THE CONTEXT
The conflict from overlap between energy production potential and biodiversity conservation appears lower for wind and solar photovoltaics (PV), than for bioenergy: about one-third of their global potential is located within top biodiversity areas (with some exceptions like Central and South America, where it is higher). However, another recent study showed that the overlap between existing solar/wind/hydropower facilities and conservation areas is by far the highest in Western Europe, with over 1200 out of a global total of 2200 facilities operating within protected (PA), key biodiversity (KBA), and wilderness areas. On the other hand life-cycle analyses show that solar and wind energy deployment is far less environmentally damaging overall than using fossil fuels. The expansion rate of hydropower is likely to decline globally, but its share in total renewable energy generation remains one of the largest, and 28% of planned global hydropower is within PAs.

Hydropower has built-in energy storage capacity and fast response time, which allows it to compensate for sudden fluctuations in supply or demand of other renewable sources (such as solar and wind power). However, dams can significantly harm local, downstream and upstream biodiversity. They alter river morphology and habitats, water flow regimes and ecological flows, seasonal flood cycles, water quality and temperature. They can block species migration and dispersal, and disrupt sediment dynamics.

Ultimately, solar power could provide substantial benefits compared to environmental costs, if energy transport and/or storage limitations are gradually lifted. It is also one of the cheapest sources of electricity available. However in the case of a future economic scenario constrained by local energy demand, without long-distance transmission, the threat to biodiversity from solar and wind could reach a level comparable to that of bioenergy. Under the unconstrained (optimistic) energy scenario, utilizing only 1% of land outside of top biodiversity areas for solar production could meet the total global power consumption whereas bioenergy or wind energy would still contribute less than 10% to global consumption. All studies considered do caution against full adoption of utility-scale solar development without adequate understanding of environmental ramifications. Utility-scale solar installations can be massive, with significant land requirements. Habitats transformed into solar farms will suffer from a wide range of impacts such as reduced vegetative cover, soil degradation, and impaired water quality. They can create a new built environment or microclimate, causing habitat degradation by altering sun exposure, moisture and surface temperature, and possibly disrupt photosynthesis.

All three types of installations (hydro, solar, wind) can impact species directly. Several vulnerable species groups like vultures, bustards, cranes, bats, raptors and many migratory species are at risk from collision with wind turbines or electrocution from energy transmission lines (though fossil fuels pose a much greater – if less obviously visible – threat to birds and bats, mainly through pollution and climate change). Contact with hydropower turbines and other machinery, as well as pressure fluctuations, can harm fish and other river species. Supporting infrastructure, including transmission lines and roads, may facilitate hunting, indirect habitat loss, fragmentation and invasive species dispersal, resulting in impacts that extend far beyond their immediate physical footprint. Offshore wind installations can pose a threat to marine mammals, sea turtles, and some fish species due to construction noise and collisions with associated vessels, while habitat alteration affects species of the sea floor. Emerging technologies such as floating solar and wind – and renewable energy development in deeper offshore waters – are gathering pace, and the risks need to be properly researched.

The risks for nature need to be taken into account right from the earliest stages in the siting and design of RE installations – and the associated infrastructure such as access roads and powerlines. Analyses suggest that strict protected areas (PAs) provide more effective protection against RE development than less strict (categories V and VI) and non-categorised PAs. Other sensitive breeding areas, key biodiversity areas and species migration routes also need to be excluded. Building a strong evidence base can help reduce the trade-offs between RE expansion and biodiversity. Studies indicate that planned RE deployment would not significantly affect area-based conservation targets, if done with appropriate policy and regulatory controls, Fortunately, the abundance of solar and wind energy means that there is often flexibility in project siting, allowing the use of already converted or disturbed land or offshore locations away from areas of high sensitivity. By contrast, large-scale hydropower is often highly constrained by location.

A recent IUCN report recommends a mitigation hierarchy consisting of sequentially and iteratively implementing four actions: avoid, minimise, restore and (if impacts could not be anticipated) offset. Early avoidance and minimisation actions are key; they include burying or rerouting power lines, infrastructure adaptation, and eliminating electrocution risks. Noise impacts in offshore installations can be minimised via strict construction protocols. New technologies offer considerable risk-minimisation potential, such as turbines able to shut down depending on bird activity and acoustic deterrents. Pro-active conservation can play a vital role: onshore wind and solar farms offer habitat-restoration and enhancement opportunities in degraded areas whilst artificial reefs around offshore turbines can enhance biodiversity and fish stocks. When offsets become necessary due to unanticipated impacts, their planning and implementation should follow best practice principles: for instance, addressing cumulative impacts to similar ecosystems by channelling resources into a single aggregated offset.

