District heating Handbook

268 Pages·164.26 MB·English

by  Taylor N.R., Stierhoff K.L.

DISTRICT HEATING
HANDBOOK
FOURTH EDITION
Vol. 1
A Design Guide
Published in the interest of the
District Heating and Cooling Industry by
International District Heating Association
1735 "Eye" 81.N.W., Washington, D.C. 20006
Preface to the Fourth
Edition
FORMORETHANTHIRTYYEARSthis book's wellknown predecessor served to
guide succeeding generations ?f engineers t? a.n unde~standing of. district
heating and how best to use It. However, dIstnct heatmg and coolIng has
developed considerably since 1951 when the Third Edition was published.
Copyright, 1983
Equipment and methods have changed and there are new factors that givethe
International District Hearing Association
industry an important role in the national concerns as to the utilization of our
Washington, D.C.
energyresources.
The Volume was first published in 1921asHandbook oftheNational District
ISBN 0-9610838-0-8
HeatingAssociation, followed by the second edition in 1932and again in 1951.
Library of Congress Catalogue # 83-080208
Beginningin the 1960'sthere was areal effort to revisethe text and publish the
4th edition, but with limited resources, a volunteer staff of authors, and
Text and illustrations are fully protected by Copyright and may not be reprinted,
overwhelming assignments to already overworked members, the effort floun-
either wholly orinpart, without permission.
dered year after year.
The National District Heating Association in the meantime became the
International District Heating Association (IDHA) and in 1980wasthoroughly
reorganized with a new staff taking a strong advocacy position for district
heating and developing affiliations with similar groups. The Edison Electric
In.stituteearly recognized the value ofarevisionto thehandbook and supported
an in-depth review by an editorial consultant. The appraisal was positive and
EEl backed IDHA in developing the fourth edition. The U.S. Department of
Energy further assisted the effort with a development contract through the
Argonne National Laboratories. The firm of Enviro-Management and Re-
search, Inc. was selected by IDHA to develop the manuscript and coordinate
the production.
The membership of IDHA contributed time, effort and resources in furnish-
ing material and checking data, but their patience and understanding in what
has seemed to be an insurmountable series of delays, cancellations, and
deviations has been exceptional.
In spite ofour best efforts there may be some mistakes in the book, and they
are our responsibility. We must enter the same plea as that used 200years ago
b~ Dr. Johnson. A lady had taken him to task for a flagrantly wrong term in
hISdictionary. When she asked him how he could make such a mistake he
replied, "Ignorance, Madam, pure ignorance."
NORMAN R. TAYLOR
KATHARINE L. STIERHOFF
Washington,D.C.1982
iii
,I
American Society of Heating, Refrigeration and Air Conditioning En-
gineers, Clinton Phillips, President, Samuel Rosenberg, Handbook
Editor, for permission to reprint material.
Babcock and Wilcox, for permission to reprint material and illustrations
from "Steam", a reference book, 39th Edition, third printing, copy-
right 1978.
We also most sincerely appreciate the unaccountable hours contributed by
Acknowledgements IDHA members and their company staffs who have furnished both helpful
suggestions, authoritative material, and who read, reviewed and corrected
seemingly endless pages oftexts.
This book could not have been written without the help of a great number of
people and organizations. The publishers and editors acknowledge gratefully
their assistance. In sofar as possible we have listed major contributions in the
chronological order of their participation as it is an indicator of the long and
complex task.
Adequate credit to all that assisted would be an impossible task, but we
sincerely appreciate every effort.
The Educational Committee, J. Earl Seiter, Chairman, 1951,who edited
and published the Third Edition.
The Educational Committee, Nelson R. Tonet, Chairman, 1972-73,
under President Joseph J. Bosl, assembled and edited a draft for the
fourth edition.
The Educational Committee, Joseph J. Bosl,Chairman, 1976-77,under
President Mack A. Riley, developed participation of federal agencies
in the Handbook.
Edison Electric Institute funded an editorial appraisal of the Third
Edition and draft material forthe new version. Asa result, EEl made
available financial support to IDHA for the Fourth Edition.
U.S. Department of Energy, made available a study grant to develop a
contemporary handbook text.
