Seasonal thermal energy storage
pilot projects and experiences in Germany
Thomas Schmidt
Steinbeis Research Institute for Solar and
Sustainable Thermal Energy Systems
Nobelstr. 15, 70569 Stuttgart, Germany
Tel +49(0)711 673 2000 0; Fax +49(0)711 673 2000 99
info@solites.de, www.solites.de
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Background
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
•
1992 – 2003:
Solarthermie-2000 – Part 3
part 3: Central Solar Heating Plants with Seasonal Storage (CSHPSS)
– storage concepts
– eight demonstration plants realised
•
since 2004:
Solarthermie2000plus*
one main focus: Seasonal Thermal Energy Storage (STES) for:
– solar
– waste heat
– cooling
– combined heating & cooling
– CHP, biomass
– etc.
* Energy Research Programme of the German Federal Ministry
for the Environment, Nature Conservation and Nuclear Safety
Central Solar Heating Plant with Seasonal Storage (CSHPSS)
Target: 50 % solar fraction referred to total heat demand
Solar collectors
Central
heating plant
District heating
network
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Seasonal
heat storage
Solar network
Demonstration projects with STES (Solarthermie2000 plus) 1/2
Hamburg (1996)
Friedrichshafen (1996)
3.000 m²
flat plate coll.,
4.500 m³
4.050m²
flat plate coll.,
12.000 m³
Water tank
Water tank
Neckarsulm (1997)
Steinfurt (1998)
5.300 m²
flat plate coll.,
63.300 m³
Borheole Themal
Energy Storage
(BTES)
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Pit
(gravel / water)
Hannover (2000)
Rostock (2000)
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
510 m²
flat plate coll.,
1.500 m³
1.000 m²
Solar-Roof,
20.000 m³
Aquifer Themal
Energy Storage
(ATES)
1.350 m²
flat plate coll.,
2.750 m³
Water tank
Demonstration projects with STES (Solarthermie2000 plus) 2/2
Chemnitz, 1. BA (2000)
Attenkirchen (2002)
540 m²
Vacuum tubes,
8.000 m³
Pit
(gravel / water)
Munich (2007)
Crailsheim (2007)
2.900 m²
7.500 m²
flat plate coll.,
flat plate coll.,
5.700 m³
Water tank
37.500 m³
Borheole Themal
Energy Storage
(BTES)
Eggenstein (2007)
1.600 m²
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
800 m²
Solar-Roof
9.850 m³
Water tank and
Boreholes
flat plate coll.,
4.500 m³
Pit
(gravel / water)
Seasonal thermal energy storage (STES) - concepts
Tank thermal energy storage (TTES)
Pit thermal energy storage (PTES)
(60 to 80 kWh/m³)
(30 to 80 kWh/m³)
Borehole thermal energy storage (BTES)
(15 to 30 kWh/m³)
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Aquifer thermal energy storage (ATES)
(30 to 40 kWh/m³)
Seasonal thermal energy storages in Germany
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Location
Type
Size
Start of operation
Rottweil
hot-water (concrete)
600 m³
1995
Friedrichshafen
hot-water (concrete)
12 000 m³
1996
Hamburg
hot-water (concrete)
4 500 m³
1996
Ilmenau
hot-water (GRP)
300 m³
1997 / 1998
Hanover
hot-water (HDC)
2 750 m³
2000
Munich
hot-water (concrete)
5 700 m³
2007
Stuttgart
gravel/water
1 050 m³
1984
Chemnitz
gravel/water
8 000 m³
1995 / 2000
Augsburg
gravel/water
6 500 m³
1997
Steinfurt
gravel/water
1 500 m³
1999
Eggenstein
gravel/water
4 500 m³
2008
Neckarsulm
BTES
63 360 m³
1997+1998+2001
Crailsheim
BTES
35 700 m³
2008
Berlin
ATES
n/a
1999
Rostock
ATES
20 000 m³
2000
Neubrandenburg
ATES
n/a
2004
hot-water / BTES
9 850 m³
2002
Attenkirchen
GRP: glass-fiber reinforced plastic; HDC: high-density concrete;
ATES: aquifer thermal energy storage; BTES: borehole thermal energy storage
Comparison of storage concepts
water tank
gravel-water
BTES
ATES
gravel-water
soil / rock
sand-water
15 - 30
30 - 40
3 - 5 m³
2 - 3 m³
• drillable ground
• groundwater
favourable
• high heat capacity
• high thermal
conductivity
• low hydraulic
conductivity (kf<10-10
m/s)
• natural ground-water
flow < 1 m/a
• 30 - 100 m deep
• natural aquifer layer
with high hydraulic
conductivity (kf>10-4
m/s)
• confining layers on
top and below
• no or low natural
groundwater flow
• suitable water
chemistry at high
temperatures
• aquifer thickness
20 - 50 m
storage medium
water
heat capacity in kWh/m³
60 - 80
30 - 50
storage volume for 1 m³ water equivalent
1 m³
1,3 - 2 m³
geological requirements
•
•
•
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
stable ground
conditions
preferably no
groundwater
5 - 15 m deep
•
•
•
stable ground
conditions
preferably no
groundwater
5 - 15 m deep
Seasonal Thermal Energy Storage (STES) - Concepts
Tank thermal energy storage (TTES)
Pit thermal energy storage (PTES)
(60 to 80 kWh/m³)
