Don Pedro Generation Life ExtensionBoard Workshop - September 22, 2020

Agenda▪ Team

▪ Value of Don Pedro

▪ Condition of Don Pedro

▪ Background

▪ Objectives

▪ Upgrade Study

▪ Benefit / Cost Analysis

▪ Project Budget & Schedule

▪ Financial Impacts

▪ Conclusions

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Team▪ TID

❑ Brad Koehn, Dan Severson, Manjot Gill, Tim Payne, Chris Martin, Wes

Monier, Willie Manuel

▪ MID

❑ James McFall, Martin Caballero, John Davids

▪ Ascend Analytics

❑ Gary Doris, Allison Weiss

▪ Stantec Consulting

❑ Don Erpenbeck, Craig Harris, Kathleen King, Uddhav Lakkundi

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Value of Don Pedro Power Plant

▪ Carbon Free Energy❑ Don Pedro produces approximately 7% of MID’s load

▪ Ancillary Services❑ Operating Reserves, Flexible Capacity, Resource Adequacy, etc.

▪ Fast Ramping❑ Hydro units can ramp up to 10MW / min making them ideal for market

dispatch and smoothing intermittent generation

▪ Flood Control❑ Bridges gap between non-generating flow and minimum spillway flow

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Condition of Don Pedro Power Plant▪ Built for 30-40 year life

❑ Commissioned in 1971, many components well beyond life span:

▪ Units 1 & 3 rotor cracks repaired, Unit 2 restricted operation

▪ Governors are obsolete

▪ Exciters are obsolete

▪ Generator controls are obsolete

▪ Stators beyond service life

▪ Wicket gates leaking

▪ Runners

▪ Generator Breakers

▪ Generator fire protection risks

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Background

▪ Balance of Plant Life Extension

❑ 50 year Life Extension Project planning began in 2010

▪ End of Life Assessment

▪ Repair, Refurbish, or Replace

❑ 2013 Balance of Plant work started

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Background▪ 2013-2019 Balance of Plant Life Extension Projects

▪ 2013 Diversion Tunnel Vent Pipe Slip Lining

▪ 2014 Diversion Tunnel Inclined Gate Certification

▪ 2015 Diversion Tunnel Slide Gate Replacement

▪ 2015 Diversion Tunnel Flow Measurement

Installation

▪ 2015 Diversion Tunnel Access Portal Installation

▪ 2015 Diversion Tunnel Fill and Vent System

Replacement

▪ 2016 Upper Laydown Grading and Security

Improvements

▪ 2017 Power Tunnel Bulkhead Gate and Controls

▪ 2017 Power Tunnel Fixedwheel Gate and Controls

▪ 2017 Power Tunnel Fill and Vent System

Replacement

▪ 2017 Fixedwheel Gate Shaft Personnel Lift

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▪ 2017 Powerhouse Draft Tube Gate Replacements

▪ 2017 Flood Control Guard Valve Replacement

▪ 2018-2019 Unit 1 and Unit 3 Rotor Repairs

▪ 2019 Main Dam Instrumentation Improvements

▪ 2019 Access Tunnel Rock Fall Protection

Improvements

▪ 2019 New Unit 4 Turbine Shutoff Valve Installation

▪ 2019 Power Tunnel Penstock Manifold Coating

▪ Miscellaneous Ancillary Equipment

Objectives

▪ Life Extension Objective:

❑ Repair, Refurbish, or Replace in the most economical method, all

necessary items in order to extend the life of the Don Pedro Power

Plant for 50 years

▪ Upgrade Study Objective:

❑ Develop upgrade options and evaluate corresponding costs and

benefits in order to aid TID and MID in determining the best course of

action in extending the life of the Don Pedro Power Plant for a

minimum of 50 years.

