Harnessing energy abundance: sustainable expansion of solar parks in Lower Saxony through harmonized spatial planning

Abstract Background The shift from fossil fuels to renewable energy sources brings substantial changes in land use. Germany, with limited land availability, needs a spatial framework to allocate renewable energy while safeguarding biodiversity and ecosystem services. This process should include public participation at the local level. Respective models have been developed for decision support on wind turbine allocation but methods are still lacking for solar parks. This paper aims to identify the safe operating space for solar energy supply that is inclusive and compatible with humans and nature. We propose criteria for Germany with different classes of legal legitimization to define the local decision space. The method is applied in the exemplary case of the federal state of Lower Saxony and the two municipalities—Springe and Wedemark. Results The results show that this decision space is sufficiently large to involve both the local public and decision-makers in determining the energy mix and siting of renewable plants. In Lower Saxony, 13% of the state's area (611.932 ha) has low spatial resistance to solar parks. With a reference plant's power density of 1.01 MW/ha, this land could generate up to 667 TWh/a, far exceeding the share needed for Lower Saxony’s contribution to Germany’s projected energy demand in 2050. This provides flexibility for regional and local stakeholders to shape their energy landscape within the bounds of downscaled national climate targets and human- and nature-compatible development. In addition, co-benefits with other extensive land-use objects, such as groundwater protection, can be provided on these sites. Conclusions Our findings offer valuable guidance for regional planning boards and encourage public participation in the decision-making process by providing transparent information about the spatial options and limits of solar development. The model can improve planning, since different planning levels could access and utilize the scalable data. Equal criteria at all levels increase the intersubjectivity and comprehensibility of approval decisions and thus also the legal certainty of land designations for solar parks.