Solar heating and cooling solutions for buildings

Transcription

1 Solar heating and cooling solutions for buildings Stephen White July 2017 ENERGY FLAGSHIP

2 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

3 Cooling Demand Matches Solar Availability

4 Demand (MW) Why solar cooling? - Policy perspective 1. Reduce greenhouse gas emissions 2. Lower energy costs/ benefit the electricity system (higher load factor/ lower tariffs) Time of Day

5 Percentage increase in sale price for green buildings compared with conventional code-compliant buildings (%) 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 35% 30% 25% 20% 15% 10% -5% 0% -5% -10% -15% -20% IPEEC, 2014 Year of Study

6 Total amount of installed Solar Cooling systems in Europe & the World Solar cooling market Mugnier, & Jakob, 2012 Source: Solem Consulting / TECSOL

7 IEA Roadmap vision of solar heating and cooling (2012) Solar cooling accounts for ~17% of TFE cooling in 2050

8 Technology Approach ENERGY FLAGSHIP

9 Routes to delivering solar heat Solar Thermal Solar Electric Roof cavity Transpired Glazed air heater Combi System Solar PV Thermal heat pump Mechanical heat pump Split system DX Unit

10 Combi-systems beget solar cooling systems?

11 Solar PV or solar thermal integration and backup Thermal storage tank Backup heater Thermally Activated Cooling Machine Hot water Solar collector panels

12 Routes to delivering active solar cold Solar Thermal Solar Electric Flat Plate Evacuated Tube Parabolic Trough Parabolic Dish Solar PV Stirling cycle Single- effect absorption chiller Adsorption chiller Desiccant dehumidification Double- effect absorption chiller Rankine Cycle Mechanical compressor driven Split system DX Unit Chiller

13 Solar [thermal/vapour compression] hybrid cooling?

14 Free (Solar?) Cooling ENERGY FLAGSHIP

15 Water Air 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? Sealed well insulated buildings? Ventilated adaptive comfort

16 Dew point cooler Gives enthalpy reduction; not just sensible - latent switch Source: Oxycom

17 Extending the economy cycle season Perth Brisbane

18 Dew point coolers entering the market

19 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?

20 Solar PV Driven Cooling ENERGY FLAGSHIP

21 Systems emerging on the market

22 Some indicative (only) information Adapted from Mugnier and Mopty, IEA Task 53, 2016

23 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?

24 Potential benefits (beyond simple energy savings) Electricity system benefit Consumer benefit Disadvantages 100% off grid solar PV/AC with separate AC backup Reduced peak demand No reverse power flow Safety Voltage Slow ramp rates Residential: leave it permanently on = guilt free luxury Commercial Solar cooling efficiency increase at part load I don t need to inform my electricity utility Wasted electricity if airconditioning is not required Needs batteries to manage fluctuations 100% Solar PV self consumption with grid backup Reduced peak demand No reverse power flow I don t need to inform my electricity utility Wasted electricity if airconditioning is not required Solar PV self consumption with grid export/import Reduced peak demand Get full value for electricity Lack of advantages

25 Solar thermal driven cooling ENERGY FLAGSHIP

26 Performance Solar thermal technology options (By heat source temperature) Water at P atm

27 Solar thermal collector efficiency

28 Absorption chillers (predominantly LiBr/water) (Mature technology, chilled water output) Chiller Coefficient of Performance (COP) Required Heat Source Temperature Availability Single Stage ºC Good. Also ammonia Two Stage ºC Large systems (>100kW) Three Stage ºC limited Broad NH 3 /water Century Carrier Yazaki, Japan ( kw) Robur, Italy (35-88 kw) Kawasaki Thermax Shuangliang York EAW, Germany ( kw) AGO, Germany ( kw)

29 Adsorption Chillers Mayekawa ( kw) Sortech (8-15 kw) Invensor (7-10 kw) Bryair ( kw) Mitsubishi Plastics (10,5 kw)

30 ~200Pa Desiccant dehumidification 35 C 14g/kg 60 C 7.0 g/kg 56 C 21g/kg 80 C 35 C 14g/kg Electric heater or Gas heater Suitable for solar pre-heat

31 Selection considerations Hazards Performance Heat rejection Absorption Adsorption Desiccant Corrosive fluid Crystallization Best COP Poor at low temperatures Cooling tower Inert solid media Works at lower temperature Lower COP? Cooling tower preferred Inert solid media Works at lower temperature Free part load cooling? Depends on conditions No cooling tower Size/weight More compact Bulky and heavy? Bulky but light Maintenance Cost Co-benefits Solution chemistry Cooling tower Comparable with conventional (at scale) Easy Cooling tower Expensive Atmospheric pressure Robust? Probably most economic? Ventilation

32 Some likely combos Air collectors Flat plate collectors Evacuated tubes - Heating and desiccant dehumidification - Desiccant or adsorption system - Single effect absorption chiller Concentrating collectors - Double effect absorption chiller - Air cooled food refrigeration

33 Indicative Performance 1 unit of Sun Low Efficiency (air cooled) Electric High Efficiency (water cooled) Low Efficiency (single effect) Thermal High Efficiency (double effect) Driving Energy Cold (heat) (0.8) 1.2 (1.4) 0.35 (0.85) 0.6 (1.1)

