National Grid / Northeast Utilities Comparison of the AC and ......•8-mile, 345-kV underground cable from Wakefield to Woburn •8-mile Woburn - Mystic 115-kV cable bifurcated with

CONFIDENTIAL - DO NOT DISTRIBUTE

National Grid / Northeast Utilities

Comparison of the AC and HVDC Solutions

Greater Boston

Planning Advisory Committee

December 18, 2014

CONFIDENTIAL - DO NOT DISTRIBUTE 1

Two Competing Solutions:

Northeast Utilities/National Grid AC Plan and NHT HVDC Plan

Wakefield

Scobie Seabrook

345kV

Tewksbury

Woburn

Mystic

115kV

Unique to AC Plan

• Merrimack Valley Reliability Project: 24-mile, 345-kV

overhead line from Scobie to Tewksbury

• 8-mile, 345-kV underground cable from Wakefield to

Woburn

• 8-mile Woburn - Mystic 115-kV cable bifurcated with

the existing cable

Unique to HVDC Plan

• 68-mile HVDC submarine cable from Seabrook to

Mystic, including two converter stations and

interconnections at Seabrook and Mystic

• Reconductor 16 miles Sandy Pond - Tewksbury

345kV

• Bifurcate, Mystic - North Cambridge Underground

Cable 345-kV

Other Upgrades Required in Both Plans (Similar,

but not Common)

• Woburn 345/115-kV Autotransformer and Woburn

Reconfiguration

• Reconductor 9 miles Y-151 115-kV NU border to

Dracut Junction

• 2nd Mystic 345/115-kV Autotransformer

• New 3+ mile, Mystic – Chelsea 115-kV underground

cable

• Both plans have additional minor AC upgrades and

a set of common upgrades.

To Sandy

Pond


The AC plan is the clearly superior option

Comparison of the AC and HVDC Plan AC HVDC

Lower Project Costs (at least $250M less)

Shorter Construction Outages

Lower Congestion Impact during Construction

Less Complex Siting and Permitting

More New England Project Experience

Shorter Repair Time and Lower Restoration

Costs

Lower Life Cycle Costs

Superior Option


$305

$680

$315

$656$151

$124

$136

$114

$61$63

$512

$770

$519

$804

$0

$100

$200

$300

$400

$500

$600

$700

$800

$900

Unique AC

Package Projects

Unique HVDC

Package Projects

Unique AC

Package Projects

Unique HVDC

Package Projects

Co

st E

stim

ate

($

Mill

ion

s)

Additions forBPS/SVC

Minor UniqueComponents

Major UniqueComponents

Total

ISO-NE Comparison (ECI) Hybrid Estimate Presented at PAC

11/18/2014

Cost Estimates Submitted to ISO Presented at PAC

11/18/2014

The AC Plan Costs at least $250M Less than HVDC Plan

Delta =

$285M Delta =

$258M


Merrimack Valley Reliability Project (MVRP)

Construction Project Information

New overhead 345 kV line between Scobie Pond and Tewksbury substations:

•$123M investment

• $41M in MA

• $82M in NH

•24.6 miles – All in existing ROW

• 18.1 miles in NH

• 6.5 miles in MA

No Expansion of ROW Required (no “taking” of homes)


• 44% (10.8 miles) @ $4.3M / mile

no relocation of transmission

structures

• 54% (13.3 miles) @ $5.1/mile -

relocating 1 set of transmission

structures

• 2% (0.5 miles) @ $19.4 M/Mile -

relocating 3 sets of transmission

structures

MVRP involves installing a new 345kV line and

straight-forward line relocations

$123M/24.6 Miles = $5M/Mile


NHT Comparison of GSRP OH Costs is Flawed

• GSRP Complexities are greater than MVRP.

• Congested corridors - most required 4 circuits to be reconstructed

• ~ 75% of circuits required a single circuit construction using vertical

monopoles, caisson foundations.

• Actual completed costs reported to MA DPU came in less than the

filed TCA estimates

• MVRP

• Northern NH, construction is a very simple H-Frame construction,

with enough space on ROW for 10 miles.