John P. Millhone
Maxine Savitz
Gerald S.Leighton
John Rodousakis
Argonne National Laboratory administered the study grant and pro-
vided invaluable technical assistance and services.
Allen Kennedy
Danilo J. Santini
Jess Pasqual
Enviro-Management and Research Inc., Naresh K. Khosla, contractors
to IDHA for research and text preparation.
Geothermal Energy Division of the Department of Energy, Eric Peter-
son, contribution of the chapter on geothermal sources for district
heating.
Dr. Gordon M. Reistad, Oregon State University, text development for
geothermal resources.
iv v
.197
Compressed Air Systems. .. ....
.198
Auxiliary Steam Plant Equipment. .. .
Water Treatment .205
Chapter 5
AIRCONDITIONING. . .. . . . . . ... .215
Statistics. . . . . . . . . . . . . . . .215
Contents System Design Considerations .215
. . . . .219
Absorption System. . . . . . . . . .. .
.223
Mechanical Compression System. .
Chapter 6
DISTRIBUTION SYSTEMS .231
;;; .231
Preface. . . . . . . . . Steam Systems. .. .. .. .. ... .. .. .. ... .. ..... .. ..
Acknowledgments ;v Hot Water Systems. . ..... 279
.. .. .. 283
Chilled Water Distribution Systems. . .. .. .. .. ...
Chapter 1 General Considerations for Distribution Loop Installation .289
THE DISTRICT HEATING AND COOLING INDUSTRY 1 Standards and Currents Installation Practices .289
An Overviewof DistrictHeatingand Cooling 1 Construction Procedures. ... 290
1 Leak Location. . .. ... .. .... . .293
The History of District Heating. ... .. .. ..
2
District Heating in the U.S. ..............
4 Chapter 7
Experience of Other Countries with District Heating
8 METERING ...295
District Heating Technology, Markets and Costs .
Benefits and Barriers. .... .. .. .. ... ....... 10 Physical Properties. ...295
11 ...299
The Future of District Heating. . ... ........ Methods of Metering. . . . . . . . . . .
.312
Hot and Chilled Water Metering
Chapter 2
OVERALL SYSTEM CONSIDERATIONS 13 Chapter 8
District Heating and Cooling Concepts . . . . . . .. 13 DISTRICT HEATING SERVICE TO THE USER .319
Principle Issues and Barriers . . . . . . . . .. . . . . . .. 16 Estimating Steam Requirements .319
Conclusions..... 49 Building Space Conditioning. ... .336
..356
Waste Heat Reclamation Systems. .. ....
..371
Chapter 3 Steam Refrigeration and Air Conditioning
.387
SOURCES OF ENERGY FOR DISTRICT HEATING SYSTEMS 51 Service Water Heating.
.400
Coal . . . . . . . .. 51 Humidication by Steam
Oil. ............ 69
Natural Gas 81 Chapter 9
90 THE ECONOMIC AND FINANCIAL ANALYSIS OF
Cogeneration. . . .. . ...
Refuse- Derived Energy . . .. . . . . . . . . 98 COMMUNITY ENERGY SYSTEMS. . . . . . .405
108
Geothermal. . .. """"" . . . . . . . . Economics and Financial Management. . . . . .. ... . ..405
129
Nonconventional Fuels for District Heating . Background for Economic Analysis of Community Energy Systems 412
Examples of Community Energy Systems. . . . . . . . . . . .413
Chapter 4 Economic Feasibility of Community Energy Systems. . . . . . . .. .415
STEAMAND HOT WATERPRODUCTION PLANT Overview of Economic Analysis of Community Energy Systems. 417
. . . . .139
Estimates of Costs and Revenues. . . . . .421
Principles of Combustion. . . . . . .. . . . .139
Boilers. .. '" '" ............... .141 Systems Comparison and Selection. . . . . . . .. . .441
Steam Separators and Superheaters. . . . . . .150 Sensitivity Analysis of Miscellaneous Considerations .449
Operation and Maintenance of Equipment .156 Sample Application of the Economic Analysis. . .. . .451
Production of Demand and Output. ... """'" .176 Rate Making Principles '," .. .458
Construction Planning, Drawings and Specifications .178 Examples of Rate Designs . .461
Instrumentation and Controls. .
