Faculty of Environmental Science and Process Engineering Study Course: ERM

BACHELOR THESIS

TITLE (English): Geothermal Energy in the state Brandenburg
TITEL (German): Geothermale Energie im Land Brandenburg

Handed in by

Sandra Gerlach

Chair: Raw Material and Natural Resource Management

Cottbus, 11.03.04

“Bachelor Thesis submitted as part requirement
for degree of BSc in Environmental and Resource Management
to the Faculty of Environmental Science, BTU Cottbus.“

Abstract

Worldwide the demand in energy is increasing continuously. The awareness that fossil energy resources are limited and the fluctuation of crude oil- and natural gas prices were leading internationally and nationally to the recognition of geothermal energy as a possible energy source among the renewable energies (Rummel et al., 1993).
Geothermal energy is the heat of the earth. According to technical applications geothermal energy can be classified into three different natural systems, the shallow geothermal system, the hydrothermal low or high pressure systems and the hot dry rock system. These three systems of geothermal energy are described according to their possibilities of technical application. Legal requirements are playing a significant role in the application of geothermal energy as well as the political situation with regard to energy politics in the different states of Germany.
Special attention is given to the state Brandenburg. At first the geologic conditions have to be outlined. From the geologic conditions and the energy political situation as well as the supply and demand structure in Brandenburg, the potential for the use of geothermal energy is arising. Applications of geothermal energy started in the beginning of the 20th century in Brandenburg are in form of thermal springs. In the second half of the 20th century the use in Brandenburg turned to the utilization of shallow geothermal energy and later to deep geothermal energy projects. Today mainly the shallow geothermal energy systems are used commercially because they are economically wise in contrast to deep geothermal energy systems which can not be used economically wise yet. Their technology is still under development. Current projects will show their stage of development.

Table of contents

Acknowledgement/ Affidavit ... 3

Abstract ... 4

Table of contents ... 5

1. Introduction
1.1. Use of natural heat of the earth until today ... 6
1.2. Definition of geothermal energy ... 7

2. Main features of geothermal energy
2.1. The different types of geothermal energy sources ... 13
2.2. Technology of geothermal energy and technological problems in connection with possible ecological effects ... 17
2.2.1. Hydrothermal energy technology ... 19
2.2.2. Hot dry rock method ... 21
2.2.3. Shallow geothermal application systems ... 23
2.3. Legal and political aspects ... 28
2.3.1. Legal requirements ... 28
2.3.2. Energy political measures ... 29

3. Geothermal energy in Brandenburg
3.1. Geology of Brandenburg ... 31
3.1.1. Character of the landscape ... 31
3.1.2. Present day climatic condition ... 32
3.1.3. Geological and hydrological overview of Brandenburg ... 32
3.1.4. Relations between tectonic structure and temperature distribution in Brandenburg ... 35
3.1.5. The temperature distribution in Brandenburg ... 36
3.1.6. Chemical composition of thermal water in Brandenburg ... 38
3.2. Geothermal potential of Brandenburg ... 40
3.3. Application of geothermal energy in Brandenburg now and then ... 46
3.4. Economical aspects ... 53
3.5. Current projects in Brandenburg ... 57
3.6. Possible future development ... 60

4. Conclusion ... 64

5. Reference List ... 65

6. Appendix

I. Table thermal conductivity ... 69
II. Drillings with temperature surveys in Brandenburg ... 70
III. Temperatures in 2000 meters depth ... 71
IV. Temperatures in 4000 meters depth ... 72
V. Map of Brandenburg ... 73
VI. Geologic timescale ... 74

