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Power players: ASRY & Centrax float shipshape idea

Solving the headache of getting power to off-grid areas

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The ASRY shipyard in Bahrain
The ASRY shipyard in Bahrain
Flexible with a high power-to-weight density, the Rolls Royce Trent engine is a strategic choice for the power barges.
Flexible with a high power-to-weight density, the Rolls Royce Trent engine is a strategic choice for the power barges.
An example of the layout of a Centrax power barge.
An example of the layout of a Centrax power barge.

Getting power to remote areas for construction can be a headache for infrastructure developers, but a JV between an English firm and a Bahrain-based shipbuilder aims to simplify portable power

With the rate of industrial and civilian expansion in the Middle East ever increasing, getting power to remote regions during construction of infrastructure, industrial areas or new housing projects can be a logistical nightmare.

But an English power infrastructure construction firm has teamed up with a Bahrain-based shipbuilding company to construct what it thinks an effective answer to the problem – efficient and highly mobile floating power barges.

Headquartered in Devon, England, Centrax has been building generator sets for some 60 years, and has a well-established history in constructing offshore structures for the oil and gas industry.

Earlier this year, the company announced it had formed a joint venture with the Bahrain-based Arab Shipbuilding and Repair Yard (ASRY), in order to equip a multi-application power barge with twin Rolls-Royce Trent 60 aeroderivative gas turbine generator sets,
in an attempt to become a leader in the barge-mounted power station market.

While the idea of a power barge isn’t a new one, Peter Ward, General Manager, Sales and Marketing at Centrax, explains that several elements set the ASRY-Centrax Ltd unit apart from existing offerings.

“There’s nothing particularly new about power barges, but what we’re doing here is trying to produce a high-quality and high efficiency version of the power barge. We’re using the Rolls-Royce Trent 60 gas turbine in the generator packages, which is the most power-dense and high-powered turbine available, so that immediately gives you a very high power density on the barge,” he says.

“We’re looking at doing this as a pre-designed product, rather than as a specific
designed product for an application. Hence we formed the joint venture with ASRI to bring together our expertise on the packaging of the generator sets, with ASRI’s marine infrastructure for building barges.

It’s the first time it’s been done as a joint venture in a pre-designed application, rather than as a main contractor contracting for a specific application,” says Ward.

While it’s the first time the firm has attempted a power barge, Centrax does already have long experience in the offshore power construction market.

“We’ve done offshore platforms before - this is the first time we’ve build a generator set on a barge,” he says, “But obviously we’ve packaged very similar equipment before.

We had some connections into several potential projects and customers, so we saw that there was a need for it.

We soon realised that the key to some of the sales is actually pre-built fast delivery, because a lot of the applications are for natural disasters, and also to get power into remote areas while land-based power stations are under construction.”

While Ward says that the packaging for barge is very similar to a land-based package, some modifications around upgraded filtration, marine coatings and other subtle differences are required.

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“We build the basic generator set in the UK, ship that out to the ASRY shipyard in Bahrain where, as far as we can, it’s fully commissioned in the yard – it’s a power station ready to go,” he says.

“It’ll then be taken off to areas of need, and at the moment the main areas of interest seem to be from sub-Saharan Africa and the Middle East, where there’s large power shortages, right across to the Far East and the Philippines.

With most of the company’s equipment – Ward estimates 90 per cent – exported, most of the work to ruggedise installations for harsh environments has already been done. “We currently have projects in Siberia, which goes down to minus 50 degrees, and equipment in the Sahara, which goes up to 55 degrees,” Ward says.

“We’ve combined all that knowledge to come up with, in effect, a hybrid, but primarily for the barges, we’re looking at the higher temperatures rather than cooler.”

The joint venture is currently in the process of building the first barge, and is working on firming up orders for some specific customer built units, and the
plan is to continue to self-finance the ongoing build.

“We wouldn’t go off and build five or six without orders,” Ward says, “but there are several scenarios. We are talking to potential customers about building several barges that they will rent out, and we would build those to order. They would be financed by the customer, and they would be available to be installed wherever required.

“We are also talking to customers about specific projects where they would buy, install and operate the barges under a normal IPP agreement. We’re starting to build the first barge to kick the whole thing off, not waiting for a specific order, to get the concept launched and moving forward.”

