Sensitivity mapping for the development of solar and wind power plants in the Republic of Croatia

Nominated by: Mate Zec (Southeast Europe Renewable Energy Siting Specialist, the Nature Conservancy)

Summary of the project

The project “Sensitivity mapping for the development of solar and wind power plants in the Republic of Croatia” supports the future designation of Renewables Acceleration Areas (RAAs) by developing sensitivity and suitability maps for wind (WP) and solar photovoltaic (SP) development. Commissioned by the Ministry of Environmental Protection and Green Transition, the project is implemented by the Hrvoje Požar Energy Institute (EIHP), The Nature Conservancy (TNC), and experts on sensitive species groups.µ

It builds on a 2018 pilot study in Zadar County by EIHP and TNC, based on TNC’s Smart Siting concept, which integrates renewable energy potential with environmental and socio-spatial conflict data to identify optimal development areas. The mapping process included broad stakeholder engagement across sectors—spatial planning, agriculture, forestry, NGOs, research institutions, and consultancies—to identify critical biodiversity and natural resource values for inclusion in the sensitivity analysis.

Innovation

The project introduces a data-driven, expert-validated approach to integrating biodiversity concerns into renewable energy siting, particularly addressing the challenge of mapping potential conflicts with highly mobile sensitive species such as bats, birds, and large carnivores. Given the lack of structured, systematically collected biodiversity data, The Nature Conservancy applied species distribution modelling (SDM) to a combined dataset of approximately one million verified observations from both official and public “community science” sources.

Through 369 model runs, the project generated probability density layers for individual species based on environmental parameters, producing a detailed, 100m resolution raster covering all of Croatia. This is, to our knowledge, the first time SDM has been applied at this scale and level of species-specific detail in Croatia.

All model outputs were reviewed and preselected using statistical indicators, then vetted by species experts, who also contributed critical non-modelled data such as locations of rare habitats and nesting sites. This intensive consultation process ensured that ecological sensitivity was accurately captured, even where data gaps existed.

To guarantee replicability and transparency, the full modelling and GIS process was made available as open-source software under the GNU General Public License. This enables the analysis to be independently re-run for Croatia (subject to dataset access) or easily adapted for use in other countries without reliance on expensive, licensed tools.

This methodology represents a significant step forward in environmentally responsible energy planning, offering a scalable, scientifically sound, and openly accessible tool for reconciling renewable energy development with biodiversity protection.

Impact

The project delivers critical tools to help Croatia accelerate its energy transition while safeguarding biodiversity. With an average permitting time of 120 months for wind and 50 months for solar, Croatia faces some of the longest renewable permitting delays in the EU, far exceeding the EU’s 24-month limit. By proactively identifying low-conflict areas for renewable energy development, the project offers a pathway to streamline permitting and reduce biodiversity risks.

Through a detailed mapping effort, the project identified 148,000 hectares suitable for solar PV and 1,700 hectares for wind energy, all with low biodiversity conflict. These areas represent an opportunity to significantly expand renewable energy infrastructure while avoiding damage to sensitive ecosystems. This effort is grounded in a large-scale dataset of around 1 million species observations across 369 species, ensuring decisions are based on sound ecological evidence.

The project also reinforces the broader European finding that renewable energy targets for 2030 can be met many times over on low-conflict land, showing that energy development and nature protection are not mutually exclusive. By applying TNC’s Smart Siting approach, the project not only maps biodiversity risks but also incorporates social, cultural, and land-use values—from agriculture and forestry to religious, recreational, and landscape features—ensuring that development is inclusive and respectful of community needs.

Importantly, the results have been made freely accessible via Croatia’s official nature protection GIS portal, offering a public, transparent tool for planners, authorities, and developers. This allows renewable energy projects to be sited with reduced environmental and social risks, supporting a faster, more equitable, and biodiversity-friendly energy transition.

Scalability and Replicability

The project was designed around the principles of transparency, adaptability, and upgradeability, ensuring its methodology and tools can be reused and improved over time and across geographies.

The analysis is fully transparent, with all spatial criteria clearly documented and every score traceable back to its original dataset. This is essential in spatial planning, where competing interests must be balanced, and decisions must be justified with clear, accessible data.

It is also adaptable. Recognising that no siting model is perfect, the methodology allows for refinements and updates as new needs, technologies, or local contexts emerge. Every aspect—from criteria weighting to data layers—can be adjusted.o ensure upgradeability, the tools and modelling pipeline have been made openly available. As biodiversity and species occurrence data improve over time, the analysis can be easily re-run using updated inputs. The entire workflow, including the species distribution modelling code, is released as open-source software under the GNU GPL 2.0 license and hosted on a public GitHub repository.

This structure enables adaptation to other geographies or broader-scale applications. Similar studies are already underway in Portugal and Montenegro, and the team is establishing a European community of practice for siting professionals to exchange insights and promote smart, biodiversity-inclusive planning.

By offering a fully documented, flexible, and open-source methodology, the project provides a strong foundation for other countries and organisations to replicate and scale responsible renewable energy siting.