reports 42

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Studies

and reports 42

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Recent titles iri t h i s series:

For details o f the complete series please see tlie list printed at the end o f this work.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

35.

36.

31.

38.

39.

40.

41.

42.

Hydrological maps. Co-edirioii lhicsco- WMO.

World catalogue o f very large floods/Répertoire mondial des très fortes crues.

Floodflow computation. Methods compiled from world experience.

Water quality surveys.

Effects o f urbanization aiid iiidiistrialization on the hydrological reginie and on water quality. Proceedings of the Anisterdam Symposium. October 1 9 7 7 / E f f e t s de l’urbanisation e t de l’industrialisation sur l e régime hydrologique et sur l a qualité de l’eau.

Actes du Colloque d’Amsterdam. Octobre 1977. Co-ediiioii IAHS-Uiiesco

-

Coédifioli AISH-Unesco.

World water balance and water resoiirces o f the e a r t h . (Etiglislr edition).

Inipact o f urbanization and industrialization on water resources planning and management.

Socio-economic aspects o f urban hydrology.

Casebook o f niethods o f computation o f quantitative changes in the hydrological regime o f river basins due to human activities.

Surface water and ground-water interaction.

Aquifer contamination and protection.

Methods o f computation of tlie water balance of large lakes and reservoirs.

.

Vol. I hlethodology Vol. II Case studizs

Application o f results from representative and experimental basins.

Groundwater in hard rocks.

Groundwater hlodels.

Vol. I

Sedimentation Problems in River Basins.

Methods of computation o f low stream flow.

Proceedings of t h e Leningrad Symposium on specific aspects o f hydrological computations for water projects (Russian).

Methods o f hydrological coinpiitations for water projects.

Hydrclcgical aspects o f drought.

Guidebook to studies of land subsidence due t o groundwater withdrawal.

Guide t o the hydrology of carbonate rocks.

Water and energy: demand and effects.

Concepts, problems and methods o f analysis with examples of their application.

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Prepared for the International Hydrological Programme by the U.S. National Committee on Scientific Hydrology

George H. Davis

Unesco

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Unesco wishes to gratefully acknowledge the contribution of the U.S. National Committee on Scientific Hydrology, under whose auspices the manuscript was prepared, and also the U.S. Geological Survey, Reston, Virginia, USA, in providing the camera-ready copy of t h i s document.

The designations employed and t h e presentation of material throughout t h e publication do not imply the expression o f any opinion whatsoever on the pari of Unesco concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

Printed in 1985 by the United Nations

Educational, Scientific and Cultural Organization I , place de Fontenoy, 75700 Paris

Printed by: Imprimerie Gedit, Tournai, Belgium O Unesco 1985

Printed in Belgium ISBN 92-3- 102328-4

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Preface

Although the total amount of water on earth i s generally assumed to Rave remained virtually constant, the rapid growth of population, together w i t h the extension o f irrigated agriculture and industrial development, are stressing the quantity and quality aspects o f the natural system. Because o f the increasing problems, man has begun t o realize that h e can n o longer follow a “use and discard” philosophy - either w i t h water resources or any other natural resources. As a result, the need f o r a consistent policy o f rational management o f water resources has become evident.

Rational water management, however, should be founded upon a thorough understanding o f water availability and movement. Thus, as a contribution t o the solution o f the world’s water problems, Unesco, in 1965, began the f i r s t world-wide programme o f studies o f the hydrological cycle ^-the International Hydrological Decade (IHD). T h e research programme was complemented by a major effort in the field o f hydrological education and training. The activities undertaken during the Decade proved t o be o f great interest and value t o Member States. B y the end of that period, a majority o f Unesco’s Member States had formed IHD National Committees t o carry o u t relevant national activities and t o participate in regional and international co-operation w i t h i n the IHD programme. T h e knowledge o f the world’s water resources had substantially improved. Hydrology became widely recognized as an independent professional option and facilities for the training o f hydrologists had been developed.

Conscious o f the need to expand upon the efforts initiated during the International Hydrological Decade and, following the recommendations o f Member States, Unesco, in 1975, launched a new long-term intergovernmental programme, the International Hydrological Programme (IHP), t o follow the Decade.

Although the I H P i s basically a scientific and educational programme, Unesco has been aware f r o m the beginning o f a need t o direct i t s activities toward the practical solutions o f the world’s very real water resources problems.

Accordingly, and in line w i t h the recommendations o f the 1977 United Nations Water Conference, the objectives o f the International Hydrological Programme have been gradually expanded in order t o cover n o t o n l y hydrological processes considered in interrelationship w i t h the environment and human activities, but also the scientific aspects o f multi- purpose utilization and conservation o f water resources t o meet the needs o f economic and social development. Thus, while maintaining IHP’s scientific concept, the objectives have shifted perceptibly towards a multidisciplinary approach t o the assessment, planning, and rational management o f water resources.

As part o f Unesco’s contribution to the objectives o f the IHP, t w o publication series are issued: “Studies and Reports in Hydrology” and “Technical Papers in Hydrology.” In addition t o these publications, and in order t o ex- pedite exchange o f information in the areas in which it i s most needed, works o f a preliminary nature are issued in the fonn o f Technical Documents.

The purpose o f the continuing series “Studies and Reports in Hydrology” t o which this volume belongs, i s to pre- sent data collected and the main results o f hydrological studies, as well as t o provide information o n hydrological research techniques. The proceedings o f symposia are also sometimes included. I t i s hoped that these volumes w i l l furnish material o f b o t h practical and theoretical interest t o water resources scientists and also t o those involved in water resources assessments and the planning for rational water resources management.

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o i l

r e f . i n i n g Water use

u r a n i u m r e f i n i n g

U r a n i u m - h e x a f l u o r i d e p r o d u c t i o n G a s e o u s - d i f f u s i o n enrichment Water use

C o n v e r s i o n

S t e am- e 1 e c t r i c pow e r g e n e r a t i o n Water use

H y d r o e l e c t r i c g e n e r a t i o n Water use

S y n t h e t i c - f u e l p r o d u c t i o n

1

3 4 4 4 6 8 8 9 1 2 12 12 15 16 16 18 18 19 22 24 26 26 30 32 32 33 34 34 34 36 36 37 39 39 39 39 40 42 46 51 51 52

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Page 2.4.3.1 C o a l g a s i f i c a t i o n

2.4.3.2 C o a l l i q u e f a c t i o n 2.4.3.3 S o l i d - f u e l p r o d u c t i o n

2.4.3.4 Water use

3. P r e s e n t w a t e r use and consumption i n t h e energy s e c t o r 3.1

3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.1.6 3.1.7 3.1.8 3.1.9 3.2 3.3

Methodology and assumptions C o a l mining

O i l p r o d u c t i o n

N a t u r a l gas p r o c e s s i n g and t r a n s m i s s i o n O i l r e f i n i n g

N u c l e a r f u e l c y c l e

S t e a m - e l e c t r i c power g e n e r a t i o n O i 1- s h a l e p r o ces s i n g

Tar-sands p r o c e s s i n g C o a l - c o n v e r s i o n processes Energy p r o d u c t io n , 1980

Water consumption i n t h e e n e r g y s e c t o r , 1980

4.

