1. Time Shifting / Storage – Above Ground
Revision A – 20/10/2010
Thermal Store
Time Shifting / Storage – Above Ground
October 2016

2. How does the system work
Low Demand
03.00
6°c A am
85°C
Demand

3. How does the system work
Low Demand
04.00
5.5°c A am
Demand

4. Low Demand
05.00
6°c A am
85°C
Demand

5. How does the system save Carbon/Energy
High Demand
06.00
6.5°c A am
85°C
Demand

6. How does the system save Carbon/Energy
High Demand
08.00
7°c A am
85°C
Demand

7. How does the system save Carbon/Energy
High Demand
09.00
8°c A am
85°C
Demand

8. How does the system save Carbon/Energy
Medium Demand
10.00
9°c A am
85°C
Demand

9. How does the system save Carbon/Energy
Very High Demand
08:00
-7°c A am
85°C
Demand
District flow achieved
But at low temperature
45°C

10. How does the system save Carbon/Energy
Failure / Under Capacity
08:00
-7°c A am
85°C
60°C
Demand
District flow achieved
But at low temperature
45°C

11. Typical 24Hr demand

12. Add CHP heat

13. Add CHP heat rejected & wasted

14. Add CHP heat rejected & wasted, boilers top up
Plant
tCO2
CHP(g) 63
£ 10,095
Boiler(g) 5 £
Grid(e) saved
-50
-£ 9,240
Total 18
£ 1,763

15. With Stores - CHP

16. With Stores – CHP + Store flow

17. With Stores – CHP + Store flow, heat rejected,

18. With Stores – CHP + Store flow, heat rejected, boilers top up
Plant
tCO2
CHP(g) 62
£ 9,942
Boiler(g) 3 £
Grid(e) saved
-50
-£ 9,100
Total 16
£ 1,364

19. Compare without & with stores
Plant
tCO2
CHP(g) 63
£ 10,095
Boiler(g) 5 £
Grid(e) saved
-50
-£ 9,240
Total 18
£ 1,763
Plant
tCO2
CHP(g) 62
£ 9,942
Boiler(g) 3 £
Grid(e) saved
-50
-£ 9,100
Total 16
£ 1,364

20. Started after commissioning of Thermal stores December 2008
Improved Control
Started after commissioning of Thermal stores December 2008
Identify strategies to manage Thermal stores charge / discharge cycles
Identify controls principles to couple CHP – Thermal stores
Identify technologies (HC900)
Create & Implement controls
Fine tune
Current development
Highlights that Warwick land is relatively underdeveloped and has tended to accommodate Post experience centres and residential
Innovative approach
Predictive controls 20

21. Self Learning Algorithm
CHP Control
Self Learning Algorithm
Selects 4 hour time window
PROCESS CONTROLLER
Records outside temp at start of period
CALCULATES TOTAL HEAT USED
Records site energy demand in period M
CHANGES STORED VALUE BY UP TO 10%
COMPARES TO VALUE STORED PREVIOUSLY
If different
Site Heat Meter
If same NO
CHANGE

23. LTHW Energy Predictive Table
CHP Control
LTHW Energy Predictive Table

24. With Stores – plus upgrade control
Plant
tCO2
CHP(g) 62
£ 9,872
Boiler(g) 3 £
Grid(e) saved
-49
-£ 9,042
Total 15
£ 1,304

25. Compare without & with stores + controls
Plant
tCO2
CHP(g) 63
£ 10,095
Boiler(g) 5 £
Grid(e) saved
-50
-£ 9,240
Total 18
£ 1,763
Plant
tCO2
CHP(g) 62
£ 9,872
Boiler(g) 3 £
Grid(e) saved
-49
-£ 9,042
Total 15
£ 1,304

26. Carbon savings is on target @ 770 tCO2 Increased generation enabled
Practical Experience
Conclusion
Overall benefits
Carbon savings is on 770 tCO2
Increased generation enabled
Reduced wasted heat secured
But
Knowledge of building loads become essential
CHP engines reliability issues become apparent

27. Measured UOW annual saving ~£97,000
Practical Experience
Savings in carbon and energy costs
Plant
Original
With 200m³ store
With store & controls
tCO2
Cost
CHP(g) 63
£ 10,094.70 62
£ ,941.75
£ ,878.77
Boiler(g) 5 £ 3 £ £
Grid(e) saved
-50
-£ 9,240.00
-£ ,100.00
-49
-£ ,042.35
Total 18
£ 1,762.54 16
£ ,364.03 15
£ ,304.25
Savings
11%
23%
14%
26%
Measured UOW annual saving ~£97,000
~770 tCO2

28. Considerations / limitations
Balance store size against capital cost and savings achieved
Don’t size for peak load only
Consider storage in buildings
Good understanding of load profile over year needed
Check electricity generated can be used
Consider operational parameters of CHP, starts per day etc.
Consider maintenance on CHP
Low return temperatures critical to maximum performance
Controls are very important, predictive control, not just current demand.