On October 23, the Clean Energy States Alliance (CESA), a national nonprofit coalition of public agencies and organizations working together to advance clean energy, held a webinar entitled The Costs and Benefits of Offshore Wind Transmission Options

The webinar focused on the results of two studies performed by the Brattle Group on two different approaches to offshore wind power transmission. 

As stated by the webinar’s moderator, Val Stori of CESA, “Offshore wind is playing an increasingly large and important role in helping the region meet its decarbonization goals.  Nearly 19 GW of offshore wind are planned in the Northeast United States by 2035 and with this vast amount of planned offshore wind capacity, long-term offshore grid planning is needed to facilitate the development of efficient, timely and cost effective transmission infrastructure.  States are trying to answer what types of offshore wind states are grappling with offshore wind infrastructure should be planned and they’re trying to and they’re trying to answer what types of offshore configurations would accommodate offshore wind’s rapid growth.” 

The webinar featured two speakers from Brattle Group, who discussed the findings of their studies, along with one speaker from Anbaric Development Partners, a Boston-based company that specializes in early stage development of large-scale electric transmission and storage solutions.  Anbaric has proposed offshore transmission solutions for the New England and New York regions.  The following are summaries of their presentations:

Johannes Pfeifenberger, Principal, The Brattle Group, presented the results of two the studies that the Brattle Group conducted on behalf of Anbaric; one on New England and one on New York.  The studies noted how much offshore wind was already committed (5,900MW for New England and 9,000MW for New York), which goes well beyond what the onshore grid can easily handle.  The studies looked at two alternative offshore transmission approaches:

  • Generator Lead Line Approach: Developers develop incremental amounts of OSW with project-specific generator lead lines (GLL).
  • Alternative Planned Approach: Offshore transmission and onshore grid upgrades are planned to minimize overall risks and coast of achieving offshore wind and clean energy goals.

“GLL has been the prevailing approach in the US, but in Europe we have seen them move toward the Alternative Planned Approach.  With the planned approach, if the offshore transmission is planned in coordination with the onshore upgrade, the costs will be lower.  In the reports, we’ve suggested what different solutions might look like, although there are many possibilities for this.  The studies show, however, the kind of advantages that you get from the Alternative Planned Approach. 

Although there were two different studies, one for New England and one for New York, the results are qualitatively similar.  We’ve found that the planned approach has:

  • Lower transmission costs
  • Reduced losses by using HVDC technology
  • Substantially lower impacts with less than half the landings to fisheries and environment
  • Increased generation and transmission competition
  • Improved landing point utilization (maybe further away but can absorb more power)
  • Improved third-party participation

You spend a bit more on transmission by moving to HVDC to the landing points that are more suitable to integrate the offshore wind power, but you substantially lower the onshore upgrades cost.  Upgrading the onshore grid is difficult, with local opposition, permitting issues, etc.  Spending more time to develop an offshore grid avoids a lot of the onshore grid upgrades at lower cost and lower risk in most cases.” 

Pfeifenberger noted that the GLL approach in New England would result in a much less complicated network of submarine export cables with far fewer cables landing at points that may be further away, but that can absorb more power.  For example, the planned approach would have a long submarine cable from the offshore wind farms off the south coast of Massachusetts all the way up to Boston, where there are strong substations that can absorb that power without substantial upgrades. 

Walter Graf, Senior Associate, Brattle Group, noted that the studies showed that the total costs of transmission are expected to be lower under a planned approach, perhaps substantially.  In the study for New England, the costs are somewhat higher for the offshore component, but are considerably lower for onshore, resulting in considerable overall cost savings, as shown in the following table:

ApproachOffshoreOnshoreTotal
GLL $2.7 billion $1.7 billion $4.4 billion
Planned $3.3 billion $0.55 billion $3.85 billion

“Even though the offshore wind industry in the US is just beginning, there are already substantial onshore upgrade costs with just the projects underway today [representing just the first 3,600MW].  The offshore costs are higher even though the total number of cables will be less because there will be more expensive collector stations, more expensive HVDC lines, etc.  But these are more than compensated for by the lower costs of onshore upgrades of the GLL approach.  It’s not just a cost story but also a risk story.  The planned approach reduces the risks inherent in onshore HVDC upgrades. 

The planned approach significantly reduces the amount of cable needed.  In the New England study, the amount of cable required (excluding the already contracted-for projects) would be reduced from 1,620 miles in the GLL approach to 831 miles in the planned approach.  Having fewer cables results in less impact on marine and coastal areas and fewer disruptions to other ocean users and the environment.  It is estimated that marine trenching could be reduced under the planned approach by 50-60%.  These results are similar in both New York and New England.  With the planned approach, you could group the cables into transmission corridors, which you can’t really do under the GLL approach.”

Peter Shattuck, Senior VP for Communications and President of Connecticut OceanGrid, Anbaric Development Partners, highlighted three core areas of the Brattle study:

  • The offshore wind industry in the US is starting to see these problems with the current GLL approach
  • Policymakers are beginning to take action to address some of these issues
  • The industry needs to ramp up those efforts

“We’re seeing the near-shore, easy locations taken up.  The best example of this is Cape Cod in Massachusetts, where there are three contracted projects.  The first one had $8 million in upgrade costs, the second had $200 million, while the third is projected to be $750-800 million or more.  So we’re starting to see that cost really hit.  It also highlights the risk issue.  We’ve seen onshore wind projects go all the way through the development process, sign contracts with the states and fall apart from lack of transmission to get on the grid.

We’re seeing the physical constraints in routing.  We’re not yet seeing any of these larger capacity cables come in for the projects that have been awarded.  They’re all using AC cables in the range of 400MW.  That means they’re underutilizing the shore approaches and connections to the onshore grid, but it also means there are more structures in the water. 

We know where the lease areas are now, but at some point we’ll see new lease areas.  If new bidders come in and all these landing points and interconnection areas are taken up, that could have a serious stifling effect on competition and that flows back to consumers in terms of potentially higher costs.

The encouraging signs are that there are processes and studies to address these issues.  The New Jersey Energy Master Plan made it clear that planned transmission could provide benefits and is working to determine what that actually looks like.  In Connecticut, the Integrated Resource Planning Process also has recognized transmission restraints and the need to address them.  And just recently we saw an announcement from the New England States’ Committee on Electricity that put forward a vision statement that had a significant focus on transmission to enable renewables. 

We need to ramp these efforts up.  We don’t have time to back into major onshore grid upgrades that may take potentially up to ten years to complete.  The good news now is that we have a window in the Northeast and Mid-Atlantic states, which have contracted for about 6,500MW of offshore wind.  That’s a lot of wind.  It will take some time to develop the infrastructure and the supply chain for the first wave of projects that coming through.  We’ll see the benefits of these projects and they’ll provide a window to take that step back and make an important focus on offshore transmission. 

We have the strategy and the tools that we need.  The strategy is to give transmission the attention that it needs.  In terms of the tools, the mechanisms are largely in place.  It could be state led.  There are models for this out there.  Texas has built a grid for onshore wind energy.  We think the tools are there. 

We’re seeing these problems.  They’re happening now.  We’re seeing encouraging first steps towards taking actions.”