With a claim to one-third of northwest Europe’s offshore renewables resources, Ireland is well placed geographically to capitalise on the development of this green economy
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With a claim to one-third of northwest Europe’s offshore renewables resources, Ireland is well placed geographically to capitalise on the development of this green economy. Offshore wind, wave and tidal energy are the three main sources of energy within Irish coastal waters.

3,000 MW of tidal energy, 4,500 MW of offshore wind and 31,100 MW of developable wave energy here


The Offshore Renewable Energy Development Plan (OREDP) estimated that Ireland has approximately 3,000 MW of tidal energy, 4,500 MW of offshore wind and 31,100 MW of developable wave energy (published in 2014). The annual electricity consumption in this country is currently less than 30 TWh. That requires generators of 3,500 MW to run all year round.

Fig 1: Ireland’s development potential for ocean energy 2030 adapted from OREDP 2014

If ocean energy can provide a total of 38,600 MW, we only need to access 10 per cent of these resources to more than meet our national electricity requirements. Although this does not take into consideration capacity factors (how much time the resource/generator are available to generate power), technological availability or costs, it still serves to illustrate the enormous potential that lies within our coastal waters.

The benefits of developing our ocean energy capacity are clear and may play a huge role in helping Ireland meet agreed 2020 and 2050 targets. However, there is another side to this industry, the supply chain associated with these new technologies. When looking at the costing of onshore wind farms the key sectors are:
• Installation and commissioning;
• Manufacture of turbine;
• Support structures and electrical equipment and;
• Operations and maintenance.

Fig 2: Levelised cost of electricity for wind turbines adapted from BVG associates https://bvgassociates.com/ note some of these figures have been rounded up

The cost components will be similar for offshore renewables. An indicative breakdown is given in Fig 2, right. Please note that this is adapted from one source (BVG Associates), however, there are numerous studies available, with each claiming various costs. The typical cost range across all studies is 25-40 per cent for operations and maintenance over the lifetime of the project.

Ongoing work involved in operating a plant


So what is operations and maintenance (O&M)? Operations and maintenance describes the ongoing work involved in operating a plant. For offshore wind farms, this will include routine maintenance, equipment upgrades, seabed licensing/rental, mobilisation of required transport and transmission costs. The routine maintenance may be divided into reactive, preventative and predictive maintenance costs.

Reactive maintenance (Fig 3) occurs if, and only if, a part fails. This strategy is risky as component failure can have an impact on the rest of a device, and the timing of this can be instantaneous with no lead in. Although initial costs for a reactive maintenance programme can be low, costs associated with repairs and downtime are high.

These costs are higher still in the offshore electricity generation sector, owing to the remote location of equipment. Preventative maintenance is a subset of planned maintenance, which looks to prevent failures through regular, planned maintenance works, or preventative maintenance (Fig 3).

This occurs at regular time intervals, but will not maximise the lifetime of the component, and may cause unnecessary downtime. High labour costs are associated with the implementation of a preventative maintenance programme.

Predictive maintenance (Fig 3), on the other hand, looks to continually monitor the condition of components in order to determine the need for maintenance. Predictive maintenance maximises the useful time of a component while still preventing failures. It also reduces downtime and labour costs by allowing strategic maintenance scheduling.

If condition-based monitoring techniques (predictive maintenance) are to be employed in offshore renewables, how can this be achieved? Currently, the wind industry tends to install SCADA systems to monitor sensors on various components.

This is a costly and data/energy intensive operation. Recent studies have looked to use historic data to model healthy and unhealthy operation to identify events which might trigger failures. These studies use a variety of mathematical, analytical techniques including machine-learning algorithms.

What is the size of this emerging industry? If we look to onshore wind, we can see the potential. In a recent article, IHS Markit predicted that the wind energy sector would spend a total of $40 billion on operations and maintenance between 2015 and 2025. That is $4 billion per year. As wind turbines age, the cost associated with maintenance will increase.

O&M is an ongoing direct job associated with this industry. In 2015, the SEAI produced a report which highlighted Ireland’s capacity to capture the different aspects of the onshore wind supply chain in meeting 2020 targets. As you can see in Fig 4, O&M is predicted to be more than 10 per cent of this cost, and yet we are not well positioned to capitalise on this.

Fig 4: Ireland’s onshore supply chain potential taken from https://www.seai.ie/resources/publications/A-Macroeconomic-Analysis-of-Onshore-Wind-Deployment-to-2020.pdf

“The development of the local expertise required for the long-term operations and maintenance of onshore wind would have structural importance for Ireland and provide an opportunity to capitalise both domestically and internationally on the renewable electricity sector.”

If this is true for onshore wind, think about the potential benefits if we grasp the O&M markets for offshore renewables, also. Europe has set a target of 10 per cent generation from ocean energy by 2050, which is 100 GW of economic activity.

The National Renewable Energy Laboratory in the US estimates onshore wind O&M costs of $33 per kW annually for each MW installed, with some other commentators stating this figure to be $50 per kW. Assuming similar costs for offshore wind, this gives a potential market of $3.3 billion annually in 2050, based on 100 GW capacity.

It is more likely that O&M costs for offshore will be higher, owing to the remote location of equipment and environmental considerations. If we assume offshore wind costs of $130 per kW, per year, the potential market now becomes $13 billion annually.

This emerging industry is one that we need to critically analyse. Ireland boasts a large centre of excellence in ocean energy, namely MaREI.

This Science Foundation Ireland research centre includes several institutions providing prototype development platforms and test beds as part of this initiative. We need to now consider the lifetime of these projects and the skillsets required to move forward and to realise our potential to capitalise on this growing industry.

For further information check out: http://oceanenergyireland.ie/, http://www.mria.ie/

Authors: Dr Emma Robinson is based in the School of Electrical and Electronic Engineering in Dublin Institute of Technology, where she lectures in control engineering. Her PhD was on the performance evaluation of an Open-Centre tidal turbine. She is currently looking to establish a network for condition monitoring experts and industry representatives with her co-author, Dr David McDonnell, who is based in the School of Mechanical and Design Engineering in Dublin Institute of Technology, where he lectures in engineering systems maintenance, with specific interest in the area of condition monitoring

http://www.engineersjournal.ie/wp-content/uploads/2018/05/a-emma5.jpghttp://www.engineersjournal.ie/wp-content/uploads/2018/05/a-emma5-300x300.jpgDavid O'RiordanElecDIT,MaREI,renewables
With a claim to one-third of northwest Europe’s offshore renewables resources, Ireland is well placed geographically to capitalise on the development of this green economy. Offshore wind, wave and tidal energy are the three main sources of energy within Irish coastal waters. 3,000 MW of tidal energy, 4,500 MW of...