as RED II). Hydropower enables energy storage and stabilization of the electric grid, and the hydraulic infrastructure may also be used for water supply and flood mitigation. On the other side, the interruption of the longitudinal continuity of rivers caused by hydropower can alter sediment transport and damage aquatic ecosystems, in conflict with the objectives of the Water Framework Directive (WFD). If a trade-off between clean energy and ecosystem protection has to be found, hydropower needs to be designed and operated in a sustainable way (Botelho et al., 2017; Suhardinam et al., 2014; Quaranta et al., 2020). The retrofitting and modernization of the hydropower fleet represents a potential strategy to contribute to the abovementioned trade-off. It is of particular interest in the European context (the average age of the hydro stations is 42 years), especially when compared with the environmental impacts and conflicts related to the construction of new hydropower plants (HPPs). The modernization of the hydropower fleet would extend its lifespan, address operational issues and increase safety (e.g. failure prevention, dam safety). Furthermore, benefits can be perceived in different contexts, e.g., on the environment, energy (optimization of the installed power and improvement of flexibility), ancillary services and market flexibility (Adams, 2018). Mitigation measures can be implemented to reduce the ecological impacts of HPPs, e.g. improving fish, sediment passage and ecological flow release, and to reduce the GHG emissions (Deemer et al., 2016), as stipulated in the requirements for hydropower in relation to the EU Nature legislation (EU Directorate-General for Environment, 2018) and in the WFD. The retrofitting can also allow adapting HPP operation to the new conditions imposed by climate change (e.g. droughts and floods). Floating photovoltaic (FPV) can be considered an effective retrofitting strategy, as an integrated FPV-HPP can improve flexibility and increase annual generation. According to data from the Solar Energy Research Institute of Singapore (SERIS), the global cumulative installed FPV capacity surpassed 2.0 GW in September 2020, distributed over more than 500 projects worldwide. Among the 50 largest FPV installations, only two of them are on hydropower reservoirs (47.5 MW, Vietnam, and 5 MW, Ghana, of FPV), Versteeg et al. (2021). Therefore, it is expected an increasing demand of FPV on hydropower reservoirs. PV can also be installed on dam surfaces (gravity and arch dams) resulting in high efficiency due to excellent sun exposition in snow-covered mountains all over the year (Kahl et al., 2019; Kougias et al., 2016). Within the context of FPV, Lee et al. (2020) estimated a potential of 729 GW of FPV from European hydropower reservoirs (covering 14% of the reservoir surface), but did not consider the additional energy generation that could be achieved due to the evaporation reduction, which is thus the aim of the present study for the European context. 1. Background: FPV benefits The installation of FPV on the surface of reservoirs of hydropower plants should be particularly considered in HPP retrofitting. FPV leads to several benefits (Silveiro et al., 2018; Cazzaniga et al., 2019; Rosa-Clot and Tina, 2020), that are listed below. 1. Grid connection. Artificial hydropower reservoirs are equipped with power generators and are grid-connected, thus the related costs of FPV are lower than those of a land installation. 2. Complementarity in operations. In temperate non-alpine regions the FPV panels give the maximum energy yield during the hot season when the HPPs may register a reduction of power. 3. No land occupancy. The main advantage of FPV plants is that they do not conflict with other land uses. 4. FPV can increase the capacity factor (CF = ratio of total generated energy to the maximum energy than can be generated if the hydro plant would always work at its maximum installed power capacity) of a hydropower plant by 40% (Table 1), while gaining 7-14% of efficiency due to the cooling effect of water, with respect to a land installation. 5. FPV generates an increase of hydropower efficiency by reducing evaporation losses. The annual water saving due to reduction of evaporation rate can range between 7000 and 10000 m 3 per installed MWp. In particular, point 5 was considered in this study for the European context. 