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Biomass, the energy alternative of the future

12/28/2010

Commissioning of the Briviesca and Miajadas plants in Spain give ACCIONA a sound base to develop this market of the future

Commissioning of the Briviesca and Miajadas plants in Spain give ACCIONA a sound base to develop this market of the future.

Where wind and photovoltaic and, more recently, solar power, are undergoing exceptional development in Spain, the same cannot be said yet of biomass, which has failed to reach the objectives of implementation plans. The last such Spanish plan, the 2005-2010 Renewable Energies Plan, or PER, foresaw the installation of 1,317 MW of biomass facilities by the end of this year, yet only 591 MW will be in place, 55% short of the target.

ACCIONA is one of the pioneers in building biomass facilities in Spain. The opening of the Sangüesa plant was a milestone since it was the fi rst straw combustion one in the south of Europe. The experience acquired in the construction and operation of the station and management of the logistics neededto supply raw material - key to the success of the project - has allowed the Company to launch new initiatives and there are fi ve plants operating today.

ACCIONA is an outstanding benchmark in developing biomass plants in Spain

The Company has just commissioned, in the last four months of 2010, installations at Briviesca (Burgos province), and Miajadas (Caceres), both generating 16 MW. With those, ACCIONA now has an installed biomass capacity of 65 MW in Spain, a market share of 11%.

The two plants together represent an investment of around 100 million euros. Combined production will be some 256 million kilowatts an hour, equivalent to supplying 80,000 homes, which will avoid the emission of 246,000 metric tons of CO2 from coal stations per year. In terms of employment, each station created 300 jobs during construction and represents 100 direct or induced posts now it is in the operational phase (25 at each plant).

ACCIONA has five other projects being developed which will generate another 82 MW - two in Castile-La Mancha (at Alcázar de San Juan and Mohorte); two in Castile & Leon (Almazán and Valencia de Don Juan) and one in the Valencian Region at Utiel.

The process -transforming straw into electricity

  • Reception & unloading of straw
    The straw bales arrive in trucks and are unloadedby crane bridges which weigh them and measure their humidity before depositing them in the warehouse, which can store enough straw for three days at full load.
  • Feeding the boiler
    A conveyor belt automatically delivers the bales to the boiler. Crumbled beforehand, they fall on to a vibrating grill that favours combustion and evacuation of unburned elements.
  • Producing steam
    Combustion of the straw heats water, circulating through tubes in the walls of the boiler, and converts the water into steam.
  • Electricity generation
    Superheated steam at 520°C moves a turbine connected to a generator, producing electricity at 11 kilovolts which is then transformed up to 45 kV for its delivery to the grid.
  • Condensation and reinitiating the process
    Water vapour used in the turbine passes to back to water in the condenser. This water is cooled down by a cooling tower and the resulting water is returned to boiler in a closed circuit to reinitiate the process.
  • Recovery of residues
    The unburned residues at the bottom of the boiler are transferred to an authorized tip and the fl y ash is retained by a sleeved fi lter for it to be used for agricultural fertilizers.
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