4.1 F u t u r e water consumption

F u t u r e energy use and r e l a t e d w a t e r consumption t h r o u g h t h e year 2000

5. E f f e c t s o f energy development on w a t e r q u a l i t y 5.1

5.1.1 5.1.1.1

I 5.1.1.2

5.1.1.3 5.1.2 5.1.2.1 5.1.2.2 5.1.2.3 5.1.2.4 5.1.3 5.1.4 5.1.5 5.1.5.1 5.1.5.2 5.1.5.3 5.1.6 5.2 5.2.1 5.2.2 5.2.3 5.3 5.3.1 5.3.2 5.4 5.4.1 5.4.1.1 5.4.1.2 5.4.2 5.4.3 5.5

E x t r a c t i o n Coal m i n i n g

Und e r ground m i n i ng S u r f ace m i n i n g C o a l b e n e f i c i a t i o n O i l and gas e x t r a c t i o n P r ima r y ex t r a c t i o n

Secondary r e c o v e r y T e r t i a r y r e c o v e r y B lowou t s

O i l - s h a l e e x t r a c t i o n and p r o c e s s i n g Tar-sands e x t r a c t i o n and p r o c e s s i n g GeothermaL e x t r a c t i o n

Vapor-dominated systems Water-dominated systems Geopressured sys tems

U r a n i u m m i n i n g and m i l l i n g T r a n s p o r t a t i o n

O i l p i p e l i n e s Coa 1 - s i U r r y 1 i n e s O i l t a n k e r s

R e f i n i n g

o i l

r e f i n i n g N u c l e a r - f u e l c y c l e Convers i o n

S t e a m - e l e c t r i c power g e n e r a t i o n Once-through c o o l i n g

Closed-cycle c o o l i n g systems H y d r o e l e c t r i c power

Coa 1 - c o n v e r s i o n processes

S e v e r i t y o f e f f e c t s and e f f e c t i v e n e s s o f c o n t r o l s

54 55 56 56

59 59 60

60 ^'

61 61 63 63 67 68 68 69 7 1

75 7 7

81 8 1 82 82 82 82 84 84 a4 84 84 85 86 87 87 87 88 88 89 89 90 90 90 92 92 94 94 9 4 94 95 96 96

6. New methods o f w a t e r use i n t h e e n e r g y s e c t o r 105

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7 . Planning a l t e r n a t i v e s

8 . Summary and conciusions

9 . References

Appendix A. Glossary

Appendix B. Conversion f a c t o r s

Appendix C. Unweighted unit-consumptive-use v a l u e s

Index

Page 107

111

115

117

123

125

127

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Foreword

Rapid i n c r e a s e s i n w o r l d o i l p r i c e s b e g i n n i n g i n t h e e a r l y 1970s marked t h e s t a r t o f a m a j o r t r a n s i t i o n i n energy s u p p l y and use p a t t e r n s . The r i s e i n p r i c e s , t o g e t h e r w i t h g e n e r a l l y d e c l i n i n g o i l and gas p r o d u c t i o n , i s expected t o l e a d t o e x t e n s i v e development o f a l t e r n a t i v e energy sources t h a t p r e v i o u s l y were too c o s t l y f o r widespread use. C h i e f among these a l t e r n a t i v e s a r e development o f o i l shale, t a r sands, and c o a l f o r l i q u i d f u e l s ; c o a l as a source o f gaseous f u e l ; and i n c r e a s e d use o f c o a l and geothermal energy d i r e c t l y f o r e l e c t r i c power genera t i o n .

Most o f t h e a l t e r n a t i v e s r e q u i r e water--as a source o f hydrogen i n s e v e r a l processes and as a c o o l i n g agent i n a l l . Many water-consuming p r o j e c t s have been proposed f o r areas t h a t have no p r e s e n t s u r p l u s o f water. A c c o r d i n g l y , t h e r e i s widespread concern about whether a v a i l a b l e w a t e r s u p p l i e s w i l l be s u f f i c i e n t t o meet p r e s e n t needs as w e l l as a d d i t i o n a l w a t e r demands f o r energy development and whether o t h e r a l t e r n a t i v e s a r e a v a i l a b l e .

I n response t o concerns about t h e impact o f energy -development on w a t e r resources, t h e I n t e r n a t i o n a l H y d r o l o g i c a l Programme (IHP) d e s i g n a t e d M r . George H. Davis ( U n i t e d S t a t e s ) and M r . A. L. V e l i k a n o v (USSR) as Co-rapporteurs t o prepare a r e p o r t on " H y d r o l o g i c a l Problems A r i s i n g f r o m t h e Development o f Energy Resources ^{, I 1}w i t h p r i m a r y r e s p o n s i b i l i t y f o r d r a f t i n g a p r e l i m i n a r y r e p o r t d i s c u s s i n g t h e problems a f f e c t i n g w a t e r r e s o u r c e s as a r e s u l t o f energy development

,

i n c l u d i n g water power g e n e r a t i o n , m i n i n g h y d r o l o g y , geothermal energy, and pumped-storage systems, and emphasizing i n p a r t i c u l a r t h e h y d r o l o g i c a l consequences o f changes i n methods o f energy p r o d u c t i o n . To t h i s end t h e Co-rapporteurs met a t Unesco h e a d q u a r t e r s i n P a r i s i n J u l y 1976 and prepared a p r e l i m i n a r y d r a f t r e p o r t . D u r i n g t h e e n s u i n g year, s u b s t a n t i v e a d d i t i o n s t o t h e r e p o r t were proposed b y M r . V e l i k a n o v , and M r . D a v i s added some new m a t e r i a l on Canadian t a r sands development. A f t e r r e v i e w i n g and e d i t i n g t h e completed d r a f t , M r . Davis t r a n s m i t t e d i t t o Unesco under c o v e r i n g l e t t e r o f J u l y 7, 1977.

I n June 1977 t h e I n t e r g o v e r n m e n t a l C o u n c i l o f t h e IHP a t i t s second s e s s i o n decided t o expand t h e p r o j e c t on H y d r o l o g i c a l Problems A r i s i n g from Energy Developments i n t o a Working Group o n "Study o f t h e H y d r o l o g i c a l Problems A r i s i n g f r o m t h e Development o f Energy Resources I n c l u d i n g Water-Power Generation, M i n i n g Hydrology

,

Geothermal Energy and Pumped-Storage Systems." The Working Group had t h e f o l l o w i n g terms o f r e f e r e n c e :

1. t o s t u d y , on t h e b a s i s o f i n f o r m a t i o n r e c e i v e d f r o m i n d i v i d u a l c o u n t r i e s and i n t e r n a t i o n a l o r g a n i z a t i o n s

,

t h e p r e s e n t and, more e s p e c i a l l y , t h e f u t u r e use o f w a t e r resources i n t h e power i n d u s t r y , w i t h t h e purpose o f f o r e c a s t i n g f u t u r e w a t e r use;

2. t o analyze methods o f a s s e s s i n g t h e e f f e c t s o f t h e power i n d u s t r y on t h e q u a l i t y o f w a t e r resources;

3. t o c o l l e c t and a n a l y z e i n f o r m a t i o n on p o s s i b l e new methods o f w a t e r use f o r energy p r o d u c t i o n ;

4. t o p r e p a r e f o r p u b l i c a t i o n a c o n s o l i d a t e d r e p o r t on t h i s s u b j e c t ;

5. t o take i n t o account i n these areas t h e work c a r r i e d o u t b y i n t e r n a t i o n a l o r g a n i z a t i o n s such as t h e O r g a n i z a t i o n f o r Economic Co-operation and Development, (OECD) and

(ECE).

Four s p e c i a l i s t s were named t o t h e group, d e s i g n a t e d Working Group 5.7 w i t h i n IHP P r o j e c t 5, " I n v e s t i g a t i o n o f t h e H y d r o l o g i c a l and E c o l o g i c a l E f f e c t s o f Man's A c t i v i t i e s and T h e i r

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Assessment": Robert O. Ankrah, Ghana; George H. Davis, U n i t e d S t a t e s ; C h a r l e s D. D. Howard, Canada; and A. L. V e l i k a n o v , t h e USSR.

Working Group 5 . 7 h e l d i t s f i r s t s e s s i o n a t Unesco House, P a r i s , f r o m September 18 t o 22, 1978, and e l e c t e d as chairman George H. D a v i s . The group updated and completed t h e d r a f t r e p o r t prepared e a r l i e r b y Mssrs. Davis and V e l i k a n o v , and p u b l i s h e d i n 1979 as Unesco T e c h n i c a l Paper i n H y d r o l o g y No. 17. The group t h e n prepared an o u t l i n e o f t h e c o n s o l i d a t e d r e p o r t r e q u e s t e d b y t h e IHP C o u n c i l a t i t s second s e s s i o n , i n c l u d i n g a t i m e t a b l e f o r i t s p r e p a r a t i o n and d e s i g n a t i o n o f r e s p o n s i b i l i t y f o r s p e c i f i c s e c t i o n s . Another t a s k addressed b y t h e Working Group was p r e p a r a t i o n o f an i n q u i r y t o be addressed t o N a t i o n a l Committees f o r t h e IHP r e q u e s t i n g i n f o r m a t i o n on p r e s e n t and f u t u r e use o f water r e s o u r c e s i n t h e energy s e c t o r w i t h t h e purpose o f f o r e c a s t i n g f u t u r e w a t e r use. F i n a l l y , t h e Working Group p r e p a r e d recommendations f o r f u t u r e a c t i v i t i e s i n t h e second phase o f t h e IHP.

