St1 Deep Heat Oy First deep geothermal project in Scandinavia - - PowerPoint PPT Presentation

St1 Deep Heat Oy

First deep geothermal project in Scandinavia Achievements today

Tero Saarno

tero.saarno@st1.fi

• Tel. +358 50 373 1923

4/2/2019 St1 Deep Heat Oy 1

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St1 Deep Heat project: plant concept

• Concept is basically an 40 MW EGS

(Enhanced Geothermal System) heat plant

• This gives better efficiency for the plant

and allows more electricity to be used in pumping

• Finnish district heating networks are all

designed with maximum temperature 120 °C and normal maximal operating temperature is around 115 °C.

• Summer time minimum temperature is

75 °C

• This causes the need to drill as far down

as 6400 m in Southern Finland

Idea is not new

Installed capacity 2016 (Source Stanford)

• ~16 GWe
• ~34 GWh

Potential (Source St1)

• 0,1% of earth crust heat energy

could produce all energy for all mankind for 10 000 years

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Mundus subterraneus - Athanasius Kircher (1601- 1680)

Kellogg, Hager, Van der Hilst (Science, 1999)

But there are many models

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Geothermal energy is:

• Cost efficient
• Reliable
• Sustainable
• Renewable
• Environmentally friendly
• Perfect base load solution to compensate
• ther renewable energy sources natural

fluctuations in networks

What has been done? Exploration well

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• Otaniemi site exploration drilling was

done during summer 2015 with NQ2 coring drill.

• Exploration well was ready 11.7.2015 at

the MVD 1963 m and TD 2015 m

What has been done? Site and Drilling

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What has been done? Seismic network

Traffic Light System

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Traffic Light System

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What has been done? Plant design

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Project status

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• Both production wells have been drilled to more than

half way down with air hammer (DTH drilling technique)

• OTA-2 is 3,3km deep and OTA-3 6,4 km.
• The deeper well was stimulated succesfully between

June-July last summer with 18 600 m3 of fresh water

What has been learned? How to stabilize a borehole more than 5km deep

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What has been learned? How to create earthquakes big enough to see where the water goes BUT small enough not to disturb neighbors

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What has been learned? Injecting huge amounts of fresh water to crystalline rock

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