Biomass feedstock cost constitutes about 35-50% of the total production cost of power. The actual percentage depends upon biomass species, yield, location, climate, local economy, and the type of systems used for harvesting, gathering and packaging, processing, storage, and transportation.
Biomass can be collected in a distributed system at the agricultural farms. The collected biomass is transported either a short distance (10-40 km) or a long distance for storage and/or pre-processing. Pre-processing may include one or a combination of several of size reduction, fractionation, sorting, and densification. The storage of wet biomass may also impart biochemical and physical modifications to the biomass termed as in-store pre processing. The pre-processed biomass is transported to the biopower facility or biorefinery where it is fed directly into the conversion reactor.
The main requirements for a successful biomass processing facility include the following:
- Identification of quality and quantity of biomass and delivery costs for its year round supply.
- Resource assessment based on available biomass species, annual yield variations, environmental factors, seasonality and competitive demands.
- Optimization based on least cost equipment and infrastructure for timely harvest, densification, storage and transport of the biomass,
- Development of regional and national strategies for locating biomass power plants and organization of supply chains with respect to biomass cost and availability.
There are three important steps involved in the conversion of agricultural waste streams into useful energy. In the first step, the biomass must be prepared for the energy conversion process. While this step is highly dependent on the waste stream and approach, drying, grinding, separating, and similar operations are common. In addition, the host facility will need material handling systems, storage, metering, and prep-yard systems and handling equipment. In the second step, the biomass waste stream must be converted into a useful fuel or steam. Finally, the fuel or steam is fed into a prime mover to generate useful electricity and heat. The moisture content of the resource is a primary factor used to select a waste to fuel conversion technology.