1. Introduction

1.1. Usage of natural heat of the earth until today

The heat in the inner of the earth has always been a matter of consideration in human life. The oldest kind to utilise geothermal energy is the use of warm water in baths. A first peak in using geothermal heat was during the Roman Empire in Europe and in the eastern Mediterranean region in form of thermal baths. In regions of cold and temperate climate like Iceland having geological favourable sites, other possibilities for the use of geothermal energy were found out like cooking and heating. Although the importance of spas and thermal baths is still increasing today, the significance of geothermal energy as substitute for fossil energy sources is much higher nowadays. Since the dependence on limited fossil energy sources was understood the relevance of renewable energies as primary energy carrier has been increasing rapidly (Buntebarth, 1980).
During the 18th century the first investigation and calculations were taking place with regard to the temperature distribution below the surface. Starting with hypothetical assumptions about the heat inside the earth by many scientists like Descartes, Leibniz and later Fourier the research of geothermal heat began which is today a part of geophysics. The first practical application of geothermal energy was carried out in 1827 in Laderello, Italy heating a tank for the production of boric acid. In Laderello the generation of electric power out of geothermal energy began in 1904 (Kühn, 1988). In 1912 the first generator with an installed capacity of 250 kW was used economically fed by hot vapour. Today two power units with each 150 MW installed capacity are in operation, using a hydrothermal steam reservoir in 3000 meters depth.
Many countries in the world are using geothermal energy for the generation of heat and power already. In countries like the USA, Japan, Italy and Island where geologic favourable sites are present a focus was set on the generation of power from geothermal energy what made them to be market leader in this area. An overview of geothermal power plants in operation today is given in figure 1.1. Furthermore, regions with a potential for geothermal energy applications in tectonic active zones are pointed out (Rummel et al., 1993).

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Figure 1.1: Installed capacity for the generation of electric power from geothermal resources worldwide (Rummel et al., 1993) (orange: Areas with potential for geothermal power plants, red dots: Active volcanoes, purple triangle: Geothermal power plants

Since 1975 the USA has the biggest concentration of power plants with a total installed capacity of 502 MW utilizing the steam originating from the Geysers. The first geothermal power plant in Japan has been set into operation in 1966. Japan has a high potential of geothermal resources due to the volcanic active zone with 600 volcanoes on which Japan is situated. Iceland is utilizing its geothermal resources since 1930 for heating purposes (Rau, 1978). In these countries the use of geothermal sources has been concentrated on regions with geothermal anomalies. Anomalies can occur when magma is located near the surface which leads to an anomal increase in temperature in the rock or the fluid contained in the rock, for example. Due to using geothermal anomalies the power plants are operating economically very efficient. Power production costs range from 2.5 to 7 Cent/kWh. Heat production costs vary between 1 and 3.5 Cent/kWh (Kleemann et al., 1993).

The first geothermal drilling in the world was carried out in Rüdersdorf (east of Berlin, Germany) in 1833. The first exact temperature survey and examination were done in Sperenberg to the south of Berlin in 1870 in a drilling of about 1272 metres depth resulting in one of the most important discoveries in the field of geothermal heat. The geothermal gradient with a value of 33.7 m/K has been discovered. This value was measured in the deepest borehole in the world within this time. Until today this value is regarded to be the average geothermal gradient (Huenges et al., 2000).
Although the first geothermal drilling was done in Germany the large scale use of geothermal heat began only in 1978 when geothermal heat from shallow regions was utilized with help of heat pumps for room heating purposes mainly. Before, the use of geothermal energy was restricted to balneological purposes in thermal baths. The first hydrothermal heating plant was set into operation in 1984 in Waren (Mecklenburg-West Pomerania) with an installed capacity of 5 MW (Kaltschmitt et al., 2003).

In Europe intensive research activities are under progress to improve the economic efficiency of power generation form geothermal resources. Six European countries including Germany are carrying out a project in France examining a hot dry rock formation. In Germany research activities are running with regard to the generation of power out of hot dry rock formation and low-enthalpy hydrothermal waters. Currently in the course of a pilot project it is tried to include an Organic Rankine Cycle into an existing geothermal heating plant in order to generate power (Huenges et al., 2000). The technology for the generation of heat and power using geothermal energy sources is still under development and capable of improvement.