2. Method A bulk assessment was carried out to estimate the additional energy generation from the European hydropower reservoirs due to the evaporation reduction induced by the installation of FPV. Global European data of evaporation collected in Hogeboom et al. (2018) were elaborated (see further details in Mekonnen et al., 2015 for the European context and in Vanham et al., 2019 for the EU27+UK context), assuming that the evaporation below the FPV is reduced by 70% (Zahedi et al., 2020, Scavo et al., 2021; Abdelal, 2021). Both the EU27+UK (EU) and the whole Europe were considered (excluding Russia and Turkey). From the JRC Hydro-power database (European Commission, 2019) it is possible to estimate the average discharged flow of reservoir HPPs in Europe and in EU27+UK, from data of annual energy generation, head and assuming a global HPP efficiency of 0.8. By assuming an annual operation of 3140 h (on average), the weighted average discharged flow per reservoir HPP is 130 m 3 /s for the EU, and 102 m 3 /s for the Europe, using the HPP power as weight (for further details, see Quaranta et al., 2021). The FPV coverage is important because it affects the evaporation reduction (Scavo et al., 2021), and in this study it has to be reasonably assumed. In general, a FPV with equivalent installed power of the HPP would make it possible to use the electric connections to the grid without any modification, reducing costs related to the infrastructures. In Alpine environment, where HPPs are characterized with high heads and low flows (i.e. high power density Wden per unit of reservoir surface), this would require a FPV surface much larger than the HPP reservoir surface. Instead, for the HPPs characterized by large flows and small heads, a small percentage is enough to obtain the equivalent power. Hence the optimal FPV surface cover is site specific. In this study we assumed 10% of FPV surface in order to reduce the impact on the reservoir and to reduce investment costs, in line with 14% of Lee et al. (2020). This value may be reasonably considered a feasible average value to be implemented at the European scale. Table 1 in Appendix 1 lists the 20 largest existing HPP reservoirs where it was assumed to install a FPV plant of the equivalent HPP power, just to show some examples, where it is shown that the required FPV surface is, on average, 8.3% of the reservoir surface. 3. Results From data of Hogeboom et al. (2019) it was estimated that the annual evaporative volume for the known hydropower reservoirs is 2,810 Mm 3 and 3,734 Mm 3 for EU and Europe, respectively, from a total reservoir surface of 10,586 km 2 and 13,567 km 2 , respectively. The weighted average evaporative volume (using the reservoir surface as weight) is V=764 Mm 3 and V=688 Mm 3 per reservoir for EU and Europe, respectively. Multiplying these values by 70% (evaporation reduction below the FPV, Zahedi et al., 2020, Scavo et al., 2021; Abdelal, 2021) and by the FPV surface (10%), and considering 3140 h of annual operation, it is possible to obtain V·0.7·0.1/(3,140·3,600) = 4.7 m 3 /s and 4.3 m 3 /s of additional flow that could be discharged over the 3140 h, on average per HPP, for EU and Europe, respectively. This is 3.6% and 4.2% of the weighted average discharged HPP flow in EU and Europe, to which it would correspond an equivalent increase in energy generation (only reservoir HPPs are here considered). Results are in line with Sanchez et al. (2021) for the African context, where it was estimated that by covering 14% of HPP reservoir surfaces with FPV, the hydro generation would increase by 2.3%. Therefore, this bulk assessment shows a global increase of hydro generation between 3% and 4% by reducing evaporation from hydropower reservoirs, when covered by a 10% of FPV surface. It must be noted that the evaporated water does not vanish, but it appears again as rainfall, perhaps in the same catchment, so that these numbers must be interpreted as maximum thresholds. Furthermore, the energy generated by FPV was not here estimated, but it remains the main benefit of a FPV-HPP hybrid plant. The above calculations refer to 10% of the reservoir surface, while evaporation reduction increases with the extension of the FPV surface. However, the extension of the coverage area should consider potential impacts on the reservoir ecosystem, since the reduction of the euphotic zone may lead to alterations of thermal and photosynthetic processes related to solar radiation, even though a FPV coverage up to 60% for some reservoir surfaces may be deemed acceptable (Haas et al. 2020). Furthermore, FPV must remain on the reservoir all year round, so the maximum extent is theoretically the minimum water surface (under very dry conditions, at the reservoir minimum). For seasonal deep storage reservoirs which will be full and empty each year, FPV is a challenge considering also the ice cover in high altitude. Thus, application may be limited for reservoirs below 1500 m a.s.l. in the Alpine context, while in Norway, where most of reservoirs are located, the icing of the surface is frequent. This bulk preliminary assessment does not consider local constraints and site-specific conditions, but is based on average large-scale calculations to capture the order of magnitude of the potential. The used data sample can be reasonably considered a representative data set for extrapolating a reasonable result, but future studies should be carried out to better estimate the evaporation reduction and the related increase of annual generation taking into account local factors. 