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Cable installation: Creating a new standard for industry best practice

In 10 years, the Offshore Wind Accelerator (OWA) has run over 150 projects supporting innovations that have led to both a significant reduction in the cost of energy and risk, whilst making offshore operations safer. To mark this milestone in R&D collaboration, we have selected 10 high impact innovations to showcase the breadth and depth of the programme.

cable-installation

One of the reasons offshore wind farms are expensive to run is due to cable damage. They can be hit or dragged by heavy anchors and other fishing equipment. They also have to negotiate the tidal zone – the area underwater at high tide but above water at low tide. They have to be buried deep enough to avoid erosion by the waves, but not so deep that they get too hot to carry current efficiently. In short, the business of bringing offshore electricity back to the mainland is fraught with risk. In fact, almost two thirds - 62 per cent - of the insurance claims submitted by European wind farms relate to cable damage.

This high risk makes it harder for offshore wind farms to attract the investment they need.

This risk was one of the key technical focus areas within the OWA.

We developed two innovative methods to optimise cable installation and assess the optimal number of turbines to match the export cable system.

First, we worked on standardising risk estimates for burial depths for cable installation. Because the industry had no standard way of estimating the risks of cable installation, the worst case scenario was often assumed.  As a result, cables were often installed at conservative burial depths, which made installation more expensive than necessary.

Almost two thirds - 62 per cent - of the insurance claims submitted by European wind farms relate to cable damage.

By developing a standard method for estimating the risk of different depths of burial at different locations, we filled an industry knowledge gap, reduced insurance costs, and gave developers, insurers, and installers more certainty.

Second, we studied the optimal number of turbines to match the export cable capacity.

Developers have traditionally determined the number of wind turbines to install in their wind farm based on their maximum export cable capacity. In practice, wind farms are rarely operating at maximum output; they stop for scheduled maintenance, and wind is not continuous. As a result, the cables are rarely used to their maximum potential.

By combining calculations of expected wind yields, turbine reliability, and other factors, we assessed the economically optimal number of turbines for a given export cable system, reducing costs in the process. The OWA concluded that as long as generation could be slightly reduced during infrequent times of high output to protect the cable, the cost of energy could be reduced by as much as £1/MWh.

This article is part of 10 years, 10 innovations: A summary of the impact of the Offshore Wind Accelerator

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