PROGRAMS AIMED AT MARKETS THAT DO NOT CURRENTLY USE VOLUMES OF COPPER

4.1 Underground transmission

Underground cables have unique properties for transmitting power: they are out of sight, often require only a narrow band of land to install, emit no electric field and can be engineered to emit no magnetic fields, have better power loss characteristics, and can absorb emergency power loads. As a result, underground cables assist the transmission of power across:

Densely populated urban areas
Areas where land is unavailable or planning consent is difficult
Rivers and other natural obstacles
Land with outstanding natural or environmental heritage
Areas of significant or prestigious infrastructural development
Land whose value must be maintained for future urban expansion and rural development

In the past, the higher cost of undergrounding and the absence of reliability data were significant deterrents. Lower-cost production, improved technologies and increased reliability have narrowed the cost differential with overhead lines. The opportunity costs from lengthy planning delays are reduced and expense and complexity of legal cases are minimized.

Underground power cables also offer lower maintenance costs. They are less susceptible to weather-related issues, such as storm damage, interruptions, costs of storm damage surveys and precautionary storm shutdowns. In addition, extreme-high-voltage underground transmission cables contain high quantities of copper.

By targeting locations problematic for overhead transmission lines at the planning stage and by proposing partial underground cable solutions, developers can:

Gain support from stakeholders who would otherwise oppose transmission projects
Reduce or eliminate planning delays
Leverage the potentially improved lifecycle cost of undergrounding
Demonstrate to investors that business risk from emerging environmental and corporate social responsibility drivers is being managed effectively

ICA, through the European Copper Institute (ECI), has been working with Europacable and other stakeholders to deliver advocacy towards local and national authorities on the business case for partial undergrounding.

4.2 Underground cabling in the urban power distribution system

Overhead lines and underground cables have both been used for low- and medium-voltage power distribution in cities since electricity distribution systems were first constructed.

While overhead is lower in upfront costs, disadvantages are:

Poor visual impact
Line outages due to tree contact, particularly during storms
Regular need for tree trimming
Public safety concerns when conductors break due to tree or branch falling
Fires caused by contact with conductors
Electro-magnetic interference

In comparison, underground cables overcome these disadvantages and for example, additionally offer:

Lower lifetime costs in most cases
Fewer disruptions
Reduced potential for cable theft
More flexibility in route location
Improved real estate values

In South East Asia and China, ICA has been working with policy makers, utilities and standards institutions to promote undergrounding, through knowledge dissemination, capacity building and best practice sharing.

4.3 Sub-sea power cables

Sub-sea power cables are used for inter-country or island connection of power grids, as well as offshore wind farms. The market has been growing due to the demand for more inter-links, which can enhance the reliability and stability of the macro-grid, and due to demand for off-shore wind farms. Reports claim that all projects in the next four years total 111 for inter-link and 173 for wind farms, respectively, with cable lengths of about 70,000 and 45,000 km, respectively.

There is usually a metal sheath surrounding a sub-sea cable which performs two purposes:

To exclude water from internal components, in particular the primary insulation. Where water comes into contact with highly electrically stressed insulation materials, it will lead to deterioration of the insulating properties and electrical failure of the insulation.
To conduct charging and short circuit currents. Charging currents arise from capacitive losses in the insulation, which are substantial for the long length of sub-sea cables. Short circuit currents of high-magnitude arise either due to faults from other components of the electric power system or from a fault in the cable itself.

There are basically three types of sheaths for cables: extruded with lead, lead alloy or aluminum; foil laminate with aluminum or copper; and welded with copper, aluminum or stainless steel. For sub-sea applications, the established type is lead for all paper-insulated cable types. The designs of extruded XLPE and EPR insulated cables without a metal sheath are being installed at system voltages up to 33kV. Above 33 kV, cables with lead are the preferred option. The use of copper sheathing to date has been minimal. However, there is a significant growth potential for copper sheathed cables because copper:

Offers a reduced cost and lighter alternative to lead for short to medium sub-sea links embedded in the sea bed
Serves as a fall-back to lead, should this material become commercially unavailable or environmentally prohibited

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