Geothermal energy has experienced a rising interest in the last years in Germany. Encouraged by the German Energy Research Programme and even more by the amendment of the German feed-in law, several projects aiming for geothermal electricity generation are under development. However, a wider use of geothermal energy for power generation is only acceptable if it results in general benefits for the environment. Based on this background, the environmental impacts and risks need to be analysed precisely before a broader market introduction, in order to meet respective mitigation measures such as regulatory guidelines or administrative directives.
To analyse environmental impacts trough geothermal power generation and identify possible environmental risks, a study was commissioned by the Federal Environ¬ment Agency of Germany (UBA). For this study, a methodology has been developed, where firstly, all possible local environmental impacts within the different phases of the life cycle of a geothermal power plant (i.e. construction, operation and deconstruction) are identified regarding the specific surrounding conditions in Germany. Thereby, effects on humans, animals, plants, soil, water, air, climate, landscape and objects of cultural value have been considered as environmental impacts.
Subsequently, the identified impacts are analysed and evaluated following a consistent methodology. The protection of the environment is an integral part of German law. Therefore the evaluation of the environmental impacts and the identification of environmental risks is based on a comparison to the existing regulations. The applicability of these regulations for the impacts of geothermal power generation and its compliance with environmental goals are assessed. This consistent approach can be characterised by the following steps:
(i) Probability of appearance: Will the identified impact occur during normal operation or is it related to failure? Analysis of site-specific geological and technical conditions.
(ii) Prevention measures: Can the identified impact be technically avoided? Analysis of the corresponding state-of-the-art.
(iii) Legal regulation: In case of existing prevention measures, are there any regulations or directives referring to the prevention measures?
(iv) Expected environmental effects: Which effects on the environment must be expected? Can they be mitigated?
(v) Identification of environmental risks: Can the effects on the environment turn into environmental risks, i.e. is the existing legal regulation (respectively the state of knowledge) sufficient or are additional regulations (respectively research) necessary?
The method developed in this study provides a way to analyse and visualise environmental risks but is potentially adaptable to the assessment of other risks.