ONS 2016: Blurring lines in the North Sea

By James Young, CTO, JDR on 8/22/2016

Obvious differences aside, what has set the business models for oil and gas and renewables apart is the attitude towards cost. When the oil price is up, the long-established oil and gas sector has traditionally adopted a high-spend approach to exploration, development and extraction.

As more of a challenger industry, that is a luxury that the renewable sector has not been able to enjoy. Striving to enhance its competitiveness and in anticipation of the end of subsidy regimes in the long term, the focus on driving down costs has been embedded in offshore wind from its very inception.

So it is perhaps not surprising that, with a prolonged slump in the price per barrel, oil and gas operators are looking at the renewables sector as a potential source of cost savings. Equally, in its constant search for cost-effective innovation, the renewables sector has been eyeing up possible solutions from its oil and gas counterparts.

The idea that there could be some technology-driven convergence between oil and gas on one hand, and renewables on the other, is not as outlandish as it may have seemed only a few years ago.

Nowhere is this convergence more obvious than in the area of offshore energy generation, where technologies used by the North Sea oil and gas community are being considered by offshore wind operators, and innovations developed for wind and tidal generation are being considered by oil and gas operators.

Higher voltage, lower costs

The first area of interest is that of high-voltage cabling developed for offshore wind generation that can also be used in the oil and gas sector as a cost-competitive solution for driving large amounts of power across the seabed.

For example, new so-called ‘wet design’ 66kV cabling significantly steps up the voltage from the 33kV inter-array standard cable voltage capacity and is being adopted by a number of new wind development projects this year. The advantages of this type of cabling is that it enables power to be transmitted to and from larger turbines that are installed further offshore—essential as the industry starts to look beyond shallower waters to build its wind farms.

The cable was initially developed to support expansion of offshore wind turbine capacity to higher power generation, enabling developers to exploit more offshore wind resources including locations further away from shore. But those high-power, deeper-water characteristics also make it a suitable technology for offshore oil and gas applications.

We are already seeing some examples of a hub-style power distribution system off the coast of Cornwall in the UK, this time for wave energy. An ‘export’ power cable runs underneath the beach in the village of St Ives and travels 25 km out into the Bristol Channel to a hub, where a number of smaller cables split-off to connect different wave-energy devices, test them and enable them to transmit power back into the grid.

This kind of subsea power distribution system, and the technologies that support it, also present great opportunities to oil and gas operators, for subsea power consumption rather than generation. Interestingly, it may be possible to combine energy generation with energy consumption on the seabed, enabling oil and gas infrastructure to be powered by future tidal energy devices.

Dynamic opportunities

In return, the possibilities offered by deepwater operations give the offshore wind industry plenty of opportunity to consider the technologies and expertise residing in the oil and gas sector. There is a drive towards floating structures for offshore wind to reduce construction costs associated with building an offshore wind farm in harsh environments and create more efficient and effective maintenance operations.

With the Continental Shelf dropping away, floating systems are going to be a very interesting development in the North Sea, offering significant growth potential. When Statoil presented its view of offshore wind up to 2030, it claimed that approximately 105 GWh of installed capacity—or about 20% to 25% of the total—would be floating offshore wind.

Naturally, managing floating structures is something that the oil and gas sector has been doing for decades. And with savings in capital and operational expenditure on offer, the offshore wind industry is looking for ways of replicating its success—in particular, by deploying more dynamic power cables that can be hooked onto floating structures, floating production storage, and offloading vessels. These cables have to be capable of installation and dynamic operation underneath a floating structure and withstand all the fatigue loads and various environmental conditions throughout the cable life.

Again, it is the use of dynamic cables that are very different from standard renewable energy cables used for fixed structures that will enable this kind of system to operate and function. With static applications the cable design often has a single layer of armouring, with a roved protective outer layer comprising a series of polypropylene strings to protect the cable. For the design of dynamic systems, cable design is more complex, ensuring the cable remains torque-neutral under high tensile loads, and the outer protective layers can withstand the arduous external environment.

Collaboration and convergence

Once again, many of the underlying differences come down to cost. Static cables for current offshore wind farms tend to be a highly cost-efficient design, optimized for a range of subsea locations and often protected by additional cable protection conduits. In contrast, cables for dynamic systems are a highly engineered, bespoke product and can sometimes be fine-tuned to suit the specific conditions prevalent at the offshore location and water-depth. We are at an interesting point in the industry where technology, across the offshore energy sector, is enabling the collaboration that market forces demand.

We have already seen plenty of opportunities for renewables and oil and gas to learn from the other. And the collaborative future goes beyond essential support technologies like cabling. Engineers are looking at the possibility of reusing oil and gas infrastructure for offshore wind projects. In the near future, the conversation and the innovation will simply be about offshore energy—and reducing the offshore costs for the benefit of developers and operators alike.

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