• Direct embed structures, wood or wood equivalent

• NHT added escalation to GSRP numbers

• No escalation is included in NHT estimates

• AC Solution included escalation on all estimates

6


NHT Criticism of NSTAR UG estimates is flawed

• Average of major GB UG estimates - $7.8M/ckt mi

• Wakefield-Woburn, Mystic-Chelsea (common), Mystic-Woburn

• NHT estimates for the UG land portion of Sealink (includes AC and DC

sections) and the land portion is $8.0 M/ckt mile

• Escalation has not been as drastic as portrayed in NHT

document • Recent quotes from XLPE cable vendors are less than MN XLPE costs (Copper

prices and oil prices lower than 2008).

• Escalation included in all AC Solution estimates, and not included in NHT estimates

• In the past 10 years, NU/NStar have installed more than 150

circuit miles of UG cables in CT and MA • Estimates reflect those recent projects and extensive experience

• NSTAR owns 250 miles of UG transmission in and around Boston

7


• AC construction sequencing limits the line and station equipment outages • the AC plan requires fewer outages

• HVDC construction sequencing (and its associated AC upgrades) is more complex

• Construction of the Merrimack Valley Reliability Project (MVRP) line will produce minimal congestion.

AC Plan Has Shorter Construction Outages

AC Plan Shorter Outages = Minimal Congestion for MVRP


AC Plan Has Shorter Construction Outages

• AC Plan

• Line outages to construct MVRP

• Station equipment outages for:

• New 345kV cable interconnections at Wakefield and Woburn Stations

• New 115kV cable interconnections at Woburn and Mystic Stations

• New MVRP 345kV interconnection at Scobie

• HVDC Plan

• Line Outages to reconductor Sandy Pond – Tewksbury (Line 337)

• Station equipment outages for:

• 345 and 115 kV cable Interconnections at Seabrook and Mystic Stations

• 345kV interconnections at Mystic and North Cambridge Stations

• New 345kV Breaker at Sandy Pond


MVRP is designed as a single circuit line to be

constructed on existing Right-of-Way.

MVRP


Minimal transmission outages are anticipated over a 15

month period, most planned during light load conditions.

• Foundation work and new structures constructed with minimal outages.

• Short outages primarily for wire pulling or line cutovers at various segments of the line and

terminal work.

• Live-line techniques are used to further minimize system impact.

Overview of Outages required for MVRP Ou

tag

e

Du

rati

on

Q4

2016

Q2

2017

National Grid Outages

L1 3-5d

L2 3-5d

L3 3-5d

L4 3w

L5 3-5d

L6 3-5d

PSNH Outages

Bus 1 Outage 4d

Bus 2 Outage 4d

L1 4d

L2 4d

L3 4d

Q1

2017

Q4

2017

Q3

2017


The northern portion of MVRP (10.8 miles – NH)

constructed entirely in an open ROW position

MVRP

•Requires NO relocation of existing transmission facilities

•Primarily located in center of ROW, except for one 3 mile long section on

the eastern edge of ROW


The central portion (13.3 miles) requires relocating

one transmission line to create a new position


Step 1: Construct new 1302 15kV

Distribution Line in open position

Outage Required: None

Construction Sequencing minimizes outages:

Sample Section in Tewksbury


Step 2: Cutover new 1302

Distribution Line

Outage Required: Yes

Short duration outage to cutover 1302

distribution line


Step 3: Remove old 1302

Distribution structures, build new

O215 230kV structures


Construct new structures for the O215 line

(in place of former 1302 structures)


Step 4: Cutover O215 Line

Outage Required: Yes

Short duration outage to cutover O215 line


Step 5: Remove old O-215 structures,

install 3124 line


No outages for construction of new 345 kV line


• Flexible Outages = Scheduled to

Minimize Congestion

• No Outage or Short Duration

Outages

• Short Duration Outages and one

3 week outage (less than 3 miles)

• Short Duration Outages for line

construction

MVRP Uses Flexible Short Duration Outages

for Construction

AC Plan Shorter Outages = Minimal Congestion for MVRP


MVRP Construction – Minimal Impact on

Congestion

• London Economics International (“LEI”) performed an

economic analysis for construction of MVRP

• One 3 week outage during shoulder month of

2017

• Any impact to specific generation will be managed

and mitigated through the ISO-NE Long Term

outage coordination process


Results indicate minimal congestion

• London Economics studied two scenarios of the N-S & Boston Import interface

interrelationship to bookend their results

• Case 1:

• High Boston Import Limit and Corresponding Lower N-S

• Outage causes 94 MW reduction in N-S interface limit

• No statistically significant changes in LMPs

• Case 2:

