70
LNG
INDUSTRY
APRIL
2016
Compared to marine diesel, power generated by
gas-powered engines can lower the emission of NO
X
by 80%
and CO
2
by 25%. The discharge of SO
2
and soot particles is
eliminated entirely when gas-powered engines are employed.
For a cruise season with 34 calls at port and an average layover
time of 10 hr, the reduction of CO
2
, for example, adds up to
320 t.
The LNG hybrid barge is the first floating liquefied gas power
plant. It possesses no propulsion of its own and is towed to its
areas of operations. With a length of 76.7 m, a width of 11.4 m
and a draught of 1.7 m, the barge carries five gas-powered
engines with a total installed electrical output of 7.5 MW. The
gas is supplied from two vacuum-insulated 15 t Type C LNG
tanks. The LNG is provided to the engines in gaseous state by
the gas processing unit (GPU), consisting of an evaporator and a
pressure control system. The barge’s extensive technical safety
equipment essentially consists of the following:
Gas lines made of double-walled stainless steel tubes, gap
filled with nitrogen.
Stainless steel collecting tanks below the LNG tanks.
Ventilation of the engine rooms with a 30-fold air exchange
per hour.
Gas warning sensor system along the gas lines, in the engine
rooms and other sensitive areas.
The principle of cogeneration is employed to generate
electricity, enabling highly efficient operation in accordance with
Germany’s Combined Heat and Power Act (KWKG). In several
stages, the heat of the running engines and exhaust gases is
extracted, achieving a thermal output of 8.8 MW.
The utilisation concept of the LNG hybrid barge consists of
summer and winter operating modes. In winter operating mode,
the barge serves as a stationary combined heat and power plant
and for six months is connected to the electrical supply network
of industry customers, the municipal natural gas network and the
district heating grid. As a self-generator of electricity, the industry
customer receives funding in accordance with the KWKG and a
prorated exemption from the EEG levy.
In summer operation, the gas generators are run to generate
power in 60 Hz and 11 kV operating mode and supply power over
a small onsite distributed generation system (isolated operation)
to the cruise ship berths. The transmission of electricity requires
technical solutions that must be safe, mobile and flexible. The
cruise ship is connected to the LNG hybrid barge via eight cables
(Figure 2).
A connector is approximately 650mm long and weighs
around 30 kg. The transfer points, barge onsite distributed
generation system and onsite distributed generation system
vessel must, if required, have the flexibility to compensate for
differences in height caused by tides and also be able to bear the
enormous weight loads of cables and connectors. A two-man
crew is needed onboard to carry and connect the cables.
The cruise ship’s power management system (control room)
sees the barge as an additional engine for generating power. By
slowly powering down and switching off the ship’s engines,
electricity production is increasingly taken over by the barge, until
all of the ship’s engines are completely shut down.
Ships with their own propulsion and carrying fuel must
basically supply themselves, i.e. the technical equipment for
external power procurement is not normally installed. Starting in
2005/2006, pre-equipped and partially equipped cruise ships
have been built and during final outfitting can be equipped with
the necessary technical requirements for the external
procurement of power. For each cruise ship, final outfitting costs
from €500 000 to €1 million and involves a shipyard stay lasting
several days. Without being technically pre-equipped, the
outfitting costs rise significantly and, in economic and technical
terms, may put retrofitting into question.
The year-round utilisation
concept
The development, construction and utilisation concept, as well
as financing, were executed by Becker Marine Systems (it is not
reliant on subsidies or grants). Through its Hybrid Port Energy
(HPE) subsidiary, the company operates the LNG hybrid barge
Figure 2.
Cables and cable handling equipment.
Figure 1.
Graph of the proportions of emissions.