(60 to 80 kWh/m³)
Borehole thermal energy storage (BTES)
(15 to 30 kWh/m³)
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Aquifer thermal energy storage (ATES)
(30 to 40 kWh/m³)
Construction of the seasonal heat storage in Munich, 5700 m³, 2007
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Concept of the Water-tank in Munich, 5700 m³, 2007
Beto
n
• prefabricated concrete elements with inner stainless
steel liner
• static connection of wall elements by in-situ concrete
and prestressing
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
• stratification device
• thermal insulation system with expanded glass
granules and vapour diffusion foil
Schutzbet
on
The central solar heating plant with seasonal storage in Munich
thermal energy storage
solar collectors on buildings
buildings without solar collectors
central heating plant
local heat distribution network
solar network
district heating network
heat transfer substation in buildings
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
• service area:
• heat demand:
• solar collectors:
• storage volume:
• heat pump:
• solar fraction:
• solar heat cost:
300 apartments
2 300 MWh/year
2 900 m² (aperture)
5 700 m³ (water)
1,4 MW absorption
47 % (design)
24 Euro-cent/kWh
System concept CSHPSS Munich
Loc al heat
distribution network
So
la
r
co
lle
c
to
rs
5700 m³
M
Seasonal thermal energy storage
Absorption
heat pump
M
Distric t
heating
network
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
max. 50°
Seasonal Thermal Energy Storage (STES) - Concepts
Tank thermal energy storage (TTES)
Pit thermal energy storage (PTES)
(60 to 80 kWh/m³)
(60 to 80 kWh/m³)
Borehole thermal energy storage (BTES)
(15 to 30 kWh/m³)
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Aquifer thermal energy storage (ATES)
(30 to 40 kWh/m³)
Research project on water-filled pits, University of Stuttgart (ITW), 2003-2007
Detailed investigations on:
• materials (insulation, liners, vapour barriers …)
• construction methods
• wall systems (heat & vapour transport)
• cover construction (floating, lightweight structure)
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Source: ITW, University of Stuttgart
Pit thermal energy storage in Eggenstein, 4500 m³, 2007
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Wall construction of the Eggenstein pit heat storage , 4500 m³, 2007
soil
drainage
protective fleece
diffusive inner liner ((lost) form work, HDPE)
thermal insulation (expanded glass granules)
compound liner (HDPE with vapour barrier)
storage medium (gravel /sand / water)
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
GW
Seasonal Thermal Energy Storage (STES) - Concepts
Tank thermal energy storage (TTES)
Pit thermal energy storage (PTES)
(60 to 80 kWh/m³)
(60 to 80 kWh/m³)
Borehole thermal energy storage (BTES)
(15 to 30 kWh/m³)
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Aquifer thermal energy storage (ATES)
(30 to 40 kWh/m³)
Borehole Heat Exchangers (BHE)
ground
surface
double U- pipe
heat
insulation
150 mm
25 mm
pipe connection
in sand underlay
covering
layer
injection tube for
grouting material
borehole
grouting
(e.g. bentonite-sandcement-suspension)
return
single U- pipe
supply
concentric pipe
grouting
borehole
heat exchanger
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Source: ITW, University of Stuttgart
borehole depth (30 - 100 m)
borehole wall
BTES in Neckarsulm, 63 000 m³, 1997, 1999, 2001
??
1999
1. Stage of expansion
168 ducts, 20.000 m³
Pilot heat store:
36 ducts, 4.300 m³
2. Stage of expansion:
528 ducts, 63.000 m³
1997
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
2001
Source: ITW, University of Stuttgart
Crailsheim: concept of borehole thermal energy storage
•
•
•
•
•
•
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
number of boreholes:
borehole depth:
storage volume:
type of BHE:
ground thermal conductivity:
ground heat capacity:
1. phase
80
55 m
37 500 m³
double-U-pipe (PEX)
2.46 W/mK
2 400 kJ/m³K
2. phase
160
55 m
75 000 m³
CSHPSS Crailsheim: vertical section of BTES
Grass
Piping connections
Soil
Foil
Gravel
Foam glass gravel
Layer with natural
ground water flow
( 5 m)
Thermally reduced
grouting
Casing
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Double-U-pipe
borehole heat
exchanger
Active
borehole
lenght
(55 m)
Limestone
Grouting pipe
Thermally
enhanced
grouting
The pilot plant with seasonal storage in Crailsheim
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
•service area: 260 apartments, school, gym.
