District Energy Schemes

DISTRICT ENERGY SCHEMES

Coming In From The Cold

Table of Contents

List of tables vii

List of figures vii

1 Foreword 1

2 Executive Summary 3

2.1 Efficiency, economy and politics 3

2.2 District energy systems' improving reputation 4

2.3 District energy systems past and present 5

2.4 Economics 6

3 Who uses district energy? 9

3.1 A selection of regions with district energy schemes 10

3.1.1 Northern Europe 10

3.1.2 Eastern Europe 13

3.1.3 Japan 13

3.1.4 South Korea 14

3.1.5 China 15

4 Examples of successful schemes 17

4.1 Måbjergværket district CHP scheme (Denmark) 17

4.2 Sheffield (UK) 18

4.3 St. Paul district heating and cooling schemes (US) 19

4.4 Värnamo biogas district heating scheme (Sweden) 19

4.5 Muanjiang district heating scheme (China) 20

5 Past faults of some district energy schemes 21

6 The revival of district energy schemes 23

6.1 What has changed? 23

6.2 Capital costs of power stations 24

6.3 Efficiencies of CHP schemes 25

6.4 Reducing emissions with district energy schemes 26

6.5 Overall economics 27

7 Selecting the plant 29

7.1 Basic principles when selecting the plant 29

7.2 Steam versus water for heating 29

7.3 Using a CHP plant to supply a district energy system 30

7.4 Recovering waste heat for use in a district energy system 31

7.5 Required heat-to-power ratio 32

7.6 Effect of the distribution temperature on the choice of plant 33

7.7 Coping with variations in the temperature of distributed water 34

7.8 Coping with hourly fluctuations in output 34

7.9 Possible build-up of large CHP plants 35

7.1 Advantages of co-firing an incinerator with natural gas 37

7.11 Reliability 37

7.12 Final choice of plant 38

8 District cooling systems 39

8.1 Economics of district cooling 39

8.2 Operational aspects of district cooling systems 40

8.2.1 Coping with peaks 40

8.2.2 Temperature of a district cooling system 40

8.2.3 Viscosity of cold liquids 40

9 The distribution system 41

9.1 Pipework 41

9.1.1 Leak detection 41

9.2 Selecting the temperature for a district heating scheme 41

9.3 Heat losses from the pipes 42

9.4 Other effects of raising the temperature 42

9.5 Overall effect of the sendout temperature on system economics 43

9.6 Customers' connections to the district energy system 44

9.7 Customers' heat exchangers 44

9.8 Precautions to be taken throughout the scheme 45

10 Operating the system 47

10.1 Starting up 47

10.2 Normal operation 47

10.3 Emissions 47

11 Analysing the market for a district energy scheme 49

11.1 Estimating potential sales 49

11.2 Designing and evaluating a complete district energy system 50

11.3 Precautions when evaluating offers of district energy supplies 51

List of tables		vii
List of figures		vii
1	Foreword	1
2	Executive Summary	3
2.1	Efficiency, economy and politics	3
2.2	District energy systems' improving reputation	4
2.3	District energy systems past and present	5
2.4	Economics	6
3	Who uses district energy?	9
3.1	A selection of regions with district energy schemes	10
3.1.1	Northern Europe	10
3.1.2	Eastern Europe	13
3.1.3	Japan	13
3.1.4	South Korea	14
3.1.5	China	15
4	Examples of successful schemes	17
4.1	Måbjergværket district CHP scheme (Denmark)	17
4.2	Sheffield (UK)	18
4.3	St. Paul district heating and cooling schemes (US)	19
4.4	Värnamo biogas district heating scheme (Sweden)	19
4.5	Muanjiang district heating scheme (China)	20
5	Past faults of some district energy schemes	21
6	The revival of district energy schemes	23
6.1	What has changed?	23
6.2	Capital costs of power stations	24
6.3	Efficiencies of CHP schemes	25
6.4	Reducing emissions with district energy schemes	26
6.5	Overall economics	27
7	Selecting the plant	29
7.1	Basic principles when selecting the plant	29
7.2	Steam versus water for heating	29
7.3	Using a CHP plant to supply a district energy system	30
7.4	Recovering waste heat for use in a district energy system	31
7.5	Required heat-to-power ratio	32
7.6	Effect of the distribution temperature on the choice of plant	33
7.7	Coping with variations in the temperature of distributed water	34
7.8	Coping with hourly fluctuations in output	34
7.9	Possible build-up of large CHP plants	35
7.1	Advantages of co-firing an incinerator with natural gas	37
7.11	Reliability	37
7.12	Final choice of plant	38
8	District cooling systems	39
8.1	Economics of district cooling	39
8.2	Operational aspects of district cooling systems	40
8.2.1	Coping with peaks	40
8.2.2	Temperature of a district cooling system	40
8.2.3	Viscosity of cold liquids	40
9	The distribution system	41
9.1	Pipework	41
9.1.1	Leak detection	41
9.2	Selecting the temperature for a district heating scheme	41
9.3	Heat losses from the pipes	42
9.4	Other effects of raising the temperature	42
9.5	Overall effect of the sendout temperature on system economics	43
9.6	Customers' connections to the district energy system	44
9.7	Customers' heat exchangers	44
9.8	Precautions to be taken throughout the scheme	45
10	Operating the system	47
10.1	Starting up	47
10.2	Normal operation	47
10.3	Emissions	47
11	Analysing the market for a district energy scheme	49
11.1	Estimating potential sales	49
11.2	Designing and evaluating a complete district energy system	50
11.3	Precautions when evaluating offers of district energy supplies	51

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