The Baltic Sea presents a unique environment for thermal energy usage through heat pumps, which has yet to be extensively explored. Its distinct characteristics, such as a strong vertical stratification dominated by salinity and relatively shallow depth, create a setting where, despite cold winters, the water beneath the halocline remains relatively warm. Identifying areas where temperatures remain sufficiently warm is the first step in utilising this resource for energy production. During winter, with water temperatures typically under 5 °C, the water flows required for meaningful power plants would be comparable to the magnitudes of small rivers, necessitating a thorough assessment of the environmental impacts of both extracting warm water and the outflow of cooler water.

We will present the first results of a project in which we have used the existing Baltic Sea reanalysis from Copernicus Marine Services to  (i) identify locations within the Baltic Sea where water temperatures reliably stay above specific trigger temperatures, thereby offering feasible sites for energy extraction and (ii) assess  the environmental impacts of intake and outflow volumes based scale analysis of the local ocean heat budget.

We will also present a decision support tool designed for end-users considering the implementation of sea-heat power plants. This tool provides a preliminary assessment of both the opportunities and risks associated with specific sites, offering a crucial first step in the decision-making process for potential sea-heat energy projects.