However, delays in the completion of new and/or upgraded transmission projects are a growing problem. One third of electricity transmission investments scheduled for 2010 were delayed, according to the European Network of Transmission System Operators (ENTSO-E), with social resistance and slower-than-expected permitting processes cited as the main reasons.
With pressure building in many locations for more powerful and more extensive electricity grids in order to accommodate wind energy, how can the cable industry help?
One part of the answer will be innovative products and technologies with the power to improve significantly the transmission efficiency of existing infrastructure. For example, the cable industry is now in a position, in many cases, to substitute traditional overhead lines (OHLs) with high-temperature low-sag (HTLS) conductors that can enable a network to operate at much higher temperatures. This, in turn, allows for capacity increases of around 50% - and all without the need for a lengthy permitting process.
Cable companies are also promoting "partial undergrounding", which should improve the social acceptability of new transmission projects. This approach helps to address the dilemma regularly faced by utilities: whether to install underground cables - which can offer accelerated permitting but which require more costly upfront investment - or to proceed with OHLs - which are cheaper but generally less acceptable to local residents.
Taking a partial undergrounding approach, OHLs are used for sections unlikely to attract public resistance, with cables going underground for shorter sections through contentious areas. There are also a variety of alternating-current (AC) and direct-current (DC) cable technologies that can be deployed in network expansion projects and that offer greater efficiency by reducing power loss and maximising distance optimisation.
In recent years, the cable industry has been gearing up for substantial electricity investments driven by an expanding global wind industry. Manufacturing capacity for both land and subsea cables has been increased at a global level. This was acknowledged by Bloomberg New Energy Finance, which reported last year that "the key European manufacturers are expected to potentially reach a manufacturing capacity up to 6,000 kilometres of HV AC and DC subsea cable cores per year by 2015".
Cable companies could offer even greater manufacturing capacity if demand grows further. But to do this, cable manufacturers need greater visibility about projects that are on the horizon and when they will go ahead. It would help if transmission utilities, with input from regulators, were able to improve their forecasting capabilities.
Nexans' offshore wind experience includes Horns Rev off the Danish coast and Belgium's Belwind. In addition, Nexans is currently involved in two UK offshore wind farms, Lincs and London Array. Our offshore experience suggests that a comprehensive approach to risk management is crucial to ensuring on-time completion of grid connection work. This includes managing supply-chain risks, but also takes in issues such as cable trenching into the seabed to prevent damage from ship anchors and fishing activities.
Pierre Kayoun is the vice-president for sales and marketing within the high-voltage and underwater cabling division of global cabling and cabling-systems firm Nexans.