**2. System description**

A real case is analysed based on the "Multi-purposes Socorridos system" located in Madeira Island, Portugal. This system was designed to supply water to Funchal, Câmara de Lobos and Santa Quitéria, as well as to regularize the irrigation flows and produce electric energy. In this system there is a pumping and a hydropower station located at Socorridos. It is a reversible type system which enables pumping (in one station) and power production (in a parallel station) of 40000 m3 of water per day. Figure 1 depicts a scheme of Socorridos system. Figures 2 to 6 show the all elements of the system under real conditions.

**Figure 1. Multi-purposes scheme of Socorridos system** 

176 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

hydraulic turbines generating electrical power (Bose *et al.*, 2004).

achieved:

need to produce energy;

when wind power is not available;

farmer, is between 425.3 and 716.9k€.

study is presented.

**2. System description** 

energy delivery;

a higher elevation, with pump and hydropower stations for energy injection or conversion. During off-peak hours the water is pumped from the lower to the upper reservoir where it is stored. During peak hours the water is released back to the lower reservoir, passing through

When a wind park is combined with a pumped-hydro system, several advantages can be

• during low consumption hours, the wind energy that otherwise would be discarded, can be used to pump water to the upper reservoir and discharged whenever there is a

• when the wind has high variability, these storage systems can be used to regulate the

• the energy stored in the pumped-hydro system can be utilized to generate electricity

• when there is a variable tariff applied, it is possible to achieve significant economical benefits by deciding optimal pumping / turbine schedules (Papathanassiou *et al*., 2003).

The optimization of pump/turbine-operation with energy consumption/production has been investigated over the last decade (Allen, G., McKeogh, F.J., Gallachóir, B., 2006; Anagnostopoulos, J., Papantonis, D., 2006). An optimization problem is a mathematical model in which the main goal is to minimize or maximize a quantity through an objective function constrained by certain restrictions. The optimization models can use several methods which nowadays are becoming more efficient due to the computer technology evolution. In Firmino *et al*. (2006) an optimization model using linear programming was developed to improve the pumping stations' energy costs in Brazil. The study revealed that the energy costs can be reduced by 15%. In Gonçalves et al. (2011) a best economical hybrid solution is applied and the study showed the installation of a micro hydro in a real small water distribution system using water level controls and pump operation optimization by using genetic algorithms shows the improvement of the energy efficiency in 63%. In Castronuovo and Peças Lopes (2004) a model for the daily operation of a wind-hydro plant was developed using linear programming. They concluded that, for the test case presented, the predicted yearly average economic gain of including a pumped-hydro station in a wind

In this paper an hourly discretized optimization model for the determination of operational planning in a wind pumped-hydro system is presented. Comparisons were made between cases with and without complementary wind energy. The economical profit for each case

A real case is analysed based on the "Multi-purposes Socorridos system" located in Madeira Island, Portugal. This system was designed to supply water to Funchal, Câmara de Lobos and Santa Quitéria, as well as to regularize the irrigation flows and produce electric energy. The system includes an upper reservoir (Covão) at 540 m, which is used to supply water for the Câmara de Lobos population. In addition to the tunnels, the Covão reservoir is used as storage for the water that flow from the mountains. In Socorridos, there is a tunnel located at 81 m that has the same capacity as the upper one.

**Figure 2.** Socorridos pumping station – outside view (on the left). Socorridos-St.Quitéria steel pipe (on the centre and on the right)1

Pumped-Storage and Hybrid Energy Solutions

Towards the Improvement of Energy Efficiency in Water Systems 179

**Figure 5.** Socorridos storage tank: inlet tunnel (on the left) and centrifugal pump (on the right)4

The pump station is located at level 85 m and has four pumps with an installed power of 3750 kW each. The hydropower station is located at a topographic level of 89 m and has Pelton turbines installed with a nominal power of 8 000 kW and a maximum flow of 2m3s-1 each. In Figure 7 the characteristic curves of the Pelton turbines and the pumps are

The penstock between Covão and Socorridos has a total length of 1266.25 m. The

**pipe L (m) Φ (mm) Material** *AB* 81.25 1000 Steel *BC* 132.00 1200 Concrete *CD* 303.00 1300 Concrete *DE* 440.00 1400 Concrete *EF* 310.00 1500 Concrete

**Figure 6.** St. Quitéria hydropower station: inside view of Pelton turbine 5

presented.

characteristics are presented in Table 1.