1.2. Definition of geothermal energy

The literal translation of ‘geothermal’ is earth heat. Energy is the ability of a system to do work. Different forms of energy can be distinguished. There is for example mechanic, thermal, electric or chemical energy. The ability to do work is showing in form of force, heat or light. The term ‘geothermal energy’ therefore refers to stored energy below the surface in form of heat.
The heat of the earth is originating from the decay of radioactive isotopes like U238, U235, Th232 and others which are contained in small amounts in the earth crust (Rummich, 1978). A further source is the original heat stored during the formation of the earth itself and the gravitational energy set free during the earth’s formation (Rummel et al., 1993).
Inside the earth there is a continuous flow of heat from the inward towards the outward. The terrestrial heat flow is generally 63 mW/m² (Huenges et al., 2000) for continents but can differ from region to region. The temperature gradient amounts in average circa 33.7 m/K (Rau, 1978).
The heat of the earth is a geopotential that is available everywhere, either in rock material itself or as fluid in porous rock (Buntebarth, 1980).
Heat transport results from conduction and convection. Conduction of rock material under high temperature and pressure is taking place in the earth mantle. Transport of heat also occurs by the circulation of fluids. An important influence on the geothermal field is represented by the movement of water and tectonic processes where heat is transported much faster by convection than the conductive transport within rock.
The temperature distribution according to depth is influenced by different parameters as the radiogenic heat production, the heat flow density, the thermal conductivity of rock material, convection by fluids and the geologic structure of the underground. The temperature has a very big influence on all physical properties of rocks as well as on the migration and transformation of substances. On the other hand the structure and the properties of rocks, bedding formation and other geological conditions are determined by the distribution of temperature in the earth crust. Hot zones originating from magmatic regions have a positive effect on the temperature distribution. If there is a region with big differences from the average, this region is called anomaly (Huenges et al., 2000).

Different types of geothermal systems can be differentiated. Geothermal heat originating from the shallow underground is the first type. Furthermore there are hydrothermal low and high enthalpy systems as well as hot dry rock systems which are sources of geothermal energy. Other types are magmatic or volcanic systems and geo-pressurized hot water systems. Volcanic systems only occur in young crustal regimes with tension tectonics around the pacific, on islands in the Atlantic, east Africa and partly Europe (Rummel et al., 1993). Volcanic systems are used successfully in countries like the USA, Italy, Japan and Iceland (Rau, 1978).
Geothermal heat can be used in various ways with different technologies for heating or cooling purposes or the generation of power. Geothermal energy is a regenerative form of energy as long as the heat extracted from the ground is smaller than the flow of heat from the inner earth to the outer part (Buntebarth, 1980).

The geothermal potential in the earth crust is enormous. The stored geothermal energy worldwide amounts approximately to 43 million EJ in depth until 3000 meters. 85% of this stored amount of geothermal heat has a temperature level below 100°C. The McKelvey-Diagram (see figure 1.2) shows the connection between the total amount of geothermal resources and the part which can be used (Kaltschmitt et al., 1993).

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Figure 1.2: McKelvey – Diagram (Rummel et al., 1993)

The vertical axis of the diagram represents the depth of possible geothermal resources and the economical use. The horizontal axis represents the knowledge of geoscientific research which is including proven, probable and possible geothermal reserves (Rummel et al., 1993). Reserves are resources which are accessible by technical devices and whose exploitation is economical sensible. Resources are the natural occurrence of matter like coal or in this case the occurrence of geothermal heat in the earth (Schieferdecker, 2001).
Out of the total amount of geothermal energy resources only a small part can be used by the technology available today (Kaltschmitt et al., 1993).

2. Main features of geothermal energy

2.1. The different types of geothermal energy sources

In general two types of geothermal energy sources can be distinguished for the application of geothermal energy, the shallow geothermal heat and the deep geothermal heat.

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