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
CONFIDENTIAL - DO NOT DISTRIBUTE 2
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
CONFIDENTIAL - DO NOT DISTRIBUTE 3
$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
CONFIDENTIAL - DO NOT DISTRIBUTE 4
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)
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• 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
CONFIDENTIAL - DO NOT DISTRIBUTE
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
CONFIDENTIAL - DO NOT DISTRIBUTE
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
CONFIDENTIAL - DO NOT DISTRIBUTE 8
• 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
CONFIDENTIAL - DO NOT DISTRIBUTE 9
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
CONFIDENTIAL - DO NOT DISTRIBUTE 10
MVRP is designed as a single circuit line to be
constructed on existing Right-of-Way.
MVRP
CONFIDENTIAL - DO NOT DISTRIBUTE 11
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
CONFIDENTIAL - DO NOT DISTRIBUTE 12
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
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The central portion (13.3 miles) requires relocating
one transmission line to create a new position
CONFIDENTIAL - DO NOT DISTRIBUTE 14
Step 1: Construct new 1302 15kV
Distribution Line in open position
Outage Required: None
Construction Sequencing minimizes outages:
Sample Section in Tewksbury
CONFIDENTIAL - DO NOT DISTRIBUTE 15
Step 2: Cutover new 1302
Distribution Line
Outage Required: Yes
Short duration outage to cutover 1302
distribution line
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Step 3: Remove old 1302
Distribution structures, build new
O215 230kV structures
Outage Required: None
Construct new structures for the O215 line
(in place of former 1302 structures)
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Step 4: Cutover O215 Line
Outage Required: Yes
Short duration outage to cutover O215 line
CONFIDENTIAL - DO NOT DISTRIBUTE 18
Step 5: Remove old O-215 structures,
install 3124 line
Outage Required: None
No outages for construction of new 345 kV line
CONFIDENTIAL - DO NOT DISTRIBUTE 19
• 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
CONFIDENTIAL - DO NOT DISTRIBUTE 20
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
CONFIDENTIAL - DO NOT DISTRIBUTE 21
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
CONFIDENTIAL - DO NOT DISTRIBUTE 22
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
CONFIDENTIAL - DO NOT DISTRIBUTE 23
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
CONFIDENTIAL - DO NOT DISTRIBUTE 24
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
CONFIDENTIAL - DO NOT DISTRIBUTE
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
CONFIDENTIAL - DO NOT DISTRIBUTE 26
MA DMF Recommended Time of Year Restrictions for In
Water Construction in Habitats Crossed by HVDC Cable
CONFIDENTIAL - DO NOT DISTRIBUTE 27
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
CONFIDENTIAL - DO NOT DISTRIBUTE 28
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
CONFIDENTIAL - DO NOT DISTRIBUTE 29
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
CONFIDENTIAL - DO NOT DISTRIBUTE 30
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
CONFIDENTIAL - DO NOT DISTRIBUTE 31
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
CONFIDENTIAL - DO NOT DISTRIBUTE 32
Questions?
Thank You
CONFIDENTIAL - DO NOT DISTRIBUTE 33
Appendix
CONFIDENTIAL - DO NOT DISTRIBUTE 34
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
CONFIDENTIAL - DO NOT DISTRIBUTE 35
• 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
CONFIDENTIAL - DO NOT DISTRIBUTE 36
Before After
MVRP Renderings
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