Renewable Energy Technology Assessments - Kauai Island Utility ...

Kaua’i Island Utility Cooperative
Renewable Energy Technology Assessments
3.1 Solid Biomass
3.0 Renewable Energy Technology
Options
Biomass is any material of recent biological origin. There is a huge variety of
biomass resources, conversion technologies, and end products, as shown in the figure
below. This report focuses on electricity generation technologies. Electricity generation
from biomass is the second most prolific source of renewable electricity generation after
hydro.
Biomass Sources Processing Fuel Products Markets
§ Forests § Drying § Solid Fuels § Electricity
- Natural regrowth § Extrusion - Charcoal § Heat
- Energy forests § Compression - Wood chips § Solid fuels e.g.(domestic)
- Forest residues § Chipping - Pellets/ briquettes § Transport
- Processing residues § Carbonization § Gaseous fuels
§ Agriculture § Anaerobic digestion - Methane
- Crop residues § Fermentation - Pyrolysis gas
- Processing residues § Gasification - Producer gas
- Energy crops § Pyrolysis § Liquid fuels
§ Wastes § Fischer tropsch
- Plant esters/oils
- Municipal etc.processors
- Ethanol
- Industrial - Methanol/alcohols
- Pyrolysis liquids
- Other liquids
Source: Renewable Energy World, March-April 2003.
Figure 3-1. Biomass Sources, Processes, Products, and Markets.
This section of the report describes solid biomass power options: direct fired
biomass and cofired biomass. Other sections describe biogas, biofuel (e.g., ethanol), and
waste to energy technologies.
3.1.1 Direct Fired Biomass
According to the US Department of Energy, there is over 40,000 MW of installed
biomass combustion capacity worldwide. The majority of this capacity is in combined
heat and power applications in the pulp and paper industry.
Direct biomass combustion power plants in operation today essentially use the
same steam Rankine cycle introduced into commercial use 100 years ago. By burning
biomass, pressurized steam is produced in a boiler and then expanded through a turbine
to produce electricity. Prior to combustion in the boiler, the biomass fuel may require
some processing to improve the physical and chemical properties of the feedstock.
Furnaces used in the combustion of biomass include spreader stoker-fired, suspensionfired,
fluidized bed, cyclone and pile burners. Advanced technologies, such as integrated
21 March 2005 3-3 Black & Veatch