There are three important steps involved in the conversion of biomass 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.
One of the most important factors in the efficient utilization of biomass resource is its availability in close proximity to a biomass power project. An in-depth evaluation of the available quantity of a given agricultural resource should be conducted to determine initial feasibility of a project, as well as subsequent fuel availability issues. The primary reasons for failure of biomass power projects are changes in fuel supply or demand and changes in fuel quality.
Fuel considerations that should be analyzed before embarking on a biomass power project include:
- Typical moisture content (including the effects of storage options)
- Typical yield
- Seasonality of the resource
- Proximity to the power generation site
- Alternative uses of the resource that could affect future availability or price
- Range of fuel quality
- Weather-related issues
- Percentage of farmers contracted to sell residues
Accuracy is of great importance in making fuel availability assumptions because miscalculations can greatly impact the successful operation of biomass power projects. If biomass resource is identifies as a bottle-neck in the planning stage, a power generation technology that can handle varying degrees of moisture content and particle size can be selected. Technologies that can handle several fuels in a broad category, such as agricultural residues, provide security in operation without adversely affecting combustion efficiency, operations and maintenance costs, emissions levels, and reliability.
Identification of potential sources of biomass fuel can be one of the more challenging aspects of a new biomass energy project. There are two important issues for potential biomass users:
- Consistent and reliable biomass resource supply to the facility
- Presence of harvesting, processing and supply infrastructure to provide biomass in a consistent and timely manner
Biomass as an energy source is a system of interdependent components. Economic and technical viability of this system relies on a guaranteed feedstock supply, effective and efficient conversion technologies, guaranteed markets for the energy products, and cost-effective distribution systems. The biomass system is based on the following steps:
- Biomass harvesting (or biomass collection of non-agricultural waste)
- Preparation of biomass as feedstock
- Conversion of biomass feedstock into intermediate products.
- Transformation of intermediates into final energy and other bio-based products
- Distribution and utilization of biofuels, biopower and bio-based products.