4. Conclusions The integration of FPV can increase the discharged water volume of the European hydropower fleet by 4% when 10% of the basin surface is covered with FPV, leading to a consequent increase in annual generation, in addition to the energy generated by the FPV. The advantages of this hybrid system is the possibility of using the same infrastructures (in particular the grid connection) without any modification and to increase the capacity factor by 20%, thus the number of operating hours from about 3100 to almost 4000 hours (for comparison, in South America it can increase from 4000-IRENA, 2020-to 5200 hours). The large increase in energy production of the hybrid system (FPV+HPP) allows a better management of HPPs, because the operation of FPV is in part anti-correlated with that of HPP plant. Furthermore the use of the same grid and infrastructures strongly reduces the costs of the FPV which can be installed in a short time and without any modification of the reservoir conditions. For seasonal deep storage reservoirs which will be full and empty each year, FPV is a challenge considering also the ice cover in high altitude, limiting FPV application to reservoirs below 1500 m a.s.l. in Alpine environment. In this study we assumed to cover 10% of the reservoir surfaces with FPV, but future studies should be carried out to consider the most appropriate surface cover for each reservoir, with more detailed analyses and site specific conditions. References 1. Abdelal, Q. "Floating PV; an assessment of water quality and evaporation reduction in semi-arid regions". Int. J. Low-Carbon Technol, 2021, 1-8. 2. Adams, T. B. "Feasibility of upgrading existing hydropower infrastructure for use in renewable energy storage", Doctoral dissertation, Massachusetts Institute of Technology, 2018. 3. Botelho, A., Ferreira, P., Lima, F., Pinto, L. M. C., and Sousa, S., "Assessment of the environmental impacts associated with hydropower".

Full text

The role of floating PV in the retrofitting of existing
hydropower plants and evaporation reduction
E. Quaranta M. Rosa-Clot A. Pistocchi
European Commission Upsolar Floating European Commission
Joint Research Centre Italy Joint Research Centre
Ispra, Italy marco@floatingupsolar.com Ispra, Italy
emanuele.quaranta@ec.europa.eu alberto.pistocchi@ec.europa.eu
Introduction
Hydropower development is a key renewable source to reach the European climate targets (2030 climate and energy
framework, the 2050 long-term strategy) and it is encouraged by the Renewable Energy Directive 2009/28/EC (and
its recast 2018 /2001/EU also known as RED II). Hydropower enables energy storage and stabilization of the electric
grid, and the hydraulic infrastructure may also be used for water supply and flood mitigation. On the other side, the
interruption of the longitudinal continuity of rivers caused by hydropower can alter sediment transport and damage
aquatic ecosystems, in conflict with the objectives of the Water Framework Directive (WFD). If a trade-off between
clean energy and ecosystem protection has to be found, hydropower needs to be designed and operated in a
sustainable way (Botelho et al., 2017; Suhardinam et al., 2014; Quaranta et al., 2020).
The retrofitting and modernization of the hydropower fleet represents a potential strategy to contribute to the
abovementioned trade-off. It is of particular interest in the European context (the average age of the hydro stations is
42 years), especially when compared with the environmental impacts and conflicts related to the construction of new
hydropower plants (HPPs). The modernization of the hydropower fleet would extend its lifespan, address operational
issues and increase safety (e.g. failure prevention, dam safety). Furthermore, benefits can be perceived in different
contexts, e.g., on the environment, energy (optimization of the installed power and improvement of flexibility),
ancillary services and market flexibility (Adams, 2018). Mitigation measures can be implemented to reduce the
ecological impacts of HPPs, e.g. improving fish, sediment passage and ecological flow release, and to reduce the
GHG emissions (Deemer et al., 2016), as stipulated in the requirements for hydropower in relation to the EU Nature
legislation (EU Directorate-General for Environment, 2018) and in the WFD. The retrofitting can also allow adapting
HPP operation to the new conditions imposed by climate change (e.g. droughts and floods).
