POWER June 2014 - 48

FUELS
HECO Successfully Cofires Biofuel
as No. 6 Oil Substitute
The Hawaiian Electric Co. has conducted a full-scale demonstration test of a
sustainable biofuel at its 90-MW Kahe Unit 3, located on the island of
Oahu. HECO is committed to using biofuels as one means to reduce its
dependence on imported low-sulfur fuel oil and to meet the requirements
of the state's renewable portfolio standard and Clean Energy Initiative.
Robert C. Carr and David McDermott
A
ll states were not created equal, particularly
when it comes to indigenous reserves
of fossil fuels. North Dakota is
experiencing a boom in oil production, which
has increased almost 10-fold since 2005, and
natural gas production from the Marcellus
shale deposit-under New York, Pennsylvania,
and West Virginia-has increased about
13 times since 2007. In fact, oil and gas production
has been the fastest growing segment
of U.S. industry since 2007. Hawaii, on the
other hand, meets 90% of its energy needs
using imported oil.
In 2008, a partnership between the state of
Hawaii and the U.S. Department of Energy
(DOE) launched the Hawaii Clean Energy
Initiative (HCEI) with the goal of making
the state energy independent. As you might
expect, the " HCEI Road Map " relies heavily
on solar, wind, sea, and geothermal energy
sources, as well as biofuel and waste-to-energy
projects (see " Expanded Honolulu WTE
Plant Delivers Triple Benefits for Oahu " in
the March 2013 issue or online at powermag
.com). Compared to most of the U.S., Hawaii
is endowed with an abundance of renewable
energy resources.
Hawaiian Electric Co. (HECO), the largest
power generator in the state, owns several
low-sulfur fuel oil (LSFO)-fired conventional
steam plants that are candidates for cofiring
liquid biofuels. Liquid biofuels are attractive
because at least a portion of the needed supply
can be grown and refined locally as long
as the right market conditions exist. HECO
views liquid biofuels as potential " bridge fuels "
until other renewable energy resources
can be brought online in the future.
Designing the Demonstration Test
The Kahe Plant, the largest generating station
in Hawaii, consists of six oil-fired generators
with a total capacity of 650 MW (Figure 1).
HECO designed a test program to fire and
cofire (with LSFO) environmentally sustain48
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| June 2014
able crude palm oil. HECO's 90-MW, tangential-fired
Kahe Unit 3 was selected for the
full-scale cofiring project conducted between
Jan. 4 and 28, 2011. Blends using between
0% and 100% biofuel were tested between
38 MW (baseload) and 88 MW (near full
load). The test program was designed to assess
the operating limitations when using
biofuel without:
■ Major equipment modifications
■ Violating environmental compliance requirements
■
Derating generating capacity
■ Compromising the ability to operate the
unit on LSFO
Palm oil was chosen because its characteristics
are similar to those of LSFO. However,
the higher heating value of palm oil is approximately
14% less than for LSFO, which
results in increased fuel flow per burner (from
8 gpm for LSFO to 9.1 gpm for palm oil) in
order to maintain the required heat input into
the boiler and avoid boiler derating.
HECO imported 1.6 million gallons of
palm oil from Malaysia for its demonstration
project, although it plans to procure locally
produced fuels as they become available (see
sidebar). The palm oil was transported by
ship in stainless steel tanks and then stored in
a dedicated oil tank at Kahe.
A parallel fuel supply system was installed
so biofuel could be independently controlled
and fed to the boiler without LSFO cross-contamination.
The new palm oil fuel-handling
system included the addition of two new biofuel
pumps, a static blender, and a fuel heater
1. Six-unit plant. Kahe Unit 3, the test unit, is a 90-MW gross tangential-fired boiler,
originally manufactured by Combustion Engineering Corp. (now Alstom), that has design steam
conditions of 1,005F and 1,965 psig. The Kahe plant consists of six boilers fired with low-sulfur
fuel oil with a total capacity of 650 MW. Courtesy: Combustion Components Associates

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POWER June 2014

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