Combustion-Turbines-and-Reciprocating-Engines-for-Grid-Support

Objectives To describe how utilities currently use combustion turbines and reciprocating engines to supportthe power delivery system; to improve industry knowledge of distributed resourc

Combustion Turbines and Reciprocating

Engines for Grid Support

Please read the License Agreement

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EPRIsolutions Project Manager

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Combustion Turbines and

Reciprocating Engines for Grid

Support

1003962

Final Report, November 2001

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Combustion Turbines and Reciprocating Engines for Grid Support, EPRIsolutions, Palo Alto,

CA: 2001 1003962

REPORT SUMMARY

This report critically reviews specific examples of utilities using combustion turbines or

reciprocating engines to support the power grid The report describes common challenges inplanning, developing, installing, and operating distributed resources in grid support

Background

Distributed resources can support power delivery systems and defer significant capital

transmission and distribution (T&D) projects This potential, however, has yet to be widelyrealized due to the lack of well-documented case examples Too often, the role of distributedresources in grid support is overly simplified by both advocates and skeptics, without

consideration of actual evidence

Objectives

To describe how utilities currently use combustion turbines and reciprocating engines to supportthe power delivery system; to improve industry knowledge of distributed resources and advancethe debate from generalities to utility engineering and economic analysis that is proven by

specific case studies; to reveal the difficulties and successes of applying distributed resources tosolve T&D expansion problems; and, to provide case studies of current projects that give utilityengineers and their managers examples they need to evaluate distributed resources within thecontext of power delivery planning

Approach

The project team started by identifying utilities across the country that might be using distributedresources for grid support, then developed a survey to elicit information about these projects.Since distributed resources can provide both utility power-supply requirements and grid support,the team asked questions to help confirm that grid support was a primary objective of theseprojects They followed up by calling each utility and encouraging them to assign a specificperson to complete the survey promptly and conducted phone interviews with utilities that didnot provide a written response

The utilities’ survey responses were the primary source of information for this report The teamanalyzed responses for successes, failures, and trends that would help indicate the potential of,and challenges with, distributed resources

completed Distributed resources can support local areas where the cost of traditional grid

capacity additions is prohibitive or where the time required to make such additions is too great.Distributed resources may be transportable, so they can be moved to new areas after the currentneed has been satisfied The case studies show that distributed resources are being used to

improve service at the regional, local, and individual customer level in a cost-effective manner.The case studies identified a few common pitfalls that can hamper project performance if notrecognized from the beginning For example, most proposed permanent installations of

distributed resources that require some type of air emissions and zoning permits Using

standardized system designs will speed procurement, reduce installation costs, and improveoperating reliability Investing extra effort during final testing and startup will improve

performance after the project is placed in service Units should be tested and checked regularly toensure their readiness for unexpected needs All readers, especially system planners, are

encouraged to fully review the survey responses in Appendix A Each response presents a uniqueexperience and provides insight into how distributed resources can be used as a power deliverytool

EPRI Perspective

The cases presented in this report and insights gained from these demonstrate that it is possible touse combustion turbines (CTs) and internal combustion engines (ICEs) for grid support Thereare still significant barriers in place that will inhibit broad proliferation, but the distributed

resource technologies are mature

Distributed resources can support power delivery systems and defer capital transmission anddistribution (T&D) projects This potential, however, has yet to be widely understood due to thelack of well-documented examples Too often, the role of distributed resources in grid support isoverly simplified by both advocates and skeptics, without consideration of actual evidence Thisreport reviews specific examples of utilities using combustion turbines and reciprocating engines

to support the power grid The report describes common challenges in planning, developing,installing, and operating distributed resources in grid support The project team started by

identifying utilities across the country that were known to be using distributed resources for gridsupport, then developed a survey to elicit information about these projects Since distributedresources can provide both utility power-supply requirements and grid support, the survey

questions help confirm the primary objectives of these projects The cases presented in thisreport and insights gained from these demonstrate that it is possible to use combustion turbines(CTs) and internal combustion engines (ICEs) for grid support There are still significant barriers

in place that will inhibit broad proliferation, but the technologies are proven

The authors acknowledge the contributions of the following utilities, without whom this reportwould not have been possible:

