kIEFER TEK LTD undertakes all the necessary studies, the authorization, the installation, the operation and the management of small hydropower projects.
The study of a hydroelectric installation includes several phases, the extent and deepening of which depends significantly on the nature and the size of the installation.
To complete a hydroelectric project three types of studies are required.
First, we make a feasibility study in order to determine if the location under consideration deserves more investigation. This study includes:
- Determination of the drop height and initial selection of the water supply point and of the plant location.
- Construction of flow duration curves for this location in order to estimate the annual energy production and calculate the annual revenue of the project.
- Estimation of the construction cost according to the morphology of the area, the length of the penstock, the type of electromechanical equipment and the distance of interconnection with the network of ΗΕDNO.
- Determination of the economic viability of the project by calculating the necessary financial indicators and conclusions.
If the results of the feasibility study are positive and the applicant wishes to proceed with the project elaboration, then we make the preliminary study of installation. The purpose of this study is the layout and dimensioning of the project after the examination and analysis of various alternatives. The level of detail of the preliminary studyis such as to be sufficient for issuing various permits required for the construction of the project.
The design is based on the results of the feasibility study and includes:
- The selection ofwater turbines and the definition of their hydraulic characteristics.
- The selection of generators, their characteristics and all the subsequent electrical equipment.
- The determination of the automation systemfeatures and of the plant operation.
- The determinationof the penstock system of the station, the water intake, the penstock (open or closed), the surge tank and other auxiliary installations.
- The building infrastructure for the installation of the mechanical equipment (ensuring that the layout of water turbines - generators allows the easy access and maintenance without interrupting the operation of the other units), the automations, all the auxiliary equipment, the substation, as well as forthe interconnection with the network.
If the preliminary study results are also positive, then we make the final installation study, which includes all the plans, calculations, economic analysis results and specifications of necessary equipment, as well as the environmental impact study. By the end of the installation study, begins the construction of the project.
For the study of a hydroelectric installation we make the following steps:
- Identification of the area, which includes the initial layout and siting of the project, the recording of thelocal conditions, difficulties, infrastructure and other competing uses of water, the study of geological conditions and the determination of electricity demand in the area.
- Collection and evaluation of the existing hydrological data and construction of the flow duration curve.
- Market research and availability check. We examine the cost of the hydraulic turbine, the generator, the generator controller and the pipes of the installation, since these will be the most expensive elements.
- Calculation of the generated power. Depending on the possible combinations of hydraulic heights and flow rates, that can be achieved, we calculate the electrical power of the plant and we evaluate whether it is adequate or not for the operation of a hydroelectric
The power of the installation is calculated from the following formula:
P = n x ρ x g x Q x H
P: the generated electric operating power (kW).
n: the overall efficiency of the installation.
ρ: the density of water (≈1000 kg/m3).
g: the gravity (≈9.81 m/s2).
Q: the flow which passes through the turbine (m3/s).
H: the head (m).
The calculation with the formula above is approximate. We consider a value as the overall efficiency of the installation (a value in the range of 55 - 75% is quite close to reality), and then knowing the values of the flow and height, we calculate the generated electric power.
The overall efficiency of the installation depends on the efficiencies of the elements that compose it and it is calculated as follows:
n = nturbine x ngenerator x ntransformer
The efficiency of the turbine also consists of partial efficiencies and is calculated from the following formula:
nturbine = nmechanical x nhydraulic x nvolumetric
The data that are usually available for the calculations are the turbine nominal efficiency and the generator and transformer nominal efficiency. Consequently we can calculate the overall nominal efficiency of the installation.
- Calculation of the installation requirements. At this stage, we determine the minimum electric power that must be generated by the generator of the plant so that all devices designed to connect and powered byit will be able to operate at the desired level.
- Calculation of the size of the generator depending on the installation requirements and the expected cost.
- Preliminary check of the economic viability.Depending on the estimation of the generated power and the requirements of the installation, we select the optimum design and compare the annual revenue to the capital cost of the investment.
- Selectionof the appropriate combination(orcombinations) of flow rate and hydraulic height, in order to have a water turbine-generatorsystem which generatesthe requiredpower andestimations aboutthe efficiency of the plant.
- Selection of the final value of output power. We estimate the final size of the generator that we will use, based on the data of the hydraulic potential and flow of the plant which have been precisely calculated.
- Installation Design. We made the plans and the map of the plant which includes all the elements of installation, their dimensions and their layout.
- Check whether some alternatives in the design of the plant could lead to a lower cost or a more favorable
- Detailed cost calculation. We calculate in detail the costs of each element of the hydroelectric installation and then the total initial cost of the project.
- Check of the economic viability of the project according to the new calculated cost. If the investmentis not economically viable, the elementsof the plant that caused the extra financial burden must be replaced with other cheaper.
- Order of materials and generally of all the necessary equipment for the operation of the project, according to the calculations which have been made, and installation of them in accordance with the plant design.
- Training of the personnel which is responsible for the monitoring, the maintenance and the general operation of the plant.
- Commissioning after checking if the installation and connection of all the components is correct.