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Princeton University Microgrid

Current status, energy mix, organizations, suppliers, equipment, controls, reported specifications, and project updates—with source-level citations.

CoverageDetailed public record
Named organizations9
System facts37
Sources reviewed11
Evidence reviewed2026-07-20

Princeton's campus microgrid is a long-running district-energy and electric system anchored by a 15 MW GE LM1600 natural-gas CHP turbine, a 2.6-million-gallon chilled-water thermal store, boilers/chillers, and campus distribution. Its solar fleet expanded from 5.3 MW in the Hurricane Sandy era to 16.5 MW AC across ten arrays in 2022. Princeton is now layering geo-exchange, electric heat pumps, hot/cold thermal storage, the TIGER plant, and the West Plant onto—not yet publicly documented as fully replacing—the legacy CHP architecture.

Research status
Operational and undergoing a multi-year energy transition. The microgrid famously islanded for roughly 1.5 days during Hurricane Sandy after an approximately 20-minute interruption/restart. Current university reporting says the 16.5 MW AC solar portfolio is connected to the microgrid, produced about 20,800 MWh in FY2025, and supplies about 19% of current campus electricity. TIGER and the West Plant are operating in parallel as of 2025. Public sources do not say that the 15 MW CHP has been retired, nor do they publish a current all-source MWh mix, newer islanding test, or battery BESS—thermal storage remains the major disclosed storage technology.
Historical classification
Building
Reported capacity
19 MW
Coordinates
40.34399, -74.65145
Evidence note: “Every company” cannot be proven from public material alone. This page lists every organization found in the recovered record and reviewed sources, preserves unknown roles, and explicitly marks undisclosed controller or equipment details.
Report missing evidenceResearch methodology

Project delivery

Who was involved in Princeton University Microgrid?

9 publicly identified organizations. Where a recovered source named a participant without explaining its work, the role remains explicitly unspecified.

Organization

EDF Renewables

Designer, builder, owner, operator, and maintainer of Princeton's expanded solar portfolio under a 15-year arrangement. [6]

Organization

GE

Manufacturer of the legacy 15 MW LM1600 combustion-turbine generator. [3]

Organization

General Electric

LM1600 gas-turbine manufacturer [3]

Organization

Princeton Energy Resources International (PERI)

Developer of the legacy real-time economic-dispatch/optimization software described in the university's Sandy-era account. [4]

Organization

Princeton University

Publicly named participant; role not specified in the recovered record [1]

Organization

Princeton University Facilities

Microgrid owner, operator, and campus utility [3][4][5]

Organization

Princeton University Facilities / Energy Plant

Owner, operator, campus utility, and modernization program lead. [3][6][8]

Organization

Public Service Electric & Gas (PSE&G)

Interconnecting electric utility [4]

Organization

Salas O'Brien

Engineering participant providing detailed public design information for geo-exchange heat pumps and thermal storage. [10]

System evidence

Energy mix, capacity, and specifications

Values can describe different project phases, generation sources, storage systems, or other components. Source citations are attached to each figure so discrepancies remain visible.

KW Solar
4500 [1]
KW Gas/Diesel
15000 [1]
Storage
NA [1]
Cogeneration electric capacity
15 MW [3][4]
Gas turbine
General Electric LM1600, natural-gas or diesel capable [3]
Chilled-water thermal storage
2.6 million gallons [4]
Campus electric demand in 2014 account
Approximately 16 MW average; 10 MW night minimum; 27 MW hot-day peak [4]
Reported CHP efficiency
Approximately 75–85% [4][3]
2012 solar field
5.3 MW and 16,500 modules [4]
Hurricane Sandy island output
Approximately 13 MW for about a day and a half [4]
Legacy CHP
15 MW GE LM1600 natural-gas combustion turbine in combined heat and power service. Princeton's plant page says CHP can achieve roughly 80% overall fuel utilization compared with separate heat and power production. [3]
Legacy chilled-water storage
2.6 million gallons, charged when electricity/cooling costs are lower and discharged during peaks to reduce chiller and electric demand. [3][4]
Solar fleet
16.5 MW AC across ten arrays following the 2022 expansion, compared with 5.3 MW and 16,500 panels in 2014. Current university materials say it supplies about 19% of electricity use. [6][7][4]
Measured solar output
University reporting shows 7,162 MWh in FY2021 and approximately 20,800 MWh in FY2025 after the expansion. [7]
Historical campus electrical load
2014 university reporting cited roughly 16 MW average, 10 MW at night, and 27 MW on a hot day. These are useful operating-context figures but are not current 2025/2026 peaks after campus expansion/electrification. [4]
New thermal storage
TIGER includes separate hot- and chilled-water tanks. Engineering reporting describes approximately 2.25 million gallons each; a campus newspaper reports 2.2 million gallons each. University project pages do not publish definitive tank nameplates. [8][10][11]
Energy mix gap
Solar is currently reported at about 19% of electricity; the remainder is a changing combination of CHP, grid purchases, and growing electrified geo-exchange/heat-pump loads. The older claim that CHP met 75–85% of demand is Sandy-era and should not be reused as today's mix. [6][4][9]

Controls and hardware

Equipment and controller details

Manufacturer and model are shown only when a source names them. Generic descriptions are not converted into guessed product assignments.