• Alliant Energy, Cedar Rapids, IA

• Central Hudson Gas & Electric, Poughkeepsie, NY

• Central Virginia Electric Cooperative, Lovingston, VA

• Dakota Electric Association, Farmington, MN

• East Mississippi Electric Power Association, Meridian, MS

• Exelon/ComEd, Chicago, IL

• Grant County Public Utility District, Ephrata, WA

• Madison Gas & Electric, Madison, WI

• Old Dominion Electric Cooperative, Glen Allen, VA

• Powder River Energy Cooperative, Sundance, WY

• Snapping Shoals Electric Membership Corporation, Covington, GA

• Wisconsin Public Service, Green Bay, WI

1 EXECUTIVE SUMMARY 1-1

2 INTRODUCTION AND SCOPE 2-1

Introduction 2-1 Report Overview 2-1

3 GRID SUPPORT WITH DISTRIBUTED RESOURCES 3-1

4 TECHNOLOGY OVERVIEW 4-1

Reciprocating Engines 4-1 Combustion Turbines 4-2 Conventional CTs 4-2 Microturbines 4-3 Generator Comparisons, Specifications, and Related Technologies 4-4

5 GENERAL ENVIRONMENTAL CONSIDERATIONS 5-1

6 CASE STUDY PROFILES 6-1

Summary of Responses 6-2 Summary Discussion by Case 6-4 Alliant Energy 6-4 Central Hudson Gas & Electric 6-5 Central Virginia Electric Cooperative 6-5 Exelon/ComEd 6-7 Dakota Electric Association 6-7 East Mississippi Electric Power Association and Tennessee Valley Authority 6-7 Grant County Public Utility District 6-10 Madison Gas & Electric 6-11 New York Power Authority 6-11

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Old Dominion Electric Cooperative 6-13 Powder River Energy Cooperative 6-13 Snapping Shoals Electric Membership Corporation 6-14 Wisconsin Public Service 6-14

7 LESSONS LEARNED 7-1

Lessons for Planners 7-2

A CASE SURVEY RESPONSES A-1

LIST OF FIGURES

Figure 1-1 Distributed Resources at a Distribution Substation – East Mississippi Electric

Power Association and Tennessee Valley Authority 1-2

LIST OF TABLES

Table 3-1 Primary Reasons for Distributed Resource Grid Support by Beneficiary 3-2 Table 3-2 Rationales for Grid Support Using Distributed Resources 3-3 Table 3-3 Distributed Resource Project Implementation, Operations, and Maintenance 3-4 Table 6-1 Study Participants, Separated by Ownership Structure 6-1 Table 6-2 Summary of Generators used by Case Participants 6-1 Table 6-3 Case Summaries and Comparisons 6-3 Table 6-4 EMEPA’s 10-Year Net Present Value Comparison of Alternatives 6-9

customer and utility needs, a suitable site, and a willingness to examine conventional thinking to

realize grid support benefits.

The case studies demonstrate that the use of distributed resources for grid support is no longer alofty, unattainable concept, but is truly occurring at utilities of all sizes around the country.Providing grid support from distributed resources can be difficult, but the case studies show that

a variety of approaches can help utilities achieve their objectives

The primary drivers for utilities profiled include:

• Deferral of capacity increases in substations or transmission lines

• More reliable customer service through a redundant electric service source at the customerlocation, or at a substation that is close to the customer

• Reduction of distribution circuit overload and improvement in outage restoration time

• Relief of transmission system congestion

The examples of distributed resources for grid support encompass several generation

technologies, various placements on the power delivery system, and utility types that range frominvestor-owned to cooperatives and public power The case studies show through actual practicethat distributed resources for grid support cannot be narrowly defined; they are not a solution foronly one type of problem, nor is there any one “best” approach The range of power deliveryproblems and available creative resources are the only defining elements

