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Small Scale Hydro-Turbines
Inherent Energy Ltd are installers of Nautilus Water Turbines, and Valley Hydro. The combination of products from these two high quality installers cover all situation in the UK Micro Hydro-Turbine market.
Water turbines generate very reliable power with a very simple design, in the UK they typically pay for themselves in 5 years. They consist of a propeller which is attached to a shaft that operates an alternator to generate power when water turns the propeller. There are quite a few types of turbines, but they fall into four major designs:
- impulse turbines,
- back to back reaction turbines
- submersible propeller turbines.
- hydro-dynamic screw
Each is ideally suited for a different type of water supply. Hydro power is the extraction and conversion of energy from water into electricity.
Hydroelectricity is generated by water flowing through a turbine. The water can either be stored behind a dam or be abstracted from run of river.
Feasibility - We need to measure the Head and Flow to determin the correct turbine and the estimated output. We will help with the application to the environment agency for an abstraction licence to obtain permission to use the water flow for micro generation.
Performance
The Nautilus is specifically designed to power off grid homes. It will power your home or village on 1.2 m of net head and discharge only 4.4 l/s at 550 watts output. On 3m of head it's possible to power several homes or a small village industry at 2300 watts output for the 254 mm throat runner, the 203 mm model will produce between 360 watts on 1.2m of head and 3.4 KW on 5.5m of head.
Technical
Back to Back reaction turbine
The water enters at the centre of the rotor and is discharged in equal quantities from the two ends. This means that there is zero net axial thrust on the rotor which minimises bearing wear. The flexible but tough material used for the rotor and stator also absorb the energy of waterborne particles (they effectively bounce), minimising erosion. The whole design is modular which reduces the amount of site-specific design work that has to done, and the level of local expertise required.
Impulse Turbines
The Pelton Turbine consists of a wheel with a series of split buckets set around its rim; a high velocity jet of water is directed tangentially at the wheel. The jet hits each bucket and is split in half, so that each half is turned and deflected back almost through 180º. Nearly all the energy of the water goes into propelling the bucket and the deflected water falls into a discharge channel below.
The Turgo turbine is similar to the Pelton but the jet strikes the plane of the runner at an angle (typically 20°) so that the water enters the runner on one side and exits on the other. Therefore the flow rate is not limited by the discharged fluid interfering with the incoming jet (as is the case with Pelton turbines). As a consequence, a Turgo turbine can have a smaller diameter runner than a Pelton for an equivalent power.
The Crossflow turbine has a drum-like rotor with a solid disk at each end and gutter-shaped slats joining the two disks. A jet of water enters the top of the rotor through the curved blades, emerging on the far side of the rotor by passing through the blades a 2nd time. The shape of the blades is such that on each passage through the periphery of the rotor the water transfers some of its momentum, before falling away with little residual energy.
The Environment Agency measures the flow in most significant rivers and streams in the UK, and data from the 1300 gauging stations can be obtained from the Centre for Ecology and Hydrology in Wallingford. Data for 200 sites is available over the internet, www.nwl.ac.uk/ih/nrfa/.
It is important to determine at the outset what the value of the electricity generated by the scheme will be, i.e. to whom the power will be sold. The electricity generated by a scheme may be used at the point of generation, in place of electricity supplied by the local electricity company.
Alternatively it may be exported via the local distribution network by agreement with the Distribution Network Operator (DNO). It is nearly always financially advantageous to consume as much of the power as possible on site, and only export the surplus into the network. If the scheme is to produce power for export to the local network, there should be early discussions with the DNO who will specify the system protection and metering equipment, and will also provide an estimate of connection costs and the best location for feeding into their system.
A useful list of Distribution Network Operators is provided on the PV-UK website (www.pv-uk.org/reference/grid-con/dno_contacts.html).
Inherent Energy provide a preliminary feasibility study which will typically require 2-3 days work and will cost between £600 and £800.
