The North Sea pioneers

wind. However, the North Sea offers opportunities not only for large-scale wind energy production but also for hydrogen production and underground CO 2 storage.

The North Sea is currently the most visible place of the energy transition. Offshore gas will still be an important component over the next few years but will be coming to an end over the next few decades as fields become depleted. At the same time, offshore wind is growing exponentially in all countries surrounding the North Sea. By 2030, offshore wind parks should be able to provide the Netherlands with 11.5 GW of clean but intermittent power. This intermittency is due to the variation of wind speed being too low or too high. There is also

Figure 1. The electrolyser units for hydrogen production will be placed on the top deck of the Q13a-A platform, with crane access.

Figure 2. Schematic explanation of the hydrogen production process from desalinated seawater. Oxygen is safely disposed of.

Figure 3. The green hydrogen produced will be admixed with the oil and gas stream via the existing gas infrastructure. the question of whether the national grid can handle all of this renewable offshore energy. Although TenneT, the transport system operator for the Netherlands, is working hard to upgrade all infrastructure, the chances are that wind turbines will need to be curtailed around 2030, wasting extensive renewable energy. As standalone sectors, both the electron-based and molecule-based parts of the energy system are facing challenges.

It is time to look closer and think smarter by integrating these two sectors. With this line of thinking, existing and producing platforms could be converting the surplus of renewable wind energy into green hydrogen, storing it in depleted gas fields, and transporting it when needed via the existing gas infrastructure to the onshore grid. Trunk pipelines can handle a higher volume of molecules at a lower transportation cost compared to power cables, and they are already in place. For example, a 36 in. trunk pipeline can handle more than 10 GW of pure hydrogen, meaning there is no need for extra cables, extra investments, or to stir up the subsurface with potential damage to the marine ecosystem. This requires working together across sectors towards integrated energy systems, linking the electrons and molecules. The North Sea Energy Program is a platform that brings all players in the offshore North Sea world together to combine knowledge and fast-forward projects through studies, research, pilots, and demos.

Wise connections will reduce carbon emissions, reduce costs, make effective use of offshore space, preserve nature, and accelerate the energy transition. Good co-operation and co-ordination will enable opportunities to be seized, put the North Sea on the map as a pioneering region for the European energy transition, and provide an example to other regions of the world.

The key to unlocking the potential of integrating offshore energy systems is the PosHYdon pilot, a pioneering project to create the first offshore green hydrogen production plant in the Dutch sector of the North Sea. Under the scheme, three energy systems will be integrated on one platform: offshore wind, offshore gas, and green hydrogen.

The pilot was commissioned by Nexstep, the Dutch Association for Decommissioning and Re-Use, and TNO, the Netherlands Organisation for Applied Scientific Research, in close collaboration with the industry. On 4 July 2019, Neptune Energy’s Q13a-A platform was selected as the pilot's location.

Neptune’s Q13a-A platform is located near the Dutch coast, 13 km from The Hague. The platform is well-suited for this project. As the first fully electrified offshore oil platform in the Dutch North Sea, it saves approximately 16 500 tpy of CO 2 – equivalent to 115 500 flights from Amsterdam, the Netherlands, to Paris, France.

A proton exchange membrane (PEM) electrolyser will be placed within a sea container and installed on the platform. It will convert seawater to demineralised water through reverse osmosis and use green electricity from offshore wind to produce hydrogen. The electrolyser will have a minimum

capacity of 1 MW and produce approximately 200 Nm 3 /hr of hydrogen. The hydrogen will be admixed with the hydrocarbon stream to shore and the oxygen produced will be safely disposed of. The pilot will provide the participants with the opportunity to develop their experience of producing hydrogen in an offshore environment, and will create a testing ground for innovative technologies and integrated systems.

