Biomass conversion involves using thermal or biochemical processes to turn organic matter like wood into energy through chemical reactions. Thermal conversion uses high temperatures to produce combustible gases from wood that can be used to generate electricity and heat. Biochemical conversion processes wood into fermentable sugars to produce fuel-grade ethanol. A typical biomass conversion plant has a feed system to input wood, a boiler or gasifier, and a steam turbine or internal combustion engine to produce energy. The primary benefit is efficient, economical energy production. Portable plants under 5 megawatts are moved when local wood resources are depleted. Facilities are sited near wood sources to reduce transport costs and must meet emissions standards.

1. Frequently Asked Questions
Biomass Conversion
7/22/04
Q: What is biomass conversion?
A: Biomass conversion turns organic matter into energy through a series of chemical
reactions. For purposes of this study, these reactions are induced through thermal or
biochemical processes. Thermal conversion uses high temperatures to destroy organic matter
in wood, creating combustible products such as carbon dioxide and water. Useful energy is
extracted from these products in the form of electricity and/or heat (steam, hot water).
Biochemical conversion turns organic matter into a fermentation product (typically some form
of sugar) which is processed to yield fuel-grade ethanol and byproducts. These products are
used to produce other fuels, chemicals, heat and/or electricity.
Q: What is involved in the production process?
A: A typical combustion process involves a feed system, a boiler and a steam turbine. A
gasification process involves a feed system, a gasifier, and an internal combustion engine or
gas turbine. A pyrolysis system includes a feed system, a pyrolysis reactor, and oil collection
and storage systems. The solid residue is comparable to wood ash from efficient fireplaces. It
can be pelletized and returned to the forest as fertilizer or disposed of in a standard landfill.
Q: What is the main benefit of biomass conversion?
A: Efficient, economical energy production. For a small system producing electricity only, the
efficiency is 20 percent. A 1-megawatt facility requires 1 dry ton/hour of wood. For 7,000
hours/year of operation, 7,000 tons of dry wood is required. Using the usual convention, a 1
MW facility can provide the base power for 1,000 homes.
Q: What size and type of timber is used?
A: The idea is to use forest thinnings with no commercial value, usually defined as wood less
than 6-8 inches in diameter at chest height. The actual fuel will probably be in the form of
whole tree chips (1” x 1” x ¼”) and associated fine material.
Q: Are biomass conversion plants portable? If so, how often are they moved?
A: Portability is a function of equipment size and governed by the ability to move equipment
intact over existing roads. A typical portable system is mounted on a trailer or skid and is
smaller than five megawatts (electric equivalent). The system is moved when the resource
(forest thinnings) runs out.
- more -

2. FAQs, Biomass Conversion
Q: Where will these sites be located?
A: To minimize costs of transporting forest thinnings, facilities should be located as near to
harvest sites as possible. A number of factors are taken into consideration in siting, including
zoning requirements, grid accessibility and road infrastructure.
Q: Will these plants operate 24/7/365?
A: It depends on the plant design and end-use requirements. Typically systems will be
designed for 24/7 operations, but will actually operate less than that. For example, a small
modular system may only be operated 8-12 hours per day, 5 days a week.
Q: What is the environmental impact?
A: All conversion facilities will be permitted and must meet both state and federal emission
limits. The primary components of concern are NOx, SOx, CO, and Particulate Matter. Many
small biomass heating and CHP systems are located in schools, and are designed to minimize
noise.
Q: Does the process consume water? If so, how much?
A: This will be process specific. Some gasification processes are dry and require no water. A
facility producing steam requires water (initial inventory and makeup water). Systems that use
air-cooling instead of water-cooling towers minimize water requirements.