The S e c r e t a r i a t o f t h e IHP c i r c u l a t e d t h e q u e s t i o n n a i r e d r a f t e d b y t h e Working Group t o a l l N a t i o n a l Committees o f t h e IHP t o g e t h e r w i t h t h e F i n a l Report o f t h e F i r s t M e e t i n g o f Working Group 5 . 7 r e q u e s t i n g responses no l a t e r t h a n July 1, 1979. Because few responses were r e c e i v e d p r o m p t l y , t h e S e c r e t a r i a t o f t h e IHP c i r c u l a t e d a second r e q u e s t i n A p r i l 1979 and a f u r t h e r r e q u e s t i n November 1979. The c i r c u l a r s r e q u e s t e d g e n e r a l i n f o r m a t i o n from a l l member c o u n t r i e s o f t h e IHP and more d e t a i l e d i n f o r m a t i o n on e n - r g y development f r o m 28 c o u n t r i e s . New Zealand, and A u s t r a l i a ) had p r o v i d e d i n - d e p t h responses € o r t h e more d e t a i l e d i n f o r m a t i o n requested.

I n v i e w o f t h e inadequate response t o t h e q u e s t i o n n a i r e s , M r . Davis proposed an a l t e r n a t e approach: u s i n g t h e a v a i l a b l e l i t e r a t u r e t o g e t h e r w i t h c o u n t r y i n p u t s as a b a s i s f o r t h e comprehensive r e p o r t r e q u e s t e d b y t h e IHP C o u n c i l . Due t o f u n d i n g l i m i t a t i o n s , Unesco was u n a b l e t o s u p p o r t a n o t h e r m e e t i n g o f Working Group 5.7 and no a c t i v i t i e s o f t h e w o r k i n g group were budgeted b y Unesco. I n May, 1981, a t a m e e t i n g i n Reston, V i r g i n i a , o f M r . Davis w i t h D r . J. S. G l a d w e l l , D i v i s i o n o f Water Sciences o f Unesco, and D r . D e l l a Laura, E x e c u t i v e S e c r e t a r y o f t h e U.S. N a t i o n a l Committee on S c i e n t i f i c H y d r o l o g y , i t was agreed t h a t M r . Davis s h o u l d proceed w i t h t h e new approach under t h e auspices o f t h e U.S. N a t i o n a l Committee on S c i e n t i f i c Hydrology, which i s r e s p o n s i b l e f o r U n i t e d S t a t e s p a r t i c i p a t i o n i n t h e Unesco I n t e r n a t i o n a l H y d r o l o g i c a l Programme.

As o f September 1980, t e c h n i c a l i n p u t had been r e c e i v e d f

If

^om ⁶c o u n t r i e s , and o n l y 3 (Canada,

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1 Introduction

On a g l o b a l s c a l e , i t i s d o u b t f u l t h a t energy development has a s i g n i f i c a n t e f f e c t on w a t e r balances. The e f f e c t s o n w a t e r q u a l i t y , however, appear t o be more s i g n i f i c a n t i n t h e h y d r o l o g i c c y c l e , as suggested b y problems o f i n t e r c o n t i n e n t a l scope such as a c i d r a i n , changes i n the8?O2 b a l a n c e o f t h e atmosphere, and r e l e a s e b y n u c l e a r power f a c i l i t i e s o f t r i t i u m and K r

,

which e n t e r t h e atmosphere and f a l l o u t i n p r e c i p i t a t i o n . (Atmospheric r e l e a s e and t r a n s p o r t , i n v o l v e d i n a l l t h r e e o f these e f f e c t s , a r e i n t h e r e a l m o f m e t e o r o l o g y r a t h e r t h a n h y d r o l o g y and, f o r t h a t reason, a r e n o t t r e a t e d i n d e t a i l i n t h i s r e p o r t . )

D e s p i t e t h e l a c k o f g l o b a l e f f e c t s o n water balances, t h e i r r e g u l a r a r e a l d i s t r i b u t i o n o f energy and w a t e r r e s o u r c e s and t h e pronounced t i m e v a r i a b i l i t y o f t h e l a t t e r cause t h e e f f e c t s o f energy development t o d i f f e r s i g n i f i c a n t l y t h r o u g h o u t t h e w o r l d . Hence, most a n a l y s e s t a k e a r e g i o n a l approach.

Some w a t e r w i t h d r a w n i n energy processes i s i n c o r p o r a t e d i n a p r o d u c t , such as s y n t h e t i c gas, some may be d i s s i p a t e d t o t h e atmosphere i n e v a p o r a t i v e c o o l i n g , w h i l e some i s r e t u r n e d t o s u r f a c e o r ground waters as a l i q u i d . A c c o r d i n g l y , i t i s q u i t e i m p o r t a n t t o d i s t i n g u i s h between water use ( t h a t i s , g r o s s w i t h d r a w a l ) and water consumption ( t h a t i s , t h a t p a r t o f t h e water n o t r e t u r n e d t o t h e water system, termed "consumptive use"). Consumptive use i s c l o s e l y r e l a t e d t o t h e g e n e r a l t y p e o f process and i t s o v e r a l l t h e r m a l e f f i c i e n c y ; a c c o r d i n g l y , i t may be e s t i m a t e d from p r o d u c t i o n s t a t i s t i c s . Gross w a t e r use, on t h e o t h e r hand, commonly i s governed b y c o o l i n g - s y s t e m design, and t h e r e f o r e must g e n e r a l l y be e s t i m a t e d on a s i t e - b y - s i t e b a s i s . Demand f o r water a t a s i n g l e s i t e may a l s o f l u c t u a t e . As Young and Thompson (1973) p o i n t o u t , w i t h r e s p e c t t o e l e c t r i c power g e n e r a t i o n , t h e t e r m "Water r e q u i r e m e n t s " i s m i s l e a d i n g because demand f o r water f o r c o o l i n g i s s e n s i t i v e t o t h e p r i c e o f w a t e r d e l i v e r e d a t t h e p l a n t and thus i s q u i t e f l e x i b l e r a t h e r t h a n f i x e d as the t e r m " r e q u i r e m e n t s " i m p l i e s . Much t h e same i s t r u e o f o t h e r energy c o n v e r s i o n processes, such as s y n t h e t i c - f u e l c o n v e r s i o n , as p o i n t e d o u t b y P r o b s t e i n and Gold (1978).

Water p l a y s a major r o l e i n many aspects o f energy p r o d u c t i o n and c o n v e r s i o n , i n c l u d i n g m i n i n g and r e c l a m a t i o n o f mined lands, o n - s i t e p r o c e s s i n g and waste d i s p o s a l , t r a n s p o r t a t i o n , r e f i n i n g , and c o n v e r s i o n t o o t h e r , more c o n v e n i e n t forms o f energy (Davis and V e l i k a n o v , 1979). I n areas where w a t e r s u p p l i e s a r e g e n e r a l l y adequate, most e n e r g y - r e l a t e d problems a r e i n t h e r e a l m o f p o l l u t i o n and i t s adverse impacts on o t h e r w a t e r u s e r s . Where r u n o f f i s g e n e r a l l y l e s s t h a n p o t e n t i a l d i v e r s i o n s , energy i n d u s t r i e s must compete w i t h o t h e r s u s e r s f o r t h e l i m i t e d a v a i l a b l e s u p p l i e s . Water s u p p l y i s e s p e c i a l l y c r i t i c a l i n areas r e c e i v i n g l e s s t h a n 250 mm annual p r e c i p i t a t i o n , g e n e r a l l y n o t enough f o r e s t a b l i s h i n g v e g e t a t i o n w i t h o u t i r r i g a t i o n . F i n a l l y , i n areas where t h e e x i s t i n g consumptive use approaches t h e p e r e n n i a l supply, any new water consumption imposed b y energy development w i l l be a t t h e expense o f e x i s t i n g uses.