Grid support is not realized in every application of distributed resources Grid benefits resultonly after careful planning and implementation focused on solving power delivery problems.Distributed resources can have unintended effects, such as burdening the grid through impropersiting or incompatible operations Distributed resources can also be of negligible support whenexisting power delivery systems already have sufficient capacity and reliability Applicationsthat do not support the grid help underscore the significance of the featured cases that do; in thepresented cases, significant grid support occurred while other objectives were met, often withdirect customer benefits

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Distributed Resources at a Distribution Substation – East Mississippi Electric Power

Association and Tennessee Valley Authority

The following thirteen utilities offered case studies for this report:

• Alliant Energy

• Central Hudson Gas & Electric

• Central Virginia Electric Cooperative

• Dakota Electric Association

• East Mississippi Electric Power Association and Tennessee Valley Authority

• Grant County Public Utility District

• Madison Gas & Electric

• New York Power Authority

• Old Dominion Electric Cooperative

• Powder River Energy Cooperative

• Snapping Shoals Electric Membership Corporation

• Wisconsin Public Service

Executive Summary

The case study examples in this report show how the potential of distributed resources to supportelectric power delivery systems can be realized Although every case had its own problems withthe technology, the local site, and public acceptance, none of these problems proved to be

overwhelming obstacles

These cases are far from the entire population (of possible cases), however their diversity

represents it well As these cases illustrate, the potential for grid support is real and the benefitsare achievable These cases should convince many in the industry that distributed resources arenow a serious alternative in terms of capacity and reliability, and are worthy of consideration inplanning electric power delivery systems

2

INTRODUCTION AND SCOPE

Introduction

Distributed resources can support power delivery systems and defer significant capital

transmission and distribution (T&D) projects However, this potential has yet to be widelyrealized due to the lack of well-documented case examples Too often, the role of distributedresources in grid support is overly simplified by both advocates and skeptics, without

consideration of actual evidence

This report critically reviews specific examples of utilities using combustion turbines or

reciprocating engines to support the power grid The report also describes common challenges inthe planning, development, installation, and operation of distributed resources in grid support

This report seeks to improve industry knowledge of distributed resources and advance the debatefrom generalities to utility engineering and economic analysis that is proven by specific casestudies

The report reveals the difficulties and successes of applying distributed resources to solve T&Dexpansion problems The case studies of current projects provide utility engineers and theirmanagers with the examples they need to evaluate distributed resources within the context ofpower delivery planning

Report Overview

The remainder of the report is divided into the following sections:

• Section 3 discusses how utilities are currently using distributed resources (DR) to providegrid support

• Section 4 discusses the background of the combustion turbines and reciprocating enginesused in the case studies

• Section 5 provides background on environmental considerations for the case studies

• Section 6 profiles utility case studies and presents tabular summaries of key data

• Section 7 provides a synopsis of tips and insights gleaned from the case studies

• Section 8 highlights key points that power delivery system planners should consider whenreviewing system performance and developing plans to meet future needs

• Appendix A presents the complete survey responses submitted by the 13 utilities that

provided case-study information for this report

3

GRID SUPPORT WITH DISTRIBUTED RESOURCES

All 13 utilities that provided information for this study indicated that their distributed resourceprojects offered some form of grid support The following list illustrates which types of gridsupport were offered and which utilities offered them:

• Deferral of distribution substation capacity increases – Alliant Energy, Dakota ElectricAssociation, Exelon/ComEd

• Deferral of providing a looped transmission system – Central Hudson Gas & Electric

• Provide a redundant supply source to a distribution substation bus – Central Hudson Gas &Electric, Grant County Public Utility District

• Provide a redundant supply source to a group of customers demanding improved servicereliability – Central Hudson Gas & Electric, Dakota Electric Association, East MississippiElectric Power Association, Madison Gas & Electric, Old Dominion Electric Cooperative,Snapping Shoals EMC

• Provide transmission or distribution system voltage support – East Mississippi ElectricPower Association, Madison Gas & Electric, Powder River Energy, Wisconsin Public

Service

• Improve outage restoration time – Exelon/ComEd

• Reduce overloads on distribution circuits – Exelon/ComEd

• Relieve transmission system congestion – New York Power Authority, Old Dominion

