1. An Introduction to Large Heat Pumps
Dave Pearson
Star Renewable Energy

2. SRE & Heat Pumps

3. SRE & Heat Pumps
ASHP
Up to 62C hot water flow
WSHP
Between
20C and 90C
Hot water flow

4. Big Heatpumps @ Drammen
GWh

5. The Basics – WSHP

6. The Basics ASHP

7. What do we consider Large Scale?
Commonly thought of as Deg C
Actual size is unbound – Just depends on parameters
(and how much room you have!)
90 Deg C is the limit (for now) – WSHP
Current 62 Deg C with ASHP but 70 Deg C
Following examples we will look at is for a 2MW system
Heating from 55C to 75C

8. Operating Temperature – Source Side
Key considerations:
How accessible is it?
How big is it?
How cheap is it?
How predictable is it?
How safe is it?
How durable is it?
How warm is it?
How clean is it?

9. Water Temperature Effect

10. Cost of Heat Cost of heat if Electricity 10p = 3.0p/kWh
And RHI is 8.7p ~ 2.6p
So minus 6.6p/kWh at best

11. Source Side Regulations
SEPA: 2~3K mix in small/large rivers and up to
£3000 registration and
£533/y fee over 2000m3 abstracted

12. Summary Heatpumps work above 50C Sources of heat are commonplace
Network design affects outcome
Better as grid decarbonises

13. Large Scale Water Source Heat Pumps and Efficiency Influencers
Nicky Cowan
Star Renewable Energy

14. System Design - Basic
Cold Side: 5/2 Deg C
Hot Side: 60/80 Deg C
COP:

15. System Design - Basic
Cold Side: 5/2 Deg C
Hot Side: 40/70 Deg C
COP: 3.2

16. System Design - Basic
Cold Side: 25/17 Deg C
Hot Side: 40/70 Deg C
COP:

17. Including Subcooler
Cold Side: 25/17 Deg C
Hot Side: 40/70 Deg C
COP: 4.25
Subcooler Provides Extra 108.9kW of Heat Capacity

18. Both Subcooler and Desuperheater
Cold Side: 25/17 Deg C
Hot Side: 40/70 Deg C
COP: 4.50
Desuperheater Provides Extra 25.3kW of Heat Capacity

19. Cost for Subcooler and Desuperheater
Extra Capacity (kW's)
129.7
Run hrs/year
3000
Years Running 20
Total Hours
60000
Tots kW's over lifetime
Cost if by gas
£ 194,550.00
kW's
£ ,500.00
KW's
£ ,200.00

20. Source Side Water Temperature Effect (55C to 75C)

21. Operating Temperatures – Hot Side Effect

22. Parallel

23. Parallel/Series – Stepping the Condensing Temp

24. Multiple Heat Pumps – Parallel or Combination?
3 heat pump system
Parallel Vs Combination for 2MW 55/75 from 8/5 Deg C
Parallel gives COP: 3.08
Combination gives COP: 3.39
Parallel Vs Combination for 4.3MW 60/85 from 50/30 Deg C
Parallel: 3.68
Combination: 4.79

25. Single, Double, Triple

26. Motor Losses and Source Pump Power!
Are you being quoted a Shaft or Absorbed power COP??
Hot side flow/return Temp (Deg C)
55/75
Source Side Temp (Deg C)
8/5
Number of Units 1
Heat Pump Capacity (kW)
1049.5
Power - Shaft (kW)
332.4
COP
3.16
Motor Losses - Say 3% (kW)
9.972
Inverter Losses - Say 3% (kW)
New COP
2.98
Source Pump Power (kW) 20
Final COP
2.82

27. Ofgem and the RHI

28. “Free Cooling”
Evaporator outlet water.
Smart city planning.
Reduce cost for electric cooling on site.

29. Why Should We Care?????????
Larger central energy plants = lower cost (£/kW)
RHI
Carbon reductions (Carbon targets)

30. Looking To The Future

31. The choice?
Listen to “Policy Needs” and act for the future now
Or wait till the Carrot is a just a faded memory!