St. George Cable Landing

Maine Aqua Ventus presented preliminary technical solutions in Spring 2017 that would bring power to shore from a subsea cable onto an existing Central Maine Power (CMP) transmission line in St. George. We collected feedback from the community that has informed the electrical engineering design. Current electrical designs are described on this page. Please contact us if you have questions or concerns about this information.

Based on community feedback, our priorities are:

  • Minimize impact to Port Clyde village
  • Minimize additional cable clutter on poles
  • Bury cables where we can

Electrical Plan

Frequently Asked Questions in St. George:

What’s in it for St. George?

  • All new equipment will be subject to St George property taxes. 
  • MAV will compensate the town for town expenses incurred as a result of this project. 
  • Upgraded power lines could result in increased dependability of electricity. 
  • MAV is open to dialogue with St. George about a formal community benefit agreement.

Will the power be sold to to Massachusetts?

The electricity generated by the project will be sold and distributed by the Central Maine Power grid to the nearest load points.

Would the transformer or STATCOM be on the shore? Will they be noisy? Could the STATCOM and 34.5 kV electricity come closer to to town?

These components would not be located on the shore. They must be located between the cable landing site and Route 73 in St. George. The STATCOM can be placed on a property behind trees or other natural screen.

Little or no sound is expected from the transformer as it does not serve electrical load and only serves as a ground reference for the cable. There may be sound from cooling fans on the STATCOM, but they are very unlikely to be heard from the edge of the 80′ x 80′ footprint.

The STATCOM would be most useful to the town in terms of reducing brown out potential for the peninsula south of Route 131/Route 73.

Where is the cable coming to shore in St. George?

We have not yet finalized the cable landing site in St. George.

Will you be landing the cable on town property? Will you be using the Cold Storage facility?

We are not considering town-owned property for cable landing. A cable landing has not yet been identified.

What sort of wear and tear will St. George roads see from construction?

Utility poles will be installed using a standard bucket truck. The STATCOM will be delivered on a tractor trailer truck and the transformer comes on a flat bed truck.

Would the added infrastructure mean more reliable electricity for St. George?

New utility poles improve system reliability and the STATCOM would provide more consistent voltage in the region.

Once the project is complete, will the infrastructure be removed?

The transformer and STATCOM can be removed after the project. The enhanced utility poles and lines will be property of Central Maine Power. The STATCOM could continue to be useful to the town in preventing brown-outs on the peninsula.

Is Electrolysis or Electro-Magnetic Fields a concern?

Based on technical aspects of the cable, we do not anticipate electrolysis or EMF will present any concern. Additional explanation is provided, below:

Electrolysis

Electrolysis can result from improper or damaged DC lines or single-phase AC cables.  However, the type of cable MAV will use has effectively zero chance of producing electrolysis. Our cable has three phase conductors next to each other with an electrical shield, and is mechanically protected by armor.  In addition to this, the induction of current from one run into another requires significant length of close parallel cable placement. Impact to any existing electrolysis issues is not expected.

Electro-magnetic fields

There are many cables along the coast, often in lobster hotspots like Rockland-Vinalhaven, and no effects on lobstering have been documented. The electrical current passing through the subsea cable will produce an electromagnetic field. However, the cable is encased in conductive sheathing (armoring), which blocks electric field radiation from entering the surrounding environment. The international scientific body of research related to EMF effects is clear—cables do not pose a threat to marine life.

The U.S. Bureau of Ocean Energy Management (BOEM) has evaluated effects of EMF from power cables by conducting in-situ studies of powered and unpowered cables using SCUBA and ROV surveys (Love, et al. 2015, 2016). Results from three years of surveys included:

  1. “Researchers did not observe any significant differences in the fish communities living around energized and unenergized cables and natural habitats;
  2. They found no compelling evidence that the EMF produced by the energized power cables in this study were either attracting or repelling fish or macro invertebrates;
  3. EMF strength dissipated relatively quickly with distance from the cable and approached background levels at about one meter from the cable; and
  4. Cable burial would not appear necessary strictly for biological reasons” (Renewable Energy in situ Power Cable Observation Final Report, BOEM, 2016).

Electrical Engineering Overview Presentation

Click here to download the full presentation file used at a public meeting held at the Town of St. George on November 27, 2017. The overview was given by Jeff Fenn, P.E., Director of Electrical Engineering at SGC Engineering, LLC at the invitation of the St. George Select Board and Planning Board. If you have questions or concerns about the presentation, please contact us.

Necessary Infrastructure Upgrades

A transformer, a STATCOM, and upgraded utility lines are needed to land a subsea cable in St. George and connect to the Central Maine Power grid.

Transformer

  • 9’ wide x 6’ deep by 6’ tall
  • Similar to existing transformer at intersection of Route 131 and 73; shown right.
  • Transformer is air cooled so there will be no vegetation within 3 feet.
  • There will be protection using curbs or bollards.
  • This transformer is used to establish a ground and not to serve load.
  • This can be located anywhere between landing and the connection with the first CMP pole.
Transformer

A standard 9′ x 6′ x 6′ transformer as seen near intersection of Route 73 and Route 131.

Power conditioning station (“STATCOM”)

  • Static Reactive Power Compensation System (STATCOM)
  • Required by CMP for voltage regulation and stability
  • This would be located next to the CMP line, as far north as Route 131/73 intersection.
  • Contains a steel container, 2-3 transformers mounted on concrete pads, and a breaker
  • Fenced in area, measuring approximately 48’ x 48’, with a 16’ wide access road around perimeter
  • Total footprint: approximately 80’ x 80’
STATCOM

An example of a STATCOM.

Underground or overhead connection to CMP

The subsea cable will bring electricity to shore at 34.5 kV. CMP currently delivered 34.5 kV power on the peninsula to the Route 131 and Route 73 intersection. In order to connect the two, existing utility poles between the transformer and Route 73/Route 131 intersection in St. George will need to be upgraded. The new poles will be approximately 5-10 feet taller than the current poles south of the Route 73/Route 131 intersection. They will look similar in height and appearance to utility poles already in place north of the Route 73/Route 131 intersection and Route 1.

Electrical Design Image

This image, provided by SGC Engineering, shows a reference utility pole with labels. Utility poles of similar height and design can be seen between Route 131/73 and Route 1.