Thermal Storage: Challenges and Opportunities. Ravi Prasher Sheetak Inc., Austin, Texas

Transcription

1 Thermal Storage: Challenges and Opportunities Ravi Prasher Sheetak Inc., Austin, Texas 1

2 Thermal 2

3 Residential and Commercial Buildings Buildings use 72% of the U.S. electricity and 55% of the its natural gas Heating & cooling is ~50% of energy consumption Source: LBNL Environmental Energy Technologies Division, 2009

4 Current System Architecture Fuel, F E Engine/ Electricity, E 1 Generator Set Air Cooling, C Fuel, F H Waste Heat Heater/Boiler Efficiency % E 2 Conditioner Waste Heat COP 3 Heating, H Power Load Energy Demand Cooling Electricity Heating Rate of Fuel Use, F = F E + F H Time 4

5 Integrated Energy Supply Systems F E F H Engine/Fuel Cell Heater/B oiler Solar/Wind Electrical Storage Low Temp. Thermal Bus High Temp. Thermal Bus Thermal Storage Power Electronics Electrical Bus Air Conditioner/ Heat Pump Absorption Cooler H E Economic Goal: Payback in 4-5 years Technical Challenges: 1) Operating System (Software) & Sensors-Actuators (Hardware) for Optimal Operation 2) Thermal storage 3) Integration C Thermal Storage 5

6 National Impact of Integrated Energy Supply Systems Ideal Scenarios Buildings Site Electrical Load (Quads) Building Site Heat Load(Quads) Today Heat Coming from Integrated Systems Heat & Air Conditioning Coming from Integrated Systems Primary Energy Consumption (Quads) Primary Energy Saved (Quads) 9 x = (30%) 14.3 (37%) US Primary Energy Consumption (Annual) 100 Quads Assumptions: 33% efficient engine, Electrical COP ~3, Thermal COP ~0.7 6

7 Thermal Storage Issues for CHP Conventional Gas Appliance >1000 C Combustion <100 C Gas Appliances Heated Fluid Heat exchanger cost is minimal Thermal Storage Low or high temperature? Exhaust ~ 500 C Heat on demand < 100 C Cold Thermal Storage Cooling on demand 7

8 Modular Thermal Hub For Building Cooling Heating, and Water Heating Srinivas Garimella/Georgia Institute of Technology Technology Impact Significant size reductions ~ 3x High COPs: integration of AC/Heating/Water heating Monolithic packaging offers small fluid charge, flexible placement, reduced labor Ultracompact Integrated Space-Conditioning and Water Heating at COP eq 8

9 Thermal Storage Issues for CHP Cost: Cost of storage = Thermal storage cost + Rate of heat delivery cost (heat exchangers) Heat exchanger cost 1/ T Physical Volume and Mass: 1 therm of NG ~ 400 kg of water (20-80 C) or PCM Average Therms/day in winter ~

10 Thermal Storage: Science + Engineering Scientific Challenge: New Materials Li ion Battery? Gas Phase Organic Metal Hydride Metal Hydroxide Metal Carbonate Phase Change Sensible Heat 10

11 Key Parameters for Thermal Storage Storage Time: Minutes to months; Insulation free(?) Discharge Time: Minutes to hours; Heat exchangers systems Energy Density: High energy density by mass and volume (kwhr/kg, kwhr/l) Low and High: Both low temperature ( K) and high temperature ( 1000 K) - minimize exergy loss and control heat transfer rates Cost: $/kwhr, $/kw, Cost of delivered energy 1/N 11

12 High Energy Advanced Thermal Storage (HEATS) at ARPA-E Modular thermal storage Base Load Solar and Peaking High-Temp Nuclear C Building and EV Thermal Management Energy density ~ 2 3X of state-of-the-art Grid Level Storage Using Heat Pumps Thermofuel: Sunlight to heat to fuel Scale Sunlight to fuel conversion efficiency > 10X of photosynthesis (Biofuels) ~10X reduction in cost Utility scale thermal storage Chemical thermal storage Increase EV range by ~ 40% <100 o C >600 o C Temperature o C 12

13 Thermal Batteries for Electric Vehicle Li Shi/ The University of Texas at Austin 500 µm Sugar derivatives-graphene foam composites with heat of fusion 2-3 x of state of the art and thermal conductivity > x of state of the art