Electric Cooperative

As can be seen, these utilities had a variety of reasons for installing distributed resources Table3-1 summarizes the primary reasons and indicates which portion of the system benefited fromthe installation Some utilities indicated more than one area of primary emphasis This explainswhy there are sum of the counts is greater than thirteen

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Table 3-1

Primary Reasons for Distributed Resource Grid Support by Beneficiary

DR Support Type Customer Distribution Transmission

Defer System Capacity

Defer Transformer Upgrade 2

Improve Reliability 3 3 2

Improve Voltage Support 3

Provide Redundant Capacity 1 4

Customer Retention 2

Limit Outage Duration 1

The primary driver indicated by the respondents for using DR was to improve reliability Innumerous cases a load with poor reliability was served with a single distribution line Forvarious reason, it was not practical to upgrade the existing line or bring addition lines Mostlybecause of the very long time required to make the changes Faced with few other alternative,

DR emerged as the best solution to reliability problem The units were place in or very near theload in question and the generator provide options for baseload, peak-shave or emergencyoperation In some cases, a DR units was leased which provided enough time to completedistribution upgrades or new line construction

A second common scenario occurs when a significant element or group of elements in theexisting power delivery system do not have adequate capacity to supply peak load demands andthe peak load duration is only a small portion of the year (typically less than 300 hours per year).Distributed resources can offer a possible solution because the combination of their capital andoperating costs, coupled with the economic savings from avoided power supply costs, may beless than the cost of upgrading power delivery systems by alternative methods Distributedresources can be moved to another location later when the load duration increases to a point thatthe alternative upgrade becomes justified

Table 3-2 summarizes the rationales that each utility provided for using distributed resources.For more details on each utility’s circumstances and needs, see Section 6 and the case-studyinformation in Appendix A

Table 3-3 summarizes the project implementation methods, project installation costs, operatingexperience, and maintenance experience associated with development of distributed resources.Some utilities used the design-bid-build project implementation process; others used the design-build process

Grid Support with Distributed Resources

Table 3-2

Rationales for Grid Support Using Distributed Resources 1

Survey Topic Alliant Energy

Central Hudson Gas &

Electric

Dakota Electric Association

Madison Gas &

Electric

East Mississippi

T&D System Capacity Addition Deferral Yes Yes No No Yes Yes

At what level (single customer, dist., trans.)? n/a

Provide redundant capacity for contingencies? No Yes Yes Yes Yes Yes

Survey Topic

Central Virginia Electric Cooperative

New York Power Authority

Old Dominion Electric Cooperative

Grant County Public Utility District

Powder River Energy Corp./

Basin Electric

Snapping Shoals EMC

Wisconsin Public Service

At what level (single customer, dist., trans.)? distribution

transmission &

distribution distribution all transmission single customer

transmission &

distribution

Provide redundant capacity for contingencies? No Yes Yes Yes Yes Yes No

1

For more detailed information than this table can provide, see Appendix A.

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Table 3-3

Distributed Resource Project Implementation, Operations, and Maintenance

Survey Topic Alliant Energy

Central Huds on Gas & Electric

Dak ota Electric

As s ociation

Madis on Gas &

Electric

Eas t Mis s is s ippi

nothing anticipated

Future air quality

Base could close, Rate may end, T line could be built

Poor perf ormance, lack of application, excessive O&M costs

turnkey to

Emissions-6-12 months

Emissions & oil retainage - 4

not enough experience

Survey Topic

Central Virginia Electric Cooperative

New York Power Authority

Old Dominion Electric Cooperative

Grant County Public Utility Dis trict

Powder River Energy Corp./

Bas in Electric

S napping

S hoals EMC

Wis cons in Public S ervice

W hat might b ring the project to an end?

Premature customer contract termination, sale to third party

Ongoing litigation

to limit operation

to 3 years

Transmission improvements to relieve congestion

w ould permit units

to be relocated to improve reliability

1 year emergency license provision Pursuing permanent license

Changes in EPA pollution requirements

The addition of a large base load

or large peaking generator peaking unit

How was project implem ented?