The PosHYdon pilot is envisioned to perform several test and demonstration functions as it is the first offshore green hydrogen project, and is therefore generating interest from industries in its outcomes and learnings. It should demonstrate offshore system integration and the multiple use of existing infrastructure. It also has the aim of gathering experience with the production of green hydrogen offshore, thereby de-risking future developments, as well as determining the long-term performance of offshore power-to-gas in terms of efficiency, performance degradation, and operational cost. Other areas of interest are: to determine the dynamic load response of electrolyser technologies; to evaluate the operational, inspection, and maintenance requirements of offshore powerto-gas; to become a test centre for power-to-gas technologies in an offshore environment; and to gain insight into hydrogen admixing in natural gas streams and its impact on industrial applications. The PEM electrolyser will be operated on an oil production facility for at least one year and the facility will remain in production during the test.

Given these key learning points, the Dutch North Sea is the perfect place for this pilot. The North Sea is shallow and there are already many active wind farms, meaning that the Netherlands can harvest large amounts of wind energy for hydrogen generation. It also has an extensive network of gas infrastructure, with the two trunk transport pipelines, NOGAT and Noordgastransport, already capable of transporting hydrogen and having the capacity to do so. In addition, the trunk lines make it possible to build wind farms further off the coast over 100 km away, as more room is needed to meet the increase in energy demand, not only in the Netherlands, but also internationally. Furthermore, the Dutch government has expressed a strong interest in making offshore wind and hydrogen a cornerstone to the clean energy system of the future for the Netherlands. Last but not least, major global players in offshore energy design, installation, and operation have their base in the Netherlands.

This pilot has attracted renowned companies such as Gasunie and Eneco to also join the PosHYdon consortium. Gasunie, which manages and maintains infrastructure for the large-scale transport and storage of gases in the Netherlands and northern Germany, is already working hard to accelerate the energy transition, including several hydrogen pilots on land. The company adds value to the pilot as it has the necessary knowledge and experience with electrolysis in-house. NOGAT B.V. and Noordgastransport B.V., the owners of the respective large gas transport pipelines in the North Sea, are also key to the project, as the hydrogen generated by wind energy can be transported onshore along with natural gas via these existing pipelines.

The Netherlands is therefore in a strong position to lead the transition to a hydrogen economy for North-West Europe. By combining hydrogen, offshore natural gas, and offshore wind power, the country’s population, the economy, and the energy transition can be fuelled by supplying stable, affordable, and clean energy. The country has the North Sea for the production of wind and gas, the ports as logistical hubs, industrial clusters which are aiming to switch to green molecules, and excellent infrastructure for transport and storage which becomes available as the gas fields deplete and are closed down. If climate ambitions are to be achieved, large-scale hydrogen infrastructure is needed imminently. The PosHYdon pilot is an important step in the right direction.

In the long-term, the objective is to scale up the technology to connect to offshore wind parks situated further afield. These wind parks are currently under development, with plans beyond 2025. These wind parks will produce up to 1 GW

each, with individual wind turbines of 12 MW power currently

Figure 4. A schematic of power-to-gas offshore in an existing platform as a system integration option. Energy generated in the form of electricity is transported over a long distance to shore in the form of hydrogen through existing pipelines.

Figure 5. A scale-up vision for power-to-gas technology offshore as a system integration mechanism. The PosHYdon project focuses on achieving the first step, a pilot facility for offshore hydrogen production.

current estimation of reduction of footprint and weight. A prerequisite for this is that oil and gas platforms will have to be electrified in the near future to ensure availability of electricity. It is estimated that 10 - 15 platforms in the Dutch part of the North Sea are suitable for hydrogen production. Their hub function allows for the parallel processing of hydrogen, natural gas, and CO 2 storage, which stimulates the energy transition from various perspectives.

The next step of scaling up towards 1 GW will probably be

developed on dedicated offshore hubs in the form of energy islands or floating hubs such as the North Sea Wind Power Hub. These will be needed to convert the renewable power production from future far away offshore wind parks into a hydrogen stream.

