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Water, wind and sun – generating clean power for the Kintradwell Estate

Issue:

Kintradwell is an 8,000 acre estate in Brora, high above the Moray Firth on the East Coast of Scotland. The estate is used as a resort for shooting and fishing, with holidaymakers accommodated in the Lodge, the estate’s principal country house.

The owner realised the potential of one of the estate’s watercourses to be harnessed for hydro-electric power generation. This would service the estate’s power needs and provide new income by exporting the electricity generated into Scottish and Southern’s grid with a feed in-tariff.

The project harnesses water from a small river high up a valley, 2.5 kilometres inland from the turbine shed located on the coast. The curve of the valley means the weir inlet, where water enters the pipeline, is out of direct line sight of the turbine shed. The location also has no fixed power supply available. This proved to be an issue as the project required constant monitoring of the water level at the weir inlet to adjust pipe valves in the turbine shed and manage water flow. It is critical for water flow to remain consistent for the successful operation of the system, because any air entering the pipes would lead to damage of the turbine blades and high repair costs. The monitoring of flow was also necessary because, as part of the process of obtaining necessary approvals from the environment agency and local council, Kintradwell Estate was to adhere to stipulations on how much water could be diverted into the hydro-electric scheme. This would ensure adequate water supply was maintained for local wildlife.

Solution:

Given the distances involved and the nature of the geography, a cable based solution was not an option, so the Kintradwell Estate turned to wireless communications specialist Wood & Douglas to develop and install a radio based telemetry system for the monitoring of the water levels and flow control.

The weir inlet monitoring includes a water level sensor that produces an analogue 4/20mA current value which is sent to the turbine pump building where pipe valves are adjusted to control water flow. Since there is no mains electricity at the weir, Wood & Douglas deployed a solar panel to charge a battery which then powered an ORION radio connected to the sensor. Given the Northerly location of the site, the solar battery system capacity was engineered to address 45 days of zero useful solar charge in the middle of winter. To help account for this, ORION was optimised for low energy usage, automatically waking every 30 minutes to send a message containing the current water level before returning to sleep mode. These critical telemetry messages take just a few seconds to send, ensuring the process draws negligible current from the battery.

As the receiving ORION radio unit at the turbine shed was out of line of site of the weir inlet, Wood & Douglas deployed a third ORION to act as a repeater station to complete the point-to-point telemetry system. Placed 1650m inland from the turbine shed and on a north-facing slope of the valley, the repeater location was not suitable for solar power. The ORION repeater is permanently powered so requires the battery to be in a good state of charge; to achieve this a small wind turbine was installed providing charging current from the breeze.

The turbine is now fully operational with constant monitoring and flow adjustments of the water enabling the site to peak generate 100kW of clean electricity. Once the water has exited the turbine shed it is discharged naturally into the sea. By selling on the electricity the intent is now to achieve a return on investment within the next five years at which point the project becomes profit generating, as well as providing constant, free, environmentally friendly power to the estate for the foreseeable future.

  • ORION remote point-to-point telemetry
  • Configured for low power consumption
  • Project encompasses solar, wind and hydro-electric power

Visit: http://www.sportinglets.co.uk/kintradwell.htm

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