A wood boiler consists primarily of five elements:
- a storage silo;
- a system of extractors and conveyers of wood pellets / chips to the fireplace;
- the boiler consists of a fireplace and a heat exchanger with the network;
- a flue gas cleaning system (dust collector);
- an ash removal system.
These plants have a very high efficiency and usefullness :
- Energetically, the efficiency of biomass boilers is excellent (90%).
- Socially, wood projects create many jobs in the forestry industry and the supply chain (1 job for 1000 tons, or about two jobs per MW).
- Environmentally, the wood is a renewable energy with no CO2 emission during the life cycle. Per KWh, wood is 2 to 5 times cheaper than photovoltaic energy, and 2 to 3 times cheaper than fuel oil.
Despite an already important role, wood as source of energy still has a significant growth potential as a means to fight climate change. It should be, according to the”Grenelle de l’Environnement”, the main contributor of renewable energy in France by 2020.
INTRODUCTION: For more than 20 years agricultural residues, mainly in the form of straw, have been used for energy generation in Denmark. In farm scale several thousand small scale boilers provide heat for the farm houses, for grain drying etc. In the heating sector straw competes with wood chips, wood pellets and natural gas to supply heat from central boiler installations connected to consumers through district heating networks. And in the larger scale straw is now also being used for power production in combined heat and power plants, either in dedicated straw boilers, or in a mixture with other fuels such as wood or coal.