Since nearly 50 % of Europe's energy demand is in the heating and cooling sector it is
expected that geothermal energy will play an important role in the transition to a decarbonized
energy system. However deep geothermal energy is currently harvested mainly from areas with
very favorable geothermal conditions. As these areas are geographically limited the use of
geothermal energy in less favorable regions is essential for unleashing the full potential of
geothermal energy since they make up the majority of the total geothermal potential in Central
Europe. Motivated by the growing interest in deep geothermal energy among e.g. energy
companies and communities this text reviews the state of the art in deep geothermal energy
with focus on direct heating in geothermally less favorable regions. It provides an overview of
technologies used to generate heat from the deep underground and discusses main technical and
non-technical risks associated with deep geothermal projects. The text addresses readers with
an interest in geothermal energy but does not require a background in geoscience or engineering
sciences. It is suitable as textbook for Geothermal Energy courses for undergraduate students
from different disciplines.