.179
Draft, Stack and Fans .191 Append;x 473
Index. . . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . .. . . . . . . . .. . . . . . . . . . . . . .510
CHAPTER 1
The and
District Heating
Cooling Industry
AN OVERVIEWQF DISTRICT HEATING AND COOLING
DISTRICTHEATINGANDCOOLINGcan be described as a method by which
thermal energy from a central source is distributed to residential, commercial
and industrial consumers for use in space heating, cooling, water heating and
process heating. The central source may be one of any number of types of
boiler units, a refuse incinerator, a geothermal source, solar energy or one
which utilizes heat developed as a by-product of electrical generation. This
latter approach, generally known as "cogeneration," has a high level of energy
utilization efficiency.
District heating systems are adaptable to a wide variety of fuel types. This
flexibilitycanbenefit the nation and the consumer byproviding thermal energy
at stable and competitive prices while, atthe same time, lessening our depend-
ence on scarce or imported fuels. The district heating concept isnot new. First
commercial applications inthe United Statesdate back asfar as 1876.However,
modern applications of the district heating concept have not been adopted
readily, despite it being particularly well suited to the energy needs of many
areas.
In the district heating process, energy is distributed to individual buildings
from a central plant by means of steam or hot or chilled water lines. Buildings
connected with the systemextract energy from the transfer medium rather than
generating the useable energy on siteat a facility in each building.
District heating is best suited to those areas with a high building and
population density in relatively cold climatic zones. In such areas, district
heating can maintain stable and competitive pricing. District cooling is appli-
cable in most areas where there are appreciable concentrations of population.
Sincewehave entered an era where formerly low-cost and abundant fossilfuels
have become scarceand expensive, district heating and cooling isgetting awell-
deserved second-look, especially in the high density central citiesofour nation.
THE HISTORY OF DISTRICT HEATING
Piped heating systems are a very old concept. Nearly 2,000 years ago piped
systemswereused by ancient Romans for heating dwellings aswellasbaths. In
more modern times, Sir William Cook in Manchester, England, in 1745,
demonstrated the potential of steam heat for buildings through a system of
pipe coils in his home. In 1748, Benjamin Franklin built an iron stove-type
furnace in an underground chamber and used it to heat a series of row houses
1
2 CHAPTER 1 TheDistrict Heating andCooling Industry 3
byrunning the flue in a brick and tiled fireproof enclosure beneath the floors. total energy demand for space and hot water heating in this country. District
A water heating system was installed in a U.S. building in 1830and, in 1844, heating systems are used in a limited number of cities, in various institutions,
the Eastern Hotel in Boston, Massachusetts, used steam for the first time as the and on college campuses. No significant growth in demand for district heating
medium for heating a large commercial building. With these advances, includ- has been noted in recent years (Fig. 1.1).However, there has been renewed
ing the introduction in 1860 of the first cast iron radiator, a major industry interest in renovating and rejuvenating district heating, because of the changes
sprang up manufacturing and installing steam and hot water heating systems. in oilsupplies and increases in all fuel prices.
In 1877,Birdsill Holly, a noted hydraulic engineer and inventor, pioneered About one-fifth of U.S. energy is used for heating and cooling. Current
the first commercially successful district heating system. Using a boiler in his estimates are that district heating systems could supply about half that energy
cellar as the central heat source, Holly developed a loop of steam distribution, . efficiently. Electrical generating efficiencies increase from about 33%for elec-
.
radiation, condensation, and return for his own home. This was followed by ! tricity alone to over 60%efficiency when hot water or steam from generation
increasingly distant extensions of the system to heat neighbors homes up to is used in a district heating system. In most cases, this leads directly to a
1,000feet away. The distribution line was iron pipe, wrapped with asbestos, reduction in the useof oil or natural gas.
