The actual amount of heat or electricity generated by a power plant operating on the principle of biomass combustion depends not only on the chosen technology (efficiency, minimum and maximum fuel flow, etc.) and operating conditions (fuel flow, availability rate, shutdowns, maintenance operations, etc.), but more simply on the physico-chemical characteristics of the consumed fuel.
The main characteristics are:
- The elemental chemical composition of the fuel's anhydrous and moist mass ;
- The moisture content ;
- The ash and volatile values content ;
- The particle size distribution ;
- The mechanical resistance ;
- The density ;
- The calorific value.
How do biomass characteristics influence the output of a power plant or boiler?
Within the framework of assessing a fuel's energy potential, and as a first approach, the electrical power of an electricity generation plant or the thermal power of a boiler operating on biomass can be described as follows:
This formula reflects the main factors that have an impact on electrical or thermal power:
- The technology: efficiency (η in %) ;
- Operating conditions: flow rate (Q) ;
- The characteristics of the fuel: wood density (ρ), lower heat value (PCI).
Of course, these characteristics depend on temperature and pressure conditions, but also on other physico-chemical characteristics, such as the moisture content.
How can the characteristics of biomass be known?
The physico-chemical characteristics are intrinsic properties of the fuel.
The nature of the fuel (wood for example), is not the only influencing factor. A large variation in properties is observed depending on the moisture content, ash content, species, particle size distribution, etc. Some models and databases provide average statistical properties, which are useful if no sample is available.
For a given wood sample, however, these characteristics can be tested, determined, and certified by laboratory analysis tests. These tests are subject to precise standards and procedures, defined by regulation or by the profession, particularly under the impetus of ADEME, which must be observed.
Thus, for example, the lower heat value can be determined by theoretical calculation, by direct reading on a chart, or by combustion in a calorimetric bomb.
Zelya Energy supports you in validating and certifying the physico-chemical characteristics of your biomass and estimating the output of a power plant or boiler.