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A Scottish island entirely renewable

Energy independence can be achieved even in the most remote places, thanks to access to alternative energy sources.

by Nicholas Newman
6 min read
byNicholas Newman
6 min read

The remote Scottish island of Eigg has received overwhelming attention due to one amazing fact. It has been virtually self-sufficient from renewable energy for more than a decade.

Prior to 2008, the island, which is home to 106 residents, was powered by diesel generators, which provided power for just a few hours a day. (The fuel had to be shipped across hostile seas from the Scottish mainland.) In 2008, however, that all changed when Eigg residents launched the world's first community off-grid power system.

The innovative program is based on a combination of battery storage, micro-hydro, wind and solar generation plants. The system has sufficient capacity to supply secure power 24/7 to the island's homes and businesses, which include two museums, the Laig Bay Brewing Company, record label Lost Map and Howlin' Fling, a semi-regular music festival.

How the island of Eigg is powered

To ensure the availability of reliable and secure sustainable energy on Eigg, the island depends on a combination of hydro-electric and wind turbines, solar PV panels and battery energy storage.

Chief amongst these is the island's hydroelectric plant, which consists of three micro turbines that harness energy from a local stream and provide around 112 kilowatts (kW). The largest turbine generates 100 kW, whilst two others provide about 6 kW each. In addition, four wind turbines produce a maximum of 24 kW.

Hydro and wind satisfy most of the island's power needs throughout the year—especially in the winter—and there is room for extra wind turbines. In contrast, during the Arctic summer, the 284 kW island's solar farm comes into its own, meeting nearly 25 percent of the island's power requirements, which tail off to as little as 10 percent the rest of the year.

To ensure year-long secure energy supplies, the island's battery bank is able to provide electricity for up to 24 hours; two 80kW diesel generators provide around five percent peak load. Surplus power is stored, and the power network is monitored and supervised in the island's control building.


The batteries at the control station of Eigg Electric

How does it all work?

Power from the generators is transmitted via an 11 kilometre network of underground electricity cables to every household and business on the island. Any surplus power is stored in a bank of batteries. Once the batteries are charged, a series of switches activate heaters in community buildings, including local churches, the community hall, medical centre and the pier lobby. In any power shortfall, energy is released from storage and is supplemented by the back-up diesel generators. In addition, the medical centre has its own back-up generator.Thanks to the £1.66 million investment, largely financed by the European Union's European Regional Development Fund, a range of UK government agencies and by the islanders themselves, Eigg has the cheapest electricity in the United Kingdom at £0.23 per kilowatt hour. The power system has proven its value—the designers estimated the cost of a mainland grid connection at between £3-5 million, twice the cost of the current Eigg electrical network.

How the system is managed

Eigg's power distribution system was constructed with aluminium wire rather than the more expensive copper. Though cheaper, this material is less efficient in electricity transmission, resulting in power restrictions for residents and businesses. Residential customers are rationed to just 5 kW an hour, whilst business customers are capped at 10 kW an hour.

To illustrate what this means in practice: 1 kW an hour is enough to run a washing machine and electric kettle at the same time. Meters show customers their electricity consumption and the approaching cut-off point when the electricity supply will goes off. For a resumption of power, customers pay a £20 penalty fee.

Power availability is indicated by a traffic light system on the pier. A red light is turned on when it is time to cut power consumption; a green light indicates normal use conditions. This system has proven very effective.

With improved insulation and energy efficiency, residents have been able to almost halve community power usage. Reflecting on the system, former Eigg electric director John Booth told Karen Gardiner from the BBC that although demand was rising, “all the evidence says we got it right at the outset and it's coping."

The island's energy system is owned, operated and maintained by the Eigg Electric Ltd., a wholly owned subsidiary of the Isle of Eigg Heritage Trust. Repair, management and servicing of the system are the responsibilities of a trained team of Eigg's residents. In essence, the energy supply is “run by and for the island," says Booth. 


John Booth, former project director at Eigg electric, poses next to two wind turbines on the island of Eigg

Generating awards

The plan's success has been acknowledged both locally and abroad. At home in Scotland, Eigg was lauded as the “Best Community Initiative” at the 2008 Scottish Green Energy Awards. A year later it won the Scottish and Southern Energy Innovation and Energy Efficiency Award. The Isle of Eigg was also a recipient of a 2010 Ashden Awards, which recognize initiatives that tackle climate change with practical action.

Visitors from as far away as Alaska, Brazil and Malawi have descended on Eigg to learn more about the island's efforts to achieve energy self-sufficiency.

Although they must contend with specific energy provisions, residents of Eigg are amenable to the rationing of their energy consumption. The reward is in the response: A consumption reduction of 47 percent thanks to continual improvements to energy efficiency and insulation.

 

The author: Nicholas Newman

Journalist who regularly writes about agriculture, aerospace, business, energy, engineering, rail, shipping, technology, transport for clients worldwide.