Floating photovoltaic (FPV) can be considered an effective retrofitting strategy, as an integrated FPV-HPP can
improve flexibility and increase annual generation. According to data from the Solar Energy Research Institute of
Singapore (SERIS), the global cumulative installed FPV capacity surpassed 2.0 GW in September 2020, distributed
over more than 500 projects worldwide. Among the 50 largest FPV installations, only two of them are on
hydropower reservoirs (47.5 MW, Vietnam, and 5 MW, Ghana, of FPV), Versteeg et al. (2021). Therefore, it is
expected an increasing demand of FPV on hydropower reservoirs. PV can also be installed on dam surfaces (gravity
and arch dams) resulting in high efficiency due to excellent sun exposition in snow-covered mountains all over the
year (Kahl et al., 2019; Kougias et al., 2016).
Within the context of FPV, Lee et al. (2020) estimated a potential of 729 GW of FPV from European hydropower
reservoirs (covering 14% of the reservoir surface), but did not consider the additional energy generation that could be
achieved due to the evaporation reduction, which is thus the aim of the present study for the European context.
1. Background: FPV benefits
The installation of FPV on the surface of reservoirs of hydropower plants should be particularly considered in HPP
retrofitting. FPV leads to several benefits (Silveiro et al., 2018; Cazzaniga et al., 2019; Rosa-Clot and Tina, 2020),
that are listed below.

1. Grid connection. Artificial hydropower reservoirs are equipped with power generators and are grid-
connected, thus the related costs of FPV are lower than those of a land installation.
2. Complementarity in operations. In temperate non-alpine regions the FPV panels give the maximum energy
yield during the hot season when the HPPs may register a reduction of power.
3. No land occupancy. The main advantage of FPV plants is that they do not conflict with other land uses.
4. FPV can increase the capacity factor (CF = ratio of total generated energy to the maximum energy than can
be generated if the hydro plant would always work at its maximum installed power capacity) of a hydropower plant
by 40% (Table 1), while gaining 7-14% of efficiency due to the cooling effect of water, with respect to a land
installation.
5. FPV generates an increase of hydropower efficiency by reducing evaporation losses. The annual water
saving due to reduction of evaporation rate can range between 7000 and 10000 m3 per installed MWp.
In particular, point 5 was considered in this study for the European context.
2. Method
A bulk assessment was carried out to estimate the additional energy generation from the European hydropower
reservoirs due to the evaporation reduction induced by the installation of FPV. Global European data of evaporation
collected in Hogeboom et al. (2018) were elaborated (see further details in Mekonnen et al., 2015 for the European
context and in Vanham et al., 2019 for the EU27+UK context), assuming that the evaporation below the FPV is
reduced by 70% (Zahedi et al., 2020, Bontempo Scavo et al., 2021; Abdelal, 2021). Both the EU27+UK (EU) and
the whole Europe were considered (excluding Russia and Turkey).
From the JRC Hydro-power database (European Commission, 2019) it is possible to estimate the average discharged
flow of reservoir HPPs in Europe and in EU27+UK, from data of annual energy generation, head and assuming a
global HPP efficiency of 0.8. By assuming an annual operation of 3140 h (on average), it is possible to estimate a
global discharged flow rate of 58,005 m3/s for EU and 123,467 m3/s for Europe (for further details, see Quaranta et
al., 2021).
The FPV coverage is important because it affects the evaporation reduction (Bontempo Scavo et al., 2021), and in
this study it has to be reasonably assumed. In general, a FPV with equivalent installed power of the HPP would make
it possible to use the electric connections to the grid without any modification, reducing costs related to the
infrastructures. In Alpine environment, where HPPs are characterized with high heads and low flows (i.e. high power
density Wden per unit of reservoir surface), this would require a FPV surface much larger than the HPP reservoir
surface. Instead, for the HPPs characterized by large flows and small heads, a small percentage is enough to obtain
the equivalent power. Hence the optimal FPV surface cover is site specific. In this study we assumed 10% of FPV
surface in order to reduce the impact on the reservoir and to reduce investment costs, in line with 14% of Lee et al.
