An Introduction to Large Heat Pumps Dave Pearson Star Renewable Energy

SRE & Heat Pumps

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

Big Heatpumps @ Drammen GWh

The Basics – WSHP

The Basics ASHP

What do we consider Large Scale? Commonly thought of as 50-100kW’s @50 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 looking @ 70 Deg C Following examples we will look at is for a 2MW system Heating from 55C to 75C

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?

Water Temperature Effect

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

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

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

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

System Design - Basic Cold Side: 5/2 Deg C Hot Side: 60/80 Deg C COP: 2.47

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

System Design - Basic Cold Side: 25/17 Deg C Hot Side: 40/70 Deg C COP: 3.99

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

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

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 15108000 Cost if by gas (@2.5p) £ 194,550.00 Subcooler @ 108.9kW's £ 3,500.00 Desuperheater @ 142.9 KW's £ 4,200.00

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

Operating Temperatures – Hot Side Effect

Parallel

Parallel/Series – Stepping the Condensing Temp

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

Single, Double, Triple

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) 9.67284 New COP 2.98 Source Pump Power (kW) 20 Final COP 2.82

Ofgem and the RHI

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

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

Looking To The Future

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