Late in November 2007 the Dutch-German consortium EcoPower Bonaire BV announced the signing of a contract with the Water and Energy Company of Bonaire to build and operate a sophisticated new sustainable wind-diesel power plant. From the end of 2009 the power plant is to supply the small Caribbean island with 10 MW wind capacity supplemented by 13 MW (bio)diesel power. Eize de Vries talked with Dirk Berkhout, a board member of EcoPower partner Econcern, about the project and its potential as a model for other island or remote regions.Along with its ‘ABC island’ neighbours Aruba and Curacao, the tiny Caribbean island of Bonaire is located some 80 km north of the Venezuelan coast. During its long history it has served as a plantation island and a salt producer.Today the island also attracts a modest number of tourists – mainly divers drawn to its outstanding marine environment – and strives towards environmental protection and conservation. With a population of 12,000 persons Bonaire’s peak electricity demand is approximately 12 MW, currently served by a set of rented container (light-fuel) diesel gensets with a rated capacity of 12 MW.
TWO PROJECT STAGES
The EcoPower BV consortium comprises the Dutch sustainable energy group Econcern, the German wind turbine and system supplier Enercon, and truck and engine manufacturer MAN of Germany that supplies the diesel generators.The EcoPower partners aim at transforming today’s largely fossil fuel-based energy supply infrastructure at the island into one based on the application of 100% sustainable energy sources within five years. The project comprises two distinct implementation stages spread over 2007 and 2009.
In 2007, as part of phase one, EcoPower installed a 330 kW Enercon E-33 wind turbine at Sorobon on the southeast coast of Bonaire. This new installation replaces an obsolete former NedWind turbine that had not been operational since 1996. The Sorbon site is characterized by a favourable wind climate, very stable wind conditions and an average wind speed of about 9.1 m/s.The existing grid cable connection has sufficient capacity to accommodate one medium-size wind turbine.The installation activities for the E-33 commenced early in 2007 and the turbine was commissioned in the May of that year. Berkhout explained: ‘The main objective of this first project phase is to gain experience with wind power on Bonaire and to reduce short-term electricity generation costs.And besides supplying clean electricity to the island, local staff will be trained into mastering skills for the long-time upkeep of Enercon type, direct drive (gearless) turbines.’
The second phase, to be completed during the second quarter of 2009, involves the construction of a wind-diesel plant comprising a 10 MW wind farm and a 13 MW diesel power plant.The diesel plant will be built by truck and engine manufacturing giant MAN of Germany near a so-called BOPEC site located at the north-west corner of the island. The wind farm will comprise either 11 x 900 kW E-44 (rotor diameter 44 metres) or 12 x 800 kW E-48 (rotor diameter 48 metres) turbines. The E-44 is a new, strong-wind version of the E-48, with about 1300 operational units in at the end of 2007. Each wind turbine is expected to operate at a high capacity factor, with some 3000-3500 full load hours annually. Berkhout said:’We deliberately concentrated on turbines of sub-megawatt size for transport logistics and maintenance reasons. All installation and maintenance activities can, for instance, be performed with a 500-tonne crane. The final decision on the wind farm design with either the E-44 or E-48 turbines still has to be taken.The judgement will be based on a thorough analysis of wind data registered by a measuring mast we installed this January on site.The wind farm itself is located on the northeast coast of Bonaire, the windward side of the island. Under ideal circumstances, this wind farm alone can fully meet Bonaire’s current electrical needs. Once completed this wind-diesel combination will be by far the biggest wind- diesel plant in the world, and already at this early stage we experience a huge interest of many countries and island communities from all over the world.’
EcoPower partner Enercon is in charge of the wind-diesel load balancing management system. The company already commercially markets a sophisticated wind powered water desalination system and a wind-diesel system. Besides a wind turbine and diesel generator, the latter comprises an in-house developed flywheel system, a containerized energy storage battery pack, and a so-called ‘black-start’ unit. This device is necessary to create operational grid conditions in an island- type grid system during start-up.According to Enercon sources, a wind penetration rate of 90% is achievable with this system. A demonstration system comprising a 600 kW E-40 turbine and an additional hydrogen production and storage unit delivered by Hydro, formerly Norsk Hydro, of Norway, was installed and commissioned on the Norwegian island Utsira in 2004. A second test and demonstration wind-diesel system comprising a 330 kW turbine operates in the vicinity of Enercon’s company HQ in Aurich, Germany. A third and larger wind-diesel was installed on one of the Falkland/Malvinas islands during the second quarter of 2007 and initial test results are now available.
Berkhout says that the Bonaire wind-diesel system is, with a combined capacity of 10 MW wind and 13 MW diesel capacity, on a totally different scale: ‘The technology Enercon has developed is at the moment not fully geared towards the capacities that will be installed on Bonaire. Our wind-diesel project therefore initially does not include flywheel technology. We will install a 2.5 MW battery system to optimize the wind contribution and to improve the grid quality. The initial project aim is a wind penetration rate of 40%-45%, but at a later stage we shall reconsider the application of additional ‘booster’ technologies such as flywheels and other short-term energy storage systems.’ But, he adds, ‘with a 40% wind penetration level and considering the massive scale of the wind-diesel system, we cannot rule out that some load balancing and other control difficulties may occur that have to be solved.’ Berkhout points out that reliability is a key criterion, as there are no alternative supply systems, such as a cable to the Venezuelan mainland, in the event of failure.’
Besides an option to boost the wind penetration rate in future, a second promising track towards achieving a 100% sustainable electricity supply involves the extraction of biodiesel fuel from algae.The diesel power plant will therefore be equipped to burn both mineral and biofuels. Bonaire has a number of large saltpans suitable for growing saltwater algae, Berkhout explains: ‘Biodiesel production derived from algae offers the highest yields per unit of mass of all plants. At the moment we are conducting a feasibility study into the entire biodiesel from algae process chain, an analysis that includes overall economics for several options.’
Both diesel fuel and its transportation is expensive and this results at the moment in high electricity costs for the island’s consumer population. Says Berkhout: ‘The cost of Bonaire’s new wind-diesel system is approximately US$55 million. We expect that part of this investment can be recovered by means of CO2 credits. Once the wind-diesel system is fully operational in 2009 electricity generation costs will go down. Power consumers on Bonaire will be among the main beneficiaries.They can potentially look forward to a 10%-20% reduction on their electricity bills. Secondly the island’s dependence on highly fluctuating – and as currently rising – oil prices will be substantially reduced. The combination of bioenergy production, the wind turbines and diesel plant will finally give a major local employment boost to the island’s population. And by 2012 it is conceivable that Bonaire will get all of its electrical energy from natural, clean renewable sources.’
Eize de Vries is Wind Technology Correspondent, Renewable Energy World e-mail: email@example.com