(2020). This value may be reasonably considered a feasible average value to be implemented at the European scale.
Table 1 in Appendix 1 lists the 20 largest existing HPP reservoirs where it was assumed to install a FPV plant of the
equivalent HPP power, just to show some examples, where it is shown that the required FPV surface is, on average,
8.3% of the reservoir surface.
3. Results
From data of Hogeboom et al. (2019) it was estimated that the annual evaporative volume from the examined
hydropower reservoirs is 2,810 ·106 Mm3 and 3,734 ·106 Mm3 for EU and Europe, respectively. By a linear
extrapolation, considering the total reservoir surface in Hogeboom et al. (2019) of 10,586 km2 and 13,567 km2 (EU
and Europe, respectively), and the real ones of 19,374 km2 and 52,071 km2, the annual evaporative volume from the
hydropower reservoirs is V = 5,143 ·106 Mm3 and V = 14,332 ·106 Mm3 for EU and Europe, respectively.
Multiplying these values by 70% (evaporation reduction below the FPV, Zahedi et al., 2020, Bontempo Scavo et al.,
2021, floating type 2; Abdelal, 2021) and by the FPV surface (10%), and considering 3,140 h of annual operation, it
is possible to obtain V·0.7·0.1/(3,140·3,600) = 89 m3/s and 32 m3/s of additional flow that could be discharged over
the 3140 h, on average, for EU and Europe, respectively. This is 0.07% and 0.05% of the total average flow for EU

and Europe (average discharged flow rate over the 3,140 h of estimated operating hours per year), respectively, to
which it would correspond an equivalent increase in energy generation from SPP of 84 GWh and 279 GWh per year
for EU and Europe, respectively. This analysis shows as the main benefit of FPV is the energy generation from the
PV rather than the evaporation reduction, although an increase of 0.07% of the annual generation from European
SPP would correspond to 279 GWh/y, i.e. to a SPP with an average power of 88 MW (3,140 h/y of operation) or to
500 mini hydropower plants with an average power of 100 kW and operating for 5,570 h/y In Sanchez et al., (2021),
the annual generation increase was estimated in +0.54% for the African context, with the same floating PV type. It
must be noted that the evaporated water does not vanish, but it appears again as rainfall, perhaps in the same
catchment, so that these numbers must be interpreted as maximum thresholds. Furthermore, the energy generated by
FPV was not here estimated, but it remains the main benefit of a FPV-HPP hybrid plant.
The above calculations refer to 10% of the reservoir surface, while evaporation reduction increases with the
extension of the FPV surface. However, the extension of the coverage area should consider potential impacts on the
reservoir ecosystem, since the reduction of the euphotic zone may lead to alterations of thermal and photosynthetic
processes related to solar radiation, even though a FPV coverage up to 60% for some reservoir surfaces may be
deemed acceptable (Haas et al. 2020). Furthermore, FPV must remain on the reservoir all year round, so the
maximum extent is theoretically the minimum water surface (under very dry conditions, at the reservoir minimum).
For seasonal deep storage reservoirs which will be full and empty each year, FPV is a challenge considering also the
ice cover in high altitude. Thus, application may be limited for reservoirs below 1500 m a.s.l. in the Alpine context,
while in Norway, where most of reservoirs are located, the icing of the surface is frequent.
This bulk preliminary assessment does not consider local constraints and site-specific conditions, but is based on
average large-scale calculations to capture the order of magnitude of the potential. The used data sample can be
reasonably considered a representative data set for extrapolating a reasonable result, but future studies should be
carried out to better estimate the evaporation reduction and the related increase of annual generation taking into
account local factors.