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Objectives▪ Workshop Objective:

❑ Present the results and details of a comprehensive analysis and

recommended alternative for the Don Pedro Generation Life Extension

Project:

▪ Alternative 3 - “Mid Up-Rate”

▪ Uprate of plant capacity from 204.7 MW to 264.3 MW

▪ Total Generation Upgrade Cost of $128M

▪ 1st Unit Online in 2023, 4th Unit Online 2026

▪ In 2026 Don Pedro Power Plant will have a full life

extension that will extend the benefits to our customers

until at least 2076

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Upgrade Study

▪ Parameters / Constraints

❑ Water Availability

▪ “Water First” Priority—releases only made if needed for irrigation, domestic

demand, flood control, or Tuolumne River

❑ Canal capacity

▪ MID’s canal: 1,800 cfs , ramp limited to +/- 1,000 cfs per hr

▪ TID’s canal: 2,500 cfs at present, ramp limited to +/- 500 cfs per hr

❑ Hydraulic conveyance and capacity (Power Tunnel)

❑ Space constraints

❑ Equipment condition and limitations (incl. transmission lines)

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Upgrade Study▪ Alternatives:

❑ Equipment Options

▪ Capacity, Efficiency, Flexibility, etc.

▪ Scenarios:

❑ Operational Considerations

▪ Energy markets, Canal Constraints, Canal Capacities, etc.

▪ Sensitivities:

❑ Uncertainty

▪ Financing rates, Cost Estimates, Market Volatility, etc.

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Upgrade Study - Alternatives▪ Alternative 0, “Existing” – 204.7 MW Plant Capacity

❑ Modeled to represent current equipment & operations for baseline

▪ Alternative 1, “Same Flow” – 229.5 MW Plant Capacity

❑ Same flow per Unit, higher capacity due to more efficient generators

▪ Alternative 2, “Max Uprate” – 284.2 MW Plant Capacity

❑ Highest Capacity Alternative, Increased Unit Flow, Maximum theoretical

flow in power tunnel

▪ Alternative 3, “Mid Uprate” – 264.3 MW Plant Capacity

❑ Mid Level Uprate, Increased Unit Flow, Design flow in power tunnel

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Upgrade Study - Alternatives▪ Alternative 4, “De-Rated U4” – 267 MW Plant Capacity

❑ Max Uprate including a De-Rate of Unit 4 to minimum river flows

▪ Alternative 5, “VFD”

❑ One Variable Frequency Drive Unit, Not Modeled, Space Constraints & $$$$

▪ Alternative 6, “Mixed Uprate” – 270.9 MW Plant Capacity

❑ Mixed Capacity Uprate, Units 1-2: Max, Unit 3: Mid, Unit 4: Same

▪ Alternative 7, “Do Nothing”

❑ Lowest Cost Option, but Reliability & Safety Concerns remove as valid option

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Upgrade Study - Scenarios

▪ “Base Case”

❑ Models Current Operations & Constraints (DAM, Canal Limits, etc.)

▪ “EIM”

❑ Considers dispatching into EIM using hourly and sub-hourly pricing

▪ “TID Canal Upgrade”

❑ Considers TID-only benefits for canal upgrade options (no impact to MID

costs or benefits)

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Upgrade Study - Sensitivities

▪ Sensitivities:

