Writing on whiteboard

Connecting offshore wind to the grid and shaping the future of energy supply.


Siemens Energy is a market leader in connecting offshore wind to the grid, with 6.5 gigawatts (GW) connected to date and a further 4.5GW under construction. Using its state-of-the art offshore substation technology the company continues to innovate and find ways to drive down costs for developers worldwide while meeting the energy demands of the future. Here Mike Grainger, Sales Director for Transmission Solutions in the UK, discusses how.

Amongst all the changes in the world today it’s probably not gone unnoticed that the UK saw two months without generating any electricity from coal. This is the first time since the industrial revolution this has occurred, and whilst dependence on coal is diminishing from 80% 10 years ago, particularly at this time of year, this is a clear signal that the energy mix is changing significantly and moving towards low-carbon generation.


The output from renewable sources, largely made up of offshore wind, overtook fossil generation in 2019 and has continued to grow throughout 2020 which is incredible. Not only for helping us reach net zero, but also because a decade ago, there wasn’t an offshore wind sector in the UK.


It’s certainly remains exciting times in the industry, making it hard to believe it was over 10 years ago that we undertook our first project, connecting a 200MW windfarm into the grid. Remarkably, a decade later we are looking at AC projects around 900MW and DC projects over 1300MW. This is a real testament to just how far we have come in connecting offshore windfarms into the grid using innovation and technology development and utilising the skills and experience of successful project delivery that exists in our UK Manchester based team.


From a standing start in 2006 the UK now has over 8.5GW of offshore wind connected making renewable energy the source of over 30% of the UK’s electricity generation needs. 

Driving continuous improvement

The way we generate and transmit energy is ever changing, as is the way we use it and what is needed today will be different to the requirements of tomorrow. It’s because of this we remain dedicated to continued learning and improvement.

While our team in Manchester is over 200 strong, we also work closely with 65 colleagues in Hamburg and an even larger number based in Erlangen, Germany, making us a truly international business with a very strong UK focus. This also brings about an environment for learning and taking best practice from each other.


Key to offshore wind farm efficiency is the overall wind farm design, from the turbine generating the power, through the cables transmitting the energy and the on and offshore substations that clean up and stabilize the electricity connected to the grid. We have focussed and invested in an in-house team of experts in the highly specialised studies group. Led by one of our System Engineers, the team looks at the holistic performance of our systems and the projects we’re working on to drive continuous development, both technical and commercial.


Ultimately the quality and the stability of power generated must ensure the project is fully grid code compliant and that rigorous standards and performance metrics are met.


This complete view means we can really evaluate and optimise the project from a technical and commercial perspective looking at programme and cost savings. In some cases, this might include reducing cable lengths or eliminating certain types of equipment so we can deliver the best outcome for the client and greater efficiencies overall, which ultimately help reduce cost for our customers. 

Leading technology development

The technology has developed in the past decade and through innovation on our Offshore Transformer Module (OTM®) – the substation platform out at sea – we’re now building bigger and more efficient connections. One of our current projects is connecting three OTMs together which is a world’s first.


Globally, we have or are in the process of connecting over 11GW of offshore wind power to the grid, but if we’re to reach the UK industry’s goal of 50GW connected by 2050, then it’s clear there’s still a long way to go and we will need to continue to innovate.


Our focus is on achieving ‘more with less’. Collaboration with our customers and understanding their requirements has been fundamental to getting this process right. 


The way we have developed the OTM means it is high in performance but compact in size (and cost). The OTM’s are cost effective, require lower maintenance, have tidier interfaces with a simpler commercial structure and are much kinder to the environment. 


What I really like is that the solution is modular, so it’s flexible to project needs. This means we can develop one, two or three circuit solutions, on single or multiple foundations, giving power ratings over 1GW


In the future they will be supported on differing foundations; jackets, monopiles or floating as we head further offshore and towards more challenging environments. Being lighter weight means fewer and more readily available resources are needed for installation too, which adds to cost savings for the project.


The question of centralized v distributed OTM is always a hot topic, and again, having single, double and triple circuit modular solutions allows Siemens to come forward with the right solution for the project.


In our quest to continually evolve, push the boundaries and reach even loftier targets of 50GW by 2050 and net zero carbon emissions, we will continue to work alongside our stakeholders and customers.


As an industry we continue with incremental gains as the market and technology matures. We are moving towards direct current projects which will transmit the power over much greater distances, with fewer losses, so the power generated offshore reaches the homes it is intended for. With increased cable voltages will come greater power transfer so the cost and resources per megawatt of generation will decrease; and we are working on several exciting developments that will make a significant impact to future outputs. 

Innovation for the future

Never one to rest on our laurels – we continue to push not just our boundaries but also those of cable technology, and as the industry is moving towards floating turbines, floating substations will be needed to cover much larger geographical areas.

With floating comes the opportunities to service a new generation of customer. Offshore oil and gas fields require significant energy and currently burn fossil fuel. Why not supply their power from wind?


Interconnectors link countries and have significant subsea cable routes. Why not connect windfarms to the interconnectors.

Battery storage technology will improve and may play a key role in helping us to store the renewable energy generated and transmit it onto the grid when it is needed. Alternatively, we can today produce green hydrogen that can be blended into the natural gas supplies making them greener or taken directly to fuel vehicles. Green hydrogen is only just beginning its journey to help decarbonise the world.


The announcement from the Crown Estate, launching the UK’s first major offshore wind leasing round in a decade, is also good news, opening up the opportunity for at least 7GW of new clean energy – enough to meet the electricity needs of over six million homes. Together this will deliver a fourfold increase in operational offshore wind capacity by 2030.


In June, Crown Estate Scotland, ScotWind opened the first cycle of Leasing, designed to help Scotland achieve its net-zero emissions target by 2045. The primary purpose of ScotWind Leasing is to grant property rights for the seabed in Scottish waters for new commercial-scale offshore wind project developments. In doing so, it will provide certainty and clarity, encouraging the low-carbon energy generation needed to meet the world-leading targets committed to in The Climate Change Act.


So, whilst Siemens Energy is delivering two major UK projects, we’re ready and focused for the next round of opportunities. We are very much looking forward to working with our customers and sharing the next technological developments with them. Because, while these sites may be more complex, I believe we have the experience, technology and innovation to help our customers deliver successful, world-class projects.


I was once asked what Utopia looks like when it comes to the future of energy supply. It’s quite simple really… Creating the right amount of clean energy to meet demand and the pace of change in how we generate our electricity, in the most efficient, economical and environmentally friendly way.  Working together we are in a great position to shape the backbone of future low carbon energy systems.