I n t h e f o l l o w i n g s e c t i o n s , d i s c u s s i o n s w i l l be p r e s e n t e d o f t h e p r i n c i p a l w a t e r - u s i n g processes i n t h e energy s e c t o r , p r e s e n t water use and consumption b y energy processes and e s t i m a t e s o f f u t u r e w a t e r use, t h e e f f e c t o f energy development on w a t e r q u a l i t y , new methods o f water use i n t h e energy s e c t o r , and a l t e r n a t i v e s a v a i l a b l e t o energy p l a n n e r s f a c e d w i t h problems o f l i m i t e d water s u p p l i e s o r s e r i o u s p o t e n t i a l e n v i r o n m e n t a l impacts.

I n t h i s r e p o r t much r e l i a n c e i s p l a c e d on d e v e l o p i n g world-wide e s t i m a t e s on t h e b a s i s o f e x t r a p o l a t i o n o f e x p e r i e n c e i n t h e U n i t e d S t a t e s and Canada b y c o r r e l a t i o n w i t h energy d a t a compiled b y t h e OECD, t h e U n i t e d N a t i o n s , and t h e W o r l d Bank. The reasons f o r a d o p t i n g t h i s approach a r e t h r e e f o l d : (1) energy p r o d u c t i o n s t a t i s t i c s a r e a v a i l a b l e by i n d i v i d u a l c o u n t r i e s world-wide and t h e s t a t i s t i c s a r e d e t a i l e d as t o energy f u e l s and c o n v e r s i o n process, and l i t t l e comparable d a t a a r e a v a i l a b l e on water use and consumption; ( 2 ) c o n s i d e r a b l e i n f o r m a t i o n i s a v a i l a b l e i n t h e l i t e r a t u r e on w a t e r use and consumption b y d i f f e r e n t energy processes i n t h e U n i t e d S t a t e s and Canada; and ( 3 ) g e n e r a l c o n s i s t e n c y i n

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Water and energy--Demands and effects

d e s i g n o f l a r g e - s c a l e energy processes t h r o u g h o u t t h e w o r l d , such as e l e c t r i c power p l a n t s and o i l r e f i n e r i e s , p e r m i t s e x t r a p o l a t i o n w i t h a c o n s i d e r a b l e degree o f confidence.

The g e n e r a l p a t t e r n o f d i s c u s s i o n w i t h i n t h e f o l l o w i n g s e c t i o n s i s t o t r e a t e x t r a c t i o n f i r s t and t o f o l l o w t h e f u e l t h r o u g h o n - s i t e p r o c e s s i n g , t r a n s p o r t a t i o n , r e f i n i n g , and c o n v e r s i o n t o end use i n s o f a r as each stage i s a p p l i c a b l e and p l a y s a s i g n i f i c a n t r o l e i n w a t e r use. A t t h i s p o i n t a caveat i s a p p r o p r i a t e w i t h r e s p e c t t o t h e m a t t e r o f p r e d i c t i n g f u t u r e water use i n t h e energy s e c t o r . T h i s s o r t o f p r e d i c t i o n i s e x t r e m e l y r i s k y , more because o f u n c e r t a i n t i e s i n f u t u r e energy growth r a t h e r than i n t h e w a t e r aspects. To paraphrase an o l d q u o t a t i o n : "The r o a d t o h e l l i s paved w i t h abandoned energy scenarios."

B e f o r e l a u n c h i n g i n t o a d i s c u s s i o n o f water-using processes, a b r i e f comment i s a p p r o p r i a t e on an energy source t h a t r e q u i r e s water i n i t s p r o d u c t i o n b u t n o t i n i t s g e n e r a l use--firewood. Wood has been used s i n c e t h e dawn o f h i s t o r y f o r c o o k i n g and h e a t i n g . As r e c e n t l y as t h e mid-18th c e n t u r y , wood s u p p l i e d more t h a n 90 p e r c e n t o f t h e energy needs o f , t h e U n i t e d S t a t e s . By t h e 1970s, however, t h e c o n t r i b u t i o n o f wood t o U n i t e d S t a t e s energy s u p p l i e s had d e c l i n e d t o l e s s than 2 p e r c e n t o f t o t a l energy consumption. With t h e r a p i d r i s e o f energy p r i c e s i n t h e 19708, t h e use o f wood as a f u e l has been r e d i s c o v e r e d , and t h e e l e g a n t t e r m "wood biomass combustion" has been c o i n e d t o d e s c r i b e i t . Undoubtedly t h e b u r n i n g o f wood can be an i m p o r t a n t source o f t h e r m a l energy even i n t h e h i g h l y developed c o u n t r i e s , e s p e c i a l l y i n f o r e s t areas, where t h e waste f r o m f o r e s t - p r o d u c t i n d u s t r i e s can be p u t t o economic use t o produce i n d u s t r i a l and space h e a t .

I n t h e d e v e l o p i n g c o u n t r i e s , wood p l a y s a more s i g n i f i c a n t r o l e i n n a t i o n a l energy budgets. I n t h e low-income c o u n t r i e s ( t h o s e w i t h p e r c a p i t a Gross N a t i o n a l P r o d u c t below US

$360 p e r y e a r ) , wood and a g r i c u l t u r a l o r a n i m a l wastes f u r n i s h more t h a n h a l f t h e t o t a l energy s u p p l i e s (World Bank, 1980). These l o c a l l y produced

,

non-commercial f u e l s account f o r v i r t u a l l y a l l t h e f u e l used i n r u r a l areas and about 25 p e r c e n t o f t o t a l energy consumption i n t h e d e v e l o p i n g c o u n t r i e s . Some 2 b i l l i o n people c u r r e n t l y use these t r a d i t i o n a l f u e l s f o r c o o k i n g (World Bank, 1980, p. 5 5 ) . Most o f these people have access t o c h a r c o a l , b u t between 500 m i l l i o n and 1 b i l l i o n people must r e l y on a g r i c u l t u r a l and a n i m a l wastes f o r t h e i r c o o k i n g f i r e s . I t i s one o f t h e g r e a t t r a g e d i e s o f o u r t i m e t h a t t h e r e a l p r i c e o f a l t e r n a t i v e f u e l s has been r i s i n g , w h i l e t h e p o o r e s t n a t i o n s have been consuming t h e i r wood s u p p l i e s f a r more r a p i d l y t h a n t h e y can be renewed. I n an o v e r a l l energy s t r a t e g y , measures a r e needed t o address t h e energy r e q u i r e m e n t s o f r u r a l households as p a r t o f a development s t r a t e g y t h a t i n c l u d e s r e f o r e s t a t i o n and t h e p l a n t i n g o f t r e e s on m a r g i n a l l a n d i n c u l t i v a t e d areas.

M e t r i c u n i t s a r e used g e n e r a l l y t h r o u g h o u t t h e r e p o r t , and, i n k e e p i n g w i t h t h e p r a c t i c e o f t h e OECD, l a r g e q u a n t i t i e s o f energy f u e l s a r e expressed i n m i l l i o n s o f m e t r i c tons o i l e q u i v a l e n t (Mtoe)

.

E l e c t r i c a l g e n e r a t i o n and Othe6 e l e c t r i c a l q u a n t i t i e s a r e g i v e n i n k i l o w a t t s ( k W ) and g i g a w a t t s (GW), where 1 GW = 1 X 10 k W . A c o n v e r s i o n t a b l e i s i n c l u d e d as Appendix B g i v i n g m e t r i c u n i t s and t h e i r E n g l i s h e q u i v a l e n t s and o t h e r c o n v e r s i o n f a c t o r s f o r q u a n t i t i e s used i n t h i s r e p o r t . S p e c i a l i z e d terms a r e d e f i n e d i n t h e g l o s s a r y , Appendix A.

.