The PosHYdon pilot on the Q13a-A platform of Neptune Energy in the Dutch offshore sector will be a first of its kind demonstration of offshore hydrogen production from renewable power. The pilot will be used as a test location and learning environment for the offshore production of hydrogen, the admixing of hydrogen into the hydrocarbon production stream, how it performs under harsh offshore conditions, the economics of offshore installation and operations Figure 6. Neptune Energy’s Q13a-A platform, where the PosHYdon pilot will take place. compared to onshore operation, and the safety and reliability aspects under test in Rotterdam (Haliade-X). As PosHYdon combines of offshore operations in conjunction hydrogen production with traditional oil and gas production, with oil and gas production. there are more possibilities for the co-production of hydrogen A two-year test programme (combined onshore and and oil and gas. offshore) will mimic the dynamic loads of offshore wind or

The next phase in the scaling up of offshore hydrogen solar power on the electrolyser, and offshore performance production will be to fit onto an existing offshore installation, will be compared to onshore efficiency and performance in the order of 10 MW – assuming the current footprint and degradation. weight per MW power. It is expected that the industry will drive The pilot will be a first demonstration and a stepping stone the development of electrolysers towards a smaller footprint towards the large-scale conversion of offshore wind power up and weight per MW power, including a CAPEX cost reduction to 1 GW in the next decade, which will be required to absorb from €1 million/MW towards €300 000/MW in 2030. This can the exponential growth of offshore wind power in the energy be achieved by the standardisation and upscaling of the system onshore. electrolyser stack and optimised balance of the plant. PosHYdon aims to enable a cost-effective, balanced, and

The maximum size of a power to hydrogen unit on an secure transition for the North Sea from an area of oil and gas existing offshore installation which has stopped the production production towards an area of renewable energy production of oil and gas, may be limited to approximately 250 MW in the for North-West Europe.

Alberto Morandi, USA, and Han Tiebout, the Netherlands, GustoMSC – an NOV company, discuss how naval architects and marine engineers are leading the way in adapting oil and gas knowledge and technologies for the offshore renewables industry.

The oil and gas sector is struggling with the ‘lower for longer’ – or even ‘lower forever’ – perception of oil and gas prices, while the renewables sector needs to expand fast enough to meet the goals of the Paris Agreement. A highly knowledgeable and skilled workforce struggling with a long downturn is searching for new opportunities. There is real momentum behind breaking the boundaries between the offshore oil and gas and offshore renewables industries and allowing ingenuity to be a game changer. This article discusses the energy transition and how naval architects and marine engineers are addressing the challenges of the offshore renewable energy sector by using skills from the offshore oil and gas sector.

There is a narrative where the last oil and gas drilling

boom and the present production out of these drilled wells are the final dance before the music stops. Oil demand would peak and then fall because of the rise in renewables and greater efforts to reduce carbon footprints. Either demand for fossil fuels falls due to the transition to a low carbon economy, or governments take more aggressive action against fossil fuels in response to climate change perceptions.

The Paris Agreement states that the long-term temperature goal is to keep the increase in global average temperature to well below 2˚C above pre-industrial levels. It also states that efforts to limit the increase to 1.5˚C should be pursued, as this would substantially

reduce the risks and impacts of climate change. In line with this goal, IEA Sustainable Development, Shell SKY, and Equinor Renewal suggest that oil demand will peak in the 2020s and drop to 70 - 90 million bpd by 2040.

Oil and gas investors have shown concern about the risk of their assets being stranded in a transition to a low carbon economy. This trend adds to the cost pressure from the current oversupply, leading energy companies to future-proof oil and gas projects and ensure that their production sits at the low end of the cost curve.

Some scenarios imply that by 2040, renewable energy could grow 10-fold or 20-fold relative to current levels. Such a radically steep rate of growth means that renewable energy development must address major challenges in terms of technology, scalability, and finance. In addition, it is noted that in the 20 th Century, the oil and gas industry developed in tandem with the communities around it, but in the 21 st Century, energy projects must insert themselves into communities that are much more developed and