The use of renewable energy sources is one of the most promising options for slowing down climate change and the variability of resources would benefit the energy systems even further. Research provides an initial assessment of the Baltic Sea region concerning the possibility of using wave energy as a supplement to the current renewables in this region. During the study, the main parameters of the environment were examined (waves, salinity, tides, and the effect of ice). In addition to the technical and economic feasibility assessment (from a supplier perspective), marketability research was conducted among sector stakeholders through a survey. The majority of the respondents among maritime and energy sector stakeholders showed interest in applying wave energy in less than a 10-year perspective, particularly in the specific areas of their industries, such as seaports. This research is important as it demonstrates the limitations of the Baltic Sea environment, effects of regional economic activity, and local and EU level political, legal, and administrative burdens in applying wave energy within the studied region. Based on this study, policies and legislative frameworks need to be adapted (e.g., environmental protection areas and open access data of sea) to facilitate change.

This study assesses the wave energy potential and spectral variability in the Väinameri—a semi-sheltered, island-filtered basin on Estonia’s west coast—by combining six months of high-resolution in situ wave spectra with deep learning-enhanced satellite retrievals. Directional spectra were recorded at Rohuküla Harbor using a wave-following LainePoiss buoy from June to December 2024. In parallel, one-dimensional wave spectra were reconstructed from Sentinel-1 SAR imagery using a long short-term memory (LSTM) neural network trained on more than 71,000 collocations with NORA3 WAM hindcasts. Spectral pairs matched within a ±1 h window exhibited strong agreement in the dominant 0.2–0.4 Hz frequency band, while systematic underestimation at higher frequencies reflected both the radar resolution limits and the short-period, wind–sea-dominated nature of the Baltic Sea. Our results confirm that LSTM-enhanced SAR retrievals enable robust bulk and spectral wave characterizations in data-sparse nearshore regions, and offer a practical basis for the site evaluation, device tuning, and survivability testing of pilot-scale wave energy converters under both typical and storm-driven forcing conditions.

Wave energy converter (WEC) development in shallow, fetch-limited coastal seas is constrained by the representativeness of test environments. We examine whether semi-controlled nearshore settings, such as harbour basins, provide more physically realistic conditions for early-stage WEC testing than idealized laboratory wave tanks. We compare controlled wave-basin experiments with semi-controlled harbour deployment using a small-scale point absorber WEC developed for Baltic Sea harbour environments. Laboratory tests were conducted at wave heights of 150-250 mm and frequencies of 0.4-0.8 Hz, while field deployment was carried out between 4 September and 17 October 2025 under moderate nearshore conditions. In the wave basin, the maximum measured electrical output reached 91.7 W, with estimated conversion efficiencies ranging from 2.5% to 24.7% for mean wave power and up to 38.0\% for maximum wave power. Measured wave parameters deviated from prescribed inputs, with wave-height differences up to 35.9% and frequency differences up to 8.1\%. In the harbour environment, significant wave height remained below approximately 0.8 m, and directional wave energy flux explained 65-71% of the electrical-output variability. Spectral analysis shows that idealized JONSWAP spectra impose a constrained spectral width (kappa approx 0.315, whereas measured coastal spectra exhibit substantially higher variability, with differences up to 84.5% for individual records and 39.7% on average. These results demonstrate that semi-controlled coastal environments preserve key spectral and directional variability absent in laboratory conditions, supporting harbour-based testing combined with validated numerical simulations as a practical and potentially cost-effective pathway for early-stage WEC development.

Wave energy converter (WEC) development in shallow, fetch-limited coastal seas is constrained by the representativeness of test environments. We examine whether semi-controlled nearshore settings, such as harbour basins, provide more physically realistic conditions for early-stage WEC testing than idealized laboratory wave tanks. We compare controlled wave-basin experiments with semi-controlled harbour deployment using a small-scale point absorber WEC developed for Baltic Sea harbour environments. Laboratory tests were conducted at wave heights of 150-250 mm and frequencies of 0.4-0.8 Hz, while field deployment was carried out between 4 September and 17 October 2025 under moderate nearshore conditions. In the wave basin, the maximum measured electrical output reached 91.7 W, with estimated conversion efficiencies ranging from 2.5% to 24.7% for mean wave power and up to 38.0\% for maximum wave power. Measured wave parameters deviated from prescribed inputs, with wave-height differences up to 35.9% and frequency differences up to 8.1\%. In the harbour environment, significant wave height remained below approximately 0.8 m, and directional wave energy flux explained 65-71% of the electrical-output variability. Spectral analysis shows that idealized JONSWAP spectra impose a constrained spectral width (kappa approx 0.315, whereas measured coastal spectra exhibit substantially higher variability, with differences up to 84.5% for individual records and 39.7% on average. These results demonstrate that semi-controlled coastal environments preserve key spectral and directional variability absent in laboratory conditions, supporting harbour-based testing combined with validated numerical simulations as a practical and potentially cost-effective pathway for early-stage WEC development.