Turnkey to customer

design build by

W hat permits were required/how long to get?

emissions - 3 months

emissions - 3-4

Emissions & zoning

8 w eeks, acoustical 4

w eeks

A ir quality 4 months

A ir quality, f uel storage

Emissions 2 months, interconnection 3 months

$216 +f ound &

Maintenance costs?

$71,233/yr total

f or 13 units

Still in dow n mode See

A pprox $10/kW/yr

Failures? (after com missioning)

SCA DA & onsite

Grid Support with Distributed Resources

In most cases, some permits or licenses were required; these applications need to be made at thevery beginning of project design so that authorization can be obtained in time for project

construction Air emissions and zoning/land use permits were the most common requirements.Temporary installations with less than a one-year lifetime require fewer permits than permanent

or long-term installations

Several utilities split the project implementation into two parts They hired a turnkey vendor to

do the complete generator design, procurement, and installation, then used their own personnel tocomplete the electrical connections to the utility grid, complete the control system connections,and perform the final check-out and startup

Diesel generators typically cost $300 to $400 per kW for permanent installations, or they areleased for short-term projects Operating costs are ten cents per kilowatt-hour or less, depending

on fuel prices Combustion turbines tend to cost more to install, but are less expensive to

operate Combustion turbine projects should be evaluated individually to account for specificdesign and construction variations Most utilities use their system control and data acquisitionsystem or dial-up methods to monitor the project equipment

4

TECHNOLOGY OVERVIEW

While a number of technologies may be suitable for grid support, the scope of this report wascombustion turbines and reciprocating engines The discussion in this section provides a generaloverview of the distributed resource technologies used in the cases

Reciprocating Engines

Nine of the thriteen case studies were projects using reciprocating engines Although these ninereciprocating engine projects were unique, each used diesel engines These engines typicallyoffer the following advantages:

• Low cost

• Utilities have used them previously with favorable results

• The economic benefits from wholesale rate incentives for peak shaving adequately cover thecost of using diesel generators, if they are operated less than 300 hours per year

• Diesel projects can be implemented within a relatively short time (2 to 6 months)

• Rental equipment is readily available

• Generators can be easily moved from one location to another

• Diesel engines have quick start capability

Most study participants agreed on the above advantages and often used these points as a rationalefor their projects Some of their comments include:

• “The generators provide savings to the cooperative.” – Central Virginia Electric Cooperative

• “Sixty to 70% of the units are customer leased, based on favorable economics.” – Dakota

Electric Association

• “Reciprocating engines are the best choice for back-up generators.” – Madison Gas &

Electric

• “The project was completed in six months.” – East Mississippi Electric Power Association

• “Mobile generators were identified as the best solution to improve customer satisfaction.” –

Exelon/ComEd

• “Fast track distributed generation…may be dispatched to relieve congestion.” – Old

Dominion Electric Cooperative

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Technology Overview

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• “These generators were available to us at the time the project was approved.” – Grant

County Public Utility District

• “Diesel engines provide quick-start capabilities.” – Snapping Shoals EMC

• “Leasing portable units was the quickest and most economical solution to the problem.” –

Wisconsin Public Service

As demonstrated in the above comments, mobility and quick installation were recurring themesthat made diesel generation more attractive than other alternatives However, diesel reciprocatingengines have their limitations of their own:

• Diesel reciprocating engines require regular test starts to confirm that the units are ready forfast start-up

• Reliability issues such as overheating problems, lubrication problems, and air intake

problems can cause unplanned shutdowns For more details, see Appendix A (questions 4.3and 5.6 in the survey responses)

• The possibility exists for diesel engines to run out of fuel if not routinely monitored andregularly supplied

• The potential exists for fuel leaks and spills

• Diesel engines create high noise and emissions levels

These issues are important and can be addressed in a variety of ways Under the case

circumstances, however, these limitations were either outweighed by other factors, temporarilydeferred, or of little concern, depending on the case For more discussion of these issues and thetechnologies to address them, see Section 6

