An important decision for you as an investor in a biomass-fired plant is the choice of fuel and fuel flexibility, which will form one of the major operational costs over the decades of operational life.
Many parameters must be considered such as moisture content, sizing, texture, types, sourcing, availability and cost structure.
The fuel cost consists of raw material, harvesting, transport, chipping and handling. As the energy density of biomass is seven to ten times lower than coal on a volumetric basis and two to four times lower on a mass basis, haulage costs are correspondingly higher and this puts a natural limit on the transportation distance, typically 100 – 150 km. It is therefore obvious to source the fuel locally and to consider the different fuels available.
This can lead to the use of a variety of different, available fuels and considerations regarding their characteristics, e.g. fuel analysis including moisture content, trace elements, size distribution, fouling/slagging tendency.
One important characteristic of the AET Combustion System and the AET Biomass Boiler is the high fuel flexibility.
The AET Dosing Bin, the AET Rotary Valves and fuel chutes are designed to provide continuous and very uniform fuel feeding. The customised AET Combustion System is designed for uniform fuel injection (via the AET Spreader Stokers) and ensures that the fuel will dry, ignite and partly burn in suspension, before landing on the grate.
The AET Bio-Grate facilitates a uniform distribution of primary air across the grate surface, independent of fuel layer, and together with a powerful secondary and tertiary air system, it ensures low NOx and CO emissions. The low emission level will be independent of the fuel types.
AET has experience with many different fuels, such as
Fuel from forestry:
Uncontaminated biomass fuel from industries:
Contaminated waste wood fuels (A1 – A4 fuel or grade A – D):
The high fuel flexibility ensured by AET technology allows fuel from many sources and thereby the possibility to control and minimise the major part of the operational cost.
Trimmings from forests are used on many plants, e.g. FunderMax-Neudörfl.
Clean, recycled wood is used for example at ENGIE - BCN.
Sawmill residue is used among others by the Western Wood Energy Plant.
Residues from cereal production such as corn can be used in an AET Biomass Boiler, e.g. at Zignago Power.
Straw can be used as additional fuel, e.g. at Zignago Power.