Biodiesel
Introduction
Biodiesel is a non-toxic, biodegradable, and renewable fuel that
can be used in diesel engines with litter or no modification.
Biodiesel can be produced from oils and sources of free fatty
acids such as animal fat, vegetable oil, and waste greases.
Biodiesel is produced by removing excess hydrocarbons from these
oils to create a shorted chain molecule that is chemically more
comparable to diesel fuel. Sodium methoxide is added to
the oil causing the mixture to settle into two simpler
constituents: glycerin and methyl ester. The methyl ester
is collected, washed, and filter to yield biodiesel. The
glycerin has several commercial uses, the most common one being
the manufacture of soap. The facility where biodiesel is
made is relatively simple and easily scaled to meet local needs.
The feedstock oil can be derived from a variety of sources
including soybean, cotton, palm, and rapeseed. Waste oil,
grease, and fats from restaurants and food processors (meat
packers) can also be used. In the U.S., soybean and corn
oil are the two most common feed stocks.
Potential for Kauai and KIUC
Given Kauai's high fuel prices and agricultural infrastructure,
biodiesel is an attractive alternative for transportation and
power production. The amounts of available restaurant
waste oil and grease are limited and too small to be considered
for power production. Dedicated oil crops would need to be
planted for large scale production. Palm oil is considered
one of the best sources of vegetable oil and is well suited for
tropical climates. The reported yield of biodiesel from
oil palms is 635-1,000 gallons per acre per year. A recent
study concluded that 17.8 million gallons could be produced from
just twenty percent of Kauai's agricultural lands. For
comparison, 2.2 million and 24 million gallons of conventional
diesel are used on Kauai each year for transportation and power
production respectively.
Cost
Capital costs for use of biodiesel are minimal as it can be
used in diesel engines with minimal modifications. Most
diesel engine manufacturers have warranted their engines for use
with 5-20% blends (B5-B20) of biodiesel. The production
cost of biodiesel ca range from being competitive with
conventional diesel to as much as 2.5 times higher depending
upon the feedstock and transportation costs. Biodiesel is
currently being sold on Maui for $2.35/gallon. However, it
is manufactured from restaurant waste oil (zero cost) and is
exempt from Maui County road tax. The levelized cost for
electricity produced from biodiesel would be between 18 to 23
cents/kW. However, KIUC is currently investigating the
price with several biodiesel suppliers.
Advantages and Disadvantages
Advantages
-
can be used in existing
equipment with little modifications
-
lower sulfur and
particulate emissions
-
utilizes existing
agricultural infrastructure and expertise
-
creates/retains
agricultural jobs
Disadvantages