Combustion Turbines

Four of the thirteen case studies were projects that used combustion turbines Some slightvariations were found in turbine and fuel type Three of the four cases employed traditional CTtechnology, using natural gas or coal bed methane as fuel, and another used microturbine

technology running propane fuel Differences between CTs and diesel reciprocating engines areevident

The CT market was almost exclusively made up of Conventional CTs (those generally sized onthe order of megawatts) until recently Microturbines in the kW range are a relatively recentdevelopment

Conventional CTs

Given the longer history and predominance of conventional CTs, it was no surprise to find thatthree of four CT projects were using them As representative of the market in general, theydiffered in size and fuel type (Specific details are provided in Section 6.) Using conventional

CT technologies for grid support has several advantages:

• Conventional CT units are manufactured in sizes large enough to meet project requirements

Technology Overview

• They operate well using natural gas fuel

• CT units can be installed quickly to meet project requirements

Again, our study showed a high degree of overlap between the characteristics of the technologyand the reasons cited for its selection Specific examples include:

• “No alternative other than this was available to meet [grid] capacity needs [for 2001].” –

New York Power Authority

• “This DG option is simply the most practical and expedient.” – Powder River Energy

Corporation

However, utilities that consider using conventional CTs must also consider the following

limitations of the technology:

• They are much less mobile than small diesel units

• They require more planning and more site work for a typical installation

• They are not commonly available on a rental basis

• Renewal of emissions permits may become more difficult in future years

In fact, changing emissions requirements may limit the total number of years certain large scale

DG installations can operate before they must be shut down or modified to meet stricter limits

For more discussion of these issues and the technologies to address them, see Section 6 andAppendices B and C

Microturbines

Microturbines typically range from 30 to 75 kW, and are seen by some as offering great potentialfor grid support Beyond the benefits of conventional CTs, microturbines promise:

• Similarly cost-effective to CTs when deployed in multi-unit packs

• Low emissions without supplementary equipment

• Small, compact installation suitable for individual customer environments

As with any developing technology, however, price alone may be a prohibitive factor untileconomies of scale are reached Other challenges faced by microturbines include:

• Optimizing the technology to obtain many hours of trouble-free operation

• Developing cost-effective inverter systems that can easily handle both interconnected andstand-alone operation

This balancing of opposing forces is demonstrated in the following response from Alliant:

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Technology Overview

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“This project will enable Alliant Energy to better understand the operation of Capstone

Microturbines…We are particularly interested in how the units will respond through numerous start-stop sequences.”

Generator Comparisons, Specifications, and Related Technologies

A wide breadth of technologies can be used effectively for grid support, including reciprocatingengines and CTs, among others Additionally, many meaningful differences exist within aparticular technology, such as the availability of “intercooled recuperated cycle” combustionturbines and “high-pressure gas-injected dual-fuel” engines Incorporating DR into a system isnot a simple process of selecting “reciprocating engine” or “CT” and then moving forward withthe permits Narrowing the possibilities to the most appropriate technologies requires answers tothe following questions:

• What unit sizes are desired?

• What are the anticipated hours of operation per year?

• What fuel options are available?

• What installation timeframe is required?

From there, case specifics will likely determine the next considerations or series of questions

5

GENERAL ENVIRONMENTAL CONSIDERATIONS

Although distributed resource technologies offer significant potential for grid support, theirbenefits, costs, and viability as a whole must be viewed within the context of their environmentalimpacts Permitting and siting requirements will differ from project to project, but typicallyinclude the following factors:

• Air emissions

• Land use

• Noise (acoustical)

• Oil spill containment

Factors that influence permitting and siting requirements, along with the time and effort to obtainsuch permits, are:

• Location relative to adjacent land uses

• How long the project will operate

• The size and number of units at one location

In our study, each utility faced particular environmental considerations We asked in Question

5.1 of the survey, “What permits were needed and how long did it take to get each of them

approved (emissions, water, waste water, interconnection, acoustical, zoning, other)?”

