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Hydro Turbine Technology Information
Hydro power systems generate electricity from a generator driven by a flow of water over a turbine. The flow can be benign as in a river or tidal flow or as is more often the case water flow is focused into the system by diverting a water course.
- Under a new scheme launching April 2010, electricity generated by micro-hydro will be entitled to claim a feed in Tariff (FIT). This is a cash reward of 17.8p per kWh for systems less than 100kW.
- Pico-hydro systems are a single unit consisting of a turbine and generator fixed in a benign flow of water to generate a small amount of electricity for off grid use (<1kW). Can also be trailed behind a boat to charge batteries.
- Micro hydro systems usually control the flow of water over a turbine by diverting water from a water course using, for example, a weir.
- Micro hydro systems can generate large quantities of electricity to be used on site or exported into the grid.
- The size of generator and power output is dictated by the water flow
- The minimum required head for a micro-system is 1.5m. Minimum flow rates at this head are around 10 l/s.
- Locations with high head (greater than 5-10m) would probably suit a header tank and generator unit. (Depending on situation)
- Locations with low head (less than 10m) may be more suited to a Archimedes Screw hydro design. (see image below)
- Very low environmental impact.
- Planning permission will most likely be required.
- Various licenses such as abstraction license, impound license and land drainage consent. All can be obtained from the Environment Agency (Scotland, N. Ireland and Wales) or Natural England (England)
An example micro-hydro system comprises of:
- A weir holds up the water at height before diverting water flow from main watercourse into:
- The intake funneling water down;
- A flume or penstock at the bottom of which sits:
- The generator using a turbine driven by the pressure of the water. Once through the generator water rejoins the main water course via a tailrace.
- Generated electricity is converted to mains electricity via a rectifier and inverter and metering unit
- Many hydro systems are also built with a dump load consisting of a water heater designed so that if the grid cannot accept the electricity for whatever reason the dump load dissipates the excess electricity as heat. An important safety feature in systems where the flow is not easily stopped
- A significant movement of water to power a turbine is the main pre-requisite for a micro-hydro system. Power from a watercourse can be calculated from its flow rate and head.
- Head: This is the vertical drop over which a watercourse drops in meters. The greater the head, the greater the potential energy available to a turbine. This is measured using a surveyors level.
- Flow: This is the volume of water moving per second. This can be calculated from flow meter readings and watercourse dimensions. It can also be modeled using catchment area details and rainfall predictions. It is important that the seasonal variation in flow rate is accurately calculated in order to correctly size the system.
- Careful design is needed in a micro hydro system in order to maximize efficient use from a water course
- Access to the watercourse area is required for installation of the generator and associated building works.
- For grid connected systems a local circuit will prevent large cabling costs, distribution network operator regulations must be adhered to and larger systems will need a three-phase electrical supply.
- Off grid systems may need a power dump system: a storage heater or heat dump to loose excess electricity during periods of low demand.
- An environmental impact assessment may be required in order to preserve the watercourses natural ecology. This might include incorporating a fish run or other environmental protection measure into the design.
- Pico hydro turbines are available from £100 to £1000 dependent on size.
- Micro hydro system price will vary widely dependent on size of system and the associated building works. A 6kW system would cost in the region of £20,000.
Financial support is available to many energy efficiency and microgeneration measures. Support is currently available via capital grants or the recently lunched Feed In Tariff (FIT scheme) More detail about the different support available is given below.
The Feed In Tariff (FIT)
In April 2010 the UK government launched the Feed In Tariff (FIT) scheme. The FIT pays a fixed rate for any electricity generated from microgeneration systems for a set 20 to 25 year period, depending on technology type. The FIT is a technology-specific rate per kWh regardless of where the electricity is used. This means that you can generate and use the electricity and still get paid for it.
The following FIT rates apply for hydro power installations:
- Less than 15kW installed - 20.9 p/kWh
- Between 15-100kW installed - 18.7 p/kWh
- Between 100kW-2MW installed - 11.5 p/kWh
- Between 2MW-5MW installed - 4.7 p/kWh
In order to qualify for the incentive for systems under 45kW in size both the technology and the installer carrying out the work have to be MCS accredited. Certification details are listed on the S&G installer web pages.
As of 24 May 2010, the Low Carbon Building Programme (LCBP) is closed to all new applications. For more details click here.
Environmental consents and permits
The following permits consents and planing may be needed for any micro-hydro installation from the Environment Agency or Natural England:
- An abstraction license: This will cost around £150 and has a 4 month statutory minimum period. It includes posting a statement of intent in a relevant local newspaper. (carried out by the authority)
- An impound license. In the case of any volume of water being held against the natural flow.
- Land drainage consent.
- flood defense consent.
- Environmental impact assessment (EIA). This takes into consideration migratory fish routes etc. It's main purpose is to prevent any damage to local ecology. For a a small domestic system this would be very simple.
Planning permission will be required for any micro-hydro scheme as it would usually involve either damning or deflection of a watercourse which require various environmental considerations. Speak to your local planning office very early in the process to prevent any delay in the project. Your installer should be experienced with the planning issues and be able to advise you and provide you with technical information to facilitate the planning process.
Due to the fact that planning in the UK is a devolved responsibility, ease of the planning process depends entirely on your Local Planning Authority (LPA). Permitted development rights for microgeneration technologies are under consultation at the moment. See 'more on planning' below for details
If you get a no obligation quote through the S&G 'get a quote' function the local installers contacted will be able to advise you further. Alternatively you can check with your local planning authority (LPA) for details. The contact details of your LPA can be found by going here and entering your postcode.
- If you have any outstanding questions once you have looked at all the information pages relating to this technology, please write to us on email@example.com and we will aim to get back to you with an answer ASAP.
- You can also use the above email address to get in touch with our independent energy experts who will be more than happy to provide you with tailored project consultancy support if required. Click here to find out more about Save & Generate's Independent Energy Assessment services, or visit the S&G Energy Consultancy web site for more details on our consultancy services.
- Our latest independent energy expert blogs on hydro provide further critical insights into developments within the industry and topics of current debate, including latest Government policy developments. Click here to read more.
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