THE ENERGY INDUSTRY TIMES - OCTOBER 2016 Industry Perspective 13 Converging futures in the North Sea Obvious differences aside, what has set the business models for oil and gas and renewables apart is the attitude towards cost. When oil price is up, the longestablished 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. So much so that certain oil and gas operators, who had previously exited the renewables sector, are now considering a re-entry – with some already taking the plunge. 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. 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’ 66 kV cabling significantly steps up the voltage from the 33 kV 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 ‘wet-design’ cable ensures long-term operations without the need for a metallic barrier layer such as an extruded circular lead sheath that, until now, has typically been a large cost component of high-voltage power cables at 66 kV. With the removal of the lead sheath barrier layer the cable is also much lighter, allowing the capital costs associated with installation to be reduced, further enabling operators to deliver more power for the same amount of copper. Although the cable itself requires a small increase in outside diameter over standard 33 kV alternatives, it can deliver double the amount of power through the same conductor size, with much less than double the overall cable capital cost. 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. What’s more, the 66 kV technology allows a cable to run from the shore to field, where a distribution hub and subsea transformer can be configured to distribute power on the seabed, at typically 11 kV to suit subsea consumers such as pumps, compressors, and other subsea processing equipment. 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, 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. In return, the possibilities offered by deep-water 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 growing drive towards floating structures for offshore wind as a means of reducing the construction costs associated with building an offshore wind farm in harsh environments and difficult weather conditions, and to create more efficient and effective maintenance operations. With the Continental Shelf dropping away, floating systems are going to be an 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 – about 20 to 25 per cent 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. Interestingly, one area where this type of cable is being considered is in the deployment of renewable technology to help power the subsea needs of oil and gas operators. Projects such as the DNV-GL led WIN WIN joint-industry project are already looking at the feasibility of using a floating offshore wind turbine with battery storage and other equipment to pump water into an oil and gas well. 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. The cable design has to minimise twist and ensure the dynamic cable stays in place and responds appropriately to the motion of the vessel and the platform to safeguard its longevity and long-term performance. Once again, many of the underlying differences come down to cost. Static cables for current offshore wind farms tend to be a highly costefficient design, optimised for a range of subsea locations and often either buried or protected by additional cable protection conduits. In contrast, cables for dynamic systems are a highly engineered product that is more bespoke and can sometimes be fine-tuned to suit the specific dynamic conditions prevalent at the offshore location and precise waterdepth. We are at an interesting point in the industry where technology, across the offshore energy sector, is enabling the collaboration that market forces increasingly demand. We have already seen plenty of opportunities for renewables and oil and gas to learn from each other. But the gap between the two industries seems likely to become narrower as those lessons are embedded in technology development. And the collaborative future goes beyond the essential support technologies like cabling. Engineers are looking at the possibility of reusing oil and gas infrastructure itself for some offshore wind projects, as well as combining new infrastructure. The future will increasingly be about knowledge sharing and integration. To drive down the costs of offshore operations, the distinction between offshore renewables and offshore oil will diminish. 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. James Young is Chief Technology Officer at JDR Cables. New ways of looking at technology are enabling closer collaboration between the renewables and the oil and gas sectors, and also addressing the cost pressures faced by both. James Young Young: To drive down the costs of offshore operations, the distinction between offshore renewables and offshore oil will diminish JDR’s new horizontal lay-up machine (HLM) machine. The HLM will enable JDR to provide the next generation of reliable and safe subsea connectivity to the oil, gas and renewables sectors
Energy Industry Times October 2016
To see the actual publication please follow the link above