Generally speaking, air emissions represented the most common permit requirement; such

permits took two to four months to obtain Air emissions concerns mainly focused on NOx, but

in some cases addressed greenhouse emissions and other air quality issues The permits that wererequired, and the time needed to obtain them in each case, are presented in Table 3-3 of

Section 3 Additional discussion of the environmental considerations in each case is reported inSection 6, and the direct survey responses are available as Appendix A

6

CASE STUDY PROFILES

Twenty-three utilities thought to be using DG for grid support were contacted Thirteen utilitiesresponded with information about their programs and projects Four utilities did not respond toour inquiries; the rest were either unable to respond fully because they had no qualifying

projects, were prohibited from responding due to management direction, or did not have thetime This section presents a general summary of the 13 utility responses that became casestudies for this project

The participating utilities represented three separate types of corporate governance and

ownership, as shown in Table 6-1

Table 6-1

Study Participants, Separated by Ownership Structure

Investor Owned Utilities Public Power Authorities Electric Cooperatives

Alliant Energy New York Power Authority Dakota Electric Association

Central Hudson Gas &

Electric Snapping Shoals EMC

The respondants indicated that the following types of DR units were used by the participatingutilities:

Table 6-2

Summary of Generators used by Case Participants

Generator Types

Total Units

Total Net Capacity Fuel Type

3 utilities used combustion

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The majority of these projects were installed between 1998 and 2001; the earliest project wasinstalled in the 1970s, and one project is currently being completed All thirteen projects providegeneration capacity to the grid, although three do so indirectly by providing standby power toindividual customers who voluntarily interrupt their load at times of system peak All 13

projects in some form, improve service reliability at the customer, distribution system, or

transmission system level

Summary of Responses

Table 6-3 summarizes the cases, listing the utilities in alphabetical order The table has beensplit into two sections to improve readability The table portrays the key characteristics of the

DR projects and the primary justification for installing them

The 13 responses broadly illustrate the types of distributed resources used across the UnitedStates Other DR projects are in operation and could be surveyed in the future to build a strongerdatabase For example, Wisconsin alone has approximately 10 investor-owned utilities, 70municipal utilities, and 25 cooperative electric utilities Various contacts and reports suggestthat at least half these utilities have some type of distributed resource installations, or haveutility-sponsored customer ownership programs This indicates that DR technologies have broadrecognition and acceptance as a way of meeting the electric energy needs of individual

customers These examples show that distributed resources can be used effectively to supportvarious transmission and distribution system deficiencies, in addition to meeting electric systemgeneration requirements

Table 6-3 shows that diesel-fueled combustion turbines and reciprocating engines are commonlyused in a variety of applications In every case, the installations provided better service

reliability to customers, along with various levels of support for transmission and/or distributionsystem voltage and other forms of capacity relief

