Solar Cooling Standard - AIRAH€¦ · • Solar cooling makes intuitive supply/demand sense • It...
Transcript of Solar Cooling Standard - AIRAH€¦ · • Solar cooling makes intuitive supply/demand sense • It...
Solar heating and cooling solutions for buildingsStephen White
July 2017
ENERGY FLAGSHIP
Solar cooling
Using solar radiation to drive a cooling process.
Displacing the use of fossil fuel derived electricity that would otherwise be used in a conventional vapour
compression airconditioner.
Solar thermal heat driving a thermal cooling process
Solar photovoltaics driving a conventional vapour
compression cooling process
Cooling Demand Matches Solar Availability
Why solar cooling? - Policy perspective
1. Reduce greenhouse gas emissions
2. Lower energy costs/ benefit the electricity system (higher load factor/ lower tariffs)
De
ma
nd
(M
W)
Time of Day
Why solar cooling? – Owner perspective
1. Reduce greenhouse gas emissions/ lower energy costs
2. Increase asset value• Access to environmentally aware (CSR)
tenants• Point of sale rating disclosure
3. Response to government policy• Compliance with minimum renewable
energy targets (development permission)• Eligibility for incentives
20102008 2011 2012 20142009
Year of Study
2013
Per
cen
tage
incr
ease
in s
ale
pri
ce f
or
gree
n b
uild
ings
co
mp
ared
wit
h c
on
ven
tio
nal
co
de
-co
mp
lian
t b
uild
ings
(%
)
-15%
-10%
0%
-20%
10%
-5%
20%
-5%
25%
35%
15%
30%
IPEEC, 2014
Mugnier, & Jakob, 2012
Solar cooling marketTota
l am
oun
t of
insta
lled
Sola
r C
oolin
g s
yste
ms in E
uro
pe &
the
Worl
d
Source: Solem Consulting / TECSOL
IEA Roadmap vision of solar heating and cooling (2012)
Solar cooling accounts for ~17% of TFE cooling in 2050
Technology Approach
ENERGY FLAGSHIP
Routes to delivering solar heat
Solar ElectricSolar Thermal
Transpired Glazed air heater Solar PVRoof cavity
Mechanical heat pump
• Split system
• DX Unit
Combi System
Thermal heat
pump
Combi-systems beget solar cooling systems?
Solar collector
panels
Thermal
storage tank
Backup
heater
Hot water
Thermally
Activated
Cooling Machine
Solar PV or solar thermal – integration and backup
Routes to delivering active solar cold
Solar ElectricSolar Thermal
Evacuated Tube Parabolic Trough Solar PVFlat Plate Parabolic Dish
Mechanical compressor driven
• Split system
• DX Unit
• Chiller
Double- effect
absorption chiller
Single- effect
absorption chiller
Rankine Cycle
Desiccant
dehumidification
Adsorption chiller
Stirling cycle
“Solar [thermal/vapour compression] hybrid” cooling?
Free (Solar?) Cooling
ENERGY FLAGSHIP
Free cooling approaches
• Economizer cycle
• Economizer cycle with direct or indirect evaporative cooling
• Night purge ventilation
• Evaporatively cooled water circulation
• Night sky radiant cooling
• Geo-exchange
Wate
rA
ir
? Sealed well insulated buildings
? Ventilated adaptive comfort
Dew point coolerGives enthalpy reduction; not just sensible - latent switch
Source: Oxycom
Extending the economy cycle season
PerthBrisbane
Dew point coolers entering the market
Implications
• Smaller temperature differentials = larger air flows
• Better suited to applications such as• Tempered air
• Underfloor cooling
• Chilled beams/ceilings (for evaporatively cooled water)
• What level of duplication of infrastructure is required for peak demand?
Solar PV Driven Cooling
ENERGY FLAGSHIP
Some indicative (only) information
Adapted from Mugnier and Mopty, IEA Task 53, 2016
Separate PV and AC (grid acting as buffer)
vs Connected PV and AC (off-grid/ self consumption)?
Is this “Solar Airconditioning” or ”Solar AND Airconditioning” ?
