ISSUE
05 June 2012
Information Tech-
TekTalk this issue UTES explained P.1 UTES applications P.2 ATES: ‘Open Loop’ system P.3 BTES: ’Closed Loop’ system P.4 Where are the aquifers? P.5 Klina Hospital case study P.6
“The price of electricity & fossil fuels has increased significantly in recent times and this exciting new concept offers to reduce the cost of heating & cooling our buildings”. UNDERGROUND THERMAL ENERGY STORAGE Underground Thermal Energy Storage is a system which utilises the inter-seasonal heat storage capability of groundwater to significantly reduce the demand for fossil fuel for the heating & cooling of buildings. The system involves the storage of excess heat energy in the summer months for use in winter heating applications and the storage of cooling potential from winter for free cooling in the summer. One of two sub-systems may be employed largely depending on whether an aquifer is present on the site.
Reducing the demand for fossil fuel in buildings. Page 1
UTES Applications
PROJECT
DETAILS
OPERATIONAL
EUROPEAN PROJECTS ABN-AMRO HEAD OFFICE, AMSTERDAM.
Cold storage: 2,800 Kw
1999
EINDHOVEN UNIVERSITY, AMSTERDAM.
ATES cooling capacity: 20 MWt
2000
PERSCOMBINATIE PRINTERS, AMSTERDAM.
ATES cooling capacity: 1.4 MWt
2000
NIKE EUROPEAN HQ, HILVERSUM.
ATES cooling capacity: 2.0MWt
1999
NATIONAL MARITIME MUSEUM, LONDON.
ATES cooling capacity: 330 kW ATES heating capacity: 278 kW
2009
See page 6.0
2000
KLINA HOSPITAL, BELGIUM .
UK PROJECTS (IN DEVELOPMENT) WESTWAY BEACONS HOUSING SCHEME
Heat only (130 dwellings)
EAST INDIA DOCKS MIXED USE SCHEME
Heating & cooling (37 storey tower)
LEAMOUTH NORTH DOCKLANDS.
-
2
Heating & cooling (12,500 M )
WANDSWORTH RIVERSIDE QUARTER RESIDENTIAL & COMMERCIAL
Heating & cooling
NORTH WEST KENT COLLEGE, DARTFORD EDUCATIONAL CAMPUS.
Heating & cooling
HAVERING COLLEGE, ESSEX, KENT SIXTH FORM COLLEGE.
Heating & cooling
-
UTES has a wide range of applications. In particular the systems are suitable for large scale and mixed-use developments. The technology may be employed in commercial buildings, office buildings, large residential estates, educational campuses, healthcare buildings and also for industrial space heating & cooling. UTES systems can be applied in new developments or added during refurbishment of old buildings.
Performs best where a demand for both heating and cooling exists. Suits residential, commercial, industrial and mixed use or community systems. Advantageous for an Energy Service Company ( ESCO) application. Can work in conjunction with Combined Heat & Power (CHP). Opportunity to use new buildings with net cooling requirements to meet heat demands of existing buildings with net heating requirements e.g. in a low carbon district heating network. Can reduce peak electrical loads, improve load security and cut costs for operating buildings with primarily a cooling requirement. Suits medium to large scale heating and cooling developments (>500 KW).
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How the ATES ‘open loop’ system works...
During the warm season, water from the cold store at around 7-10°C is passed through a heat exchanger providing direct cooling water to the building. The heat pump is available automatically as support in periods of peak demand. The store circuit water will pick up energy from the building and thus be raised in temperature to around18-20°C (or higher for fresh air load). This water, the temperature of which is higher than the natural groundwater temperature, will be run to an underground ‘warm energy’ store. The heat stored in the warm energy store is used for heating during the winter. Water from the store at around 20°C is passed through a heat exchanger and connected into a heat pump, which in turn provides water around 40-50°C for use in building heating.
While the groundwater passes through the heat pump it cools to around 7°C. The cooled water is run to the underground ‘cold energy’ store.
The cold stored in the ‘cold energy’ store is used for cooling, completing the annual cycle.
Any excess heat or cold in the system over a year is balanced using an external heat exchanger.
WARM WELL & COLD WELL ISO THERMAL DIAGRAM
Page 3
How the BTES ‘closed loop’ system works...
A BTES system consists of a radial, circular array of boreholes resembling standard drilled wells. Rather than penetrate the aquifer as in the ATES system, BTES is closed loop and after drilling, a plastic pipe with a “U” soil, the borehole is then filled with a high thermal conductivity grouting material. bend at the bottom is inserted down the borehole. To provide good thermal contact with the surrounding soil, the borehole is then filled with a high thermal conductivity grouting material. In the cold season, the heat stored in the outside of the array is used for heating. Water from the store at around 15 - 20°C is passed through a heat pump, which in turn provides water around 40-50°C for use in building heating. While the groundwater passes through the heat pump it cools to around 7 - 10°C. The cooled water is returned to the centre of the underground array. Thus, charging the store with ‘cold energy’ for use in summer.
During the warm season, water from the cold store at around 7-10° C is passed through a heat exchanger providing direct cooling water to the building. The heat pump is available automatically as support in periods of peak demand.
The store circuit water will pick up energy from the building and thus be raised in temperature to around 18-20°C (or higher for fresh air load).
This water, the temperature of which is higher than the natural groundwater temperature, will be run to the outside of the array and charge the store with ‘warm energy’.
Page 4
Groundwater map
A groundwater map like the sample shown above may be viewed as a treasure map to any large consumer of energy. The location of major and minor aquifers on the Isle of Man coincides with centres of population such as D o u g l a s, Ra m s e y , Pe e l a n d Castletown.
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Where an aquifer exists under certain hydrological conditions then so does the potential to store excess heat energy in the summer and make use of that stored energy in the winter months for heating.
Energy Performance Case Study
Registered address: Epsilon Consultants Ltd 7 Heather Lane Douglas Isle of Man IM2 7EF 01624 677278 07624 346826
PROJECT DETAILS
VALUE
Project name
Klina Hospital (Belgium)
Bedspaces
400
UTES type
ATES + Heat pump.
HVAC type
Cooling + pre-heating ventilation air
Operational since
August 2000
Pumping rate
100 m3/h
Well depth
85.0 m
Borehole diameter
800 mm
Well separation
100 m
HVAC PARAMETERS
VALUE
Evaluation period
2003, 2004, 2005
Total cooling demand
1,789 MWh
ATES cooling (direct)
1,394 MWh (78%)
Heat pump cooling
395 MWh (22%)
ENERGY SAVING ON COOLING *
76% (SPF = 14.8)
Total heat demand
2,841 MWh
ATES heating (direct)
534 MWh (19%)
Heat pump heating
2,307 MWh (81%)
ENERGY SAVING ON HEATING *
39% (SPF = 5.5)
CO2 emission reduction *
63% * compared with fossil fuel base case
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