felt, and paper, buried about three feet deep in a wooden box filled with Currently, oil isthe primary fuel for district heating boilers, developing 48%
sawdust. His initial efforts were so successful that he was able to raise the ofthe steam (Fig. 1.2).Use ofcoal and refuse as primary fuels isunder serious
necessarycapital tofound the Holly Steam Combination Company inLockport, consideration. There is growing motivation to expand existing district heating
N.Y., which began servicewith 14customers. By 1879Holly's corporation had systemswherever circumstances make such augmentation possible. While many
nearly three milesofline in service,and by 1880the steam servicewas extended roadblocks exist, there are both government and private efforts underway to
to include several factories. By the following year the industry had grown so increase the contribution of district heating in the years ahead.
fast that the first district steam equipment manufacturing corporation was Fewer significant U.S. district heating systemspresently employ hot water as
formed. themedium fortransporting the energy than steam network facilities.Feasibility
Within a decade, district heat using a steam transfer medium had expanded studies are underway to assessthe various aspects of district heating develop-
toten citiesin Pennsylvania and others asfar away as DuBuque, Iowa, Denver, ment in the United States. Among the areas being studied are comparisons of
Colorado, and New York City. hot water and steam transportation mediums, space cooling, cogeneration
In 1879,the same year Thomas Edison was installing electric lines in New efficiencies,fuel savings, and costs.
York City, the Steam Heating and Power Company of New York wasfounded.
140
Soon thereafter a competing firm, the New York Steam Company was estab-
lished. As many small electric utility companies evolved to meet the new and
growing demand for electricity utilization, it became apparent that use of the 130
exhaust steam from their power generation was an obvious opportunity to add
to profits.
120
Asefficienciesof scalebegan to be added to electrical generation, the district
heating industry suffered. The advent ofclosed-cycleturbine generators lacking
exhaust steam, and oflarger, more efficientbut lesscentrally located generating 110
facilitieslimited the growth potential of the steam industry. Steam being a by- en
I I.D..J
product of the generating process which could be sold very inexpensively, had :z:E 100
been a second profit center for electric utilities. However, generation of steam
I
separately from electricity greatly increased costs and utilities were forced to 0 DELIVERED
:.:.:.:iJ 90
raise rates. In 1909,the year the National District Heating Association was i
founded, about 150district heating systemsexisted in the United States. Many
operated marginally oratlow profit. The costofconverting from exhaust steam 80
SOLD
to livesteam had been a shock to the industry. From that low point, however,
I
the management and profitability ofdistrict heating systemsimproved dramat-
70
ically through most ofthe first half of this century. II
I
SinceWorld War II,district heating in the U.S. has remained virtually static,
aslow-cost and abundant fossil fuels and electricity have overshadowed many 60
of the advantages of district heating. However, European nations during the
same period had significant successwith hot water-based district heating.
'71 '72 '73 '74 '75 '76 '77 '78 '79 '80
DISTRICT HEATING IN THE UNITED STATES
YEAR
District heating in the United States isbased, primarily, on the use of steam. It FIGURE 1.1
District heating and cooling systems account for less than one-percent of the I' Ten year summary of steam sendout and sales
II
4 CHAPTER 1 .1 TheDistrict Heating andCoolingIndustry 5
D .OIL
COAL DGAS . TURBINE U.S.S.R
DENMARK
70
SWEDEN
60 FINLAND
W.GERMANY
50
FRANCE
a-ls HOLLAND
::IE 40
U.S.A.
z
0
::::i
-l 30 U.K.
Sj
ITALY
20 -,-
0 500 1000 1500 2000
10
MEGAWATTS THERMAL PER MILLION PEOPLE
FIG URE 1.3
0
1976 1977 1978 1979 1980 Installed district heating and cooling capacity
YEAR
FIGURE 1.2 systems and hot water cooling devices are not efficient in comparison with
Pounds of steam produced by fuel type electrically-driven units.
Electrical generating practice in the U.S. differs greatly from the European
EXPERIENCE OF OTHER COUNTRIES WITH DISTRICT HEATING
customs. In Europe, turbines generally utilize back-pressure design in sizes
ranging from 50to 300MW with throttle pressures below 2,400psi,whereas in
District heating and cooling capacity in several countries are compared in
this country, units generally use a condensing design with capacities ranging
Figure 1.3.
from 600 to 1300MW at pressures from 2,400to 3,500psi.