Potential benefits (beyond simple energy savings)Electricity system
benefit
100% off grid solar PV/AC with separate AC backup
• Reduced peak demand
• No reverse power flow
• Safety• Voltage
• Slow ramp rates
100% Solar PV self consumption with grid backup
• Reduced peak demand
• No reverse power flow
Solar PV self consumption with grid export/import
Reduced peak demand
Consumer benefit
Residential: • leave it permanently
on = guilt free luxuryCommercial• Solar cooling efficiency
increase at part load
I don’t need to inform my electricity utility
I don’t need to inform my electricity utility
Get full value for electricity
Disadvantages
• Wasted electricity if airconditioning is not required
• Needs batteries to manage fluctuations
Wasted electricity if airconditioning is not required
Lack of advantages
Solar thermal driven cooling
ENERGY FLAGSHIP
Solar thermal technology options (By heat source temperature)
Perf
orm
ance
Wa
ter
at
Patm
Solar thermal collector efficiency
Absorption chillers (predominantly LiBr/water)
(Mature technology, chilled water output)
ChillerCoefficient of
Performance (COP)
Required Heat
Source TemperatureAvailability
Single Stage 0.6-0.75 80-120ºC Good. Also ammonia
Two Stage 1-1.3 160-180ºC Large systems (>100kW)
Three Stage 1.6-1.8 200-240ºC limited
Broad
Carrier
Thermax York
Century
Kawasaki Shuangliang
Yazaki, Japan
(35 - 175 kW)Robur, Italy
(35 - 88 kW)
EAW, Germany
(30 - 200 kW)
AGO, Germany
(50 - 500 kW)
NH3 /water
Adsorption Chillers
Sortech (8 - 15 kW)Invensor (7 - 10 kW)
Mayekawa (50 - 350 kW)
Mitsubishi Plastics
(10,5 kW)
Bryair (35 - 1180 kW)
Desiccant dehumidification
Electric heater or Gas heater
Suitable for solar pre-heat
35°C
14g/kg
60°C
7.0 g/kg
35°C
14g/kg
56°C
21g/kg
80°C
~2
00P
a
Selection considerations
Absorption Adsorption Desiccant
Hazards Corrosive fluid Crystallization
Inert solid media Inert solid media
Performance Best COP Poor at low
temperatures
Works at lower temperature
Lower COP
Works at lower temperature
Free part load cooling ? Depends on conditions
Heat rejection
Cooling tower ? Cooling tower preferred
No cooling tower
Size/weight More compact Bulky and heavy ? Bulky but light
Maintenance Solution chemistry Cooling tower
Easy Cooling tower
Atmospheric pressure Robust
Cost Comparable with conventional (at scale)
Expensive ? Probably most economic
Co-benefits ? Ventilation
Some likely combos
Air collectors → - Heating and desiccant dehumidification
Flat plate collectors → - Desiccant or adsorption system
Evacuated tubes → - Single effect absorption chiller
Concentrating collectors → - Double effect absorption chiller
- Air cooled food refrigeration
Indicative Performance
1 unit of Sun
Driving Energy
Cold (heat)
Electric ThermalLow Efficiency
(air cooled)High Efficiency(water cooled)
Low Efficiency (single effect)
High Efficiency (double effect)
0.2 0.2 0.5 0.5
0.6 (0.8) 1.2 (1.4) 0.35 (0.85) 0.6 (1.1)
Thermal systems are ideally integrated
Large Hotel
2%
14%
1%
29%54% Air Conditioning
Lighting
Laundry
Other
Hot w ater
Large Office Buidling
13%
37%
49%1%
Air Conditioning
Lighting
Office equipment
Other
Medium Size Hospital
18%8%
15%
39%20% Air Conditioning
Lighting
Laundry
Other
Hot w ater
Cost competitiveness (example installed systems)
Neyer, Mugnier and White, 2015
Cost of energy savings compared with PV
Hotel in Madrid (3050 m2 floor area), “advanced” flat plate
collectors and single effect absorption chiller
Sensitivity to buffer tank size , collector area and chiller size
Technical Integration
ENERGY FLAGSHIP
Average Hobart diurnal profile
WinterSummer
Average Townsville diurnal profile
WinterSummer
But every day and every hour is differentStorage and/or backup required
Generic flow-sheet for matching an intermittent heat source and a variable demand for cooling
Solar
Collector
Evaporator
(+possible backup AC)
Cooling
Tower
Ten Key Principles
Principle 1: Choose applications where high annual solar utilization can be achieved
• Is there a load in the shoulder season?
• Can solar be the lead with conventional peaking?
Principle 2: Avoid using fossil fuels as a backup for single effect ab/adsorption chillers
Principle 3: Design to run the absorption chiller in long bursts
• If in doubt oversize the field not the chiller
Principle 4: Use a wet cooling tower where possible
The Key Principles (con)
Principle 5: Select solar collectors that achieve temperature even at modest radiation levels
Principle 6: Keep the process flowsheet simple and compact
Principle 7: Match storage temperature and hydraulics with the application
Principle 8: Minimise parasitic power
Principle 9: Minimise heat losses
Principle 10: Apply appropriate resources to design, monitoring and commissioning
Building Integration
ENERGY FLAGSHIP
Bolt on or fabric integrated?
