Renewable Energy Technology Assessments - Kauai Island Utility ...

Kaua’i Island Utility Cooperative
Renewable Energy Technology Assessments
3.0 Renewable Energy Technology
Options
has been accepting waste since 1953 and was expected to close in 2004, but has recently
been given permission to operate until 2009. One cell of the landfill is already closed and
capped, with one remaining active cell. The landfill does not have an existing gas
collection and flaring system. The US EPA Landfill Methane Outreach Program
(LMOP) recently completed a feasibility study of the landfill for the County. 12 The study
estimated a 15-year sustainable power production of 0.7 MW at a production cost of 7.8
cents/kWh. However, there are a number of factors that impact these findings. The
feasibility study was based on landfill closure in 2004. Additional waste accumulated
during the extended operating period will increase landfill gas production potential to
perhaps 1 MW. Annual energy generation potential from the larger facility could be
expected to be about 7 GWh/yr. The production cost estimate is based on private
ownership and the smaller facility size. Finally, it is uncertain if the study authors
considered the higher construction and operating costs of power production facilities in
Kauai versus the mainland. Additional study on these topics would be warranted if
biogas passes the screening phase. The developable potential for landfill gas is
summarized in the following table.
Year Energy,
GWh
Table 3-8. Developable Potential from Landfill Gas.
Capacity,
MW
Notes
3 3.5 0.5 Assumes development of half of Kekaha landfill
5 7.0 1.0 Assumes full development of Kekaha landfill potential
10 7.0 1.0
20 7.0 1.0 Additional LFG may be available from future landfills,
however, this will likely just offset the expected decline
of Kekaha
3.3 Biofuels
Biofuels – liquid fuels derived from biomass – are increasingly gaining
acceptance for transportation and power generation purposes. The two most common
biofuels used today are ethanol and biodiesel. Ethanol is generally a supplement for
gasoline, while biodiesel displaces diesel. The table below introduces some of the key
characteristics of the fuels and contrasts them with conventional fuels. This section
describes the two fuels in further detail.
12 SCS Engineers for US EPA, “Landfill Gas Utilization Feasibility Study Kekaha Landfill”, April 2004.
21 March 2005 3-21 Black & Veatch