Significant installations ofdistrict heating inEurope did not occur until after
In addition to these engineering and load differences today, electric utility
World War II. Since that time, however, it has developed rapidly and with
plants take eight to ten years to site, design, and build. Developers cannot
excellentpublic acceptance. Asthe growth ofdistrictheating isrelatively recent,
project the utility needs for their buildings on such a long-range basis. In
the European public viewsit as a "modern" development and approach it with
Europe, the considerably smaller plants are built more nearly in the same time
the enthusiasm that greets innovation.
frame as housing and commercial developments.
The contemporary success of district heating in Europe has aroused new
Over the past 25years, most northern European countries have centralized
interest in this country and has led to a movement toward adoption of Europe
heat production and combined the generation of heat and electricity. More
methods in this nation's cities. While direct application of European methods
than 30%of allhomes in Denmark are supplied by district heating and 90%of
may not be transferrable to the United Sfates directly because of major
alltownswithpopulations exceeding 2,000people have somesortofcentralized
differences inpower plants, in heating and cooling loads and in patterns of city
heat supply. The Danish national energy plan includes a heating program that
development, the potential remains great.
would allow 40%of the country's total heat consumption in 1990to be met by
The European method useshot water from back-pressure turbines distributed
residual heat from electric power station generation. In Sweden 35 cities and
to customer loads created incrementally as new communities are developed. In
towns have district heating systems using hot water as the heat distribution
this country, new building construction as a percentage of the total existing
medium supplied from plants having only hot water boilers.
building volume islow. European systems have sustained winter demand and
When heat loads exceed 100MW, combined heat and power plants are the
carry noappreciable air-conditioning loads in summer. Inthe U.S. where steam
usual source. The U.S.S.R. has 970 combined heat and power stations with a
isavailable, itisgenerally used forheating while electricity powers most cooling
capacity of 45,000 MW out of a total capacity of 207,000 MW for all electric
machinery resulting in poor load factors for both systems. As a result, electric
power stations. West Germany has 472district heating networks. The govern-
utilities in the past have heavily promoted electric heating. Existing buildings
ment is studying the feasibility of a national grid of district heating systems
equipped for steam or electric heat cannot be adapted readily to hot water
6 CHAPTER 1 TheDistrict Heating andCoolingIndustry 7
supplied bylarge power stations. It hasbeen estimated that 40%ofthe heat for England
space and water heating could be supplied in this way. England is beginning to explore expansion of a district heating concept. A
The district heating programs ofseveralcountries are detailed inthefollowing
policy of regenerating electricity at the absolute lowest cost has led away from
sections.
experiments in cogeneration. Anew philosophy has recently been propounded
which would have the government look at cogeneration in terms of electricity
Finland as a by-product of heat rather than the alternative.
In Finland 14%of all homes are served by district heating systems. The
West Germany
majority of these,because ofthe efficienciesofhigh density, are in Helsinki. In
that city, 65%ofthe homes are kept warm through district heating, with a goal West Germany is heavily dependent upon imported fuels. As a result, the
for 1990of 85%.Feed and return pipelines for the Helsinki system total 250 government is studying a variety of alternative space heating technologies.
miles. Many cities and towns currently have district heating systems. Although dual-
The energy for much of Finnish district heating is supplied by waste heat purpose power plants are not widely favored, industrial cogeneration doeshave
from nuclear plants. The waste heat isnot only utilized in the system, but also public support.
reduces by half the effluent heat discharged into the ocean in nuclear cooling A government study is assessing the possibilities of a nationwide district
processes. In Helsinki, district heating not only has aided in the elimination of heating "super-grid" to interconnect all cities with populations of 40,000 or
environmental pollution, but also has turned a profit for the city. more. Such a grid would utilize heat from allavailable sources.