**Table 1.** Covão-Socorridos penstock characteristics.

**Figure 3.** Socorridos pumping station: centrifugal pumps and control valves 2

**Figure 4.** Socorridos pumping station: plant of the ground level (on the top) and transversal and longitudinal views (on the bottom)3

St. Quitéria hydropower plant is located at the downstream end of St.Quiteria pipe branch, at immediately upstream a water treatment plant and a storage-tank. This hydropower station has a single Pelton turbine with a nominal flow rate of 1 m3/s and a by-pass to the water treatment plant (Figure 6).

**Figure 5.** Socorridos storage tank: inlet tunnel (on the left) and centrifugal pump (on the right)4

**Figure 6.** St. Quitéria hydropower station: inside view of Pelton turbine 5

**Figure 3.** Socorridos pumping station: centrifugal pumps and control valves 2

**Figure 4.** Socorridos pumping station: plant of the ground level (on the top) and transversal and

St. Quitéria hydropower plant is located at the downstream end of St.Quiteria pipe branch, at immediately upstream a water treatment plant and a storage-tank. This hydropower station has a single Pelton turbine with a nominal flow rate of 1 m3/s and a by-pass to the

longitudinal views (on the bottom)3

water treatment plant (Figure 6).

The pump station is located at level 85 m and has four pumps with an installed power of 3750 kW each. The hydropower station is located at a topographic level of 89 m and has Pelton turbines installed with a nominal power of 8 000 kW and a maximum flow of 2m3s-1 each. In Figure 7 the characteristic curves of the Pelton turbines and the pumps are presented.

The penstock between Covão and Socorridos has a total length of 1266.25 m. The characteristics are presented in Table 1.


**Table 1.** Covão-Socorridos penstock characteristics.

This pumping station was designed to pump 40000 m3 of water stored in Socorridos reservoir during 6 h, for the electricity low peak hours (from 0 to 6 am). In the remaining hours of the day, the water is discharged from Covão reservoir to Socorridos hydropower station, in reverse flow direction, in order to produce energy. By the end of the day, the total volume of water in the system is in Socorridos reservoir.

Pumped-Storage and Hybrid Energy Solutions

Towards the Improvement of Energy Efficiency in Water Systems 181

The water consumption in Câmara dos Lobos follows the Manual of Basic Sanitation pattern (DGRN, 1991) and the inflow to Covão reservoir was assumed to have a constant value throughout the day. In Figure 9. the consumption in Câmara dos Lobos and discharge inlet

**Figure 9.** Water volume consumption (Câmara de Lobos) and inlet volume (Covão), in m3, for one day.

• the connection to Sta.Quitéria was neglected. This was due to two factors - the energy production is low when compared to the Socorridos hydropower station and the

• the three pumps in the pumping station of Socorridos and the turbines have the same

• it was considered that Socorridos and Covão the reservoirs are cylindrical. Then Socorridos reservoir has a maximum water level of 5 m and a diameter of 101 m. Covão reservoir has a maximum water level of 7 m and a diameter of 85.4 m. The minimum

Costs associated with the operation of pumping systems represent a significant amount of expenses of a water supply system (Ramos and Covas, 1999). For this reason, it is desirable to optimize the operation of pumps such that all demands are met and, simultaneously, the

For modelling purposes, several assumptions were made to this system:

hydropower station does not operate all year;

water levels in both reservoirs are 0.5 m.

nominal discharge (2 m3s-1);

**3. Optimization procedure** 

total pumping cost is minimized.

in Covão for one day are presented.

**Figure 7.** Turbine (Left) and Pump (Right) characteristic curves and operating conditions.

The electricity tariff used in this study, for Socorridos system, is based on the 2006 electricity tariff from Madeira Electricity Company (www.eem.pt), as presented in Figure 8.

**Figure 8.** Electricity tariff used in the model (Source: www.eem.pt).

The water consumption in Câmara dos Lobos follows the Manual of Basic Sanitation pattern (DGRN, 1991) and the inflow to Covão reservoir was assumed to have a constant value throughout the day. In Figure 9. the consumption in Câmara dos Lobos and discharge inlet in Covão for one day are presented.

**Figure 9.** Water volume consumption (Câmara de Lobos) and inlet volume (Covão), in m3, for one day.

For modelling purposes, several assumptions were made to this system:

