Twenty thousand cables under the sea

Power and telecommunication cables expand their scope

By Morand Fachot

Electrical power generation and the primary sources used to produce electricity and their environmental impact, attract a lot of attention. Yet, one key element of power distribution to users is often overlooked. This oversight is equally applicable in the communication domain. The missing – but essential – link is the cables and wires sector. Submarine cables used to transmit power or to exchange electronic data or voice represent a particularly interesting and fast expanding segment of this market.

Special vessels are needed to lay submarine cables, a very complex operation (Photo: ABB) Special vessels are needed to lay submarine cables, a very complex operation (Photo: ABB)

A significant market

According to a recently-published report by the US (United States) market research company BCC Research, the global cable market was valued at some USD 127 billion in 2010. This market is expected to increase at 9,4 % CAGR (compound annual growth rate) to reach nearly USD 200 billion in 2015.

Power cables will continue to make up the bulk of demand for cable, accounting for more than three-quarters of the market. Their share was valued at nearly USD 98 billion in 2010 and is expected to increase at 9 % CAGR to reach more than USD 150 billion by 2015.

The telecom cables market is limited to the ICT (information, communications and technology) arena. It was valued at USD 29 billion in 2010 and is expected to increase at 11 % CAGR to reach USD 49 billion by 2015.

Wide range of materials

Telegraph cables, the first cables to transport a very small amount of electric power, appeared in the first half of the 19th century. Conductors were made out of copper and different materials were used to protect, insulate and allow them to cope with the environments in which they were installed, which were initially in the ground. The first submarine cable was laid between England and France in 1850.

Today, cables used for the transmission of telegraph, radio signals or data services are made of copper and optical fibres.

Power cables appeared later, in the second half of the century, with the first distribution system, installed by Thomas Edison in New York in 1882, actually using copper rods rather than cable. Nowadays cables used for power distribution are made of copper or aluminium. Of late they have also started to incorporate carbon-fibre core conductors.

The range of materials used to insulate and protect the various cables is extensive, as they must ensure proper operation in a multitude of physical environments, temperatures or under a variety of mechanical constraints.

A long history

Submarine cables were introduced shortly after the first telegraph cables were created.

From the outset, the production of submarine cables was a complex operation: many layers were required so as to protect the conductors from water ingress, mechanical and friction damage and rupture. Laying submarine cable was also an operation fraught with difficulty and beset by unknown issues.

The first transatlantic cable was laid between Newfoundland (Canada) and Ireland, a distance of some 4 000 kilometres, in 1858.

The rapid development of submarine telegraphic cable is evidence of the importance attached to this technology that has been instrumental in expanding global trade and allowing near instant communication. In 1914, more than 595 000 kilometres of submarine cables linking all continents had been laid, just 64 years after the first link between England and France was established.

Submarine power cables were introduced much later than their telegraphic counterparts, owing to the far more complex technical issues involved. Until recently they made up an insignificant share of the overall power cable sector and were used mainly to bring power to islands or offshore installations.

If submarine power and telecom cables still represent a relatively small share of the global cable market, they are set to expand considerably in the future.

Power cables

An October 2011 report by Pike Research, a firm that provides in-depth analysis of global clean technology markets, forecasts a more than five-fold increase in submarine power cable projects, from just over 60 worldwide in 2011 to more than 350 by 2020. The main drivers for this growing global demand will be:

  • the quest for new renewable energy sources, such as offshore wind and marine wave farms that need connecting to grids;
  • grid operators turning to submarine power transmission cables to help supplement or replace aging and inadequate grid infrastructures;
  • the planned interconnections between countries with spare renewable energy capacities, such as Iceland or Norway, and those in need of additional power, such as the United Kingdom or Germany;
  • the replacement of local power generation on offshore oil and gas platforms with power fed from the mainland.

Europe will lead the expansion for submarine power transmission deployments, with nearly three-quarters of all projects by 2020. From 2011 to 2015, purchasers and developers have proposed to install an additional 14 000 kilometres of HV (high-voltage) submarine cables in 53 separate projects in Europe – nearly three times the total in the last 11 years.

Data and content transmission

Nowadays, the massive expansion of the transmission of data required by the ICT sector is causing unprecedented growth of the global submarine cable network.

ACE (Africa Coast to Europe) is one project that demonstrates this admirably. Extending over 17 000 km from Penmarch in Brittany, France, to Cape Town in South Africa, this USD 700 million high-bandwidth system will be ready in 2012. Optical fibre cables, laid at depths close to 6 000 metres below sea level, will give this network a potential capacity of 5,12 TBps (terabytes per second) and help reduce the North-South digital divide.

For some installations, such as offshore wind and tide generation farms or oil and gas platforms, combined power and optical fibre cables can be fitted in the same casing.

Early IEC involvement in kind…

Work by IEC first President, William Thomson, Lord Kelvin, was essential to the successful introduction of submarine telegraph cables. Thomson was knighted in recognition of his work on the transatlantic telegraphic cable project.

He invented the Mirror galvanometer in 1858. This was the first instrument that allowed the operation of long submarine cables and made it possible to realise transmission speeds five or six times those achievable with any other instrument.

In 1870 he devised the Siphon recorder, the first instrument used on long cables that recorded the received signals.

Thomson also designed the first modern deep-sea sounding machine for assessing the depth of water, an essential piece of equipment when laying submarine cables. His Kelvite Mark IV Sounding Machine, developed with the Royal Navy between 1903 and 1906, was still being produced with only minor modifications in the 1960s.

…continuing today

Work to prepare International Standards for cables and related systems and for testing these is not new. A number of IEC TCs (Technical Committees) and SCs (Subcommittees) have been created for this purpose.

SC 18A: Electric cables for ships and fixed offshore units, brings together technical experts from 20 countries to prepare standards for testing methods or the production of certain elements such as cable sheathing and insulation.

TC 20: Electrical cables prepares International Standards for the design, testing and end-use recommendations (including current ratings) for insulated electrical power and control cables, their accessories and cable systems, for use in wiring and in power generation, distribution and transmission.

TC 86: Fibre optics, prepares standards for cables used to transmit data and voice, which are increasingly widely deployed in submarine environments.

That major submarine power cable and optical fibre producers and suppliers mention compliance of their products with IEC International Standards in their trade publicity material attests to their belief that these are essential and a true mark of quality.

Section of hybrid power / optical fibre submarine cable (Photo: ZTT) Section of hybrid power / optical fibre submarine cable (Photo: ZTT)
Special vessels are needed to lay submarine cables, a very complex operation (Photo: ABB) Special vessels are needed to lay submarine cables, a very complex operation (Photo: ABB)
Pioneer of submarine cables: IEC first President Lord Kelvin Pioneer of submarine cables: IEC first President Lord Kelvin