Solar heating and cooling solutions for buildings Stephen White - PowerPoint PPT Presentation

Solar heating and cooling solutions for buildings Stephen 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) Demand (MW) Time of Day

35% Why solar cooling? compared with conventional code-compliant buildings (%) 30% Percentage increase in sale price for green buildings – Owner perspective 25% 20% 1. Reduce greenhouse gas emissions/ 15% lower energy costs 10% -5% 2. Increase asset value 0% IPEEC, 2014 • Access to environmentally aware (CSR) -5% tenants -10% • Point of sale rating disclosure -15% Year of Study -20% 3. Response to government policy 2008 2009 2010 2011 2012 2013 2014 • Compliance with minimum renewable energy targets (development permission) • Eligibility for incentives

Solar cooling market Solar Cooling systems in Europe & the World Total amount of installed Mugnier, & Jakob, 2012 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 Thermal Solar Electric Roof cavity Transpired Glazed air heater Combi System Solar PV Thermal heat pump Mechanical heat pump • Split system • DX Unit

Combi-systems beget solar cooling systems?

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

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

“Solar [thermal/vapour compression] hybrid” cooling?

Free (Solar?) Cooling ENERGY FLAGSHIP

Free cooling approaches • Economizer cycle • Economizer cycle with direct Air or indirect evaporative cooling • Night purge ventilation • Evaporatively cooled water circulation ? Sealed well insulated buildings Water ? Ventilated adaptive comfort • Night sky radiant cooling • Geo-exchange

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

Extending the economy cycle season Perth Brisbane

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

Systems emerging on the market

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

Solar thermal driven cooling ENERGY FLAGSHIP

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

Solar thermal collector efficiency

Absorption chillers (predominantly LiBr/water) (Mature technology, chilled water output) Coefficient of Required Heat Chiller Availability Performance (COP) Source Temperature 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 NH 3 /water Broad Carrier Century Yazaki, Japan Robur, Italy (35 - 175 kW) (35 - 88 kW) EAW, Germany AGO, Germany (30 - 200 kW) (50 - 500 kW) Shuangliang York Thermax Kawasaki

Adsorption Chillers Mayekawa (50 - 350 kW) Invensor (7 - 10 kW) Sortech (8 - 15 kW) Mitsubishi Plastics (10,5 kW) Bryair (35 - 1180 kW)

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

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

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 Electric Thermal 1 unit of Sun Low Efficiency High Efficiency Low Efficiency High Efficiency (air cooled) (water cooled) (single effect) (double effect) Driving Energy 0.2 0.2 0.5 0.5 Cold (heat) 0.6 (0.8) 1.2 (1.4) 0.35 (0.85) 0.6 (1.1)

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

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

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

Technical Integration ENERGY FLAGSHIP

Average Hobart diurnal profile Summer Winter

Average Townsville diurnal profile Summer Winter

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

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

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 • Achieving core building duplication functionality • Improved aesthetics • 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 m 2 floor plate area