Each power barge is capable of giving 64 megawatts at the terminals, which translates to a net export of 125 megawatts.

“Two or more of these self-contained units can be linked together, which makes a nice-sized building block for large projects,” says Ward. “It maximises the power density of the barge, and obviously that reduces the cost per kilowatt down to what we think is marketable.”

The Rolls-Royce Trent engines are also a strategic choice. “The Trent is at the forefront of gas turbine technology, hence its very high efficiency,” Ward explains. “It’s very flexible and has a high power to weight density; it will start very quickly without any real impede on its maintenance cycle, and be ready to run at 100 per
cent load within ten minutes of a cold start.”

The unit’s portability, however, is the key. At 82 metres in length, 28 metres in width and drawing 4.5 metres, it’s easily positioned close to shorelines or a fair distance up rivers.

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“For short distances they can be towed by tug, and for longer sea journeys to coastal ports, the barges would go on a transport ship,” says Ward. “If it was going to Africa, for example, we would put one or two of these barges onto a submersible vessel, take them close inshore, float them off and then tug then either up-river or to a coastal port.”

Once in place the onshore infrastructure required to accept the barges is minimal. “Basically, we’ve got the facilities for high-voltage transformers on the back of the barge, so we generate 11kV but we can transform that up to 132kV.

Those transformers we would normally expect to be supplied by the end user because they would be location specific, but the bottom line is that the minimum connections you’d need would be the high-voltage connection into the local grid.

The barge already has its own emergency generator sets on board, and accommodation, so you if you wanted to go to the extreme, you really only need an HV connection.”

Despite being designed ostensibly as a temporary solution, Ward is also confident that the barges can, and will, be used as a more permanent piece of infrastructure.

“Our feeling is that in a lot of cases, particularly where they are used to bridge the gap between concept and actual build of a land-based power station in remote areas, once they’re actually there they probably won’t move for a considerable amount of time,” he says.

“In the projects we have seen in some remote areas, once the barges are up and running, and electricity demand is continually growing, we find that even if they do build the land-based power station, there would be some sort of peaking application for the barge.”

The Trent engine is also dual-fuel, so customers are afforded the opportunity of running them on DF2 diesel oil or gas fuel, which could either be conventional piped natural gas, or supplied from an LNG vessel. “We do have options for supplying fuel barges for sitting alongside, and we can organise and supply the vessels,” Ward explains.

“They would primarily come from ASRY, but we wouldn’t do the fuel contracts – that’s the developer’s role. Running the power barge on LNG would be the most practical way of doing it.”

A big advantage to the power barge approach is timescales. Ward estimates that to build a 200 megawatt land-based power plant in Europe would take in excess of five years from concept to build. “Once we get moving with the first barge, then we’d be looking at maybe a six or seven month lead time,” Ward explains.

“Obviously you’ve got to get it to the site so we’d be looking at maybe, from early discussions to actually getting power out, about 12 months.

“With a power barge, you are able to get around a lot of the planning and logistical problems, particularly when you’re going into remote areas where the logistics of physically building a power station and commissioning it is quite a task in itself. With a barge, everything is already constructed and commissioned in a controlled environment within the yard.”

Aside from its obvious applications in disaster-struck regions and difficult to reach areas where large-scale construction is taking place, the power barges also fit the backup bill for renewable infrastructure, and the inevitable peaking periods.

“The Trent is very suited to this application – within 15 minutes we can have 125 megawatts being generated.

They’re aeroderivative so there’s no penalty for stopping and starting the machine, so you can cycle them through the day to shape the grid loading. You could have them on for two hours in the morning and two hours in the evening for the peaking periods, so they fit very well both for shaping the electrical demand curve and also as fast backup if you get a drop in wind, for example.”

The cost of a barge will depend on the customer’s requirements – items like transformers and water-treatment systems are optional – but Ward is confident that electricity generation from the unit will be competitively priced.

“In terms of dollars per kilowatt, you’re looking at somewhere between 1,000 and 1,500, depending on scope. That would depend on the customer’s requirements, and if it’s in a less onerous location they may well want to put the treatment plant onshore, for example, but it falls within that sort of price range – we think it’s comparable with commercially built fixed stations.”

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