High temperature borehole thermalenergy storage (HT-BTES) – GeoTermos atFjell school in Drammen, Norway
Randi Kalskin Ramstad, Asplan Viak / Department of Geoscience and petroleum NTNU
Geir Andersen, Drammen Municipality, Building department
Maria Justo Alonso, SINTEF Community
Henrik Holmberg, Asplan Viak

IEA HPT TCP National Workshop – Heat pumps in Norway, 10th of May 2022

Outline••••

In general:•••

The energy wellHigh temperature borehole thermal energy storage – HT-BTESThe dream

History of the GeoTermos project

The first experiences and temperature profile measurements (DTS)
Summary GeoTermos

The energy well
• Closed loop – borehole with collector pipe
• Most common• Well suited - can be established most places• Typical depth in Norway: 150-300 m• Large and small ground source heat pump plants• Not visible

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Superficial deposits

Collects heat and cooling from the ground
Stored heat in the bedrcok, e.g. not from moving groundwater
Can be placed below buildings, parking lots, etc.
Recommendation: Large installations should be designed as a seasonal
borehole thermal storage.

Bedrock

Principles for high temperature borehole thermal energy storage•

The boreholes are «charged» with excess heat during summer ➔ Thetemperature in the bedrock increases.

•Charging more heat than what is extracted during winter, increases thetemperature in the storage.

•The thermal energy storage can deliver significant amounts of heat (kWh)and thermal power (kW) during the winter.

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Effective use of energy wells, more kWh/meter borehole per year•

NB: Borehole thermal energy storage with medium to high temperaturelevels requires a minimum number of boreholes. Ratio volume/surface area size matters

Low investment / stored energy (Energiforsk 2019).
Can increase the capacity of a district heating system (reduce the need forextra systems for peak load).

The dream: «Move» heat from summer to winter600
El-production solar PV
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Yellow: Electricity demand from the grid (kWh)Green: El-production solar PV (kWh)5004003002001000The dream comes true..

History••

Inspired by Drake Landing Solar Community••The investment is partly funded by Enova. Project page

Conceptual study (report) partly funded by Enova – state
enterprise to strenghten energy security of supply as well as
reducing greenhouse gas emissions.

Pre-investigations: Three response tests (TRT) to map thestorage properties, i.e. no / minimial heat leakage withflowing groundwater.

Drammen, west of Oslo Norway

GeoTermos at Fjell school in Drammen

Built: 2018-2019
Area: 10 000 m2
GeoTermos = high temperature borehole
thermal energy storage for direct heating
and cooling of the school.

A demonstration plant in the research
project RockStore

GeoTermos – summer heat for winter use• Borehole thermal energy storage with 100 boreholes of 50 m, 4 m between theboreholes. → thermal battery.

• The storage and the boreholes are charged with on-site heat. The temperature in thecenter of the storage is 50-55 oC during charging.

•Heat from the air. The charging temperature is increased by the use of a CO2-heat pump driven
by solar electricity.

•Also some heat from solar collectors.

GeoTermos – summer heat for winter use•

Low temperature water borne heating system (25 oC – floor
heating with short distance between the pipes in the floor, as
well as effective ventilation batteries) for direct heating (without
using the heat pump, only a circulation pump)!

➔Unique local energy system and nearly off grid. Very low

demand from the electricity grid mid winter to cover heating
demands.

Note the switch: The heat pump is used in the summer, and not in
the winter.

Installation of optical fibre cables for temperature profile
measurements (DTS)
11 energy wells with fibre
cable (marked with red)

Undisturbed temperaturein the ground was around
8 oC

Vertical cross section temperature profiles – charging in 2 years(2020-21) and extraction winter 2021/22

The thermal battry GeoTermos
Winner of «the local climate measure of the year 2020»

Miljøpris for GeoTermos | Drammen kommune

Summary GeoTermos at Fjell school• High temperature sesonal storage of heat from the summer in boreholes (100*50m) - as athermal battery.

• Heating of the school with «free heating» from the boreholes. Limited use of the heatpump during the winter. Delivered approximately 153 000 kWh the winter 2021/22• Nearly off-grid system. Reduction of peak heat in the winter• The next GeoTermos is planned at Krokstad nursing home in Drammen municipality.
• Dedicated operating personell is a success criteria.
• Further development. Scaled and adjusted systems can have a great influence on theenergy system in Norway – areas, cities and industry.

Thank you!

Contact:Randi Kalskin Ramstad, Asplan Viak AS and Department of Geoscience and Petroleum NTNU
Randi.Kalskin.Ramstad@asplanviak.no, Randi.Kalskin.Ramstad@ntnu.no 97513942

Geir Andersen, Drammen Municipality, Building department

Geir.Andersen@drammen.kommune.no, 97732820

Maria Justo Alonso, SINTEF Community, Maria.Justo.Alonso@sintef.no, 94428591

Henrik Holmberg, Asplan Viak, Henrik.Holmberg@asplanviak.no, 95749363