IEEE Electrification Magazine - March 2015 - 60

St. John

St. Thomas
Anna's Retreat
Cruz Bay

Charlotte Amalie

Annual Average of Daily Sun

Caribbean Sea

<5.6 5.8> kwh/m2

St. Croix
Christiansted

Frederiksted Southeast

Grove Place
0

10 km

Figure 5. The solar radiation of the U.S. Virgin Islands. (Source: Clean Power Research.)

(WAPA). WAPA generation assets are primarily located on St.
Thomas and St. Croix and consist of steam turbines operating on number 6 fuel oil, combustion turbines operating on
number 2 fuel oil, and a limited amount of internal combustion (diesel) generation. Capacity is derived primarily from
combustion turbines (72%) and steam
turbines (28%). The mean household
size in the U.S. Virgin Islands is 2.2
people. The total per-capita electricity
consumption, including losses and
water production, is estimated to be
the equivalent of 8,000 kWh per person per year. Thus, the total annual
household electricity consumption is
about 17,600 kWh. With an average
price of US$0.51/kWh for electricity,
the total annual household electricity
expenditure amounts to US$8,976,
which is about 28% of the median
household income (US$32,000). This
extremely high cost of energy has
seriously stifled the economic development of the U.S.
Virgin Islands.

whose heat rate has been estimated at 10,500 Btu/kWh.
To enhance the efficiency of existing generation assets,
WAPA installed waste heat recovery steam generators
(HRSGs) in St. Thomas in 1997 and St. Croix in 2010.
WAPA intends to upgrade the St. Thomas HRSGs to
increase efficiency but has not yet
established a time frame in which to
complete these upgrades.

Solar energy has the
potential to make a
meaningful
contribution to the
U.S. Virgin Islands'
energy future if it is
deployed widely.

Solar Energy

The sun in the U.S. Virgin Islands is
strong. The solar radiation map in Figure 5 shows that the U.S. Virgin
Islands have a good solar resource for
solar photovoltaic (PV) generation,
with an average solar irradiation
greater than 5.7 kWh/m2/day. Thus,
solar energy has the potential to make
a meaningful contribution to the U.S.
Virgin Islands' energy future if it is
widely deployed. The National Renewable Energy Laboratory estimates that, under a base case
scenario, 10 MW of solar PV will be deployed by 2025,
which represents between 7% and 10% of peak load.

Generation Efficiency
Because of the use of low- and high-pressure steam for
desalination, coupled with outmoded controls and nonstandardized operations procedures, WAPA's generation
fleet operates at a relatively inefficient heat rate (greater
than 15,000 Btu/kWh). This can be compared with the
heat rate for Guam, an island in the South Pacific that
also relies on number 6 and number 2 fuel oil and had a
system average heat rate of 9,720 Btu/kWh, or Hawaii,

I E E E E l e c t r i f i c ati o n M agaz ine / march 2015

Wind Energy
The consistency of the trade winds from the east provides an
excellent source of untapped power in the U.S. Virgin Islands.
This resource is particularly pronounced along the southern
coastline and exposed ridges of the islands (Figure 6). The
National Renewable Energy Laboratory estimates that, under
a base case scenario, 22.5 MW of wind will be deployed by
2025, which represents between 15% and 20% of peak load.

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