2

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2 Principal water-using processes in the energy sector

The p r i n c i p a l w a t e r - u s i n g processes i n t h e energy s e c t o r , i n o r d e r o f t o t a l w i t h d r a w a l s , a r e ( 1 ) h y d r o e l e c t r i c power g e n e r a t i o n , ( 2 ) s t e a m - e l e c t r i c power g e n e r a t i o n , and ( 3 ) o i l r e f i n i n g .

Most o t h e r w i t h d r a w a l s i n t h e energy s e c t o r a r e minor i n comparison. I f we t a k e i n t o account t h e d i s t i n c t i o n between water use and water consumption, h y d r o e l e c t r i c power g e n e r a t i o n i s g e n e r a l l y c o n s i d e r e d t o be o f l i t t l e consequence as a consumptive use because water i s passed through h y d r o e l e c t r i c t u r b i n e s w i t h no s i g n i f i c a n t change i n p h y s i c a l o r c h e m i c a l c h a r a c t e r . A l t h o u g h e v a p o r a t i o n f r o m man-made r e s e r v o i r s i s a m a j o r element o f w a t e r consumption i n many countries--because r e s e r v o i r s serve many purposes o t h e r t h a n h y d r o e l e c t r i c g e n e r a t i o n , i n c l u d i n g f l o o d c o n t r o l ; i r r i g a t i o n , m u n i c i p a l , and i n d u s t r i a l water supply; and r e c r e a t i o n - - i t i s d i f f i c u l t t o e s t i m a t e on a r a t i o n a l b a s i s how much e v a p o r a t i o n i s p r o p e r l y chargeable t o h y d r o e l e c t r i c power g e n e r a t i o n .

As d i s c u s s e d i n Chapter 3.0, t h e l a r g e s t consumers o f water i n the energy s e c t o r i n o r d e r o f t o t a l w o r l d consumption a r e (1) s t e a m - e l e c t r i c power g e n e r a t i o n , ( 2 ) o i l r e f i n i n g , ( 3 ) o i l and gas p r o d u c t i o n ( c h i e f l y f o r water f l o o d i n g ) , and n a t u r a l gas p r o c e s s i n g . The impacts o f these consumptive uses i s tempered somewhat because much o f t h e water consumed i s s a l i n e : sea w a t e r i n t h e case o f o i l r e f i n e r i e s and s t e a m - e l e c t r i c p l a n t s and f o r m a t i o n water i n t h e case o f o i l p r o d u c t i o n .

S t e a m - e l e c t r i c power p l a n t s g e n e r a l l y a r e s i t e d c l o s e t o e l e c t r i c l o a d c e n t e r s so as t o m i n i m i z e t r a n s m i s s i o n - l i n e l o s s e s . However, many o f t h e l a r g e l o a d c e n t e r s a r e c l o s e t o t h e sea and a l a r g e p a r t o f t h e s t e a m - e l e c t r i c g e n e r a t i o n i s c o o l e d b y sea w a t e r o r b y e s t u a r i n e waters. A l t h o u g h they a r e n o t c l a s s i f i e d as s a l i n e , e s t u a r i n e w a t e r s a r e n o t s u i t a b l e f o r many water uses, and thus t h e i r use does n o t d e p l e t e consumable fresh-water r e s o u r c e s .

O i l r e f i n i n g , on the o t h e r hand, i s g e n e r a l l y done a t c o n v e n i e n t s i t e s a l o n g t r a n s p o r t a t i o n r o u t e s from p r o d u c i n g t o m a r k e t i n g areas. Because most o f t h e w o r l d ' s o i l t r a d e t r a v e l s i n marine t a n k e r s , t h e most c o n v e n i e n t l o c a t i o n s f o r r e f i n e r i e s commonly a r e seaports; among these a r e such c e n t e r s as Rotterdam, Houston, Los Angeles, New York, Aruba, T r i n i d a d , Singapore, and Abadan.

I n o i l and gas p r o d u c t i o n t h e m a j o r consumptive uses a r e f o r water f l o o d i n g (secondary r e c o v e r y ) , which i s w i d e l y p r a c t i c e d t h r o u g h o u t t h e mature o i l f i e l d s o f t h e w o r l d , and f o r enhanced o i l r e c o v e r y ( t e r t i a r y r e c o v e r y ) , w h i c h i n c l u d e s steam f l o o d i n g and m i s c i b l e - f l u i d f l o o d i n g , b o t h o f which r e q u i r e l a r g e volumes o f water. The use o f w a t e r i n o i l p r o d u c t i o n i s somewhat d i f f e r e n t t h a n most o t h e r consumptive uses i n t h a t w a t e r i s used t o f l u s h o i l o u t o f t h e p r o d u c i n g f o r m a t i o n s r a t h e r t h a n b e i n g d i s s i p a t e d t o t h e atmosphere. However, because t h e w a t e r so used i s permanently removed f r o m t h e a c t i v e h y d r o l o g i c c y c l e , i t i s c l a s s i f i e d h e r e as a consumptive use. Where s a l i n e water i s a v a i l i a b e ( s u c h as f o r m a t i o n waters produced w i t h o i l ) , i t i s used i n water f l o o d i n g i n p r e f e r e n c e t o f r e s h w a t e r , but i n most w a t e r - f l o o d i n g p r o j e c t s t h i s makes up a r e l a t i v e l y s m a l l p a r t o f t h e w a t e r r e q u i r e m e n t .

The m a j o r consumptive uses i n n a t u r a l - g a s p r o c e s s i n g a r e f o r c o m p r e s s o r - s t a t i o n c o o l i n g and f o r g a s - c l e a n i n g f a c i l i t i e s . For t h e most p a r t , f r e s h w a t e r i s used i n these i n s t a n c e s . F i n a l l y , t h e water needed t o o p e r a t e c o a l - s l u r r y p i p e l i n e s ( a b o u t e q u a l volumes o f c o a l and w a t e r ) can be thought o f as a consumptive use, a l t h o u g h l i t t l e water i s removed f r o m t h e f l u i d phase o f t h e h y d r o l o g i c c y c l e . Nonetheless, such w a t e r i s l o s t t o t h e a r e a o f o r i g i n o f t h e p i p e l i n e and r e p r e s e n t s t o o t h e r w a t e r u s e r s an u n r e p l e n i s h e d w i t h d r a w a l comparable t o consumptive use.

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Water

and

energy--Demands

and

effects

2.1. EXTRACTION

2.1.1. Coal m i n i n g

Coal assumed importance as an energy source w i t h the b e g i n n i n g o f t h e i n d u s t r i a l r e v o l u t i o n i n Europe. I n t h e U n i t e d S t a t e s , t h e c o a l i n d u s t r y began w i t h m i n i n g o f b i t u m i n o u s c o a l i n V i r g i n i a and a n t h r a c i t e i n P e n n s y l v a n i a . P r o d u c t i o n i n c r e a s e d s t e a d i l y i n t h e i n d u s t r i a l i z e d c o u n t r i e s d u r i n g t h e 1 9 t h c e n t u r y , and b y 1900 c o a l was t h e dominant source o f energy f o r space h e a t i n g , as a source o f c o a l gas, f o r steam g e n e r a t i o n , and f o r coke i n s t e e l p r o d u c t i o n . A t t h a t t i m e c o a l s u p p l i e d 90 per cent o f energy consumption i n t h e U n i t e d S t a t e s and comparable l e v e l s i n Europe.

D u r i n g t h e p e r i o d 1900-1950 c o a l consumption grew l e s s r a p i d l y t h a n t o t a l energy p r o d u c t i o n because more c o n v e n i e n t and c o m p e t i t i v e l y p r i c e d n a t u r a l gas became a v a i l a b l e and new uses of o i l , e s p e c i a l l y i n the t r a n s p o r t a t i o n s e c t o r as l i q u i d f u e l , i n c r e a s e d r a p i d l y . By 1950 c o a l made up o n l y 38 per c e n t o f t h e U n i t e d S t a t e s energy s u p p l y , and i n 1972 i t reached a low o f about 20 p e r c e n t .