• Reduced materials duplication
• Improved aesthetics
• Achieving core building functionality
• Maintaining performance
• Diverse product range
Lichtblau et al 2010
IEA Task41 categorization
Farkas, 2013
Source: Monier
Source: SOLID
And other functions
IEA Task41
Transpired air collectors
The attic- To suck or blow? That is the question
Impacts of orientation and tilt angle
Output per kW of panel purchased vs
Output per m2 floor plate area
Near horizontal panels don’t care about orientation
Precinct Integration
ENERGY FLAGSHIP
Zero Energy Precinct Example
• 151 Units
• 11kV connection
– Private network
– No backflow
• Residential demand
– 550 kVA peak demand
– 780 MWh/annum
• PV potential from available roof area
– 2740 MWh/annum
Norm
alis
ed P
ow
er
Norm
alis
ed P
ow
er
Winter
• Nett daily shortfall
• Export at midday is approximately
the same as average demand
Summer
• Nett daily surplus
• Exporting (shifting to my neighbours)
around 3 times more electricity
than average demand at midday E
xport
Needs to be transported
somewhere or stored
? More generation capacity , Add battery storage, or Shift demand
Going 100% solar electricity
Examples
ENERGY FLAGSHIP
SolaMate air heater example
BlueScope PV/T example
SW Orientation
NE Orientation
Sproul and Farschimonfared, 2016
CSIRO residential hot water, heating and cooling product
Provides cooling even when the sun is not shining
Low temperature heat source requirement
No cooling tower required (but does require water)
Positive pressurization of building
Observations: Rowes Bay operating by itself
Observations: Operating in tandem with peak smart
Around the cities
Total
solution
as isP
art
ial/hybrid c
oolin
g
Total comfort solution
(% of hours)
Large ESCO systems make economic sense
• Wide variety of reported capital cost numbers- lets say ~US$2,500 / kWcooling installed
• Even better when there is a high DHW load
United World College,
Singapore
• 1575kW single effect
absorption chiller
• 3900m2 flat plate collectors
with transparent teflon sheet
• 60m3 storage at ~88°C
• ESCO financingS.O.L.I.D
.
=2.5 m2/kW
=15 L/m2
Some absorption chiller installations in Australia
Source: ECS
District heating and cooling
Building A : 11 000 m² - offices and shops
Building B : 10 600 m² with 167 dwellings
Montpellier Heating and System net utilities => System owner
TECSOL: engineering company
Buildings situation
AXIMA : Company in charge of the works
SERM building, Montpellier (France), 2010
• 900 kW gas heating
• 700 kW chiller
System selection
Selection
- 240 m² double glazed flat plate collectors (Block A, limited by roof area)
- solar circuit in drainback mode (with water glycol + HX)
- 35 kW absorption chiller
- 1500 liter hot buffer storage tank for the chiller (Block A)
- + 10 m3 DHW storage capacity in Building B for dwellings)
Application
- Hot water preheat (all year round)
- Autonomous solar cooling (when
hot water temperature is high enough)
=6.9 m2/kW
=43 L/m2
Schematic
Hot water gives year round solar utilization
Month
Sola
r H
eat C
olle
cte
d/
DH
W H
eat D
em
and
Solar Irradiation
(kWh)
Collected solar heat
(kWh)
Solar DHW Production
(kWh)
Solar Cooling
Production (kWh)
Parasitic electricity
consumption (kWh)
Electrical Seasonal
Performance Factor* (-)
Jan-14 14,214 4,092 3,734 0 190 19.7
Feb-14 21,409 6,789 6,435 0 218 29.5
Mar-13/14 37,977 13,153 12,504 0 308 40.6
Apr-13 33,255 12,236 11,588 0 290 40.0
May-13 47,124 17,350 16,478 0 380 43.4
Jun-13 53,349 13,236 7,497 2,765 902 13.4
Jul-13 55,769 16,639 11,311 3,983 1190 13.6
Aug-13 48,656 12,467 8,628 1,970 840 14.2
Sep-13 37,744 10,513 9,316 676 554 18.9
Oct-13 24,645 8,541 7,843 0 240 32.7
Nov-13 17,309 5,133 4,789 0 220 21.8
Dec-13 15,164 4,341 3,851 0 157 24.6
TOTAL 406,616 124,490 103,974 9,394 5,489 21.5
Case study performance
TAFE commercial kitchens demonstration• Unique solar desiccant cooling design
• Flat plate/ 2-rotor desiccant cooling• Solar hot water
• Worlds largest solar desiccant cooling system • 80 kWth
• 400m2 collectors, 9000 litres
=5 m2/kW =23 L/m2
Preheating water and precooling airPre-cooled
air out
Ambient air in
Novel two wheel intercooled desiccant wheel system
Solar hot water heating contribution
• Preheating cant
heat the ring main
Solar space heating and cooling contribution
• Evaporative
cooling not
included/ valued (despite doing the
bulk of the cooling)
• Temperature not
always available
to run the DEC
Conclusion
• Solar cooling makes intuitive supply/demand sense
• It can add to the value of the building asset
• Solar PV driven systems are emerging on the market but manufacturers and electricity utilities need to work together
• A wide variety of thermal technologies and solar thermal collectors have been demonstrated but work best satisfying integrated building thermal needs
Conclusion• 10 Principles for good integration
• Year round solar utilization
• Integration with backup systems
• Good quality solar collectors
• Energy only economics are ok at large scale and for hot water lead
• Desiccant cooling has cost, maintenance and part load advantages, but is probably not well suited to providing a 100% solution (but nor would you expect a 100% solution from intermittent solar)
• But don’t forget low-cost building-integrated solar air heating options too
ENERGY TECHNOLOGY
Thank youEnergy TechnologyStephen WhiteEnergy for Buildings Manager
t +61 2 4960 6070e [email protected] www.csiro.au/