Renewable Energy Technology Assessments - Kauai Island Utility ...

Kaua’i Island Utility Cooperative
Renewable Energy Technology Assessments
a Quantity,
Resource Basis
tons/yr
Table 3-2. Kauai Biomass Resource Estimates.
Combustion
Fuel? b
Est. Heat
Content,
MBtu/ton
3.0 Renewable Energy Technology
Options
Potential
Heat,
MBtu/yr
Potential
Energy,
GWh/yr c
Potential
Capacity,
MW d
Swine Manure dry 180 No
Poultry Litter dry 1,520 e No
Bagasse Fiber dry 18,000 f Yes 16 288,000 19.9 2.8
Molasses AR 15,000 No
Cane Trash dry 37,000 Yes 16 592,000 40.8 5.8
Municipal Waste AR 80,000 g Yes 10 800,000 55.2 7.9
Sewage Sludge dry 246 Yes 14
h h h
Fats/Oil/Grease dry 800 Yes 34 27,200 1.9 0.3
Total 1,707,200 118 16.8
Source: Except as noted, tonnage estimates adapted from University of Hawaii, Hawaii Natural Energy
Institute. Energy related estimates by Black & Veatch.
Notes:
a
Basis for tonnage estimate. Dry or as-received (AR).
b
Indicates if the fuel is suitable for combustion in its raw form.
c
Potential annual electricity generation by burning the fuel in a multi-fuel power plant assuming a net
plant heat rate of 14,500 Btu/kWh.
d
Potential power capacity assuming an annual capacity factor of 80 percent.
e
Includes poultry litter from Hawaii and Maui counties.
f
Excess bagasse not currently used. Gay and Robinson processed a total of 74,000 dry tons of bagasse
in 2002 and used 56,000 dry tons to meet internal steam and power needs.
g
Estimate from landfill gas study, based on more recent data. Source: SCS Engineers for US EPA,
“Landfill Gas Utilization Feasibility Study Kekaha Landfill”, April 2004.
h
Included with municipal solid waste.
In addition to the existing resources identified, there is very good potential for
development of new biomass resources on Kauai. For example, Bill Cowern of Kauai
Mahogany has started a plantation of mahogany and eucalyptus and will soon begin
harvesting material. As of mid-2004, 1,100 acres had been planted, with a total of 3,000
acres planned. The annual maintenance of growing stock and harvesting processes will
generate significant amounts of residue, up to 35,000 air-dried tons per year when fully
operational. Mr. Cowern has indicated that he believes he will have enough residue to
generate 3 MW of power for his own use in a small power plant. 5 If used in a larger,
more efficient utility scale power plant, this same quantity of residue might be enough for
5 MW of capacity producing 35 GWh/yr of energy annually. As with bagasse, this
resource is dependent on the viability of the underlying business.
If waste agricultural resources are not present or do not develop in sufficient
quantities to support a biomass plant, dedicated energy crops could be grown on the
5 Bill Cowern (Kauai Mahagony), personal communication, June 15, 2004.
21 March 2005 3-8 Black & Veatch