UNEXPLODED ORDNANCE - Wind Energy Network

INDUSTRY NEWS
Marine report recommends installation of concrete
gravity bases for deep water offshore windfarms
The impact on the marine
environment of offshore
windfarms is an important
issue. A new report supports
the inert placement of
concrete gravity bases
against the disruption of
driving steel piles into the sea
bed.
Marine report
The report, ‘A Review of Marine
Environmental Considerations
Associated with Concrete Gravity
Base Foundations in Offshore
Wind Developments’ by marine
consultancy MarineSpace
Ltd with specialist input from
ABPmer and Fjordr, examines the
environmental impact of concrete
gravity bases with particular
reference to the issue of placing
offshore wind farms in the deeper
waters associated with the Round 3 offshore
renewable programme.
Commissioned by MPA The Concrete
Centre and the Offshore Wind Gravity
Foundation Interest Group, it focuses
on the potential environment footprint of
concrete gravity bases compared with other
foundation solutions for offshore windfarms.
BMT Nigel Gee Hits Hat-Trick in 10 days
BMT Nigel Gee Ltd, a subsidiary
of BMT Group Ltd, the leading
international maritime design,
engineering and risk management
consultancy, is pleased to announce
that three new Windfarm Support
Vessels built to a BMT design have
been launched over a period of ten
days from three different shipyards,
two in Europe and one in Asia.
Vessels
The vessels range from a 19.4m propeller
driven conventional catamaran design to
a 26m Extreme Semi-Swath (XSS), fitted
with active motion damping systems
consisting of T-Foils and interceptors.
Sea trials for two of the vessels have been
completed, both of which have met all
expected performance criteria. The XSS
is currently in transit to the open sea in
order for trials to commence in the coming
weeks.
Tenders
To date, The Crown Estate has offered
five rounds of tendering for offshore
windfarms. These include Round 1, Round
2, Scotland, Round 1 and 2 extensions
and Round 3. The majority of Round 1
and 2 windfarm sites are located within
12 nautical miles of the UK coastline and
are typified by shallow water, sediment
Ed Dudson, Technical Director of BMT
Nigel Gee, comments: “To finally see
our designs come to life and take to the
water is an extremely proud moment
- so for it to happen three times in ten
days is fantastic. We are confident that
these vessels will set a new benchmark
for quality and capability in the offshore
seabed habitats and
relatively benign water
conditions. For these
sites steel monopoles
have been the
foundation construction
of choice. However, the
water depths of 20m
– 60m, more exposed
conditions of up to
200km from shore and
mixture of seabed types
of the Round 3 sites
will call for a different
construction approach
such as concrete gravity
bases, tripod, steel
jacket, suction caisson
and floating platform.
Concrete gravity
bases
Concrete gravity bases,
due to their robustness
and minimum maintenance, look set to
have the advantage over other solutions
when the harsh marine conditions of the
deeper waters of Round 3 are considered.
In addition the report has found that, when
compared with other foundation solutions,
concrete gravity foundations offer particular
environmental benefits.
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