C o a l ' s d e c l i n i n g r o l e i n t h e U n i t e d S t a t e s energy s t r u c t u r e was a c c e l e r a t e d b y government encouragement o f development o f n u c l e a r energy, encouragement o f i m p o r t s o f i n e x p e n s i v e f o r e i g n o i l , and t h e maintenence o f low p r i c e s f o r n a t u r a l gas t h r o u g h p r i c e r e g u l a t i o n . A l s o , t h e d r i v e f o r improvement o f a i r q u a l i t y i n t h e l a t e 1960s and e a r l y 1970s tended t o cause i n d u s t r i a l c o a l u s e r s t o seek c l e a n e r b u r n i n g f u e l s . These t r e n d s were m i r r o r e d i n most o f t h e i n d u s t r i a l c o u n t r i e s o f t h e w o r l d t o v a r y i n g degrees, a l t h o u g h i n Europe t h e l e a d i n g c o a l p r o d u c i n g n a t i o n s , t h e F e d e r a l R e p u b l i c o f Germany and t h e U n i t e d Kingdom, made s t r e n u o u s e f f o r t s t o m a i n t a i n domestic c o a l p r o d u c t i o n f o r s o c i a l and economic reasons.

U n l i k e t h e U n i t e d S t a t e s , which f o r much o f t h i s c e n t u r y had enjoyed a s u r p l u s o f n a t u r a l gas, t h e l o c a l n a t u r a l - g a s s u p p l i e s were s m a l l and t h e i n t e r n a t i o n a l t r a f f i c i n n a t u r a l gas had n o t y e t begun. However, w i t h t h e development o f t h e huge Groningen Gas F i e l d i n t h e N e t h e r l a n d s i n t h e 1950s and, t h e N o r t h Sea o i l and gas f i e l d s n o t l o n g a f t e r , t h e U n i t e d Kingdom and t h e Western European n a t i o n s r a p i d l y expanded t h e i r use o f n a t u r a l gas f o r space h e a t i n g and i n d u s t r y . The Western European n a t i o n s now i m p o r t s i g n i f i c a n t q u a n t i t i e s o f n a t u r a l gas v i a p i p e l i n e from t h e USSR and from N o r t h A f r i c a v i a sea-going t a n k e r s .

Coal s u f f e r e d g r e a t market e r o s i o n t o these a l t e r n a t i v e f u e l s a t t h e same t i m e t h a t i n c r e a s i n g concern (and subsequent F e d e r a l R e g u l a t i o n s ) f o r t h e h e a l t h and s a f e t y o f m i n e r s and f o r p r o t e c t i o n o f t h e environment w e r e r e d u c i n g p r o d u c t i v i t y and i n c r e a s i n g t h e c o s t of c o a l . The o n l y market segments i n t h e U n i t e d S t a t e s where c o a l was n o t d i s p l a c e d were markets f o r m e t a l l u r g i c a l uses and f o r e l e c t r i c - p o w e r g e n e r a t i o n , where r a p i d , c o n t i n u i n g g r o w t h made p o s s i b l e s t a b i l i z a t i o n o f c o a l demand d e s p i t e c o a l ' s l o s s o f market share. Coal p r o d u c t i o n i n t h e U n i t e d S t a t e s reached a low o f l e s s t h a n 400 m i l l i o n m e t r i c t o n s per year i n 1960 b u t t h e n i n c r e a s e d g r a d u a l l y t o a l e v e l o f about 540 m i l l i o n m e t r i c t o n s i n 1972. I n p a r t a t l e a s t , t h i s was due t o t h e f a r - s i g h t e d p l a n n i n g o f e l e c t r i c u t i l i t i e s , which, f o r e s e e i n g t h e coming r i s e i n p e t r o l e u m p r i c e s , m a i n t a i n e d a c o n s i d e r a b l e base o f c o a l - f i r e d g e n e r a t i n g c a p a c i t y .

With r a p i d i n c r e a s e s i n w o r l d o i l p r i c e s b e g i n n i n g i n 1973, t h e demand f o r c o a l as an a l t e r n a t i v e f u e l i n c r e a s e d s h a r p l y , and t h i s was r e f l e c t e d i n i n c r e a s e s i n c o a l p r i c e s and p r o d u c t i o n . I n t h e U n i t e d S t a t e s , p r o d u c t i o n i n c r e a s e d a t a r a t e o f 6 t o 7 p e r c e n t a n n u a l l y and reached 742 m i l l i o n m e t r i c tons i n 1981. Comparable p r o d u c t i o n g a i n s have n o t been r e a l i z e d i n Europe, but A u s t r a l i a and South A f r i c a , r e f l e c t i n g i n c r e a s e d w o r l d demand, have r e c o r d e d r a p i d i n c r e a s e s i n c o a l p r o d u c t i o n , p r o d u c i n g 81 and 76 m i l l i o n m e t r i c tons, r e s p e c t i v e l y , i n 1979 (OECD, 1982b).

Coal p r o d u c t i o n i s d i v i d e d i n t o two b a s i c c a t e g o r i e s : underground and s u r f a c e m i n i n g ( F i g u r e 2.1.1). The s e l e c t i o n o f a m i n i n g t e c h n i q u e depends m a i n l y on t h e t h i c k n e s s o f c o a l and t h e t h i c k n e s s and c h a r a c t e r o f the o v e r l y i n g m a t e r i a l s . Although s u r f a c e m i n i n g i s t h e predominant p r o d u c t i o n method i n t h e U n i t e d S t a t e s , a c c o u n t i n g c u r r e n t l y f o r 55 p e r c e n t o f t h e t o t a l p r o d u c t i o n , 68 p e r c e n t o f t h e r e s e r v e s are a c c e s s i b l e o n l y b y underground m i n i n g . 2.1.1 . I . Underground m i n i n g . The m a j o r underground m i n i n g techniques c u r r e n t l y used i n t h e U n i t e d S t a t e s a r e r o o m - a n d - p i l l a r and p a n e l m i n i n g . I n Europe, w h e r e m i n i n g i s g e n e r a l l y a t g r e a t e r depth than i n t h e U n i t e d S t a t e s , p a n e l m i n i n g i s g e n e r a l l y p r e f e r r e d . Room-and-pillar m i n i n g c u r r e n t l y accounts f o r more than 90 p e r cent o f U n i t e d S t a t e s p r o d u c t i o n , but p a n e l m i n i n g i s expected t o make up an i n c r e a s i n g p r o p o r t i o n o f t h e t o t a l i n t h e f u t u r e .

Room-and-pillar m i n i n g i n v o l v e s removal o f c o a l from i n t e r s e c t i n g t u n n e l s p e n e t r a t i n g the c o a l seam; c o a l p i l l a r s a r e l e f t i n a r e c t a n g u l a r p a t t e r n t o p r o v i d e s u p p o r t f o r t h e r o o f and o v e r l y i n g d e p o s i t s . Recovery i n the r o o m - a n d - p i l l a r system averages about 55 p e r c e n t , b u t

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F i g u r e 2.1.1. B l a c k Mesa c o a l mine i n n o r t h e a s t A r i z o n a , USA. D r a g l i n e , r i g h t c e n t e r , i s s t r i p p i n g overburden t o expose c o a l and c a s t i n g overburden on c o n i c a l heaps t o l e f t . F a r t h e r l e f t a r e r e g r a d e d and r e c l a i m e d l a n d . Coal i s

t r u c k e d o u t o n h a u l r o a d s , as a t l e f t c e n t e r . T h i s mine i s d e d i c a t e d e x c l u s i v e l y t o s u p p l y i n g N a v a j o and Mojave power p l a n t s ( F i g u r e s 2.4 and 7 ) . (Photo b y U.S. Bureau o f Reclamation.)