14 Advanced Thermo-Adsorptive Battery (ATB) Climate Control System Prof. Evelyn Wang / MIT Illustration of Key Technical Concepts Vapor manifold Stack plates Adsorbent layers Vapor flow Cooling air flow ATB Adsorbent Stack Design High capacity adsorption materials (MOFs)

15 Sheetak s Thermal Storage Condenser V2 Heat Hot Reactor MgCl 2 composite+h 2 O Hot Air Water Reservoir V1 Evaporator Cold Air Expansion device o Hot and cold storage integrated into a simple elegant system o Heating by exothermic hydration of MgCl 2 /other salts o Cooling by water expansion 7x energy density of ice 15

16 Thermal Storage Test Bed Condenser Chamber Hot Reactor Chamber Evaporator Chamber

17 Solar Combine Heat and Power (S-CHP) T sun = 5500 o C Heat Electricity T water < 100 o C Exergy loss Combined Heat & Electricity ~ 15% efficiency Energy loss Very expensive & complex 17

18 S-CHP Using Thermolectric Generator (TEG) Heat + Electricity Thermoelectric Generator Integrated Solar Water Heater 18

19 S-CHP Using Thermolectric Generator (TEG) BaYbCoSb 3 films GMZ & MIT Sheetak Cost of TE addition is minimal: Electricity cost ~ $0.25/W p Uses commercially available evacuated tube collector Does not require any tracking Increases the capital utilization of SWH all year round 19

20 Solar PV or CSP? + = Higher LCOE + Thermal + storage = Lower LCOE possible! 20

21 Similar principles can be applied for fossil generators as well 21

22 High-Temperature applications: CSP Target Efficiency Current systems C = 100 C = 1000 C = Temperature ( C) Storage Cost ($/kwh t ) SOA Target 15 SOA: 3 fluids: Oil, Molten salt, Steam Molten salt Sensible storage T = 100 o C ( o C) 22

23 Novel Approaches Halotechnics, Inc ~400 o C molten glass 1200 C Low viscosity molten glass instead of molten salt s thermal storage for solar generation 23

24 Phase Change Materials with Enhanced Radiation Heat Transfer Dr. Yogi Goswami / University of South Florida Use of high temperature PCMs with tailored radiative properties Encapsulating the tailored PCM using an electroless deposition technique Layer -2; Rigid encapsulating layer Layer -1; Flexible thin layer with high emittance PCM pellet with the required void space to account for volumetric expansion and tailored radiative properties Low Cost Electroless Encapsulation of High Temperature PCMs with Uniquely Tailored Heat Transfer Characteristics

25 Thermal Storage to Store Electricity High T thermal storage High T thermal storage Heat pump W Engine Mode W Low T thermal storage Low T thermal storage This can potentially enable electrical storage with cost of pumped hydro but geographically independent References: 1) 2) Prof. Robert Laughlin, Nobel Laureate, Stanford University 25

26 Thermal Management of IC Vehicles Weilenmann, et al., Atmospheric Environment, 43, 2419 (2009) Cold Start of IC vehicles increases fuel consumption and GHG emissions 26

27 Thermal Management of Electric Vehicles Climate control of the cabin can decrease the range of EVs by as much as 40% 27

28 Thermal Storage for ICV and EV Cold battery Heat exchanger to the cabin Thermal charger/active heater& cooler Heat battery Used sometimes in conjunction with the thermal battery to provide peak load or in case of emergency E n g i n e Cold coolant Discharge Hot coolant Exhaust ~ o C Thermal Battery Charge Discharge C a b i n Connected to the wall plug in garage Electrical battery 28

29 Other Thermal Components All Solid Heat Exchanger Long-distance Heat Transport Switchable Insulation (thermal diode) 29

30 Back Up

31 Thermal Energy Storage with Supercritical Fluids Dr. Richard Wirz / UCLA & Dr. Gani Ganapathi/JPL Energy density ~ 2 3x of PCM

32 32 Courtesy: Arun Majumdar

33 Grossman, MIT Charging Discharging Transportable like a fuel rechargeable like a battery. Energy density similar to a Li-Ion battery 33

34 High Efficiency Solar-Electric Conversion Power Tower Abengoa Solar Inc. Receiver Heat Exchanger Hot liquid tank Power Cycle Tower Cold solid tank Metallic heat transfer fluid and storage

35 Utility Scale Electricity Storage Both pumped hydro or compressed air storage is geographically limited Cost of Pumped hydro but geographically independent storage: Is it possible? Thermal storage demonstrated at utility scale Can we use it for electricity storage? 35