34 Thermal systems are ideally integrated Large Hotel Large Office Buidling 29% 54% Air Conditioning 13% 1% 49% Air Conditioning Lighting Lighting 1% 14% 2% Laundry Other Hot w ater 37% Office equipment Other Medium Size Hospital 20% 39% Air Conditioning Lighting Laundry 15% 8% 18% Other Hot w ater

35 Cost competitiveness (example installed systems) Neyer, Mugnier and White, 2015

36 Cost of energy savings compared with PV Sensitivity to buffer tank size, collector area and chiller size Hotel in Madrid (3050 m 2 floor area), advanced flat plate collectors and single effect absorption chiller

37 Technical Integration ENERGY FLAGSHIP

38 Average Hobart diurnal profile Summer Winter

39 Average Townsville diurnal profile Summer Winter

40 But every day and every hour is different Storage and/or backup required

41 Generic flow-sheet for matching an intermittent heat source and a variable demand for cooling Cooling Tower Solar Collector Evaporator (+possible backup AC)

42 Ten Key Principles Principle 1: Principle 2: Principle 3: Principle 4: 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? Avoid using fossil fuels as a backup for single effect ab/adsorption chillers Design to run the absorption chiller in long bursts If in doubt oversize the field not the chiller Use a wet cooling tower where possible

43 The Key Principles (con) Principle 5: Principle 6: Principle 7: Principle 8: Principle 9: Select solar collectors that achieve temperature even at modest radiation levels Keep the process flowsheet simple and compact Match storage temperature and hydraulics with the application Minimise parasitic power Minimise heat losses Principle 10: Apply appropriate resources to design, monitoring and commissioning

44 Building Integration ENERGY FLAGSHIP

45 Bolt on or fabric integrated? Reduced materials duplication Improved aesthetics Achieving core building functionality Maintaining performance Diverse product range Lichtblau et al 2010

46 IEA Task41 categorization Farkas, 2013 Source: Monier Source: SOLID

47 And other functions IEA Task41

48 Transpired air collectors

49 The attic - To suck or blow? That is the question

50 Impacts of orientation and tilt angle

51 Output per kw of panel purchased vs Output per m 2 floor plate area

52 Near horizontal panels don t care about orientation

53 Precinct Integration ENERGY FLAGSHIP

54 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

55 Normalised Power Normalised Power Export Going 100% solar electricity Needs to be transported somewhere or stored Summer Nett daily surplus Exporting (shifting to my neighbours) around 3 times more electricity than average demand at midday Winter Nett daily shortfall Export at midday is approximately the same as average demand? More generation capacity, Add battery storage, or Shift demand

56 Examples ENERGY FLAGSHIP

57 SolaMate air heater example

58 BlueScope PV/T example NE Orientation SW Orientation Sproul and Farschimonfared, 2016

59 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

60 Observations: Rowes Bay operating by itself

61 Observations: Operating in tandem with peak smart

62 Partial/hybrid cooling Around the cities Total comfort solution (% of hours) Total solution as is

63 Large ESCO systems make economic sense Wide variety of reported capital cost numbers - lets say ~US$2,500 / kw cooling installed Even better when there is a high DHW load =2.5 m 2 /kw S.O.L.I.D. United World College, Singapore 1575kW single effect absorption chiller 3900m 2 flat plate collectors with transparent teflon sheet 60m 3 storage at ~88 C ESCO financing =15 L/m 2

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65 Some absorption chiller installations in Australia Source: ECS

66 SERM building, Montpellier (France), 2010 TECSOL: engineering company District heating and cooling Building A : m² - offices and shops Building B : m² with 167 dwellings 900 kw gas heating 700 kw chiller Montpellier Heating and System net utilities => System owner AXIMA : Company in charge of the works Buildings situation

67 System selection Application - Hot water preheat (all year round) - Autonomous solar cooling (when hot water temperature is high enough) Selection 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 liter hot buffer storage tank for the chiller (Block A) =43 L/m 2 =6.9 m 2 /kw m3 DHW storage capacity in Building B for dwellings)

68 Schematic

69 Solar Heat Collected/ DHW Heat Demand Hot water gives year round solar utilization Month

70 Case study performance 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, Feb-14 21,409 6,789 6, Mar-13/14 37,977 13,153 12, Apr-13 33,255 12,236 11, May-13 47,124 17,350 16, Jun-13 53,349 13,236 7,497 2, Jul-13 55,769 16,639 11,311 3, Aug-13 48,656 12,467 8,628 1, Sep-13 37,744 10,513 9, Oct-13 24,645 8,541 7, Nov-13 17,309 5,133 4, Dec-13 15,164 4,341 3, TOTAL 406, , ,974 9,394 5,

71 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 kw th 400m 2 collectors, 9000 litres =5 m 2 /kw =23 L/m 2

72 Preheating water and precooling air Pre-cooled air out Ambient air in

73 Novel two wheel intercooled desiccant wheel system

74 Solar hot water heating contribution Preheating cant heat the ring main

75 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

76 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

77 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

78 Thank you Energy Technology Stephen White Energy for Buildings Manager t e stephen.d.white@csiro.au w ENERGY TECHNOLOGY