Small-Scale PHES Demonstration

Team Members: SwRI & Malta Inc.

PI: Natalie Smith, SwRI

Project Vision

Total project cost: $2.5M

Current Q / Total Project Qs Q9 / Q12

Bringing the Brayton Battery to life:

Solving system integration and operation challenges

Energy Summit

May 24-27, 2021

The Concept: Pumped Heat Energy Storage (PHES)

PHES Value Proposition

‣ 10+ hours of storage

‣ Separation of engine and storage

‣ Well-established component technologies

‣ Safer than other thermal-based ES technologies

‣ Potential for high round trip efficiency (RTE)

Technology Challenges

‣ First implementation challenges

‣ Control and operational unknowns

– Steady state

– Transients

‣ Charge compressor

‣ Reverse flow heat exchangers

1

Charge Mode Use excess energy to run heat pump

& store energy in hot and cold reservoirs

Discharge Mode Use thermal reservoirs to run heat engine

& generate power

The Concept: Pumped Heat Energy Storage (PHES)

2

Charge Mode Use excess energy to run heat pump

& store energy in hot and cold reservoirs

Discharge Mode Use thermal reservoirs to run heat engine

& generate power

340°C305°C

27°C12°C

340°C305°C

27°C12°C

The Team = SwRI + Malta+ Gas Turbine OEM

3

Benefiting government, industry and the public through innovative science and technology

Meet the Future of Energy Storage

kW-scale demonstration development, transient modelling, and testing

TEA and T2M

GT OEM

TEA

The Team = + + Gas Turbine OEM

4

Turbomachinery Mechanical Design

PM, Controls, Aero Cycle Optimization & Transient Modelling

TEA and T2M

Aaron Rimpel Josh Just Tommy Kerr, Ph.D.

Michael MarshallBrittany TomNatalie Smith, Ph.D.

Thomas Revak

Balance of Plant

George Khawly

Ben Bollinger, Ph.D.

GT OEMTEA

John Klaerner

Project Objectives to Address Technology Challenges

‣ Understand limitations of operational modes

– Steady state operation

– Startup, shutdown, mode switch

– Validation data for transient analysis

– Address first implementation challenges

‣ kW-scale Demonstration Facility

– Lower cost and lower risk test

– Predicted RTE = 10%

– Storage capacity for 1 hour operation charge/discharge

– Discharge Mode generates 5 kW

– 200 kW thermal

5

Demonstrate operation and verify system control strategies

of a closed air Brayton PHES at laboratory scale

TRL 2 TRL 4

Cycle Analysis Facility Design Procurement Transient Analysis Assembly Commission Test

Results: Cycle Optimization from Full- to Small-Scale

6

Full-scale: Higher temperature chloride salts up to approximately 800°C & improved compressor efficiency allow a pathway to greater than 60% RTE

Small-scale:

‣ To minimize costs and risk, several cycle condition compromises were implemented

60% High temperature salts and improved component efficiencies

48.9% Full-scale system with current technologies

24% Small-scale turbomachinery efficiencies

10% Storage media & temperature limits

‣ NPSS model accounts for turbomachinery maps, HX and valve performance, piping losses and thermal mass

‣ Optimizations with specified machinery and additional limitations resulted in

‣ lower pressure ratios

‣ lower overall performance Tom, Smith, McClung, 2020, “Cycle Considerations forthe Conceptual Design of a PHES,” GT2020-15657.

Results: COTS to Custom Turbomachinery

7

‣ Initial plan: COTS machinery with minor redesigns

‣ Turbocharger sized for application

‣ Issue: Ease of ‘simple’ modification while maintaining mechanical integrity for required steady state and transient operation

‣ Result: Custom-designed turbocompressors

‣ Thermal protection provisions

‣ Rotordynamic integrity

‣ Thrust balance

Results: Transient Considerations from Modelling to Operation‣ Transient Considerations

– Equipment safety (rotordynamics, thermal, stall)

– Transient length

– Sequencing

• Machinery ramps

• Storage media

– Performance and storage media usage

‣ Charge Mode Start-up

– Compressor recycle

• Required for surge protection

• Overheating concerns with hot recycle

– Storage media and machinery ramping sequencing

– Example consideration: From ambient conditions with warm oil tanks and ambient coolant tanks, the heat transfer directions will be initially incorrect

Challenges and Potential Partnerships‣ Challenges & Risks:

– COTS Hardware:

• Closing the cycle with COTS hardware while ensuring controllability and optimized system performance

• Complete redesign of COTS hardware to de-risk demonstration operation

– Fast Transients:

• Enabling optimal transient time while protecting hardware

• Extensive transient cycle modelling has informed a phased test matrix

– Next: What does actual implementation look like?

‣ Collaboration:

– Follow-on projects to progress PHES development using our Energy Storage Test Facility including different storage media, conditions, and working fluids

Technology-to-Market

‣ Final Goal: Full-scale system (10 or 100 MW)

demonstration and deployment

‣ Status: Approximately 2024 for a 100 MW system

‣ Accelerate Development:

– Market readiness supported by improved policy and regulation

– Continued iterative component and system improvements to progress the SOA

• Charge compressor

• Molten salt technology

‣ Potential First Markets:

– Power plants in areas with high renewable penetration

Small-Scale PHES Demo

Objective: Demonstrate operation and verify control strategies of a closed air Brayton PHES at lab scale

Outcomes:

‣ Steady state and transient operation data to inform full-scale system design

– Ambient effects

– Sequencing considerations

‣ Dedicated energy storage test facility

– Predicted RTE = 10%

– Storage capacity for 1 hour steady state operation

– 50 kWth

– Discharge Mode generates 5 kW

Cycle Analysis Facility Design Procurement Transient Analysis Assembly Commission Test

N

Control Room

Sept 2021 Dec 2021