In 1976, Helsinki had four cogeneration heat and power stations-four
Switzerland
heating plants for peak loads and 36transportable heating plants. Two addi-
tional heating stations are planned by 1984and another pair by 1993. With a relatively high standard of living, it is not the economics of fossil
fuelswhichhave prompted Switzerland tobegin expansion ofitsdistrict heating
systems,but aconcern forthe environment. With arelatively lowurban density
Sweden
and abundant water power, district heating isstill in its infancy in this nation,
Sweden relies on approximately 50 district heating systems, owned by the however, its implementation has begun on a small scale.
communities they serve to provide space heating and domestic hot water. In
Stockholm, about 50%ofthe inhabitants are served bydistrict heating with the Italy
goal for the year 2000 set at 90%.District heating is strongly emphasized as The climate of this sourthern European nation is milder than most other
part of the nation's national fuels policy. nations on that continent. Brescia, on Lake Garda in North Central Italy, has
Sweden isheavily dependent upon imported fossilfuels. It isestimated that, a municipally-owned urban district heating system employing a back-pressure
in Stockholm alone, district heating saves an estimated $11 million or more turbine with 30MW electrical generating capacity. Asecond unit isjust coming
annually in reduced fuel oilconsumption. District heating systemsare required on line. Supplemental boilers provide superheated water during peak periods
to connect any eligible applicant to the system. Loans and grants are made and during warm weather when heat isneeded only for domestic hot water.
available so the new subscriber can afford to make the connection. In small or
new communities, mobile boilers may provide the heat but, as the community Union of Soviet Socialist Republics
grows,a more permanent installation ismade. Russia isthe largest user of district heating in the world, with a cogeneration
capacity far more than the rest of the world combined. Over 1,000 stations
Denmark provide heat and electricity to800Sovietciti~s.The centrally planned economy,
which can dictate the size, location and composition of new communities,
One of the earliest European nations to use district heating, Denmark has
makes installation of district heating systems easy and efficient. As a result,
used cogeneration technology for nearly 60 years. Fifty percent of all energy
over half of domestic heat in the U.S.S.R. is provided by district heating
consumption in Denmark isfor space heating, with district systems supplying
through cogeneration.
40%of allDanish households.
In planning new communities, loads are forecast on a five-to-ten year basis.
A deliberate emphasis has been put on use of energy sources such as coal,
Before anew thermal power station isbuilt, an 8to 12billion Btu/hr heat load
uranium, and residual fuel oil as well as domestic and industrial wastes in
and a 200 MW electrical load are required. Until that point is reached, local
district heating applications.
heat-only boiler plants supply the hot water, while electric needs are provided
Denmark is a pioneer in the use of refuse, where about 60%of all waste is
through a link with the national grid.
used for district heating. This supplies 5%of the total heat consumed in the
nation. The national goal isto increase this percentage to 75%of all waste. Czechoslovakia, Rumania, Poland, Hungary, and Bulgaria
Hook-up to district heating is not mandatory; however, costs of district
Czechoslovakia leadsEastern European nations indeveloped district heating
heating are kept low enough to generate demand strictly on the basis of
capacity. Altogether, 157cities have district heating systems in that nation.
competition. A subscriber agrees topurchase heat for aminimum of20years-
Poland and Rumania have concentrated on large district heating systems. In
usually the repayment period ofthe loan covering connection charges.
11
I
8 CHAPTER 1 The District Heating and Cooling Industry 9
I
Poland and Czechoslovakia, where coal isabundant, district heating isstill in I megawatts of capacity needed. Often, only a small portion of the total system
its early stages, with small sized systems predominant. cost isneeded initially, with the bulk of the costs being provided through sales
In Rumania, 50%of all space heating is provided through district heating revenues.
systems; however, only one-third of that comes from cogeneration, the bulk In contrast, a system for a smaller city core area would require only a few
I
being from single-purpose equipment. Bulgaria has abundant coal and, there- hundred megawatt capacity and but a few miles of distribution piping. Con-
fore, has led in the highest use of cogeneration facilities of any of the Eastern struction could range from only a fewyears up to about ten years, with capital
I
European block nations. requirements running in the tens of millions of dollars. Some characteristics
would be common to systems inboth areas:
DISTRICT HEATING TECHNOLOGY, MARKETS AND COSTS
1. A variety of building types and energy uses will be included. Several
simultaneous services willbe required.
