From energy point of view, biomass is organic matter (based on carbon, hydrogen and oxygen) of non-fossil origin that has an intrinsic chemical energy content. It includes all terrestrial and aquatic vegetation, better known as virgin biomass, and all the biodegradable organic waste, such as municipal solid waste, animal waste, agricultural and forestry residues, and certain types of industrial waste.
From a regulatory point of view, biomass used for energy production can be defined according to the Legislative Decree no. 387 of 29 December 2003 - "Implementation of Directive 2001/77/EC on the promotion of electricity from renewable energy sources in the internal electricity market".
Biomass as a renewable energy source
The chemical energy contained in the biomass derives directly or indirectly from photosynthesis. Through this process, CO2 and water from the environment are used, thanks to the light energy captured from the sun, to nurture the growth of organic matter. In a nutshell, the energy contained in biomass is nothing but stored solar energy which is converted into power with null CO2 balance.
TYPES OF BIOMASS USABLE AS FUEL
Any kind of biomass based on carbon, hydrogen and oxygen (CHO) can be converted into syngas. Noticeably, the performance of the gasification process depends on the physical and chemical properties of the biomass fed. The parameters that most influence the process are the following:
- Water content: moisture in the biomass must be reduced to a very low value (<10%) before feeding the gasifier
- Ash content: ashes are inorganic compounds that do not add heating value and affect the performance of the system if present in significant quantity or with particularly low melting point
- Heating value: measures the energy content of the fuel and determines the biomass consumption of the plant at constant output
- Composition: the relative content of C and H and the chemical species prevailing in the biomass (lignin, cellulose, resins) affect the relative amount of gas, liquid and solid products of pyrogasification and their qualitative characteristics
- Size: it is a relevant parameter from the point of view of both plant and process. Too fine or dusty material does not allow the reactor bed to "breathe" properly, preventing the correct flow of the syngas. If the available biomass is too fine or dusty, the proper particle size of the material can be achieved through the production of pellets or briquette
Powermax gasification plants can be fed with a wide variety of biomass, separately or mixed.
RENEWABLE ENERGY PRODUCTION INCENTIVES
The use of biomass for the production of renewable energy is of great environmental interest and is endorsed by regulators through incentive schemes that promote its development .
The incentive paid to the production of electricity from RES (feed-in tariff) is a function of:
- | installed capacity (small plants with capacity <300kWe are favored) |
- | type of biomass used (use of by-products is favored) |
- | use of heat from high efficiency cogeneration (CHP/District Heating prizes) |
- | emissions (low emissions prize) |
The following table summarizes the structure of the feed-in tariff for the generation of electricity from biomass in Italy:
Example of feed-in tariffs in the capacity range 0÷300kWe
Most favorable cases:
A. Dedicated crops: 229 + 40 (CHP) + 30 (emissions) = 299 c€/kWh
B. By-products: 257 + 10 (CHP) + 30 (District heating) + 30 (emissions) = 327 c€/kWh
Example of feed-in tariffs in the capacity range 300÷1.000kWe
Most favorable cases:
A. Dedicated crops: 180 + 40 (CHP) + 30 (emissions) = 250 c€/kWh
B. By-products: 209 + 10 (CHP) + 30 (District heating) + 30 (emissions) = 279 c€/kWh
