Mar 21, 2012 - isleofeigg.net
On 1st February 2008, the Isle of Eigg entered a new era, with the switching on of our island electrification project, which makes 24 hour power available for the first time to all residents and businesses on the island.
Until then we were entirely dependent upon making our own power and the clattering of generators was always to be heard. Now, the generators are silent and suddenly we have leapt to the forefront of electricity generation using renewable energy resources. Our project is a world leader in the integration of multiple renewable energy sources into a grid system to supply an isolated and scattered small community.
Building Laig Hydro dam
Solar Cell Installation
Lifting Wind Turbine
This project has been conceived and driven by the enthusiasm of the whole community of the Isle of Eigg, and is the culmination of 10 years of achievement since the purchase of the island in 1997.When it was recognised that conventional mains power was not a practicable proposition, the islanders decided to create and run their own all island electricity system; a system that was to depend as much as possible upon renewable resources.
The system that has been created through the vision of the islanders, generates power at a number of locations around the island, from the renewable resources of Hydro Electric, Wind and Solar energy, and makes this available to all households and businesses via an island wide high voltage distribution grid. The renewable resources will contribute over 95% of the island's electricity demand and it is believed to be the first time that these three resources have been successfully integrated into a community grid system.
The project has been designed and brought into being by our contractors Scottish Hydro Contracting together with sub-contractors E-Connect Ventures Ltd, Wind and Sun Ltd., Energy Renewed Ltd., G.G. MacKenzie Contractors Ltd., by our project managers, Synergie Scotland Ltd., and by the voluntary contribution of many islanders.
The major renewable energy source is a 100kW Hydro Electric Generator. This is supported by two smaller Hydro Electric Generators of 10kW and 9kW, by four 6kW Wind Generators and by 30kW of Solar Electric Cells. Each of these sources has been sensitively sited to cause minimum visual and physical impact upon our beautiful island. The power generated at their remote locations is brought together and distributed to the the households, businesses and community buildings on the island through 11km of buried high voltage cable. Two 80kW diesel generators have been installed to provide emergency back-up and to cover periods when the power generated from the renewable resources is less than demand.
The overall control of the power generation of the system depends upon a bank of batteries connected to the distribution grid through a series of linked inverters. The inverters allow the flow of electrical energy between the batteries and the grid, depending upon the balance of demand and supply, and they adjust the supply of power from the sources of generation so as to maintain the charge of the batteries.
In this way, the inverters ensure that the demands upon the system are met, using as the controlling factor the state of charge of the batteries. The batteries have enough capacity to provide power for the island for periods of up to 24 hours, if energy from renewable resources is not available.
After this, as the batteries discharge, the inverters bring in one of the generators to supplement the power supply and to re-charge the batteries. The limited capacity of the system requires that we limit demand, and with the approval of the residents, domestic and small business supplies have been capped at 5kW, and larger business supplies at 10kW. Everyone has adapted well to using power within these limits, and the concept should make a very real contribution to energy economy and load spreading, both of which will help to optimise the stability, efficiency and value of the system for all users.
The system will be operated for the benefit of the community by Eigg Electric Ltd., a subsidiary company of Isle of Eigg Heritage Trust. It will be serviced and maintained by a trained island maintenance team. Electricity charges are collected via pre-payment card operated meters, and are set at a level necessary to allow Eigg Electric Ltd. to fulfill its duties to the community. This has been a technically challenging and unique project, which owes its success, not just to the individual specialist capabilities of residents, of the project manager, and of the contractor and all the sub-contractors, but to the way in which all who have been involved with it have co-operated, jointly discussed every aspect of the project and worked as a team throughout.