4. Conclusions
The integration of FPV can increase the discharged water volume of the European hydropower fleet by 280 GWh
when 10% of the basin surface is covered with FPV, in addition to the energy generated by the FPV. The advantages
of this hybrid system is the possibility of using the same infrastructures (in particular the grid connection) without
any modification and to increase the capacity factor by 20%, thus the number of operating hours from about 3100 to
almost 4000 hours (for comparison, in South America it can increase from 4000 –IRENA, 2020- to 5200 hours). The
large increase in energy production of the hybrid system (FPV+HPP) allows a better management of HPPs, because
the operation of FPV is in part anti-correlated with that of HPP plant. Furthermore the use of the same grid and
infrastructures strongly reduces the costs of the FPV which can be installed in a short time and without any
modification of the reservoir conditions. For seasonal deep storage reservoirs which will be full and empty each year,
FPV is a challenge considering also the ice cover in high altitude, limiting FPV application to reservoirs below 1500
m a.s.l. in Alpine environment. In this study we assumed to cover 10% of the reservoir surfaces with FPV, but future
studies should be carried out to consider the most appropriate surface cover for each reservoir, with more detailed
analyses and site specific conditions.
References
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Carbon Technol, 2021, 1-8.
2. Adams, T. B. “Feasibility of upgrading existing hydropower infrastructure for use in renewable energy storage”, Doctoral
dissertation, Massachusetts Institute of Technology, 2018.
3. Botelho, A., Ferreira, P., Lima, F., Pinto, L. M. C., and Sousa, S., “Assessment of the environmental impacts associated
with hydropower”. Renewable and Sustainable Energy Reviews, 70, 896-904, 2017.
4. Cazzaniga, R., Rosa-Clot, M., Rosa-Clot, P. and Tina, G. M., “Integration of PV floating with hydroelectric power
plants”. Heliyon, 5(6), e01918. doi:10.1016/j.heliyon.2019.e01918, 2019.
5. Deemer, B. R., Harrison, J. A., Li, S., Beaulieu, J. J., DelSontro, T., Barros, N., ... and Vonk, J. A. “Greenhouse gas
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Acknowledgements
The Authors want to thank Kakoulaki Georgia and Gonzalez Sanchez Rocio for their input and constructive comments.
The Authors
E. Quaranta PhD in Hydraulic Engineering, is a scientific officer at the Joint Research Centre of the European Commission, with
expertise in the water sector. One of his focus is hydropower, in particular low head hydropower, fish passages, hydropower
innovations and European potential. He is author of several scientific publications and also informative articles on hydropower
topics, with collaborations with research centres and hydropower industries. Dr. Quaranta is president of the Young Professional
Network of the International Association for Hydro Environment and Research (Italian section) and coordinator of the exploratory
research SustHydro at the European Commission.
A. Pistocchi, PhD is an environmental engineer and land planner, and a scientific officer/project leader at the Joint Research
Centre of the European Commission.

M. Rosa-Clot has accomplished his studies in Scuola Normale with 110/110 et laude in 1966. After one year of fellowship as
researcher at Columbia University (New York 1968) he became charged Prof. of Quantum Physics and General Physics in Pisa
(69-87) In the period 75-78 he was fellow of the Theoretical Division at CERN. Subsequently (1988-2009) he has been full
professor of Nuclear Physics in Florence University. In the period 1998-2003 he was Scientific director of CRS4 (Centre of
numerical simulation in Sardinia) and since 2017 he is scientific director of the private companies UPF (Upsolar Floating) and
KMM (Koiné MultiMedia). As far as research activities are concerned, he is author of more than 100 works published on
international review in theoretical physics, nuclear physics, econophysics, environment and energy problems. He is authors of
two books about floating PV technology.
Appendix
Table 1 lists the 20 largest existing HPP reservoirs where it was assumed to install a FPV plant of the equivalent
HPP power, with their installed power P, annual energy generation E, reservoir surface, power density Wden (installed
power divided reservoir surface) and energy density per m2 of reservoir surface Eden. It was assumed to install a FPV
plant of the same HPP installed capacity, with a power density of 180 W/m2. From Table 1 the variability among the
different plants in terms of surface coverage can be observed. It can be seen that the percentage of the basin covered
by the FPV is on average 8.7% and rarely exceeds the 10%. The average annual energy generation increases by
23.6%, with an analogous increase in the overall capacity factor. Table 1 may be slightly misleading since the very
large plants examined do not represent the majority of plants, and refer to HPPs with low heads and high flows (i.e.
large reservoirs), but it is quite evident that there is a very strong variability among the different plants.