The disposal of used solar panels presents another potential concern. Since they were first introduced in the 2000s, tonnes of solar panels are reaching the end of their lifespan. They contain heavy metals such as lead and cadmium, which can be hazardous for ecosystems as well as hard to extract, making recycling difficult and costly. Costs are currently 10 to 30 times higher for recycling than for dumping panels in landfills, which is where they could end up – or exported to developing countries, which lack the infrastructure and regulations for proper disposal. The JRC report (2016) expects their disposal to become a relevant environmental issue over the coming years. It pointed to the lack of scientific research on the end-of-life phase of solar panels. Projections by IRENA anticipate large amounts of waste from solar panels by 2030, possibly reaching 78 million tonnes by 2050, assuming customers will keep the panels in place for their entire 30-year lifespan. However, other studies predict earlier replacements, indicating a much higher level of waste. The main prospective solutions currently being investigated are: (i) new techniques to make recycling cost-effective by extracting valuable materials (like silver and silicon) contained in the panels, and (ii) making the manufacturing process cleaner (purifying silicon for cells and, more recently, replacing it with perovskite cells based on non-toxic metals). While the latter does not address the disposal of currently accumulating panels, techniques for their cost-effective recycling as part of a circular economy are improving significantly.

RELEVANT EU POLICIES ON SOLAR PV, WIND, HYDROPOWER AND OTHER RENEWABLE ENERGY SOURCES
Solar power is the fastest-growing energy source in the EU. It can be rolled out rapidly, offers substantial climate benefits, and is one of the EU's cheapest energy sources: the cost of solar power has decreased by 82% over the last decade. As part of the REPowerEU plan, the EU Solar Energy Strategy (2022) aims to double annual solar energy generation by 2025 (compared to 2020) and quadruple it by 2030. The strategy foresees that the required utility-scale expansion will increasingly face competing uses of land and public acceptance challenges. It calls for MS to undertake a mapping exercise to identify appropriate locations for renewable energy installations and go-to areas with simple and fast permitting procedures, while limiting the impact on other uses of land and ensuring environmental protection. To this end it recommends innovative forms of deployment and multiple use of space. The European Solar Rooftops Initiative is one of its flagship initiatives. Rooftops have housed most solar installations so far, but huge untapped potential remains. According to some estimates rooftop installations could provide almost 25% of EU electricity. Considered low-hanging fruit, they can be deployed rapidly, shield consumers from volatile prices, and avoid conflicts with nature. Beyond rooftops, the solar strategy points to other opportunities for solar energy generation provided by buildings, such as building-integrated PV, whose potential remains to be unlocked. Other innovative solutions mentioned include repurposing former industrial or mining land for solar energy installations; using water surfaces with minimal environmental impacts such as artificial lakes created by hydroelectric dams; deploying agri-voltaics (PV systems in agriculture can contribute to crop protection and yield stability, a potential win-win for renewables, agricuture and sustainability); and installing solar panels along highways or railway tracks. The EU biodiversity strategy specifically mentions solar-panel farms providing biodiversity-friendly soil cover as a win-win solution for energy and biodiversity. Any intervention on water bodies must respect the conditions set out in the Water Framework Directive and the Marine Strategy Framework Directive. Best practice measures to mitigate harmful impacts of solar farms on EU natural habitats and species focus on appropriate site planning, as well as enhancing biodiversity values on solar farms, and improving boundary features to enable wildlife mobility.

Since 2012, PV waste has been formally included as Waste of Electrical and Electronic Equipment within recast WEEE Directive, which requires producers and importers of PV panels to take responsibility for their end-of-life management. The regulation has started to come into force among EU MS. Several European projects have been launched to reduce disposal hazards,  as well as optimise value towards supporting a circular economy, by extracting high-purity valuable materials from dead PV panels. These include CABRISS and Photorama co-funded by Horizon 2020, ReProSolar co-funded by Horizon Europe, and FRELP, co-funded by the European LIFE programme (for details, see section on EU-supported projects and initiatives on biodiversity, climate change and energy). FRELP is also discussed in the JRC report analysing material recovery from silicon PV panels (2016).

