United Kingdom

United Kingdom

Offshore: Cabling crunch will hit in five years

OFFSHORE: The offshore wind industry will face a supply chain bottleneck around 2015, because the sluggish trickle of offshore projects is discouraging supply chain companies from investing in the eye-watering amount of cabling required to make the UK's offshore dream come true. This is the stark warning from a leading electricity network supplier. "We can see lots of work in the middle of the next decade but, to realise that, we must make huge investments within the next 18-20 months, just when the market is dangerously quiet," says Matthew Knight, business development manager for Siemens Transmission and Distribution.

Over 100 GW of offshore wind projects are under development or planned in European waters. Nearly 13 GW is fully permitted, of which around 4.5 GW is being built or construction begins in the next two years. But, says Knight, by 2015 the supply chain will reach a cliff face of offshore projects. The remaining UK projects from Round 2 of site licences granted for offshore development will be proceeding just as 25 GW kicks in from Round 3, as well as 6 GW in Scottish waters, plus more in Germany and the Netherlands.

Dogger Bank, one of the UK's nine Round 3 development areas, could accommodate up to 9 GW of wind. More than 100 kilometres from the onshore grid, and with two direct current (DC) cables per circuit, it will require around 3000 kilometres of cables, which is around 1.5 years' worth of current global electricity cable capacity, says Knight. "And it is just one of the Round 3 zones," he says. Yet all elements of the supply chain are wrestling with current lack of orders, making it difficult to gear up for the expected rush.

The future in HVDC

Siemens Transmission and Distribution is considering setting up a centre of competence for its high voltage direct current (HVDC) technology aimed at the offshore market. "That involves investment in new premises and new people," says Knight. HVDC, with its ability to transmit electricity over long distances with lower losses, is better for future wind farms built far from shore than the alternating current (AC) cables more commonly used on land and closer to shore. Over long distances the savings eventually make up for the cost of converting AC to DC and then back to AC for use on the grid. With many of the next generation offshore projects being built far out to sea, HVDC will play a bigger role. With its ability to connect into different asynchronous power grids, the technology will also form the basis of a future European offshore supergrid to connect countries and hook up wind farms in the process.

Siemens and other leading HVDC manufacturers are developing HVDC voltage-sourced converter (VSC) technology. This is more compact than conventional HVDC, minimising environmental and construction costs, and is modular, making smaller staged developments possible. It is also more controllable, which gives flexible and dynamic support to AC grids, and can restore a system to operation without an external energy source. Plans for Siemens' HVDC base are advanced, says Knight, but progress is frozen until the company can be sure of the market.

Knight says that, while there is political will for offshore wind in the UK, the building cost is causing developers to pause before investing. A steady stream of projects is needed to enable economies of scale, he says.

For the supply chain, investing in the expectation of a viable market is risky. "It's what they call a cliff-edge investment," says Knight. "You stand on the edge, you spread your arms and you jump and you hope you're going to fly. Several companies are in that position at the moment. It's looking favourable but there is a huge chance of crashing at the bottom."

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