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Water and energy--Demands and e f f e c t s

as t h e d e p t h o f m i n i n g i n c r e a s e s t h e p r o p o r t i o n o f c o a l t h a t must be l e f t t o s u p p o r t t h e r o o f i n c r e a s e s and u l t i m a t e l y reaches a p o i n t where complete r e c o v e r y t e c h n i q u e s become more p r a c t i c a b l e . The p r i n c i p a l s t e p s i n v o l v e d i n room-and-pillar m i n i n g a r e u n d e r c u t t i n g t h e seam, d r i l l i n g b l a s t h o l e s , b l a s t i n g , and l o a d i n g and removing t h e c o a l . Roof b o l t s a r e used t o m a i n t a i n t h e s t r u c t u r a l i n t e g r i t y o f t h e r o o f , and v e n t i l a t i o n i s advanced as m i n i n g p r o g r e s s e s ( F i g u r e 2.1.1.1, b l o c k A). I n t h e p a s t these t a s k s were done b y hand, but i n r e c e n t decades t h e y have been l a r g e l y mechanized. C u r r e n t l y , most r o o m - a n d - p i l l a r m i n i n g i s done w i t h c o n t i n u o u s - m i n i n g machines which combine t h e f o u r - t r a d i t i o n a l s t e p s i n t o a s i n g l e o p e r a t i o n . The c o n t i n u o u s m i n e r uses a r o t a t i n g - d r u m head w i t h r e p l a c e a b l e t e e t h t o excavate t h e c o a l , which i s t h e n loaded i n t o s h u t t l e c a r s ( F i g u r e 2.1.1.1, b l o c k B).

Panel m i n i n g d i f f e r s from r o o m - a n d - p i l l a r m i n i n g i n t h a t t h e need t o r e t a i n c o a l p i l l a r s f o r r o o f s u p p o r t i s e l i m i n a t e d . A l t h o u g h l i m i t e d t o f a v o r a b l e g e o l o g i c c o n d i t i o n s and areas where immediate subsidence o f t h e o v e r l y i n g s u r f a c e can be t o l e r a t e d , r e s o u r c e r e c o v e r y can be i n c r e a s e d t o 85 p e r c e n t t h r o u g h p a n e l m i n i n g . The p r e f e r r e d method o f p a n e l m i n i n g i s t h e l o n g w a l l t e c h n i q u e

,

i n which c o n t i n u o u s m i n i n g machines a r e used t o c u t two p a r a l l e l t u n n e l s i n t o t h e c o a l seam up t o 1.5 km l o n g and 200 m a p a r t . These t u n n e l s a r e used f o r v e n t i l a t i o n , access, and c o a l removal. The p a n e l o f c o a l between t h e two t u n n e l s i s removed by a s h e a r i n g machine t h a t employs a r o t a r y head t o c u t a s l i c e o f c o a l up t o 1 m t h i c k f r o m t h e exposed face. The c o a l i s removed from t h e w o r k i n g face b y a c o n t i n u o u s conveyer. S e l f - a d v a n c i n g h y d r a u l i c r o o f s u p p o r t s , which p r o t e c t t h e machinery and o p e r a t o r s , move f o r w a r d t o a new p o s i t i o n as t h e s h e a r i n g machine t r a v e r s e s t h e face, and t h e unsupported r o o f over t h e mined-out a r e a i s p e r m i t t e d t o c o l l a p s e ( F i g u r e 2.1.1.1, b l o c k C ) .

T h i s method r e s u l t s i n immediate r u p t u r e o f t h e o v e r l y i n g s t r a t a and leakage downward o f ground w a t e r f r o m any a q u i f e r s i n t h e overburden. Where s i g n i f i c a n t a q u i f e r s o v e r l i e t h e c o a l , p a n e l m i n i n g can have a severe adverse impact on ground w a t e r r e s o u r c e s . However, t h e a l t e r n a t i v e o f r o o m - a n d - p i l l a r m i n i n g i s n o t n e c e s s a r i l y more e n v i r o n m e n t a l l y d e s i r a b l e o v e r t h e l o n g term, as p i l l a r s tend t o c o l l a p s e over time and t h e r e s u l t i n g c o l l a p s e and l a n d subsidence phenomena a r e prolonged, f o r many decades i n some cases. Moreover, where mines a r e above t h e g r a d i e n t o f nearby streams, t h e abandoned m i n e t u n n e l s , g e n e r a l l y p a r t l y c o l l p a s e d , commonly a c t as s u b s u r f a c e d r a i n s , d i s c h a r g i n g l a r g e volumes o f degraded water t o nearby streams. Indeed, i t i s e s t i m a t e d t h a t o f t h e 16,000 km o f streams i n t h e e a s t e r n U n i t e d S t a t e s s e v e r e l y degraded t h r o u g h a c i d d r a i n a g e and r e l a t e d c h e m i c a l problems ( A p p a l a c h i a n R e g i o n a l Commission, 1969)

,

t h r e e - q u a r t e r s o f t h e problem can be a t t r i b u t e d t o underground m i n i n g (Johnson and M i l l e r , 1979).

L o n g w a l l m i n i n g i s t h e p r e f e r r e d method i n Europe, where seams c u r r e n t l y mined a r e g e n e r a l l y much deeper t h a n i n t h e U n i t e d S t a t e s and t h e w e i g h t o f t h e overburden i s p r o p o r t i o n a l l y g r e a t e r . I n t h e U n i t e d Kingdom, f o r example, 95 p e r c e n t o f c u r r e n t m i n i n g i s b y t h e l o n g w a l l method. S h o r t w a l l m i n i n g , a v a r i a t i o n o f p a n e l m i n i n g , named f o r t h e s h o r t e r p a n e l f a c e worked, g e n e r a l l y on t h e o r d e r o f 50 m, uses c o n t i n u o u s m i n i n g machines i n c o m b i n a t i o n w i t h h y d r a u l i c r o o f s u p p o r t s . T h i s method has g a i n e d f a v o r i n t h e U n i t e d S t a t e s because i t r e q u i r e s l e s s c a p i t a l and i s more f l e x i b l e than l o n g w a l l m i n i n g . However, p r o d u c t i v i t y i s s a c r i € i c e d because s h u t t l e c a r s i n l i e u o f c o n t i n u o u s conveyers must be used t o t r a n s p o r t t h e c o a l .

Research i s c u r r e n t l y under way on h y d r a u l i c m i n i n g systems i n which r e m o t e l y c o n t r o l l e d , h i g h - p r e s s u r e w a t e r j e t s a r e used t o b r e a k t h e c o a l loose; t h e r e s u l t i n g coal-water s l u r r y i s t h e n pumped t o t h e s u r f a c e , where t h e c o a l and water a r e separated. Should t h i s t e c h n o l o g y g a i n wide acceptance, i t c o u l d have i m p o r t a n t water-resources i m p l i c a t i o n s because l a r g e amounts o f water would be needed f o r t h e c i r c u l a t i n g systems. However, makeup water demand i s p o o r l y known; w i t h e x t e n s i v e r e c i r c u l a t i o n o f water i t would be p o s s i b l e t o keep makeup demand a t a reasonable l e v e l .

2.1.1.2. Surface m i n i n g . Surface p r o d u c t i o n o f c o a l i s c a r r i e d o u t by t h e area, c o n t o u r , auger, and p i t methods, depending on t h e t h i c k n e s s and a t t i t u d e o f c o a l seams and overburden and t h e t o p o g r a p h i c r e l i e f o f t h e t e r r a i n . Area m i n i n g , which i s e x t e n s i v e l y used i n f l a t t e r r a i n , as i n t h e midwestern and w e s t e r n p a r t s o f t h e U n i t e d S t a t e s , e n t a i l s removal o f overburden by c u t t i n g successive t r e n c h e s , t y p i c a l l y 30 m wide and 1.5 k m l o n g , t o expose t h e c o a l seam ( F i g u r e 2.1.1.2). The c o a l i s t h e n excavated and loaded i n t o t r u c k s t h r o u g h t h e use of l a r g e power s h o v e l s . F o l l o w i n g c o a l e x t r a c t i o n , another p a r a l l e l t r e n c h i s . excavated and t h e overburden m a t e r i a l i s p l a c e d i n t h e p r e v i o u s l y excavated t r e n c h . The i r r e g u l a r rows o f s p o i l a r e graded t o approximate the o r i g i n a l t e r r a i n , and t o p s o i l , which was segregated i n t h e o r i g i n a l e x c a v a t i o n work, i s spread and seeded t o p r o v i d e a c o v e r o f v e g e t a t i o n w h i c h m i n i m i z e s e r o s i o n . Recovery i n t h e a r e a m i n i n g system t y p i c a l l y i s 80 t o 90 p e r c e n t of t h e c o a l r e s e r v e s . F o r many y e a r s t h e r a t i o o f overburden t o c o a l t h i c k n e s s t h a t was economic t o mine was about 10 t o 1; however, w i t h i n c r e a s e d c o a l p r i c e s i n r e c e n t years and t h e development o f more e f f i c i e n t earth-moving equipment, r a t i o s up t o 60 t o 1 a r e now e c o n o m i c a l l y f e a s i b l e .

