Seasonal Thermal Storage

Transcription

1 Seasonal Thermal Storage State of the Art and Future Aspects H. Kerskes Institute for Thermodynamic and Thermal Engineering (ITW) Universität Stuttgart Pfaffenwaldring Stuttgart Internet:

2 Outline Small scale seasonal thermal energy storage for single and multifamily houses Large scale seasonal thermal energy storage solar assisted districted heating systems Relevance of seasonal thermal energy storage state of the art new developments future aspects

3 Small solar thermal combisystems Typical size of solar combisystems m² collector area l tank volume solar fraction 15 30% market share (Germany) > %

4 Market development of solar thermal systems in Germany (source BSW)

5 Waste of Heat Institute for Thermodynamics and Thermal Engineering m² collector area installed in Germany 9.7 GW peak power installed approx 30 % = 2.9 GW on solar thermal combi systems typical stagnation time of combisystems 200 h/a 2.9 GW * 200 h/a * 0.3 = 175 GWh/a = kwh/a of heat not used, enough for people Reason: low heat demand in summer, no long term storage capacity Solution: seasonal heat storage

6 Small scale seasonal thermal storage Solarhouse 50+ : the next standard high solar fraction > 50% large collector areas 30 m² to 60 m² large hot water storage tanks to litres Quelle: Sonnenhausinstitut e.v.

7 State of the Art Institute for Thermodynamics and Thermal Engineering large steel tanks new buildings: insertion during construction phase building stock: on site welding of steel tank 17,5 m 3 Speicher; Quelle: 7

8 New developments Large hot water storage tanks cylindrical polymeric tanks on site fabrication, laminating Tank Fa. Haase; Quelle: volumes: m³ 8

9 Institute for Thermodynamics and Thermal Engineering New developments Large hot water storage tanks steel frame with polymeric panels pressure less tank in situ construction and sealing cubical shaped tank space efficient well fitted to localities 9

10 Future hot water stores modular concepts / ideal for building stock very flexible in design easy to install well insulated (VIP) perfect temperature stratification pre fabricated containers polymeric tank materials cost efficient by industrial manufacturing of modules 10

11 Heat Storage Technologies storage thermal thermo chemical sensible heat latent heat heat of reaction liquid solid solid-liquid liquid-vapour water rock melting evaporation aquifer Thermo-chemical heat stores - first developments in adsorption processes - first approaches with chemical reactions

12 Small scale seasonal thermal storage Solarhouse 50+ Targets for solar systems: significant decrease in storage size, collector size and system costs next improvements Quelle: Sonnenhausinstitut e.v.

13 Small scale seasonal thermal storage Solarhouse 50++ Targets for solar systems: significant decrease in storage size, collector size and system costs Adsorption Heat Stores half of collector area half of storage volume

14 Small scale seasonal thermal storage Solarhouse 50 super+ Targets for solar systems: significant decrease in storage size, collector size and system costs Chemical Heat Stores half of collector area 1/5 of storage volume

15 Advantage of thermo-chemical heat storage high energy density almost loss free heat storage storage energy density factor Water * 60 kwh/m³ 1 Latent kwh/m³ 1 2 Adsorption kwh/m³ 2 3 Reaction kwh/m³ 4 10 disadvantages: high power output difficult * with T = 50 K high regeneration temperature ( C)

16 Potential study - simulation results Energy savings comparison of hot water storage and TCM storage (storage density 250 kwh/m³)

17 Conclusion Small Scale Storage Large hot water stores are well introduced to the market Further improvements of hot water stores -reduction of heat losses / innovative insulation materials -optimized charging and discharging unit / stratification devices -cost reduction / polymeric tank materials, industrial manufacturing -integration into building / modular concepts Thermo-chemical heat storage is basic research Requirements for accelerated development - research on storage material - research on system design - demonstration projects

18 Large scale seasonal thermal storage central heating Heizzentrale plant flat plate Flachkollektoren collectors Gas seasonal Saisonaler thermal Wärmespeicher energy store Brennwert- Kessel Wärmeübergabestation substation heat transfer Wärmenetz heat distribution solar Solarnetz network network Central Solar Heating Plant with Seasonal Thermal Energy Storage (CSHPSTES)

19 Renewable heat production Regenerative Wärmeerzeugung Scenario sustainability Germany - Szenario NACHHALTIGKEIT, Deutschland REG-Strom für Wärme Endenergie, [ PJ/a ] Geothermie Kollektoren Nahwärme Kollektoren Einzelanlagen Biomasse Nahwärme Biomasse Einzelheizung Quelle: DLR, ITT

20 Concepts of Large Scale Seasonal Thermal Energy Stores Q Storage capacity: = ρ c (ϑ max -ϑ min ) V hot water tank thermal energy store (HW TES) pit thermal energy store (PTES) KWh/m³ ~55 KWh/m³ Erdsonden-Wärmespeicher borehole thermal energy store (BTES) aquifer-thermal energy store (ATES) KWh/m³ KWh/m³

21 Types of seasonal thermal energy stores features (1) tank thermal energy store (HW) pit thermal energy store (PTES) + high thermal capacity (water) 70 kwh/m³ + high dis-/charging power + freedom of design (geometry) + thermal stratification (-) limited size (< m³) - high construction costs + reasonable construction costs + medium (gravel-water) to high (water) thermal capacity kwh/m³ + nearly unlimited store dimensions (-) sophisticated cover (water) - limited freedom of design (slope angle)

22 Types of seasonal thermal energy stores features (2) Erdsonden-Wärmespeicher borehole thermal energy store (BTES) aquifer-thermal energy store (ATES) + low construction costs + easily extendable - low thermal capacity kwh/m³ - low (dis-)charging power, buffer required, heat pump recommended - limited choice of locations - no thermal insulation at side and bottom + very low construction costs (+) medium thermal capacity kwh/m³ (-) operation (low/medium (dis-) charging power, heat pump recommended) - very limited choice of locations - no thermal insulation

23 Future large scale seasonal thermal energy store Future characteristics very cheap / < 50 /m³ sealing by polymeric foil free flowing evacuated insulation material Source: ITW Source: ITW

24 Future large scale seasonal thermal energy store Future characteristics pit hot water store filled with water and/or thermochemical storage materials commercial products self supporting cover modular system size steps of 5000 m³ up to any size

25 Retro fitted houses Solar renovation of apartment building 18 flats 350 m² solar roof Solar combisystem Crailsheim, Germany Quelle: ITW

26 Future large scale seasonal thermal energy store 3. extension 2. Erweiterung 2. extension 1. Erweiterung Retro fitted houses with easily extendable borehole TES in any size Forschungsspeicher 1.extension

27 Future Borehole thermal energy stores

28 investition costs per m³ water equivalent [ /m m³] Ilmenau Institute for Thermodynamics and Thermal Engineering Costs of seasonal thermal energy stores Crailsheim Rottweil Steinfurt Eggenstein Chemnitz Neckarsulm Hannover Rostock Hamburg Bielefeld München Friedrichshafen (Crailsheim) realized study hot water (HW) gravel-water (KW) BTES storage volume in m³ water equivalent [m³] Kettmannhausen Berlin- Potsdam source: Solites

29 Conclusion Large scale Large seasonal heat stores are feasible and work, very high solar fractions are achievable solar heat costs depend on - size of the system - system technology - boundary conditions - solar fraction Further improvement of STES technology - reduction of construction costs - improvement of energy efficiency reduction of heat losses - increased storage density Requirements: accelerated market development Goal: Market capability of STES until 2020