Over the coming years, wind power is expected to retain its position as top provider (36%) of electricity from renewable sources in the EU. A significant expansion of wind energy (offshore plus onshore) is thus foreseen, in light of the significantly larger share of renewables expected in the energy mix by 2030. Offshore RE (wind, wave and tidal) avoids some of the challenges faced by onshore renewables, such as natural obstructions or competition for space with other human activities. The EU Offshore Renewable Energy Strategy (2020) assigns it an important role in attaining climate targets. The required scale-up of the offshore wind industry to meet the 55% GHG reduction by 2030 is estimated to require less than 3% of European maritime space. It can thus be compatible with the EU-BDS 2030, which calls for expanding the EU’s network of marine protected areas from 11% to 30% of EU maritime space, of which a third must be strictly protected (only 1% was in 2020). The EU-BDS 2030 specifically mentions ocean energy and offshore wind as potential win-win solutions for climate and biodiversity. Offshore RE development has to comply with EU environmental legislation and integrated maritime policy including the Habitats and Birds Directives, the Marine Strategy Framework Directive, Maritime Spatial Planning Directive, and the EU-BDS 2030. Maritime spatial planning will be crucial for ensuring that designated sea spaces are compatible with biodiversity protection, and fulfilling the obligations to reach good environmental status enshrined in the Marine Strategy Framework Directive, notably in view of the update of marine measures in 2022.

Hydropower accounted for 33% of EU renewable electricity production in 2020 and 17% of total EU electricity production. It is foreseen to continue to play an important role, with thousands of new plants planned or under construction. Its flexibility and storage options help stabilise the EU electricity system by integrating variable RE production from other sources such as solar and wind. At the same time dams and other barriers have significantly impacted EU freshwater ecosystems, and are a key driver of a collapse of freshwater migratory fish populations in Europe by 93% since 1970. 33% of planned hydropower in Europe is within protected areas.

Key pieces of EU legislation addressing environmental impacts of hydropower include the Water Framework Directive (WFD), the Floods Directive, the Nature (Birds and Habitats) Directives, and the Environmental Assessments Directives. Environmental impacts include changes that can affect wildlife and river morphology, causing a fragmentation of the river system. In 2020 the EU-BDS 2030 emphasised the need for greater efforts to achieve WFD objectives of restoring freshwater ecosystems and natural river functions. It set a of removing river barriers to enable at least 25,000 km of free-flowing rivers by 2030, thus facilitating the passage of migrating fish and improving water and sediment flows. This was made legally binding under the proposal (2022) for a Nature Restoration Law. It focuses on removing obsolete barriers, such as dams no longer useful for hydropower generation.

Though closely linked with broadly similar objectives, the WFD and Nature Directives have distinct specific aims. Whilst the WFD aims at "good ecological status" of water bodies, the Nature Directives aim at a favourable conservation status for specific species across their natural range.  Since reaching good ecological status is not necessarily sufficient for reaching favourable conservation status, the WFD explicitly recognises the need for additional conservation measures: it states that ‘where more than one of the objectives relates to a given body of water, the most stringent shall apply’.  The Commission's guidance document on hydropower in relation to EU nature legislation (2018) states that these additional needs should be included in the WFD river basin management plan via specific provisions regarding protected areas (PAs). It cites several good practice examples of mitigating effects and applying ecological restoration measures to hydropower, as well as of integrated planning approaches. However, the the European overview of the second river basin management plans (2021) concluded that these additional needs for protecting water-dependent habitats and species were unknown for 44% of PAs under the Nature Directives, while work to determine the needs for another 13% was still ongoing. Specific water objectives had been set only for 17% of PAs under the Nature Directives.

The Commission's REPowerEU plan (2022) calls on MS to swiftly map, assess, and ensure suitable land and sea areas that are available for renewable energy projects, commensurate with contributions towards the revised 2030 renewable energy, and other factors including the targets of the EU Biodiversity Strategy. In identifying go-to areas MS are required to prioritise artifical and built surfaces, and degraded land not usable for agriculture, and to exclude Natura 2000 sites and nature parks and areas, as well as bird migratory routes. They are to use all appropriate tools and datasets, including wildlife sensitivity mapping, to identify areas where renewable energy plants would not have a significant environmental impact. To support MS in identifying such “renewables go-to areas” for the rapid deployment of new RE installations, the JRC's Energy and Industry Geography Lab has developed (2022) a visual tool that consolidates information on a wide range of energy and environmental factors.