Table 1. List of the 20 largest reservoir HPPs (from Cazzaniga et al., 2019), assuming to install a FPV plant of the same power
and with a power density of 180 W/m2. The columns 1 and 2 in the FPV part give the surface necessary to install a power
equivalent to that of the HPP and the % of the basin which should be covered by FPV. Columns 3 and 4 give the yearly energy
yield taken from the PVGIS for the different locations and the total energy produced by a FPV of identical power to that of the
HPP. Column 5 shows the increase in percent of the energy produced by the FPV plant and column 6 shows the value of the
energy density of the FPV.
Hydropower plant
FPV Wdens =180 W/m2
1
2
3
4
5
1
2
3
4
5
6
Name
P
E
Surf.
Wden
Edens
Surf
Surf.
Produ
ctivity
E
E rate
Edens
MW
TWh
/y
km²
W/m2
kWh/y/m2
km2
%
kWh/y/
kWp
TWh/y
%
kWh/y/m2
Three Gorges Dam,
China
22,500
99
1,084
20.8
91.3
125.0
11.5%
939
21.1
21.3%
169.0
Itaipu Dam, Brazil
14,000
89
1,350
10.4
65.9
77.8
5.8%
1282
17.9
20.2%
230.7
Guri, Venezuela
10,235
53
4,250
2.4
12.5
56.9
1.3%
1546
15.8
29.9%
278.4
Tucuruí, Brazil
8,370
41
3,014
2.8
13.6
46.5
1.5%
1505
12.6
30.7%
270.9
Grand Coulee, USA
6,809
20
324
21.0
61.7
37.8
11.7%
1162
7.9
39.6%
209.2
Xiangjiaba, China
6,448
31
96
67.2
322.9
35.8
37.3%
707
4.6
14.7%
127.3
Sayano, Russia
6,400
27
621
10.3
43.5
35.6
5.7%
812
5.2
19.2%
146.2
Krasnoyarsk, Russia
6,000
15
2,000
3.0
7.5
33.3
1.7%
770
4.6
30.8%
138.6
Nuozhadu, China
5,850
24
320
18.3
75.0
32.5
10.2%
1290
7.5
31.4%
232.2
Robert-Bourassa,
Canada
5,616
27
2,835
2.0
9.5
31.2
1.1%
881
4.9
18.3%
158.6
Churchill Falls,
Canada.
5,428
35
6,988
0.8
5.0
30.2
0.4%
914
5.0
14.2%
164.4
Bratsk, Russia
4,515
23
5,470
0.8
4.2
25.1
0.5%
838
3.8
16.5%
150.8
Xiaowan Dam, China
4,200
19
190
22.1
100.0
23.3
12.3%
1210
5.1
26.7%
217.8
Ust Ilimskaya, Russia
3,840
22
1,922
2.0
11.4
21.3
1.1%
771
3.0
13.5%
138.8
Jirau, Brazil
3,750
19
258
14.5
73.6
20.8
8.1%
1010
3.8
19.9%
181.8
Jinping-I, China
3,600
17
83
43.4
204.8
20.0
24.1%
1380
5.0
29.2%
248.4

Santo Antonio, Brazil
3,580
21
490
7.3
42.9
19.9
4.1%
1472
5.3
25.1%
265.0
Tarbela, Pakistan
3,478
13
250
13.9
52.0
19.3
7.7%
1330
4.6
35.6%
239.4
Ilha Solteira, China
3,444
18
1,195
2.9
15.1
19.1
1.6%
1513
5.2
28.9%
272.3
Ertan Dam, China
3,300
17
101
32.7
168.3
18.3
18.2%
1240
4.1
24.1%
223.2
Tot / Average
131,363
629
32,840
4.0
19.2
729.8
8.3%*
1,129
148.3
23.6%
203.1
*average of the column