EERE PowerPoint 97-2004 Template: Green Version · Screen shot of GT-Mod modeling platform. 10 ......

1 | US DOE Geothermal Office eere.energy.gov

Public Service of Colorado Ponnequin Wind Farm

Geothermal Technologies Office 2015 Peer Review

Geothermal Systems Engineering

GT-Mod

Thomas Lowry

Sandia National Laboratories

Systems Analysis Project Officer: Timothy Reinhardt

Total Project Funding: $250k

May 11, 2015

This presentation does not contain any proprietary

confidential, or otherwise restricted information. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin

Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

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Jan 10 Jan 15 Jan 20 Jan 25 Jan 30 Jan 35 Jan 40

Date

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Pro

du

ction

Tem

pe

ratu

re [K

]

Production Temperature as f(Well Distance)

5 %

25 %

50 %

75 %

95 %

10 12 14 16 18 20 22 24 26 28 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

LCOE [c/kW-hr]

Cum

ula

tive p

robabili

ty

Resource Temperature = 275 C


Relevance/Impact of Research

GT-Mod is a systems-based model of geothermal energy

production that simulates system and sub-system

interdependencies and feedbacks to capture non-linear coupled

responses to uncertainties in one or more input values. This

approach allows users to:

• Produce probabilistic output of economic and physical performance as a

function of uncertainty and various system configurations

• Conduct probabilistic risk assessment to identify and prioritize technology

development strategies

• Optimize system design and operation

• Answer ‘what if’ questions with regards to technology advancement,

system design, and thermal performance


• Impacts

– Allows us to gain insight in an environment of uncertainty

– Lowers risks and costs of development

– Identifies and prioritizes areas where improvements and/or better understanding

will impact the bottom line the most

• Innovation

– System dynamics: combines realistic, physics based simulations at the

component level to simulate total system performance

– Risk assessment addresses the always-constant uncertainties to produce

probabilistic output of total system performance

– Modular architecture can be easily extended and adapted to other problems or

other analyses: 2015 work is being extended to direct use applications

• Challenges

– How to include ‘realistic’, physics based simulations in a system dynamics model?

– Connect physical performance with economic performance

– How do we define uncertainty?

Relevance/Impact of Research


Scientific/Technical Approach

Geothermal Energy as a Complex System of Systems

• Systems are interdependent

• Each are linked and considered simultaneously

• Focus is on dynamic complexity

Inflow

System

Heat

Conversion

System

Outflow

System

Injection

System

Heat

Extraction

System

Production

System

System ‘A’ System ‘B’



Inflow Pipes Outflow PipesPower Plant

Production Wells

Reservoir

Ambient Conditions

GringartenCarslaw and Jaeger

Injection Wells

Production Well Casing Design Injection Well Casing Design

Production Well Heat Transfer

Stochastic Lookups

Injection Well Heat Transfer

From high-resolution reservoir simulations

Adding binary power plant module for 2015

GETEM



Use of SYSTEM DYNAMICS (SD)

• SD is a formal modeling discipline that captures the dynamic complexity between connected systems and sub-systems

• Dynamic complexity is a function of direct influences, feedback, and delays

• SD is scalable to the spatial or temporal scale of interest

Evaporator1.5 MPa

Preheater1.5 MPa

Turbine/Generator

85% Isentropiceff.

Condenser320K

ProductionWell

InjectionWell

To CoolingTower

Pump75% Isentropic

eff.

FromCoolingTower

1

2

4

5

6

A

B

C

Dynamic complexity example from new binary power plant module



• Mathematically,

uncertainties are expressed

as PDF’s (probability

distribution functions)

• They are a reflection of what

we don’t know

• Uncertainty is not

necessarily a 1:1 transfer

between independent and

dependent variables

• Uncertainty = Risk

Truncated Normal

Normal

Triangular

Uniform

Exponential

Uncertainty and Risk



• Risk is the consequence

times the probability:

• Consequences can be defined in

many different ways

• User defines PDF’s and

consequence

• Output is probabilistic

• Allows for answering ‘inverse

questions’:

– Given a set of uncertainties, what is

the probability that you will hit your

target?

– What do we need to know better to

have a XX% chance of reaching our

target?

Risk Assessment

t n

nPtnCR )(),(

R = risk, C = consequence, P = probability,

n = # of probability intervals, t = time

Pro

bab

ility

LCOE [¢/kW-hr]


Accomplishments, Results and Progress

AOP Objectives

• The objective for FY15 is to continue the advancement and maturing of GT-Mod to support the DOE GTO in its work with regards to the Quadrennial Technology Review, the Geothermal Vision Study, and other needed analyses as directed. Development work will focus on additional functionality as needed to complete the various analyses as well as increasing the general usability and usefulness of GT-Mod to allow for broader adoption and application of the tool in out years.

• Complete validation analysis for ad hoc “what-if” analysis as defined by the program

• Complete analyses for the DOE GTO’s vision study as defined by the office

Screen shot of GT-Mod modeling platform.



• Project has transitioned from

development phase to analysis phase

• Developed and presented dimensionless

parameter approach for reservoir

performance simulation

• Developed Laplace Transform inversion

for use in SD models

• Created lookup table interface that allows

the model to use high resolution reservoir

simulations

• Created stand-alone power plant model to

be integrated later this year

• 10 conference presentations/proceedings,

1 journal article, 1 in review

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1

LCOE [c/kW-hr]

Cum

ula

tive p

robabili

ty

Resource Temperature = 275 C

25 kg/s

50 kg/s

Influence of thermal drawdown solution method on uncertainty

and risk for 50 and 25 kg/s flow rates at 275 oC. The red line is

the Gringarten analytical solution and the blue line is the annual

drawdown rate method.



• Reservoir modeling with FEHM

• Fracture properties – Dip (5o, 18o, & 80o)

– Strike (80o, 10o)

• Pumping Rates (60, 90, 120, 150, 200 kg/s)

• Well Separation Distance (390, 600, 800 m) Dip Relative to Well-Pair Plane

Strike Relative to Well-Pair Plane

Comparing horizontal, inclined, and vertical well

orientations



• Horizontal wells are economically

equivalent to the other

configurations (for scenarios

tested)

• Because the thermal

performance of horizontal wells is

more consistent across the

different scenario’s, the economic

risk is reduced

• Pumping requirements for

horizontal wells may be higher in

low, fracture-dip formations

• Results indicate that there may

be an optimal relationship

between fracture strike and dip

and well orientation

• Stimulating the reservoir will help

reduce pumping costs but not

improve thermal performance


Future Directions

• Extend the focus of GT-Mod beyond EGS to examine deep direct use

applications

– Power plant module

– Add economic calculations for LCOH

– Add other comparison metrics (e.g. equivalent power, CO2 offset, etc.)

• For power plant module

– Add ability to use different working fluids (currently isopentane only)

– Add ability to optimize plant design

– Expand to more complex systems (out years)

• Analysis

– Revisit reservoir simulations for horizontal well analysis

– Examine combined EGS and direct use systems

– Support GTO in vision study analyses as needed


Mandatory Summary Slide

GT-Mod allows users to:

• Produce probabilistic output as a function of uncertainty

• Conduct probabilistic risk assessment to identify and prioritize technology

development strategies

• Optimize system design and operation

• Answer ‘what if’ and inverse questions

Extending functionality to look at direct use in both standalone

and co-generation systems

Main role is in support of the GTO for analyses as needed

EERE PowerPoint 97-2004 Template: Green Version · Screen shot of GT-Mod modeling platform. 10 ......

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