Photovoltaics is one of the government’s two renewable energy development priorities. But the impact on biodiversity of parks located in natural or agricultural zones raises questions.
During his trip to Saint-Nazaire on Thursday, September 22, Emmanuel Macron recalled the goal of ten times the installed capacity of solar electricity production by 2050. The goal he announced at Belfort last February. The head of state confirmed that he wants to balance installations on the roofs and parks on the ground. On the eve of the submission of a bill to accelerate the use of renewable energy sources in the Council of Ministers, the question arises of the impact on biodiversity of photovoltaic parks built in natural or agricultural areas.
Some stakeholders have already looked into this issue. This is the case of Enerplan, a union of solar energy professionals, which launched a piecemeal initial study on the impact of above ground parks, the results of which were made public in March 2021. He showed that not all results were negative, especially for flora. In July of the same year, the Environmental Transition Agency (Ademe) proposed a roadmap to reduce the environmental impact of photovoltaics, which recommended installation on buildings as a priority.
New brick brings that knowledge to the Bird Protection League (LPO) on the occasion of XIIare National meeting on biodiversity, held from 7 to 9 September in Bezanon. The Association for the Protection of Nature has indeed presented a synthesis of scientific knowledge about the impact of photovoltaic power plants on the earth. The report is nearing completion.
Impact on natural habitat
The most significant environmental impact of photovoltaic systems is the impact on natural habitats. , explains Geoffroy Marx, head of the renewable energy and biodiversity program at the LPO. The area occupied by the panels is approximately 0.5 ha per MW. Waterproof surfaces are quite small, explains the specialist but the artificial surface is standard due to the shade and changing conditions of water and sunlight.
Artificial surface is standard due to shade and changing water and sunlight conditions.
Outside of the grip of the panels during the work, significant impacts are recorded due to excavation, archaeological excavation, connection, soil compaction or clearing. Once construction is completed, natural habitats and flora are altered. Habitats may become fragmented and ecological corridors may change. Processions of representatives of the fauna are directly or indirectly affected: insects, reptiles, amphibians, birds, bats, etc. , number M. Marx. But the impacts vary greatly from site to site: they are all the more important when the environment is rich in biodiversity.
Vegetation will develop during the exploitation phase. Ordinary plants will take up space in the spaces and between the rows. Adapted and adopted management measures, such as late mowing, will need to be applied to find the original vegetation. Invasive alien plants can spread or even be imported if topsoil is introduced from outside. , also explains the representative of LPO. The effect of the shading panels themselves on the vegetation depends largely on the design of the project. Geoffroy Marx cites the Parc de Cestas (Gironde), France’s largest solar plant, where vegetation struggles to return under panels only 80 cm from the ground. This does not apply to low density agrovoltaism projects. As for the fences surrounding power plants, they negatively affect terrestrial fauna by restricting the movement of mammals, but may have a limited effect on certain species.
Decomposition of some insects and small vertebrates
The main impact on species is related to the loss of natural habitats, which can cause deficiency of certain insects and small terrestrial or aquatic vertebrates, then, by ricochet, birds and bats that feed on them . The opening of the environment may, on the other hand, encourage the arrival of bird species in these environments at the expense of species from forests or forest edges. This openness will also encourage sunlight beneficial to pollinators. But the shade of the panels, on the contrary, will repel insects, which will find it difficult to determine the color of flowers that produce less nectar.
The panels can also serve as traps for some insects, which confuse them with water surfaces and come there to lay their eggs. Therefore, it is recommended not to locate parks in close proximity to wetlands or water areas, explains Mr. Marks, who also mentions the possibility of applying textures or white stripes to the panels. The risk of bird deaths from impacting the panels is minimal, but there have been cases of injuries to the jaws of bats seeking water. Texture will also play a role here, as well as the slope of the panels.
Although the creation of parks on land near bodies of water is not recommended, on the other hand, we are seeing the development of floating parks. But knowledge of their impact on biodiversity is still limited. Operators highlight the benefits associated with lower water temperatures, beneficial effects on algae growth and reduced water evaporation. In fact, there are some negative consequences, corrected by a representative of the Association for the Protection of Nature. And to quote randomly: Pollution risks and troubles associated with boats, changing the banks and bottom of a body of water, electromagnetic fields, reduced brightness and photosynthesis, degradation of swimmers in the water, a reef effect favorable to invasive alien species or even bird droppings, which can be cause of water pollution.
Do not place power plants in natural areas
Site selection is important as habitat change leads to all other impacts. , explains Geoffroy Marx. Therefore, in many publications it is recommended not to locate power plants in natural areas or instead of agricultural areas. The public authorities, for their part, want to promote a balanced development of installations on rooftops and on the ground. We see complementarity , explains Bertrand Ocordognier, project manager for renewable electrical systems at Ademe. In fact, the production is more and the cost is lower.
But it is necessary to give preference to photovoltaics on roofs or power plants on already artificial grounds.s, says a representative of the LPO, which opposes the development of renewable energy projects in natural areas, especially in Natura2000 areas. In its opinion on the Renewable Energy Acceleration Bill, the National Council for Ecological Transition (CNTE) also laments the lack of specific provisions for the development of rooftop photovoltaic systems. whose environmental impact is much lower than that of ground-based photovoltaic systems .
As far as agrovoltaism is concerned, mitigation measures such as raising the panels, lower density or mobile panels, however, seem possible, says Geoffroy Marx. But the development of this technique, which Emmanuel Macron wants to promote, is not to the taste of agricultural organizations. In an open letter, the Confederation of Farmers warns the latter about a marketing concept aimed at legitimizing land and financial opportunism in an economic and climate context that is hard to bear for the peasant world. . The Young Farmers, for their part, are calling for a moratorium on the phenomenon of profiteering and misappropriation of the food calling of farms in an unprecedented demographic context .
In any case, in case of installation on the ground, restoring local biodiversity requires management measures that are adapted and adopted explains Mr. Marks. However, this points to a big black spot in this area: the lack of a protocol for monitoring the operational phase in relation to the initial state of the environment before the creation of the park. This is why the LPO is campaigning to classify photovoltaic parks as secret installations. like onshore wind turbines.
Article published September 23, 2022