Reasons Why Subsea Power Cable Fails and Ways on How to Reduce Power Cable Failure

Subsea Power Cable Failure

The most rampant causes of subsea power cable causes, according to various studies conducted recently The world is on the brink of chaos accelerated by the increasing hazards and disasters engineered by climate change. The continued dependence on conventional systems (the use of fossil fuels such as natural gas, crude oil and coal) of power generation is no longer reliable hence the need for viable substitutes.

The growing natural and socioeconomic demand for renewable forms of energy generation highlights the essential role of subsea power cables. Otherwise known as submarine power cables, subsea cables are used for transmission of power from offshore wind farms and power generation centres to the offshore substations and onshore destinations. Subsea power cables are a critical infrastructure in the generation and distribution of renewable energy globally. The increasing demand for renewable power has led to an exponential increase in the number of offshore wind farms mainly in Europe and other parts of the globe. It is estimated that the demand for offshore wind farms will grow at an annual rate of 15% over the coming years, thus accounting for 45% of expected demand. This exponential growth in the demand can only mean one thing; a major scramble and astronomical demand for subsea power cables. Going by recent reports it is estimated that the global demand for power cables will grow to an estimated length of 24,103km by 2025.

The upsurge in the demand for subsea power cables and the growth being forecasted according to experts will lead to a monumental increase in the cost of repairs arising from damages or complete replacement in the days ahead. As the industry and the market continues to grow, a decline in the products quality with premature failures might become more rampant. GCube Insurance Services reported that subsea cable failures accounted for 77% of the total financial losses in global offshore wind projects in 2015. Subsea cable failures are costly to repair, and may result in a significant loss of revenue due to disruption in power supply. For example, the cost for locating and replacing a section of damaged subsea cable can vary from €0.72 million to €1.87 million.

There is a variety of subsea power cables in terms of composition, length and diameter but despite the variation the basic function of conveying electric power remains the same. Subsea cables can vary from 70mm to 210mm diametrically speaking. In terms of function there are basically two type of power cables viz the AC or High Voltage Alternating Current (AC) Cables and the High Voltage Direct Current (DC) Cables. The major differential factor when selecting between HVAC and HVDC is basically the distance to be covered. For a route length less than 80km the HVAC cable is most suitable, while distances beyond 80km is best fit for the HVDC cables.

A typical AC cable is made up of three phase cables and in its construction is either laid in a bundle three core formation or sometimes as a three separate cables. In simple terms the DC cables consists of two conductors which are either laid individually or bundled together. The DC cable construction depends on the DC system, it can either be Bi-polar or Mono-polar.

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