• Low Boston Import Limit and Corresponding Higher N-S

• Outage causes 286 MW reduction in Boston Import limit

• Boston Zone LMPs in outage case rise by $1.40/MWh on average over the 3-week

period (Fall 2017); energy market costs-to-load increase in Boston Zone by $2.8

million

• The probability ( 0.1%) is extremely low - based on 2013 reported hourly

operating limits = $2,800


HVDC Plan – Sandy Pond - Tewksbury Line

Reconductoring Will Require Significant Outages

• De-energized reconductoring of the Sandy Pond - Tewksbury line assumed by ECI

• Requires multiple continuous 345kV outages over multiple spring/fall outage seasons

• Requires multiple mobilizations and de-mobilizations.

• Outages may be reduced through non-traditional ‘live-line’ techniques

• Some areas still require continuous outages for safety reasons

• Anticipate 2 Continuous, 6 week outages on Sandy Pond – Tewksbury (12 weeks total) plus approximately 35 additional daily outages

• I161 – anticipate approximately 11 Daily Outages

• Higher construction costs than estimated by ECI

• May be limited by safety/constructability considerations

• Bus outage to add Breaker at Sandy Pond

Sandy Pond - Tewksbury Line reconductoring has potential to create out-of-merit generation commitment


Station Work is More Complex for the

HVDC plan

• NU has developed detailed outage sequencing plans for the

construction work at the following stations:

• Woburn - Outage impact the same for AC and HVDC Plans

• Wakefield - 4 short duration outages for AC Plan

• Mystic - HVDC 13 long outages and AC Plan 4 long outages

• North Cambridge - 1 long outage for HVDC Plan

• NU reviewed the outage plans submitted by New Hampshire

Transmission for the plan:

• Mystic - Incomplete information

• Seabrook (HVDC Plan only) - Incomplete information and

questionable timing


HVDC Project has Unique and Complex

Permitting

Permitting off-shore transmission facilities is time-consuming

• Deepwater Cable (28 months)

• Neptune HVDC Cable (45 months):

• Comcast/NSTAR Martha’s Vineyard Cable (25 months)

Additional agency approvals including:

• NEPA Review

• MA Coastal Zone Management

• MA Ocean Management Plan

• MA Underwater Archeology Board

• MA Division of Marine Fisheries

Time-of-Year restrictions on marine construction


HVDC Plan Has More Federal and State Permitting

Environmental Reviews and Licenses Both AC Only HVDC Only

NH Site Evaluation Committee X

MA Energy Facilities Siting Board/Section 72 X

Massachusetts Environmental Policy Act (MEPA) including NHESP/MHC

review X

NEPA X

Massachusetts Ocean Management Plan X

MA Underwater Archaeology Board X

MA Division Of Marine Fisheries X

Federal and State Permits Both AC Only HVDC Only

US Army Corps Section 404/Section 10 X

USFW consultation X

MA DEP 401 WQC X

MA Waterways, Chapter 91 License X

Article 97 X

MA DOT Road Work X

DCR Road Work X

MCZM Consistency Review X

NHDOT easements/road work permits X

MA DOT/MBTA ROW Easement X

MA DOT MBTA Crossing X

MA DOT Road Crossing X

Superior Option


MA DMF Recommended Time of Year Restrictions for In

Water Construction in Habitats Crossed by HVDC Cable


AC

Solution

HVDC

Solution Discussion

Siting & Permitting

Risk • HVDC Solution has 50 mile off shore segment

• Few precedent projects in

Massachusetts waters

• Complex/hard bottom areas

• LEDPA approval

Marine Resource

Impacts • HVDC Solution crosses important fishing and

lobster areas, • mapped sea scallop habitat,

• blue mussel habitat,

• ocean quahog habitat and

• near shore surf clam areas.

