A project on Graciosa, Azores, has become key for the credibility of island-based storage following concerns over another plant more than 1,500km away.
The Younicos project on Graciosa is set to go live within weeks amid speculation that another attempt to power an island off renewables, in El Hierro, Canary Islands, has failed to meet expectations. El Hierro’s Gorona del Vento plant, which combines an 11.5MW wind farm with a pumped hydro storage system, was launched with much fanfare in 2014. Its initial aim was to replace 80% of diesel generation needed for the island grid.
Last month, the plant operator revealed the EUR €82m Gorona del Viento had allowed El Hierro to run continuously off nothing but renewable energy for 55 hours. And last week Gorona del Viento said the plant supplied 67% of the island’s power throughout July and had set a new record of 76 hours with 100% renewable production.
Covering between 70% and 80% of demand
“The hydroelectric plant is a system that can cover between 70% and 80% of El Hierro’s annual electricity demand,” said Gorona del Viento’s CEO, Juan Pedro Sánchez, in a press note. Some observers dispute this claim, however. Two years ago engineers linked to the project warned it would never be able to cover more than 55% of island electricity demand. And Hubert Flocard, named as an ex-director at the Nuclear Physics Institute of the French National Scientific Research Centre (Centre National de la Recherche Scientifique), recently called the project “a technical semi-failure.”
Based on data from last year, he said: “The renewable fraction for the three most favourable months, July to September, has been 42%. For the half year, the figure is even more disappointing, with only 30% renewables.” The figures meant Gorona del Viento’s energy production was costing several times more than the diesel it replaced, he said.
Limited wind resource
As well as “limited wind resource, which according to data could not have allowed a renewable fraction larger than 50%,” Flocard said the plant’s government contract could stop it from optimising environmental performance. Overall, Flocard predicted Gorona del Viento would only be able to cover 46 % of El Hierro’s electricity demand.
The respected blog Energy matters , which Flocard is a collaborator on, has echoed this research with regular updates on Gorona del Viento and an ongoing analysis of data from network operator Red Eléctrica de España. In July, Energy Matters contributor Roger Andrews called Gorona del Viento a “failed project” after reviewing the first full year’s worth of operational data on the plant. The whole project was based around a volcanic crater “which it was believed would provide enough energy storage when filled with water and linked to a lower reservoir to smooth out fluctuations in wind generation,” he said.
“No one bothered to do the sums”
“Unfortunately no one bothered to do the sums and check the wind records,” he surmised. “Had they done so they would have found that the storage was adequate to fill El Hierro’s demand for only about two windless days and that low-wind periods on El Hierro can last for months.” Gorona del Viento is not known to have responded to the research carried out by Flocard or Energy Matters. Nor did the company respond to a request for further information from Energy Storage Report.
However, for Rogers, who has also questioned the economics of the Eigg island microgrid project in Scotland, the results of the Gorona del Viento project are a damning indictment of renewable energy’s potential overall. “Intermittent renewable energy is not going to replace dispatchable fossil fuel generation without adequate energy storage backup,” he said.
A prohibitive amount of energy storage
“And since the amount of energy storage needed is almost always prohibitive it follows that an energy future based entirely on intermittent renewables is not a realistic prospect.” It is against this backdrop that the island of Graciosa in the Azores is preparing to launch another project that aims to replace diesel generation with intermittent renewable energy. The Graciosa hybrid power system, for island utility Electricidade dos Acores, will feature a 4.5MW wind park and 1MW solar plant connected to a 2.6MW lithium-ion battery system equipped with Leclanché cells.
Project developer Younicos claims: “Diesel generators will only be needed for back-up in weeks with very poor weather conditions. “This means we can cover an annual average of up to 65% of the island’s power demand with renewables.”
More of a success than El Hierro
Younicos is confident Graciosa will be more of a success than El Hierro because of the choice of storage medium. The company told Energy Storage Report it believes battery-based systems are the most easily deployable, cost effective option for producing clean power today.
Younicos spokesman Philip Hiersemenzel said: “We already proved that we can keep a grid stable using up to 100% intermittent renewables for hours and indeed days in our technology centre in Berlin. “As soon as Graciosa becomes operational in autumn, we’ll be proving it every day in real life. Our main challenge with Graciosa was financing. We knew the technology would work 10 years ago and we proved it three years ago. “Today I’m confident we could build similar systems anywhere in the world in under 12 months, provided that the financing is there.”
A payback of under 15 years
At €24m, the Graciosa project is just over a third of the cost of Gorona del Viento, giving it a potential payback period of under 15 years, according to Younicos. It is also aiming to serve a smaller level of demand than the project on El Hierro. Graciosa’s 4,500 inhabitants use about 13.5GWh a year, compared to the 46GWh or so of consumption on El Hierro, which has a population of more than 10,000. This lower bar may help Graciosa in achieving its targets.
But it can hardly afford to miss them, either. With island microgrids now under scrutiny, it is key for the Graciosa project to achieve the level of renewable energy coverage its backers claim… and at a cost that beats diesel.
By Jason Deign