The event described here can be limited to specific settings and might not be encountered in every geothermal projects. More details about this topic are presented in a report that can be found on GEOENVI website.
The development of a geothermal field, similarly to the development of any other type of energy resource (wind, solar, hydro, nuclear, etc.), inevitably involves the presence of structures and components that produce surface disturbances. They are generally encountered during plant construction and equipment installation, drilling and testing and also during operation.
Surface disturbances include:
- effects on landscape and land occupation (for instance construction of roads and of the geothermal plant, drill pad and other infrastructures on site and deviation of rivers; land clearing),
- visual impact (with steam plum, drill pads, etc.),
- disturbances associated with increased road traffic and dust production, from noise and vibration generated by engines and pumps for the wells and plants activities.
The effect on landscape is a key factor especially in areas of touristic and cultural interest or in residential sites. Land use, which is limited with respect to other energy sectors, refers to the drilling pads (often temporary) and wellheads, plant facilities, the pipelines for the transport of the fluid and the transmission lines of the electric power.
The nuisances might also come from noise and vibration generated by a variety of activities. Most of them are limited to the construction or decommissioning phase, therefore very limited in time. Drilling activities, passage of trucks and other vehicles during the different stages of the geothermal project, engines and pumps during the plant operations may be sources of vibration. Noise is produced by drilling operations and by well tests after drilling and during the initial setup and construction of drilling site due to truck traffic. Noise diminishes with distance (by about 6 dB every time the distance is doubled), although lower frequencies (e.g. noise from drill rigs) are attenuated less than higher frequencies (e.g. steam discharge noises); wind may also influence the transmission of the noise.
In the rare case of strong degassing from the wells and plants or in case of liquid and solid effusions, smell might also be triggered. However, in some geothermal areas, like in Tuscany, there are natural emissions of geothermal gases from the soil – regardless the presence of geothermal plants. Due to this, the smell of these geothermal areas is normally affected by the natural presence of H2S.
The development and operation of a geothermal field inevitably involves the presence of structures and components. The corresponding disturbances at surface, which have variable duration, are inherent to all geothermal projects and, more broadly, to all industrial activities. Being considered in the environmental impact assessment, they must be taken into account by project owners at an early stage, from design and conception phases, to prevent unnecessary and unwanted adverse effects.
The table here below provides an overview of this topic in terms of risk and impact assessment i.e. its causes, consequences, the phases concerned, the influencing contexts or the principal monitoring and mitigation measures that can be adopted.