Siting & Permitting

Schedule • AC Solution: 18-21 months

• HVDC Solution: > 24 months

Proponent

Experience in MA

and NH

• NU and National Grid have successfully sited

many projects comparable in scale and

complexity to the AC solution

The AC Plan is the Superior Option for Siting and

Permitting Approvals


Resiliency – 345kV OH Transmission Lines

are Extremely Reliable

• 345kV line forced outages are rare and quickly repaired

• Overwhelming majority of storm-related losses of customer service are due to the distribution system

• Recent Example: Unprecedented 2011 Halloween Snowstorm 2.5 feet of snow while trees were leafed and ground was wet

• No 345-kV outages from vegetation contact in MA or NH

• Only one 345-kV line (in CT) forced out of service from vegetation contact

• Did not cause any loss of customer service

• Source: FERC and NERC, Report on Transmission Facility Outages During the Northeast Snowstorm of October 29- 30, 2011

• Undersea Cable Failures are less frequent; however, duration for repairs are on average 1-3 months and more costly than AC Overhead repairs


Expandability - AC Systems Facilitate Future

Grid Expansion

• Expanding System to accommodate new generation is routine in AC systems and extremely challenging and expensive in HVDC systems

• Integrating Off-shore wind to the HVDC Plan would require converting the system from a two terminal HVDC system to a multi-terminal HVDC System

• High Costs

• Complex

• Requires control changes at original terminals

• Upgrades to accommodate future need, such as Mystic 7 Retirement, will be less expensive with AC Plan


HVDC Plan Has Higher Life-Cycle Costs

Than AC Plan

• Life-Cycle Costs (over 40 year life) results in a $23M to

$35M Incremental NPV Cost for HVDC Plan

• HVDC Plan –Incremental staff – estimated at 12 FTEs

(NHT’s Feb 27, 2014 Seacoast On-line Article)

• HVDC Plan - Incremental costs for HVDC Control

Replacements at 20-25 years

• HVDC Life-Cycle Cost differential may increase when

property tax differential is taken into account

• AC Plan Unique Components – O&M Costs anticipated to

be $84k per year


The AC plan is the clearly superior option

Comparison of the AC and HVDC Plan AC HVDC

Lower Project Costs (at least $250M less)

Shorter Construction Outages

Lower Congestion Impact during Construction

Less Complex Siting and Permitting

More New England Project Experience

Shorter Repair Time and Lower Restoration

Costs

Lower Life Cycle Costs

Superior Option


Questions?

Thank You


Appendix


While both plans require multiple outages to interconnect to

existing stations, the AC plan’s impact on congestion should be

less than the HVDC plan’s.

Station Outages Required

AC Plan

Outages Required

HVDC Plan

Potential Congestion / Restriction/Out-of-Merit

Dispatch Impact

Wakefield • 2, 3-5 day bus outages for

cutting in new cable

• 3-5 day line outage on 2,

345kV Lines (not

coincident)

None Potential Impact - Only for AC Plan

Woburn • 1, 345kV line outage 30

days

• 1, 345kV line outage 60

days

Same as AC Potential Impact – Same for both plans

Mystic • 3, 115kV Bus Outages

each ranging from 30 to

60 days

• 1, 345kV Line Outage ~

60 Days

• 11, 115kV Bus

Outages each ranging

from 30 to 60 days

• Coincident Outage of 2,

345kV Lines ~60Days

Potential Impact – Greater for HVDC plan

Seabrook None NHT’s plan - 10 days for

1-345kV Line outage, no

description of bus outages

Potential Impact – Only for HVDC Plan

(1) Market Sensitive Information has intentionally been removed


• National Grid & NU are well-positioned to complete regulatory processes associated with the AC project.

• Both companies have successfully sited major overhead and underground transmission projects in Massachusetts.

• EFSB approvals within the last five years include:

• NU

– Greater Springfield Reliability Project

– Lower SEMA Project

• National Grid

– Salem Underground Cable Replacement Project

– Interstate Reliability Project

– Worcester Grid Underground Cable Project

• Joint

– Hampden County Reliability Project

• DPU approvals within the last five years include:

• National Grid: Four additional overhead transmission projects

• NU: One additional transmission project; two additional underground cable projects and two substation zoning exemptions

• Joint: One additional underground cable project

• National Grid also recently received approval from the NH SEC for a new 230 kV transmission tap line in Littleton, NH -- the first NH SEC approval for a transmission project in over a decade.

• NU and National Grid have successfully coordinated multi-state approvals for joint projects:

• Greater Springfield Reliability Project (Connecticut and Massachusetts)

• Interstate Reliability Project (Connecticut, Massachusetts, and Rhode Island)

Ability to Deliver – Siting and Permitting


Before After

MVRP Renderings

Documents

National Grid / Northeast Utilities Comparison of the AC and ......•8-mile, 345-kV underground cable from Wakefield to Woburn •8-mile Woburn - Mystic 115-kV cable bifurcated with