Case Study Profiles

Table 6-3

Case Summaries and Comparisons

S urvey Topic Alliant Energ y

Central Huds on Gas & Electric

Dak ota Electric

Combus tion Turbines

Rec iproc ating Engines

Rec iproc ating Engines

Rec iproc ating Engines

Rec iproc ating Engines

S ize k W & Install Date

Four 30 kW - 6/29/01

Tw o 25 MW - late 70's

Sev enty - 50 kW

to 14 MW 2000-01

Forty - 550 to

2250 kW - 01

2000-Fiv e - 1825 kW 1/1/98

Three - 2000 kW Spring, 2001

all Diesel, nat'l gas

Top 2-3 Reasons For Project

1 Def er Sub trans f ormer upgrade

1 Trans miss ion

c ustomers , buildings , neighborhoods

2 Unders tand Caps tone Mic roturbines

2 Bac kup f or dis t transf ormer

f ailure

2 Cus tomer reliability

2 Generators

av ailable f or grid

s upport

2 Improv e s y s tem reliability

2 Prevent dis tribution s ub and c irc uit

ov erloads

not prov ided

3 Sy s tem generation

3 Improv e v oltage regulation

3 Provide

s tandby capacity

to reduc e outage duration

Tim e from projec t authorization

S urvey Topic

Central Virg inia Electric Cooperative

New York Power Authority

Old Dominion Electric Cooperative

Grant County Public Utility Dis trict

Powder River Energ y Corp./

B as in Electric

S napping

S hoals EMC

W is cons in Public S ervice

Generator Type

Rec iproc ating Engines

Combus tion Turbines

Rec iproc ating Engines

Rec iproc ating Engines

Combus tion Turbines

Rec iproc ating Engines

Rec iproc ating Engines

S iz e k W & Ins tall Date

One of Tw elv e -

2000 kW 11/1999

Elev en - 44 MW 6/1/2001

Ten - 2000 kW

In progres s

Tw enty - 1600 kW 7/2001

Three - 5 MW 1s t Qtr, 2002

Fiv e - 1.85 MW 3/1999 Three - 1.85 MW In- progres s

Sev enty - 68 to

1500 kW Total

102 MW 6/1/2001

24.9, 69, 115, &

138 kV

Top 2-3 Reas ons For P rojec t

1 Competitiv e reas on to improv e reliability

1 NY PA obligation to

s upply 80% of

NY C peak demand In City

1 Reliability improv ement @ deliv ery points

w ith c ritic al loads

or undes irable reliability

1 Capac ity to

c ov er low w ater

y ear f or hy dro units

1 V oltage s upport

f or radial 69 kV trans mis s ion

1 Prov ides low er

c os t peaking pow er during Summer

1 Meet res erv e

c apac ity requirement of

to s y s tem

2 Prov ide v oltage

& s y s tem s upport

to trans mis s ion

3 Prov ide low er pric ed energy during high c os t periods

3 Blac k s tart

c apability if grid

3 Prov ides bac kup f or HQ

w hen Subs tation

is outaged

3 Reduc e ris k to market pric ing

Continuing bas ed

on generation needs

Tim e from projec t authoriz ation

to c om m erc ial s ervic e?

$216 +f oundation

EPRIsolutions Licensed Material

Case Study Profiles

6-4

Summary Discussion by Case

A condensed profile of each case study is provided in the following summaries The surveyresponses were the primary source of information for most of the report Confidentiality

concerns limited the information that some utilities were willing to provide Utility web sitesand presentations provided additional information for the Alliant Energy, East Mississippi, andNew York Power Authority case studies

Alliant Energy

Alliant Energy (Cedar Rapids, IA) presented its Capstone Microturbine project to defer a

distribution substation capacity upgrade in a straightforward application of distributed resourcesnear Racine, Minnesota Alliant reports that the project construction and startup was completedwith relative ease The project started operating on June 29, 2001, and the longest-running unithas logged 66 hours to date with no problems

Alliant Energy’s utility operations serve more than 1.2 million customers in mid-sized cities andrural areas within Iowa, Illinois, Minnesota, and Wisconsin Alliant’s service territory covers54,000 square miles, with more than 9,700 miles of transmission lines and 8,000 miles of naturalgas mains Alliant was formed by the merger of IES Utilities, Interstate Power Company, andWisconsin Power and Light Company

Alliant’s rural Racine Junction Substation is a 24.9-12.47 kV, 750-kVA substation The peakload on the substation was 842 kW (112% of capacity) in 1999 Alliant examined three

alternatives to resolve the substation transformer overload:

• Alternative #1 involved upgrading the substation and replacing the substation transformerswith three new 500-kVA units at an expected cost of $111,000

• Alternative #2 involved converting the circuit to 24.9 kV from 12.47 kV

• Alternative #3 was to install four 30-kW Capstone Microturbines to alleviate substationtransformer overloading during peak load periods

Alliant opted to use the Capstone Microturbines to gain firsthand, working knowledge of the use

of distributed resources on the utility system The Capstone Microturbines were placed in

service on June 29, 2001 and are fueled with propane The generators are to be used during thesubstation peak load period to defer a capacity upgrade and permit Alliant to better understandthe load growth in the area before committing to a final, long-term solution Alliant also hopes

to gain operating experience to better understand the performance of the Capstone

Microturbines

This project was developed in a design-build fashion using Alliant engineers Planning anddesign began in November 2000 Air quality permits were not required, but the County Planningand Zoning Committee required a Conditional Land Use Permit for the site, which took fourweeks to obtain