District heating systemscan be classified according tothe type ofarea they
serve, with different system technology and design necessary for optimum 1 2. Thermal energy sources probably will be surplus heat from electric and
industrial plants, urban waste disposal facilities,geothermal wells,or solar
performance ineach area type. Typical classifications byservicearea ormarket collectors.
are:
3. Distribution network costs willcomprise a majority of the system costs.
1. Densely populated urban areas.
4. Institutional arrangements for achieving a successfulsystemwillbe exten-
2. High density building clusters.
siveand complex, involving both public and private sectors.
3. Industrial complexes.
4. Low density residential areas. High Density Clusters
Studies of existing systems have shown that district heating can be econom-
High density developments include such potential system users as suburban
ically productive in the first three markets listed above. The experience of
shopping centers, a university campus, a high density highrise residential
European communities show that, when correctly applied, single family resi-
dential areas could be served economically also. complex, orahigh density mixed suburban development. Characteristics ofthe
Three main factors determine whether or not district heating willbeeconom- systeminclude:
ically productive in a given environment. 1. Both plants and distribution network willprobably be new and designed
. Heat-load density. specificallyfor the application.
. Annualloadfactor. 2. The distribution network may be relatively small, comprising a small part
. Rate of consumer connections. of total system cost.
A majority of the capital investment required for a district heating system 3. Coal fired systemsmay be used for larger systems, with oil and gas used
in smaller applications.
goesinto the costlyfacilitiesneeded for transmission and distribution. Thiswill
run from 50%to 75% of the total. To be cost effective, District Heating and 4. Central source may be a new cogeneration plant or a facility making use
of surplus heat from an existing industrial or electric plant.
Cooling (DHC) requires a high heat-load density. Economics alone may rule
5. Institutional arrangements are usually simple, involving only a few deci-
out single-family residential areas under current conditions. Changes in eco-
sion-makers.
nomics or technology such as development of low-cost, non-metallic piping,
6. Financing would be from a few million to a few tens of million dollars.
improved installation techniques, and low-cost metering could change the
outlook, however. Construction would run from a few years to ten years in one or two
phases.
For economical operation, a district heating system must connect the maxi-
mum number of users in a service area tothe system as soon as practical. This Industrial Complexes
rate of consumer connections sets the pace for revenue which, in turn, deter-
mines the economic success or failure of the system. Once the system is in Special demands of systems for industrial complexes rule the type of system
operation and the initial consumer connection rate satisfactory, the cost of ~ and its economics. Steam, hot water, or both may be necessary, and industrial
connecting new buildings into the system is often lessthan the cost of furnace process loads willdominate systemuse. Central plant technology and fuelswill
or boiler installations. Cost of conversion for existing buildings depends on be similar to those for high density clusters.
multiple factors, such as age, type and condition of existing equipment, since Institutional arrangements should besimple,but varied thermal requirements
conversion to district heating becomes most attractive when existing systems may make distribution systems complex. A high utilization factor makes for
favorable economics.
are in need of replacement.
Densely Populated Urban Areas LowDensity Residential Areas
In the central core of densely populated metropolitan areas, district heating A district heating system for low-density residential developments typically
systems should be multi-purpose in order to serve as large a number of would serve an area dominated by single or duplex residential units. Such
consumers as possible. A twenty- to thirty-year phased construction period systemswould probably have the following in common:
would not be unlikely for such a system. Massive amounts of financing would I 1. Cost of the distribution system, most likely low temperature hot water,
1 would dominate construction costs.
be required for the miles of distribution pipes and the several thousand
1
10 CHAPTER 1 TheDistrict Heating andCoolingIndustry 11
2. Water-source heat pumps could augment system capacity. district heating system installation. This cooperative structure can be
3. Fuel source could be gas, oil cogeneration, geothermal wells or solar utilized on a much broader scale.
central plants. On the other side ofthe scale are barriers which must be overcome if district
4. Central source is likely to be new, with capacities of less than one heating is to expand as an effective enterprise in the United States. These
barriers are:
megawatt to afewmegawatts.