•heat demand: 4 100 MWh/year
•solar collectors:7 300 m² (aperture)
•buffer storage: 100 + 480 m³ (water tank)
•STES:
37 500 m³ (BTES)
•el. heat pump: 530 kW
•solar fraction: 50 % (design)
•solar heat cost: 19 Euro-Cent/kWh
(Source: Stadtwerke Crailsheim)
Seasonal Thermal Energy Storage (STES) - Concepts
Tank thermal energy storage (TTES)
Pit thermal energy storage (PTES)
(60 to 80 kWh/m³)
(60 to 80 kWh/m³)
Borehole thermal energy storage (BTES)
(15 to 30 kWh/m³)
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Aquifer thermal energy storage (ATES)
(30 to 40 kWh/m³)
Aquifer thermal energy storage (ATES)
Head of the well
Seal
Base plate
charging
Beladung
cold
kalte
well
Bohrung
Clay-cementsuspension
discharging
Entladung
hot
warme
well
Bohrung
Injection pipe
Production pipe
Screen
Gravel
Pump
Source: Geothermie Neubrandenburg GmbH
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Aquifer thermal energy storage (ATES) in Rostock, 1999
• aquifer 15 – 27 m below ground
surface
• 2 wells
• 30 m deep
• distance 50 m
• max. flowrate 15 m³/h
• temp. 5 – 50 °C
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
ATES in Berlin, heat and cold storage,1999
Cold storage
upper aquifer, 60 m below surface
temperatures 5-28 °C
cold from ambient and heat pumps
2 x 5 wells, 60 m
max. flowrate: 300 m3/h
distance between wells: 300 m
Heat storage
lower aquifer, 285-315 m below
surface
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Picture: GTN, Neubrandenburg
temperatures up to 70 °C
heat from CHP
2 x 1 wells, 320 m
max. flowrate 100 m3/h
distance between wells: 300 m
ATES in Neubrandenburg, 2004
• waste heat from gas and
steam cogeneration plant
during Summer
• ATES in 1300 m depth (55°C),
former geothermal heating
plant
• temperature increase to 80 °C
• discharge during winter for
district heating network.
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Picture: Geothermie Neubrandenburg GmbH
Investment cost per m³ wa ter-equiva lent [Euro/m³]
Investment cost of seasonal heat storages in Germany
500
Ilmenau
450
Crailsheim
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Steinfurt
400
350
Kettmannhausen
300
(HW-GRP)
Hannover
250
(HW-HDC)
Stuttgart
(K/W)
Hamburg
200
Bielefeld
150
100
BerlinBiesdorf
Munich
Chemnitz
Friedrichshafen
(HW)
Neckarsulm
50
(1. phase)
Potsdam
Rostock
Crailsheim
0
100
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
realized
study
hot-water (HW)
gravel/water (GW)
BTES
ATES
Rottweil
(HW)
(HW-GRP)
1,000
10,000
Storage volume in m³ water-equivalent [m³]
GRP: glass-fiber reinforced plastic; HDC: high-density concrete;
ATES: Aquifer Thermal Energy Storage; BTES: Borehole Thermal Energy Storage
100,000
Investment cost of the Munich STES (5700 m³ Tank)
connection to
central heating plant
5%
others
3%
ground work
12%
charging/
discharging device
8%
insulation
14%
910 000 Euro
static construction
38%
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
stainless steel liner
20%
Investment cost of the Crailsheim BTES (37 500 m³)
insulation
14%
connection of
borehole heat
exchangers
12%
others
2%
360 000 Euro
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
borehole heat
exchangers
(installed)
72%
Conclusions
• 17 seasonal thermal energy storages have been built in Germany in the last two
decades
• four seasonal storage concepts are successfully demonstrated;
each concept is in operation in at least three plants
• experiences from the first pilot plants leaded to higher efficiencies and cost reduction in
next generation storages
• there is no optimum storage concept for all applications – concepts have to be chosen
individually according to local ground conditions and application
main experiences:
• no serious failures (leakages …) have been observed by now
• moisture protection of the insulation is important
• system (integration) is crucial: e.g. the system temperatures fix the storage capacity!
focus for future work:
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
• cost reduction (investment and heat cost)
• non-solar applications will be investigated more detailed (e.g. combined heat and cold
storage, combined solar and biomass heat storage…)
Nobelstr. 15
70569 Stuttgart
Germany
www.solites.de
Steinbeis
Research Institute
for Solar and
Sustainable
Thermal
Energy Systems
Thank you for your attention!