Turbine selection
There are many engineering solutions which can be used to generate hydro power.
In order to select an appropriate technology, you will need to know the following parameters of your hydro site: a hydraulic head and a flow rate. At this stage you should have been aware of these values.
If you have not done this preliminary research, please look for the information which is available in Section 1 on Hydraulic Head and Flow Rate.
Turbine Costs
Having analysed the data for different types of turbines received from the manufacturers, the following formulae were derived:
Kaplan Turbine Cost
The relationship between the costs of Kaplan-type turbines CK and a flow rate Q in m3/s indicated two different bands.
For flow rates between 0.5m3/s - 5.0m3/s the cost of a turbine can be expressed as below:
CK = 15000 × (Q × H) 0.68 (£, 2008),
or
CK = 3500 × (kW) 0.68 (£, 2008),
For higher flow rates, between 5.0m3/s - 30m3/s, the cost of a Kaplan turbine can be estimated using the following formula:
CK = 46000 × (Q × H) 0.35 (£, 2008)
or
CK = 14000 × (kW) 0.35 (£, 2008)
Francis Turbine Cost
The relationship between the costs of Kaplan type turbines CF and a flow rate Q in m3/s indicated three different bands.
For flow rates between 0.5m3/s –2.5m3/s the cost of a turbine can be expressed as below:
CF1 = 142000 × (Q × H 0.5) 0.07 (£, 2008),
or
CF1 = 122000 × (kW/H 0.5) 0.07 (£, 2008).
For flow rates between 2.5m3/s –10.0 m3/s the cost of a turbine can be expressed as below:
CF2 =282000 × (Q × H 0.5) 0.11 (£, 2008),
or
CF2 = 223000 × (kW/H 0.5) 0.11 (£, 2008).
For flow rates greater than 10.0 m3/s the cost of a turbine can be expressed as below:
CF3 =50000 × (Q × H 0.5) 0.52 (£, 2008),
or
CF3 = 16500 × (kW/H 0.5) 0.52 (£, 2008).
Pelton Turbine Cost
The relationship between the cost of Pelton turbine CP and a flow rate Q in m3/s can be expressed by the following formula:
CP =8300 × (Q × H) 0.54 (£, 2008),
or
CP= 2600 × kW 0.54 (£, 2008)
Grid Connection
Small-scale hydro plants can be connected to the national electricity grid or can be stand-alone systems.
If a hydro plant is connected to the national grid, a power producer can sell an excess of the electricity production to electricity companies. In the case of off-grid generation, the electricity is consumed directly by a user or can be stored in the batteries.
Privately-owned distributed generation including hydroelectricity generation is a fast-growing sector. Small-scale hydro resources are often found in less populated areas with lower load demand. Due to the capacities of small-scale hydroplants, they will be connected to medium or low-voltage networks.
Historically, electricity networks were designed to transfer electrical power from the high-voltage transmission grid to customers distributed on lower-voltage systems. The design is based on the assumption that power is transported in one direction and that load patterns are fairly predictable with well-known daily and seasonal variations. These networks were operated passively to ensure that consumers were supplied with the quality of electricity within statutory limits.
However, in cases where distribution generation is comparable to or higher than the local demand it will likely affect the network power flows and the voltage could go beyond the statutory limits [Harrison et al]. The distributed generation is geographically dispersed and delivers intermittent supplies of energy to the distribution network. The connection of distributed generation can result in power flows going in both directions. The presence of distributed small-scale hydro generation can affect the operation of the distribution network in a number of ways [Harrison et al], including:
- Bi-directional power flow and the potential to exceed equipment thermal ratings;
- Reduced voltage regulation and violation of statutory limits on supply quality;
- Increased short circuit contribution and fault levels;
- Altered transient stability;
- Degraded protection operation and coordination.
To connect to the distribution network, the developer should submit an application form to a local Distributed Network Operator (DNO). DNOs will then assess the impacts an individual distributed generation scheme can have on the distribution network.
Due to the high costs of grid connection, the hydro plant should be located close to the existing grid infrastructure.