Denmark found that after correcting for wind variability and other
parameters, the load factor for UK onshore wind farms declined from a
peak of about 24 percent when new to 15 percent after 10 years and 11
percent after 15 years. For Danish onshore wind farms the decline was
slower but still significant, falling from a peak of 22 percent when new to
18 percent at age 15.
To add to the technical issues, local opposition to onshore installations
has led to the formation of numerous protest groups, with protestors
citing a variety of concerns including possible effects on health, lowered
property values, visual & noise pollution, and birds or bats falling victim
to turbine blades. The ensuing lawsuits can cause years of delay to
projects—or even lead to their cancellation.
To migitate community problems and take advantage of stronger, more
predictable ocean winds, wind farms are increasingly moving offshore,
starting with coastal areas and migrating further afield as technical
problems are surmounted.
There are several options for the turbine base, depending on the depth
of the water, including: a single column (up to 100 feet); a gravity base
structure (65 to 250 feet ); a tripod structure (65 to 250 feet); and a
tethered floating system (deep water use).
The turbine itself represents 33 to 50 percent of the costs in offshore
projects, the balance being infrastructure, maintenance, and oversight.
Larger turbines with increased energy capture make more economic
sense due to the extra infrastructure in offshore systems.
For example, the Thornton Bank wind farm, constructed 19 miles
off the Belgian coast in water ranging from 39 to 89 feet deep, contains
54 turbines for a total capacity of 325 MW. The most recent turbines,
manufactured by REPower, have 6. 15 MW rated output, a rotor sweep
of 413 feet, and weigh 470 tons (nacelle plus rotor). The turbines are
connected together by 33 kV cables; a 150 kV cable connects the whole
installation to shore.
Despite the daunting technical issues, projections for 2020 predict a
wind farm capacity of 40 GW in European waters, providing 4 percent of
the European Union’s demand for electricity. And China is aiming for 30
GW offshore by 2020, which would make it the world leader.
U.S. offshore wind projects, however, have struggled to reach
completion. The $2.6 billion Cape Wind project off Massachusetts has
been under development for 13 years, stalled by legal battles with local
fishermen and Native American tribes. And in January two local utilities,
NSTAR and National Grid, announced they would cancel power-purchase agreements with the 468-megawatt project after it missed a
Dec. 31 deadline to complete financing.
In a more encouraging development, however, Deepwater Wind LLC
received $290M in financing to start building its Block Island offshore
wind project in Rhode Island, the first one in the US. The relatively
small 30 MW wind farm will use 56 MW turbines and is scheduled to be
operational by the end of 2016. ECN
Paul Pickering has over 35 years of engineering and marketing experience in the electronics
industry, including time spent in automotive electronics, precision analog, power semiconductors,
flight simulation and robotics. Originally from the North-East of England, he has lived and
worked in Europe, the US, and Japan. He has hands-on experience in both digital and analog
circuit design, embedded software, and Web technologies. He has a B.Sc. (Hons) in Physics &
Electronics from Royal Holloway College, University of London, and has done graduate work at
Tulsa University. In his spare time he plays and teaches the guitar in the Phoenix, AZ area.
PICO ELECTRONICS, Inc.
143 Sparks Ave., Pelham, New York 10803
Call Toll Free 800-431-1064 • FAX 914-738-8225
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100-1500 VDC Output
NEW SAR SERIES!
High Voltage Isolated 100 to
1500 VDC Output
Adjustable, Down To 0 VDC Output
Output Power 3 Watts
Miniature Design: 1.1” x 0.8” x 0.4” ht.
12 grams Typical Weight
Surface Mount &
Thru Hole Models Available
Output Center Tap for Dual Output Use
Input/Output and Over/Under
Over Temperature Protection
Fully Encapsulated for Use
In Rugged Environments
Military Screening Options
per Selected MIL-STD-883
Methods with Expanded Operating
-40˚ to +85˚C
For full characteristics of these and the entire
PICO product line, see PICO’s full line catalog at