Biomass Feasibility Project Final Report - Xcel Energy

Conversion
Technology
Pile Burner
Stokers
Fluidized Bed
Combustion
Suspension
Coal-Fired
Co-firing
Fixed Bed
Gasification
Fluidized Bed
Gasification
Anaerobic
Digestion
Table V-3: Bio-Power Conversion Technology Benefits and Limitations
Potential Benefits Technical Limitations Economic Limitations
-- Very simple design
-- Cheap to build
-- Can handle wet and/or dirty fuels.
-- More efficient than pile burners
-- Low fly ash carryover
-- Efficiencies could be improved with
higher pressures, higher
temperatures, and reheat.
-- Can handle fuels w/ MCW from 15%
to 65% (1)
-- Handles fuels with high ash content,
irregularly shaped, or high MCW
-- Lower NOX & SOX
-- Fuel flexibility
-- Reduced fuel costs
-- Reduced SOX, CO2, NOX
-- Reduced disposal costs
-- May not affect efficiencies
-- Simplest design
-- Can use fuels up to 55% MCW (1)
-- Higher outputs fixed beds (1)
-- Reduced water and air pollution,
avoidance of odor, onsite power
and heat, reduced treatment costs,
reduced disposal costs
-- Up to 65% MCW
-- Cyclical operations, erratic
combustion, slow response times.
-- Emerging opportunity fuels cannot
be fired. (1)
-- Fuel sizes ≤ 3” (6)
-- Not suitable for more difficult ag.
residues like rice/wheat straw. (1)
-- More prone to NOX. (1)
-- Alkalis and free chlorine. (1)
-- May have maintenance problems
-- Fuel sizes ≤ 3” (6)
-- Small, uniform particle sizes
-- (Fuel sizes ≤ ½”) (6)
-- Fuels with low MCW
-- Benefits of co-firing occur only up
to 15% (by heat content)
-- Sensitive to gas impurities
-- Low-level gas quality.
-- Handles large, dense, uniformly
sized fuels.
-- Tar removal can be significant
-- Sensitive to gas impurities
-- Up to 55% MCW
-- Slow decomposition rate and
incomplete decomposition
-- Variations in gas flow and slow rates
of gas flow
-- Need to separate organics and
inorganics
-- O&M costs
-- Inability to follow loads
-- Variations in fuel cost
can upset profitability (1)
-- High capital costs
-- High O&M costs for fuel
preparation
-- Optimum size: 50 MW
-- Fuel drying equipment
-- Ash composition
changes and may affect
its salability
-- Lower ranges only (< 500
kW). (1)
-- Competitive with DG
power only (1)
-- Gas treatment reqs
-- Not commercially
available
-- Limited to 2-3 MW (1)
-- Electricity generation
alone is viable in niche
applications only (1)
(1) Schmidt and Pinapati, 2000 (2) Bain et al. 2003 (3) BTG, n.d. (4) Oland, 2004 (5)Craig and Mann, 1996 (6) FEMP, 2004
RESEARCH PURSUITS
In 2002, the Biomass Research and Development Technical Advisory Committee (BRDTAC)
issued a report detailing a research and development roadmap to identify public policy
measures for promoting and developing biobased fuels, power, and products. The committee,
representing a wide-range of experts, was established by the Biomass R&D Act of 2000. As a
result of their efforts, the following table of short-term and long-term bio-power research needs
were identified. These findings are presented here to provide the reader with an understanding
of what future bio-power research may be trying to address and thereby provide insights into
challenges that bio-power faces today.
An updated report from BRDTAC is due out sometime in 2007.
Page 66
Identifying Effective Biomass Strategies:
Quantifying Minnesota’s Resources and Evaluating Future Opportunities