A letter (https://acore.org/resources/letter-to-the-northeast-states-collaborative-on-hvdc-transmission-standards/) signed by 13 US clean energy and environmental organisations was sent to policymakers in coastal Atlantic states on 11 April, requesting the states complete the necessary planning and solicitation for offshore transmission systems to support the long-term growth of the offshore wind in the USA. The groups urge these states to utilise the de facto global hardware standards that have emerged through collaborative work between European utilities and the electric equipment supply chain (notably standardised 2 GW 525 kV HVDC syetms).

Initiated by the American Council on Renewable Energy (ACORE) and the American Clean Power Association (ACP), the letter details how the USA is well-positioned to benefit from what is effectively Europe’s standardised 525 kV HVDC hardware design for converter platforms and transmission cables. If adopted by Atlantic coastal states, the groups state that these de facto standards will allow offshore wind energy to increase at the scale and pace necessary to realise state energy goals.

Additional benefits of implementing these hardware standards include:

  • cost-effective access to the global supply chain;
  • quicker, scalable transmission solicitations;
  • improved certainty for offshore developers and the global and US transmission supply chain; and
  • development of less than half as many offshore grid systems, reducing environmental impacts while delivering the same amount of low-cost, clean energy.

“America cannot afford to drag its heels any longer in planning and deploying the transmission necessary to achieve the clean energy transition,” said ACORE President and CEO Ray Long. “Widespread growth in US electricity demand is going to require more energy than ever before, and offshore wind is a key component of meeting that demand. The standards for offshore transmission systems laid out in this letter will help facilitate the timely build out of the infrastructure necessary to support this critical industry.”

Reflecting broad consensus among key players in the US offshore wind business, 11 April also saw DNV, the “independent energy expert and assurance provider”, issue a set of recommendations and a timeline to build a fully functional offshore HVDC transmission network to support US offshore wind power goals. As the first phase of a Joint Industry Project (JIP) exploring the feasibility of incorporating HVDC transmission into the US grid concludes, these guidelines emerge from extensive collaboration across the sector, incorporating insights from a multitude of stakeholders. An offshore HVDC transmission system will ensure developers and investors achieve a secure return on their investments, says DNV, noting that this network is critical to achieving the Biden administration’s goal of bringing 30 GW of offshore wind power online by 2030.

The foremost recommendation from this study is for agencies, governor’s offices, developers, HVDC equipment manufacturers, and service providers to work together towards building an offshore transmission system that will unlock the full potential of offshore wind projects, meeting deadlines and budgetary constraints effectively.

Most imperative, says DNV, is an urgent need for states to focus on procuring 320 kV HVDC symmetric monopoles without AC or DC interlinks. This strategy not only safeguards ongoing project success but also helps secure continued public backing for offshore wind development. Leveraging mature technology and a larger fleet of vessels for offshore converter station transportation and installation, this approach minimises risks, providing immediate benefits to existing and upcoming offshore wind projects while bolstering public trust in the industry, argues DNV.

The study also recommends a step-by step build-up of infrastructure that takes into account the global HVDC equipment market and recent procurements and partnerships in Europe that are driving the market. The phased approach to procuring and installing an HVDC transmission network is intended to overcome current barriers and create a clear pathway to an offshore transmission network. Participants in the JIP laid out short-, mid-, and long-term milestones for building an HVDC transmission network, starting with symmetric monopoles at 320 kV, leading to a fully functional, 525 kV HVDC network with DC interlinks. Ultimately, the creation of a fully functional HVDC transmission network will maximise public benefits by increasing energy deliverability and enabling intra- and inter-regional power transfers.

“It is crucial to the success of the US offshore wind industry that state agencies and governor’s offices pay greater attention to market constraints and the evolution of offshore transmission technology,” said Richard S. Barnes, region president for Energy Systems North America at DNV.

Specific recommendations from the JIP include:

  • Establish a task force with industry and state participants to review the feasibility of AC mesh solutions given the significant supply chain constraints that have emerged since AC mesh solutions were first envisioned.
  • Enable the connection of 525 kV HVDC bipole circuits from the Northeast through the Mid-Atlantic.
  • Investigate options to reduce the size and weight requirements of offshore platforms for 525 kV HVDC bipoles.
  • Define the planning, operational, and functional performance expectations for DC interlinks between 525 kV HVDC bipoles.
  • Identify any points of interconnection and/or navigable channels that should be reserved for 525 kV HVDC bipoles.

In September 2023, the US Department of Energy awarded DNV the role of co-ordinating offshore wind and transmission developers, utilities, regional transmission operators, equipment manufacturers, and other key stakeholders to identify gaps in US HVDC standards. Additionally, DNV co-ordinated the European Union’s Horizon 2020 PROMOTioN project to research, develop and demonstrate the key technologies and regulatory and economic frameworks essential for accelerating the deployment of meshed HVDC offshore grids. The operational and market benefits of HVDC transmission technology were set out in a an ACORE-sponsored 2023 report from The Brattle Group and DNV.