The ambitious objective of making the island of El Hierro 100% RES reliant will be achieved through a variety of measures. These comprise the installation of a mixed system of electricity production that combines a wind farm with a hydroelectric power station (also used for the production of desalinated water for irrigation), the production of biogas from waste, the installation of solar photovoltaic, solar thermal and wind technologies in the residential sector and the introduction of an integral alternative transport system. In addition, the Plan seeks to implement corrective measures to preserve the landscape and to minimise the ecological impacts derived from the electric grid.
100% RES electricity supply project
The Government of the Island El Hierro (Cabildo de El Hierro), UNELCO (the local utility) and ITC (the Technical Institute of the Canary Islands) are collaborating in a project whose objective is to meet the island's electricity demand entirely from RES by 2005.
The supply will be ensured by a mixed system comprising a wind farm situated in the North East of the island and a hydroelectric pump-storage power station with a system of artificial lakes. The pump storage system consists of a 15 MW wind farm that harnesses wind energy to pump water to a reservoir 600 m above sea level. This water runs downhill through a pipeline to sea level, where it drives a turbine. Output can be varied to match demand, thus guaranteeing sufficient electricity supply. There is another reservoir next to the turbine with a capacity of 250,000 m3 that collects fresh water for pumping it back up to the top reservoir, thus completing the cycle.
The mechanism also includes a seawater desalination plant; once the reservoirs are full, the plant can cover evaporation losses from the system and supply irrigation water for the island’s foothill farms, thus guaranteeing fruit and vegetable crops and providing forage for livestock on the island.
The energy-water binomial
This close relationship between water and energy, together with the integral character of the Sustainable Development Plan, have contributed to tightening the links between them and to promote their joint use for energy and irrigation purposes.
Seawater desalination is essential in order to ensure a constant supply of water for the wind-powered hydraulic system. It is also clear that another of storing the surplus energy generated by the wind farm is to produce desalinated water. In this context, the final implementation of the 100% RES project implies an important increase in the desalination capacity of El Hierro and, as a consequence, a significant increment in irrigation capacity. In this way, new organic farming projects can be linked to renewable energy.
El Hierro – “zero waste”
One of the basic features of the island’s sustainable development strategy is the group of actions generated under the initiative “El Hierro - zero waste”, which consists of the production of biogas by exploiting stockbreeding effluents and sewage for methanogen fermentation. This project is the result of an international co-operation initiative with the island of Cuba, which counts on important technical experience and human training that could be profited in El Hierro. The first phase of this ambitious programme has already been concluded, and the digesters installed in an experimental farm sponsored by the Local Island Council are now operative.
Transport’s energy dimension could not be left out of an integrated sustainable development project that aims to become a working model for other island regions of the world. Thus the Island Council, in co-operation with the local transport co-operative, started to take the first steps to consolidate an alternative transports system.
The demonstration projects planned are the following:
· Incorporation of a hybrid bus to the local fleet. Initially, its use will be limited to the shuttle between the airport and the capital and may use biogas as fuel.
· Introduction of an electric, battery-powered minibus in the area of El Golfo, for mixed tourist-public use. It would rely on a photovoltaic station for its recharge.
· Development of an extensive pedestrian network.
· Creation of an advanced information and management transport system within the framework of the sub-programme “El Hierro- Digital Island”.
· Development of an ingenious ticketing system for the optimisation of journeys in scattered rural areas, occasionally turning the private vehicle into collective transport, supported by electronic systems for fare payments . This will favour an integrated system of rational use and energy saving in the transport sector.