Ground Source heating and cooling - Elements in a sustainable energy supply Outline of my talk Setting and policy Introduction to ground source heating The GeoEnergy project on Closed loop borehole Geological parameters affecting the energy output Tools for planning and design of Ground Source Heat systems Environmental concerns Future research areas Conclusions Geological Survey of Denmark and Greenland Danish Ministry of Climate, Energy and Building
Claus Ditlefsen1, Ingelise Møller1, Inga Sørensen2, Henrik Bjørn2, Anker Lajer Højberg1 & Thomas Vangilde-Pedersen1 1Geological
Survey of Denmark and Greenland, 2VIA University College, Denmark
Settings To address global warming and rising energy demands a transision towards a fussil free energy supply must take place.
Policy •
Overall, it is the policy of the Danish government that by 2050 energy and transport will be a 100% based on renewable energy.
•
To guide this transision, the following milstones have be established: –2020: Half of the electricity supply are covered by the wind power –2030: Coal in power plants as well as private oil burner phased out –2035: Electricity and heat is supplied by renewable energy exclusively If we do not begin this transistion now very large costs, must be paid by future generations
Near surface energy budget
Heat pump
Modified from Banks(2008)
The heat pump
o
25 C o
o
16 C
11 C o
40 C
o
o
11 C
5C
The main type of plants
From Burkhard Sanner
Tools for Ground Source Heating and Cooling Based on Closed Loop Boreholes Objective: Provide better tools for planning and designing Ground Source Heat systems for heating and cooling Develop a best practise to protect environment and consumers
Work package structure Work Package 1 Database and geology GEUS
Work Package 2
Work Package 3
Measuring equipment and procedure
Temperaturegradients and surfacetemperatures
VIAUC GEUS
Work Package 4 Drilling methods and grouting VIAUC
Work Package 5
Work Package 6
Work Package 7
System design and energy balance
Lectures and supplementary training
Impacts on the adjacent aquifers
Guidelines and dissemination
VIAUC
VIAUC
GEUS
GEUS
Work Package 8
Geological parameters affecting the energy output
Heat flow with groundwater by convection Thermal conduction by diffusion
Thermal proporties of some geological materials
Mineral
Thermal conductivity W/mK
Specific heat capasity MJ/m3K
Quartz
7.7
1.9-2.0
Feldspar
1.5-2.5
1.6-2.2
Mica
2.0-2.3
2.2-2.3
Calsite
3.6
2.2
Water (10 C)
0.6
4.15
Air (1 atm.)
0.024
0.0013
From Banks (2008)
From VDI (2010)
Sampling at different geological locations
Measuring thermal conductivity in the laboratory
Linear Heat Source Probe
∆T = (Q / 4 π λ) (ln t + B)
Thermal conductivities of common, shallow sediments
Thermal conductivity W/ mK
Number of samples
Number of localities
Gytja
0,68
3
1
Fine grained smectitic clay
0,98
3
1
Silty clay
1,02
12
5
Fingrained mica sand
1,90
8
4
Glacial till deposits
1,95
20
6
Sand and gravel
2,24
4
4
Quartz sands
2,75
3
3
Sediment type
Boringsdatabasen JUPITER bygger boreprøvelaboratoriet & borearkivet hos GEUS
The borehole database JUPITER Borehole archive / database founded in 1926
>270.000 borehole descriptions
=> 6 boreholes / km2
Information on is freely available on the web
Boringsdatabasen JUPITER bygger boreprøvelaboratoriet & borearkivet hos GEUS
New web based tool to estimate thermal conductivity in new project areas
100%
10.000
80%
8.000
8.333
8.551
8.137
8.204
6.916
20%
6.000 4.000
4.561
40%
8.256
7.448
7.336
8.400
8.540
7.448
8.092
8.540
60%
8.982
12.000
9.128
120%
2.000
0%
Sens‐X HPB [J] pr år / BL01 HPB [J] pr år:
FSH‐15
FSH‐14
FSH‐13
FSH‐12
FSH‐11
FSH‐9
FSH‐10
FSH‐8
FSH‐7
FSH‐6
FSH‐5
FSH‐4
FSH‐3
FSH‐2
BL‐1
FSH‐1
0
HPB [kWh] pr år:
kWh (år)
Modelling of heatflow and groundwater flow (FEFLOW)
Results Priliminary results indicate that there may be a difference of 40 % or more in the energy extraction between sites with a favourable and unfavourable geology. The varying thermal conductivity of shallow Danish sediments is of great importance for the energy output. The results can ensure proper sizing of plants under different geological conditions
Future research areas • Groundwater protection in connection with heat storage and ground source heating and cooling Which activities may safely take place within areas within water extraction areas, and which may not.
• Heat storage: How much heat can cost efficiently be stored in the shallow subsurface ? Where and how ? • Methods for mapping shallow geothermal resources and integration them in areal planning • Combining ground source heating with existing central heating plant and other energy sources • The Geological Surveys of Europe, EuroGeoSurveys (EGS), represents 33 Member Organizations, and thus over 20.000 specialists working in numerous applications of geosciences to the EU society and economy. To further integrate geoscience research in the EU research programs, EGS is working for the establishment of an ERA-NET on geosciences in Horizon 2020. 16
Conclusions In lagre parts of Denmark shallow ground source heating and cooling will be obvious complements to other renewable energy sources, epecially for heating and cooling of resident houses and office building. Recent studies have shown that the varying thermal conductivity of shallow Danish sediments is of great importance for the energy output. This knowledge can ensure proper sizing of plants under different geological conditions A web based tool utilising the national borehole database gives planners and constructors the opportunity to evaluate the thermal conductivity locally Groundwater protection in connection with heat storage and ground source heating and cooling is a major concern that must and can be secured
Thank you for your attention
Shallow geothermal boreholes -reported to the nationale borehole database (Jupiter) 140
120
80
Antal
Nuubber
100
Jordvarmeboringer 60
40
20
Årstal Year
20 10
20 08
20 06
20 04
20 02
20 00
19 98
19 96
19 94
19 92
19 90
19 88
19 86
19 84
19 82
19 80
19 78
19 76
19 74
19 72
0