5. Institutional arrangements may be moderately complex. 1. Electric utilities, which are essential partners in large cogeneration facili-
6. High capital costsand low utilization make this type of systemmarginally ties, see problems as well as benefits. Most utility executives are faced
economical in most areas.
with a myriad of problems in the marketing and generation of electricity
alone and, hence, hestitate to take on the burdens ofwhat isessentially a
BENEFITS AND BARRIERS
new industry. Many executives who are associated with or familiar with
Revitalizing district heating isanalogous to opening a new frontier. Despite existing district heating systems believe them to be marginal operations,
the fact that district heating has been in commercial application for over 100 to be abandoned rather than expanded. Some utilities, however, are
exploring district heating with a positive attitude.
years, new development in this industry has all the aspects of entering a new
venture. Benefitsbeckon temptingly while barriers appear toloom insurmount- 2. Federal policy currently does not support district heating. Neither tax-
able. To break down the barriers and to reap the benefits isa challenging and, exempt revenue bond financing on a major scale nor investment tax
credits are available for district heating systems under current law. The
perhaps, alengthy task, but the rewards are great.
The benefits include: policies of the Economic Regulatory Administration at present do not
1. Conservation of scarce natural resources through using energy more encourage cogeneration, and those of the Federal Energy Regulatory
efficiently, increasing conservation efforts, and maximizing the useofeach Commission do not allow necessary fuel adjustment pass-through to
encourage utility company participation and support.
Btu expended. If implemented in the U.S. today, district heating could
saveup to2.5million barrels ofoil or natural gasequivalents each day by 3. Feasibility studies are very expensive, time consuming, and tangled in a
the year 2000. District heating does this by utilizing waste heat which web of red tape. In a time of where every dollar is precious and every
otherwise goes unused to displace consumption of oil and natural gas. minute important, necessary studies are long and costly.Asimple prelim-
Much greater fuel efficiency is achieved through cogeneration. inary study for adistrict heating systemfor alarge citymight cost $50,000.
2. Stabilization of energy costs and supplies. District heating system central A detailed study could run $500,000or more. Lack of clear support and
direction add to delays and increase costs.
plants can usecoal,nuclear fuel, urban solid refuse, geothermal resources,
or solar energy instead of the sensitive supplies of imported oilor natural
THE FUTURE OF DISTRICT HEATING
gas reserves. These fuels all are to a greater or lesser degree, more stable
in both supply and price than oil or natural gas. Despite the barriers and some years of neglect, the future for district heating
3. Stabilization of thermal services and their costs. For industry to invest inthe United Statesisbright. Barriers canand willbeovercome. The technology
capital in expansion, a reasonable return on investment must be likely. If isnot a problem as the barriers are in the social,political and financial arenas.
interruption in needed services is likely or if costs lack stability, business These barriers are difficult, but they can be removed. Bearing more weight than
cannot afford to make the investment. District heating systems provide any other factor in the equation isneed-which isthere and pressing.
the necessary cost and service stability. The capacity is there as well. If implemented fully in appropriate markets,
4. Creation ofshort- and long-term employment opportunities. Construction an analysis for Argonne National Laboratories shows that thermal capacity for
of a small system provides employment for skilled and unskilled workers district heating in the United States would be approximately 300,000 mega-
for several years at the very least. Construction of a major urban system watts-a fifteen-fold increase over present district heating output. Some sug-
can provide many jobs for nearly a working lifetime. Operation and gestions which have been made to help lower the barriers include:
maintenance of the system provides employment for others, while the 1. Education of government and industry officials and potential customers
availability of reasonably priced, stable thermal services means growth concerning district heating.
and business expansion which provides still more employment opportu- 2. Development of apractical arrangement sopublic and private capital can
nities.
bejoined for district heating development. One such arrangement might
5. Reduction of environmental pollution and improvement in air quality. be public investment of capital with local utilities handling operation of
District heating systemsreplace small,uncontrolled sourcesofairpollution the system.
with afully controlled central source. Though air quality in the immediate 3. Relaxation of such environmental regulations as might be necessary to
vicinity of a central source may experience an increase in emissions, the allow coal-fired cogeneration to serve U.S. cities.
net effect often will be adramatic reduction in pollution concentration. 4. Improved communication and coordination between government and
6. Establishment of abasefor future cooperative efforts inthe field ofenergy industry to achieve district heating goals.
planning and management. Cooperation among city governments, utili- The agenda is set; the course clear. The United States is ready for a
ties, industry, building owners and citizens is essential to almost any renaissance in district heating.