01

Cogeneration turbine

General Electric — LM1600

Dual-fuel aeroderivative gas turbine drives the 15 MW generator; exhaust heat produces campus steam. [3]

02

Economic dispatch system

Model not publicly disclosed

Real-time model monitors electricity and fuel prices plus campus electric, steam, and chilled-water demand to guide operators; vendor and software release are not disclosed. [3][4]

03

Thermal energy storage

Model not publicly disclosed

2.6 million gallons of chilled water shift chiller load to lower-cost hours; newer TIGER and CUB facilities add separate hot- and cold-water storage tanks. [4][5]

04

Heat-recovery steam generation

Model not publicly disclosed

Gas-turbine exhaust heats water to make steam for heat, hot water, sterilization, and steam-driven cooling; equipment model is not stated. [3][4]

05

CHP gas turbine

GE — LM1600

15 MW natural-gas turbine-generator with heat recovery serving the campus steam/district-energy plant. [3]

06

Legacy thermal energy storage

Model not publicly disclosed

2.6-million-gallon chilled-water tank; energy-equivalent MWh depends on operating temperature differential and is not published on the current plant page. [3]

07

Solar PV

Model not publicly disclosed

Ten arrays totaling 16.5 MW AC, connected to the campus microgrid; module/inverter models and DC nameplate were not found on the public project page. [6][7]

08

TIGER energy plant

Model not publicly disclosed

Electric heat pumps/chillers, hot- and chilled-water thermal storage, two transformers, controls, and a natural-gas backup generator. University pages do not disclose the backup generator's MW or model. [8]

09

Geo-exchange field and heat pumps

Model not publicly disclosed

Engineering reporting cites 583 bores approximately 850 feet deep and a buildout to four 1,750-ton heat-pump chillers (about 7,000 tons total), with 19,680 ton-hours of cooling storage; treat these as design/engineering figures rather than a university as-built asset register. [10]

Technical record

Architecture, performance, and project updates

Concise technical facts, milestones, operating results, and later developments. Dated notes distinguish historical design claims from current evidence.

  • General

    Gas cogeneration plant also provides heating and cooling for roughly 180 buildings. [1]

  • Generation

    The heart of the Princeton microgrid is the cogeneration plant (center), which was constructed in 1996. [1]

  • Grid interaction

    Operators import or export power based on real-time economics and can disconnect the campus to run as an electrical island during utility outages. [4]

  • Hurricane Sandy

    After a roughly 20-minute interruption and turbine restart, the campus islanded at about 13 MW until reconnection shortly before midnight on October 31, 2012. [4]

  • Combined heat and power

    The gas turbine produces electricity while exhaust heat supplies steam; the district-energy plant also dispatches steam- and electric-driven chillers. [3][4]

  • Modernization

    The upgraded microgrid is adding solar, geo-exchange, heat pumps, natural-gas backup generation, and paired hot/cold thermal-storage tanks at TIGER and CUB. [5]

  • Hurricane Sandy operation

    After the regional grid failed, the campus experienced about a 20-minute interruption while the plant restarted, then served about 13 MW in island mode for roughly 1.5 days before reconnecting before midnight October 31, 2012. This was a successful island operation, not seamless UPS service. [4]

  • Economic dispatch

    The legacy controller optimizes CHP, grid purchases, chillers, boilers, and chilled-water storage against hourly electricity/fuel costs and plant constraints; resilience/islanding is layered on a normally economic campus utility operation. [4][3]

  • Transition architecture

    Princeton is converting building heating from steam to lower-temperature hot water and using electric heat pumps, geo-exchange bores, and large hot/cold stores. TIGER and the West Plant operating in parallel provide geographic and equipment redundancy while construction continues. [5][8][9]

  • Storage boundary

    No current source cited here documents a campus electrochemical BESS. The 2.6-million-gallon legacy tank and new TIGER tanks store thermal energy and should not be reported as battery MW/MWh. [3][8]

  • Current performance gap

    Princeton publishes solar output and decarbonization progress but not a current CHP capacity factor, total campus MWh by source, islanding test history after Sandy, outage reliability indices, or an exact retirement date for the LM1600. [7][9]

Provenance

11 sources

Primary owner, government, university, supplier, and engineering sources are preferred. Archived references preserve claims whose original pages moved or disappeared.

  1. [1]
    Recovered Microgrid Projects record

    Internet Archive · Archived source · captured 2021-04-20

  2. [2]
    From Princeton University

    princeton.edu · Archived source · captured 2021-04-20

  3. [3]
    The Princeton Energy Plant

    Princeton University Facilities · Primary source

  4. [4]
  5. [5]
  6. [6]
    Path to Net-Zero: Solar Expansion Project

    Princeton University Facilities · Primary source

  7. [7]
    Geo-Exchange at Princeton University, June 2025

    Princeton University Facilities · Primary source

  8. [8]
    Thermally Integrated Geo-Exchange Resource (TIGER)

    Princeton University Facilities · Primary source

  9. [9]
    West Plant Heat Pump Circulating Geo-Exchange Water Through Poe Field

    Princeton University Facilities · Primary source

  10. [10]
    Princeton University Central Energy Plants

    Salas O'Brien · Primary source

  11. [11]
    Inside TIGER: Princeton's New Geo-Exchange Facility

    The Daily Princetonian · Secondary research

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