Siemens Energy expands offshore grid access

HVDC offshore converter platform, grid access in Norway, 2025

“I love my job,” says Dennis Sobotta, Siemens Energy’s project manager on site for the platform. He looks up at the thirty-meter-high grey cubes: “It’s amazing to work with all these people and to follow how the HVDC platform is growing and getting closer to its sail-away.” Sobotta adds that he values contributing to Siemens Energy’s work toward a sustainable future, but admits that it’s not always clear to people what “offshore” work actually means. “When I talk to people about my job, I often have to explain that I don’t work in the oil industry—that’s what most people think ‘offshore’ is all about.”

Dennis Sobotta at the HVDC Platform Norway

In fact, the HVDC platform bears little resemblance to an oil platform at all. It features a cleanroom-style design housing advanced electrical equipment essential for integrating offshore-generated energy into the land-based power grid. While wind farms harness steady wind patterns to generate electricity some 100 kilometers off the coast, HVDC technology converts the power from alternating current (AC) to direct current (DC) and transmits it efficiently across long distances back to shore. On land, a second converter transforms the DC back into AC and feeds into the grid.

Christian Alexe at the HVDC platform in Norway

“Siemens Energy has been a pioneer from the outset, maintaining its position as a market leader for almost two decades,” says Alexe. “We’ve consistently demonstrated our performance as a reliable partner. Initially, bringing the technology offshore presented significant challenges, but once we overcame them, we continuously enhanced our capabilities from project to project—even as they were growing.”

Over the past decade, Siemens Energy has not only scaled up power capacity but also optimized the design, modularity, and integration capabilities of its offshore platforms, enabling longer transmission distances, higher efficiency, and improved grid support.

Connecting offshore wind farms to the grid is one of the most complex aspects of the energy transition, especially when space is limited on offshore platforms. For these space-constrained environments, Alexe emphasizes that direct-current gas-insulated switchgear (DC GIS) offers a decisive advantage. While a comparable air-insulated switchgear in standard configuration would require around 4,000 cubic meters, the DC GIS needs only 200 cubic meters. Moreover, it doesn’t require a dedicated room on the platform - it can be integrated directly into the space of another system.

When Denmark installed its first offshore wind farm just off its coastline in 1991, it was a modest project - 11 turbines producing less than 5 megawatts. But it sparked a transformation in how electricity is generated and delivered. Fast forward to today, and offshore wind farms are scaling up to the gigawatt range and moving even farther from land. This evolution demands new solutions for transmitting vast amounts of power over long distances. With the EU targeting more than 80 gigawatts of offshore wind by 2030, grid operators face mounting pressure to keep pace with connecting these now large-scale wind farms to the grid.

The team at HVDC offshore converter platform, grid access in Norway, 2025

“We’ve made remarkable progress since HelWin1 - one of our first HVDC platforms - went into operation in 2015 with a capacity of just 576 megawatts,” explains Alexe. “Building on our 900-megawatt standard, we’re now deploying bipolar systems that double the voltage and power, enabling each platform to transmit up to 2 gigawatts. That’s a 3.5-fold increase in transmission capacity in just a decade - an essential leap as we prepare the grid for the demands of tomorrow’s offshore wind.”

According to Alexe, turning these platforms into HVDC interconnection hubs could unlock a flexible, multi-terminal grid - but industry-wide cooperation is essential. At the same time, grid projects worldwide continue to face challenges, including long lead and approval times as well as a growing shortage of skilled workers and engineers. Siemens Energy is experiencing substantial growth in its grid business and is ramping up its factory network, including a new converter production facility in Nuremberg, Germany, a new GIS production site in Dammam, Saudi Arabia, and expanded investments in power transformer manufacturing globally.

“Siemens Energy is matching the rapid growth in grids by scaling up production, expanding its workforce, and strengthening global project delivery - meeting the energy transition head-on and providing the grid that’s needed,” Alexe points out.

HVDC offshore converter platform, Converter hall

Leading a team of up to 20 specialists, Dennis Sobotta proudly guides us to the heart of the platform - the HVDC converter room. While he finds the work deeply rewarding, it comes with its share of challenges. “Installing thousands of IGBT-based power modules across two converter rooms - all while other installation tasks are happening around us - demands meticulous planning,” he explains. “One transformer alone is 9 meters long and weighs 323 tons, and must be lowered into place with absolute precision using a crane. There’s no room for mistakes.”

Once the technical installation is complete and all equipment is safely mounted for offshore deployment, the next challenge comes into view: the weather. “Installing offshore platforms means working at sea, which I love, but it also means working in harsh conditions. I always need to have a Plan B for what we can do when the wind prevents us from lifting a massive tube to the top of the HVDC platform or completing other tasks,” explains Sobotta.

In just a few months, the HVDC platform will set off toward its offshore destination - and Sobotta will head to his next assignment, this time even farther from home: Dubai. Spending more than two years away from family might sound tough, but for Sobotta, it’s been a rewarding journey. “Both my teenage daughters have visited me on-site during projects, and I always make time to go home for family breaks,” he shares. “In fact, they’ve both been inspired by what I do. My older daughter is joining Siemens Energy this year in Finance at our Hamburg office, and my younger one is already planning to follow in my footsteps. She’s interested in field commissioning and wants to help build the next generation of offshore projects.”

HVDC offshore converter platform, shipyard, crane

Pioneers of power: Siemens Energy scaling up grid access

Two decades of leading offshore grid access

Scaling from megawatts to gigawatts

Let’s take a look inside the HVDC platform:

Building HVDC converters and the talent for the future

Pioneers of power: Siemens Energy scaling up grid access

Two decades of leading offshore grid access

Scaling from megawatts to gigawatts

Let’s take a look inside the HVDC platform:

Building HVDC converters and the talent for the future

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