❑ Discount Rate

▪ 3% to 5% to 7%

❑ Cost Estimates

▪ -30% to 0% to +50%

❑ Market Volatility

▪ 2015 actuals to 2018 actuals to 2022 projections

❑ Benefits

▪ All Value (Energy, Carbon Free, AS, Flexible Capacity) to Energy-Only Value

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Upgrade Study – Costs

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Alt. 1 Alt. 2, 3, 4 & 6

Turbine

Runner ✓ ✓

Model Test no yes

Runner to Shaft Coupling Bolts ✓ ✓

Shaft to Generator Shaft Coupling

Bolts✓ ✓

Stationary Wearing Rings ✓ ✓

Wicket Gates ✓ ✓

Wicket Gate Bushings ✓ ✓

Headcover ✓ ✓

Headcover Facing Plates ✓ ✓

Bottom Ring ✓ ✓

Bottom Ring Facing Plates ✓ ✓

Turbine Shaft & Shaft Sleeve ✓ ✓

Shaft Seal ✓ ✓

Guide Bearing ✓ ✓

Operating Mechanism ✓ ✓

Linkage Pins and Self-Lubc'd

bushings✓ ✓

Servomotors ✓ ✓

Discharge Ring ✓ ✓

Draft Tube ✓ ✓

Stay Ring/Spiral Case ✓ ✓

Stay Vane Reuse Recontouring

Site Machining ✓ ✓

Pre-Outage Inspections/Signature

Testing✓ ✓

Start-Up, Commissioning, Post-

Outage Inspections/Signature Testing✓ ✓

Turbine Aeration ✓ ✓

New

Refurb + modifications

Refurb

Alt. 1 Alt. 2, 3, 4, and 6

Generator

Stator winding ✓ ✓

Stator core & clamping system ✓ ✓

Stator frame ✓ ✓

Stator sole plates ✓ ✓

Rotor poles ✓ ✓

Rotor rim ✓ ✓

Rotor spoke ✓ ✓

Generator shaft ✓ ✓

Stub shaft ✓ ✓

Field leads, slip rings, brush rigging ✓ ✓

Upper bracket ✓ ✓

Combined bearing ✓ ✓

Lower bracket ✓ ✓

Guide bearing ✓ ✓

Generator air coolers ✓ ✓

Brakes & Jacks ✓ ✓

Excitation ✓ ✓

Generator breaker ✓ ✓

Balance of Plant

Governor System ✓ ✓

PRV ✓ ✓

Metering and Protection ✓ ✓

Unit MCC ✓ ✓

Unit Main Transformer ✓ ✓

Plant Control System Upgrade

(DCS)✓ ✓

Upgrade Study – Benefit / Cost AnalysisExample Benefit Cost Ratio (BCR) Table:

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Alternative Alternative NameCosts

(million)

Benefits

(million)BCR

Incr. Cost

(million)

Incr.

Benefits

(million)

Incr.

BCR

1 “Same Flow” 94 663 7.1 -- -- --

2 “Max Uprate” 109 696 6.4 15 33 2.2

3 “Mid Uprate” 101 689 6.8 7 26 3.5

4 “De-Rated Unit 4” 111 692 6.2 17 29 1.7

6 “Mixed Uprate” 105 691 6.6 11 29 2.5

Upgrade Study – Benefit / Cost Results▪ Results Summary

❑ Alternative 3 – highest Incremental BCR compared to least cost alternative (Alt. 1)

for most scenarios:

▪ When considering all modeled benefits, Alt 3 is preferred for:

▪ All 135 combinations of sensitivities and scenarios when assessed for the plant

▪ Even when considering energy-value only, Alt. 3 is preferred for:

▪ 116 of 135 combinations of sensitivities and scenarios

▪ TID & MID staff are in consensus on Alternative 3 as the

preferred life extension option for Don Pedro Power Plant

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Schedule

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Free float is currently estimated as 70 days

Budget▪ Cost Estimates (MID & TID)

❑ Split costs between TID and MID according to ownership %

❑ EXCEPT for:

▪ Transmission upgrade costs – allocated by ID

▪ TID Upper Main Canal costs – allocated entirely to TID for the applicable scenarios

(canal rehab does not impact MID costs or benefits)

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Alt. 1 Alt. 2 Alt. 3 Alt. 4 Alt. 6

Total cost, less transmission $119,419,200 $133,407,400 $128,410,800 $135,957,200 $133,644,600

31.54% of total cost less transmission $37,664,816 $42,076,694 $40,500,766 $42,880,901 $42,151,507

MID transmission cost - $450,000 $450,000 $450,000 $450,000

MID total cost $37,664,816 $42,526,694 $40,950,766 $43,330,901 $42,601,507

68.46% of total cost less transmission $81,754,384 $91,330,706 $87,910,034 $93,076,299 $91,493,093

TID transmission cost $1,800,000 $6,650,000 $1,850,000 $6,650,000 $1,850,000

TID total cost $83,554,384 $97,980,706 $89,760,034 $99,726,299 $93,343,093

Cumulative Project Budget

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$-

$10,000,000

$20,000,000

$30,000,000

$40,000,000

$50,000,000

$60,000,000

$70,000,000

$80,000,000

$90,000,000

$100,000,000

$110,000,000

$120,000,000

$130,000,000

$140,000,000

2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029

Estim

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Cum

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Budget, 2

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Year

Conclusions▪ Value as a long-term asset for MID

▪ Most components are at or beyond their end of life

▪ Balance of Plant Life Extension since 2014

▪ Upgrade study modeled future scenarios

▪ Mid-Uprate option clear leader in cost/benefit

▪ $128M estimated total project cost ($41M MID)

▪ 1st Unit outage starts in 2022, 4th Unit outage ends in 2026

▪ Project costs are in long-term capital plan

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Questions?

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