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P r i n c i p a Z w a t e r - u s i n g processes i n t h e energy s e c t o r

Coal removal

A.

-

conventional mining.

Continuous mining and loading

.

B.

-

Continuous mining.

- Overburden

Elevation view

I

Mining _Conveyor

'

machine

C.

-

Longwall mining.

F i g u r e 2.1.1.1. P r i n c i p a l types o f underground c o a l m i n i n g : ( a ) C o n v e n t i o n a l t e c h n i q u e s used i n r o o m - a n d - p i l l a r m i n i n g , ( b ) Continuous miner, ( c ) L o n g w a l l m i n i n g . (Source: U.S. Department o f Energy, 1981a.l

Contour m i n i n g i s p r a c t i c e d where n e a r - h o r i z o n t a l c o a l beds c r o p o u t a l o n g t h e s i d e s o f mountains, as i n t h e A p p a l a c h i a n r e g i o n o f t h e U n i t e d S t a t e s . The o v e r b u r d e n i s removed w i t h e x c a v a t i n g machines, b e g i n n i n g a t t h e o u t c r o p . As t h e exposed c o a l i s removed, a d d i t i o n a l c u t s a r e made i n t h e s l o p e u n t i l i n c r e a s i n g overburden t h i c k n e s s makes f u r t h e r m i n i n g uneconomic. When such a l i m i t i s n o t reached b e f o r e e x c a v a t i n g t o t h e t o p o f t h e slope, t h e e n t i r e t o p o f a mountain may be removed and t h e f u l l c o a l seam mined o u t . I n t h e p a s t , s p o i l commonly was disposed o f b y p u s h i n g i t t o t h e o u t e r edge o f t h e e x c a v a t i o n and l e t t i n g i t s l i d e down t h e downslope. However, c u r r e n t law i n t h e U n i t e d S t a t e s p r o h i b i t s t h a t p r a c t i c e , so, t o m i n i m i z e h a n d l i n g c o s t s , g r e a t i n g e n u i t y must be employed i n moving and s t o r i n g t h e overburden u n t i l t h e r e c l a m a t i o n stage.

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Water and energy--Demands and e f f e c t s I

F i g u r e 2 . 1 . 1 . 2 . Area s u r f a c e m i n i n g used i n l e v e l t e r r a n e . (Source: U.S. Department o f Energy, 1981a.) ,

Auger m i n i n g commonly i s used i n c o n j u n c t i o n w i t h c o n t o u r m i n i n g t o p e r m i t f u r t h e r m i n i n g f r o m t h e c o a l face a f t e r t h e economic l i m i t o f overburden removal has been reached. I n t h i s technique, h o r i z o n t a l auger machines d r i l l h o l e s up t o 2 m i n d i a m e t e r and as much as 60 m deep i n t o t h e exposed c o a l face. A l t h o u g h r e c o v e r y i s l e s s t h a n w i t h complete removal o f t h e seam, as much as 30 t o 50 p e r c e n t o f t h e c o a l w i t h i n reach o f t h e augers can be r e c o v e r e d b e f o r e t h e f a c e i s covered and t h e s i t e i s r e c o n t o u r e d and r e v e g e t a t e d .

Where t h i c k seams a r e found w i t h l i t t l e overburden, a v a r i a t i o n o f area m i n i n g b y o p e n - p i t methods i s employed. Here t h e overburden and s o i l a r e s t r i p p e d b a c k and l a r g e shovels a r e used t o excavate t h e face i n a broad, expanding p i t . Because t h e c o a l commonly makes up a l a r g e p r o p o r t i o n o f t h e m a t e r i a l between t h e o r i g i n a l l a n d s u r f a c e and t h e base o f t h e c o a l seam, r e c l a m a t i o n c o n s i s t s o f g r a d i n g what overburden i s a v a i l a b l e toward t h e p i t so as t o p r o v i d e m i n i m a l i n w a r d slopes. Brown c o a l i s e x t e n s i v e l y mined i n t h e F e d e r a l R e p u b l i c o f Germany and A u s t r a l i a f o r mine-mouth e l e c t r i c a l p r o d u c t i o n from s i m i l a r p i t s as much as 200 m deep.

2 . 1 . 1 . 3 . Coal b e n e f i c i a t i o n . T h i s i s an a d j u n c t o f c o a l m i n i n g t h a t i s g e n e r a l l y c a r r i e d o u t a t o r near t h e mine and i s commonly termed " c o a l p r e p a r a t i o n " o r "cleaning." Because t h i s t e c h n o l o g y , where used, i s c l o s e l y t i e d t o t h e m i n i n g process, i t i s t r e a t e d i n t h i s r e p o r t as an element o f m i n i n g . I n t h e e a s t e r n U n i t e d S t a t e s about 60 p e r c e n t o f undergound-mined c o a l and 25 p e r c e n t o f surface-mined c o a l i s t r e a t e d b y t h i s process. The o b j e c t i v e s a r e t o reduce i m p u r i t i e s such as s h a l e and p y r i t i c s u l f u r and t o p r o v i d e a size-graded p r o d u c t t o meet customer s p e c i f i c a t i o n s . The predominant method employed i n c o a l c l e a n i n g i s t h e use o f j i g s , shaker t a b l e s , and h i g h - d e n s i t y f l u i d s t o p r o v i d e g r a v i t y s e p a r a t i o n o f t h e r e l a t i v e l y l i g h t c o a l from h e a v i e r m i n e r a l and r o c k which has about t w i c e t h e d e n s i t y o f c o a l . The f l u i d s commonly employed a r e suspensions o f c l a y i n water, i n which t h e d e n s i t y can be a d j u s t e d b y t h e a d d i t i o n o f i r o n o x i d e , b a r i t e , o r o t h e r dense m i n e r a l m a t t e r . The m a j o r reasons f o r c o a l b e n e f i c i a t i o n a r e t o improve i t s h e a t i n g v a l u e and t o remove i m p u r i t i e s such as s u l f u r t h a t can r e s u l t i n a i r p o l l u t i o n . However, c o a l - c l e a n i n g p l a n t s have themselves r e s u l t e d i n w a t e r p o l l u t i o n , i n some cases, through r e l e a s e o f water c o n t a i n i n g f i n e l y d i v i d e d c o a l p a r t i c l e s and t h r o u g h l e a c h i n g o f t h e p l a n t wastes. As shown i n Appendix C, t h e w a t e r consumption a t t r i b u t e d t o c o a l - c l e a n i n g processes i s e s t i m a t e d t o exceed t h a t o f m i n i n g a comparable w e i g h t o f c o a l .

2 . 1 . 1 . 4 . Water use. The p r i n c i p a l uses o f water i n c o a l m i n i n g a r e f o r d u s t c o n t r o l i n b o t h s u r f a c e and underground m i n i n g , f o r r e v e g e t a t i o n o f surface-mined l a n d s i n a r i d and s e m i - a r i d r e g i o n s , and i n c o a l - c l e a n i n g . Water i s used l i b e r a l l y t o m i n i m i z e a i r b o r n e d u s t i n undergound mines because c o a l d u s t i s a s e r i o u s h e a l t h h a z a r d t o t h e miners. S i m i l a r l y , w a t e r

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reports 42

Studies

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Prepared for the International Hydrological Programme by the U.S. National Committee on Scientific Hydrology

George H. Davis

Unesco

Preface

Contents

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Foreword

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1 Introduction

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2 Principal water-using processes in the energy sector

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