The Greenest Island in the World?

The smallest and most isolated of the Canary Islands, El Hierro, has a way of combining hydro and wind power that may allow it, one day, to get all its energy from renewable sources. PHOTO: BBC

The smallest and most isolated of the Canary Islands, El Hierro, has a way of combining hydro and wind power that may allow it, one day, to get all its energy from renewable sources. PHOTO: BBC

The question is not about who has the densest forests or flora resources showing up high estimates in green. It is one of keeping up a sustained model of efficient use of alternative and natural sources of energy. And on that front, El Hierro seems like it’s well on its way to self-sufficiency on the energy front.

For more than 30 years, El Hierro has been dreaming of becoming self-sufficient. And this year it took a big step forward. At the end of June its new hydro-wind facility, Gorona del Viento, came fully on stream and in July and August it provided roughly half of the island’s energy needs.That means the island’s 10,000 inhabitants are suddenly less reliant on supplies of diesel arriving over unpredictable seas from Tenerife, 200km away. In July, Gorona del Viento saved 300 tonnes of fossil fuels, but that is predicted to rise to 500 tonnes per month before long – the equivalent of saving 40,000 barrels of oil and 19,000 tonnes of emitted CO2 per year.

The system consists of five wind turbines with a total capacity of 11.5MW and two water reservoirs – one at 700m above sea level, the other down near the coast. The reservoirs are connected by two 3km-long pipes, and any water running from the upper to the lower reservoir passes through a series of water turbines, generating electricity.

Fresh water is used, rather than sea water, to ensure that the aquifers are not contaminated if there are any leaks.

What’s unique about it is the way the wind part and the hydro part work together.

“When we get enough wind from the wind farm, we produce electricity and distribute it through the grid. Whatever is left, we use it to pump water from the lower reservoir to the higher one, and then, when the wind drops, we let that water fall through a set of hydraulic turbines and we generate electricity again for the population,” says Juan Gil, chief engineer at Gorona del Viento.

Juan Pedro Sanchez, an industrial engineer who works as an adviser to Gorona del Viento, foresees steadily increasing the length of time the plant is used to cover 100% of the island’s needs. This was done for two hours on 9 August, the next step will be to try it for 24 hours and ultimately it should be possible for weeks on end, he thinks.

“I think that in a year or so, the plant could supply all the electricity the island needs for about 200, 250 days,” Sanchez says.

El Hierro is not the only island to aim for renewable energy self-sufficiency.

  • Since 2008, residents on the Scottish island of Eigg have made a concerted drive to cut down on the use of fossil fuels, reduce waste and invest in sustainable resources. Nearly 100 people live on Eigg and their electricity is now supplied by hydro, wind and solar energy

  • Denmark’s island of Samso, with a population of 4,000, produces all its electricity from renewable sources and aims to be fossil fuel free by 2030. The islanders own shares in the turbines, and have set up an Energy Academy to disseminate their expertise

Read more here.

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