Geothermal Update for Bulgaria (2014-2018)

Abstract

The main aim of the article is to show geothermal situation in the country over the period from 2014 to 2018. Bulgarian territory covers an area of approximately 111,000 sq.km and it is a part of two regional tectonic structures - the Moesian plate (Northern Bulgaria) and the Alpine-Himalayan belt (Southern Bulgaria). Almost all natural geothermal springs are situated in Southern Bulgaria as the latter has a complex geological structure. Most of the known geothermal waters in Northern Bulgaria are reached by deep drilling works at depths between 2,000 and 6,000 m. The total flow-rate of geothermal sources in the country is estimated to be about 3,000 L/s with temperature range of 25-100 oC. Geothermal waters have only direct utilization due to the fact that 72% of them are with temperature up to 50oC. The installed capacity amounts to 99.37 MWt (2018), excluding the low grade energy use by ground source heat pump (GSHP). Traditionally, most of geothermal potential is used for balneology (about 60%) and up to 30% - for direct water supply. Most of the hydrothermal sites are developed in the framework of mountain or sea resorts. Due to the relatively low geothermal temperature, electricity generation from geothermal water is not currently available in the country.