Dachsberg Wind Farm

Critics argue that, because trees also sequester CO₂, it does not make sense to erect wind turbines in forested areas to generate climate-friendly electricity. As a general rule, we must reforest, to an equivalent extent, any land that we clear – either temporarily or permanently – for the construction of wind turbines. Overall, we actually plant more trees than we fell, because when offsetting, we have to take into account that we are replacing mature trees with small, young trees. The forests we are reforesting are ecologically valuable mixed woodlands. This means that no forest is lost as a result of the wind turbines; on the contrary, wind energy promotes ecological forest regeneration in Brandenburg. Regardless of this, the amount of CO₂ that a wind turbine saves is many times greater than what trees can store. Here’s a quick calculation: according to CO₂online, a beech tree, for example, sequesters approximately 12.5 kilograms of CO₂ per year. Pine trees, which are the predominant species in the Bliesendorfer Heide, sequester less CO₂ than beech trees. To build a single wind turbine, just under 8,000 trees must be permanently cleared to make way for the site and access roads. These 8,000 trees – beech trees in this example – would therefore sequester around 100 tonnes of CO₂ in a year. A single wind turbine of the type we are planning saves over 10,000 tonnes of CO₂ per year, whilst the entire wind farm saves 90,000 tonnes annually.

Infrasound is one of the concerns about wind energy that has been raised most frequently by citizens’ initiatives in recent years. What is infrasound? Infrasound refers to particularly low-frequency sounds that the human ear generally cannot hear. Infrasound is omnipresent in our environment: the wind generates infrasound, as do ocean waves and thunderstorms. Artificial sources of infrasound include road traffic, air-conditioning systems and pumps. The cars and lorries travelling along the A10 through the Bliesendorfer Heide produce infrasound. Like most technical devices, wind turbines also generate sounds across a broad frequency spectrum, including low-frequency sound. However, the sound levels are so low that, even at close range, they are well beyond the limits of human perception and pose no potential health risk.
*** Translated with www.DeepL.com/Translator (free version) ***

Heinz Rudolph, head of the Brandenburg State Fire Service Academy, recently told the *Märkische Allgemeine* that wind farms actually make forests “somewhat safer” (see *Märkische Allgemeine*). Among other reasons, the expert cites the fact that the access roads to the wind turbines can make it easier for the fire services to reach potential sources of fire in the woods.

Modern wind turbines are equipped with effective and tested fire safety mechanisms. Wind turbines, such as those we are planning for the Bliesendorfer Heide, are designed – right from the choice of materials used in the turbine – in such a way that a fire cannot spread within them. In addition, they are fitted with automatic and double-secured fire warning and suppression systems. If the sensors detect smoke, the turbine shuts down automatically. Furthermore, we must install additional access points for fire-fighting water in the woodland – these will also help should a carelessly discarded cigarette cause a fire in the woodland.

Wind energy has undergone over 30 years of technological development since its inception – just like cars, wind turbines have become safer over this period and are now considered safe in terms of fire safety.

Wind turbines, such as those we are planning for Dachsberg, are fitted with smoke detectors and heat sensors that monitor the turbine continuously. If the sensors detect smoke or an elevated temperature, the wind turbine switches itself off automatically.
At the same time, the plant operator is automatically notified, as is the fire brigade via a direct line.

To prevent fires in the nacelle, the wind turbines are fitted with an automatic fire-suppression system. This system also reacts to smoke and heat – and, in the event of danger, floods the interior of the nacelle with a gas that smothers the flames.
Should the fire in the nacelle prove impossible to extinguish, the fire service must prevent it from spreading to the surrounding woodland. To this end, we are constructing two new, additional fire-fighting water wells near the wind turbines. Incidentally, these wells also make the woodland safer from other fires, such as those caused by a discarded cigarette.

The wind turbines are fitted with a lightning protection system. If lightning strikes a rotor blade, the current is channelled via the lightning conductors on the rotor blades and the nacelle to the structural components of the nacelle. From there, the lightning is conducted on to the nacelle’s/tower’s lightning conductor, where it is channelled down the tower. Finally, the lightning current is discharged via the earthing system.

There is strong evidence to suggest that the fact that wind turbines act as lightning conductors also makes the forest as a whole safer, as lightning no longer strikes the surrounding trees.
To prevent fires from occurring in the first place, wind turbines have been continuously developed in recent years and have become increasingly safe. To ensure the turbines function properly, we must maintain them regularly.
 

A dune in the middle of the forest: whilst this may sound unusual, it is not at all uncommon in Brandenburg. The Renneberge parabolic dune is one of the most striking features of the Bliesendorfer Heide landscape. During the planning stage, we therefore took care from the outset not to detract from the dune’s appearance. On our behalf, the geologist and environmental consultant Dr Werner Stackebrandt drew up a ‘Report on the Assessment of Impact on the Renneberge Parabolic Dune in the Dachsberg Wind Farm’. The conclusion: none of the planned wind turbines will have a significant impact on the dune’s appearance. Nevertheless, he has set us some tasks: For one of the wind turbines, we have amended the plans for the access roads and the crane site in order to avoid even a possible “minor impact”. “Whilst the impacts on the curved dune had already been classified as minor under the previous planning stage, these have now been completely eliminated,” concludes Dr Werner Stackeberg.

The risk of accidents at wind turbines is very low: wind turbines are serviced every year or even every six months. As with cars, there is a TÜV inspection: every 2–4 years, the turbines are thoroughly inspected. This includes the supporting structures, the machinery – including the electrical equipment of the control and safety systems – and the rotor blades. The German Wind Energy Association (BWE) estimates that there are around 10 accidents involving wind turbines nationwide each year, including fires and damage to rotor blades or towers. With 30,000 wind turbines installed across the country, this is a very small number. And the impact on the surrounding area is generally minimal – quite unlike, for example, at a nuclear power station. BWE Managing Director Wolfram Axthelm recently illustrated just how small the risk is to *Der Spiegel* using a comparison: the liability insurance premium for a wind turbine is barely any more expensive than that for a moped (*Der Spiegel*, No. 19 / 4 May 2019, p. 20).

We are planting young trees across a larger total area than we are clearing of existing stands. This allows us to offset the removal of existing trees by planting young trees in their place. A total of 49,340 m² is being afforested for the first time. This means that an area that was previously unwooded is being planted with trees for the first time. In addition, there is an area of approximately 37,000 m² for the reforestation of construction sites at the plant locations. High-quality mixed and deciduous forests are being planted across all afforestation areas. These offer significantly greater ecological potential than forests consisting predominantly of pine trees.

All potential bat roosts in the trees that are due to be felled are mapped by a specialist, and the entrances are sealed with a special device which allows the bats to fly out but prevents them from re-entering. Felling will only take place once there are no longer any bats in the roost in question. Bat boxes will be installed as compensation for all felled trees containing roosts and for all trees with potential to provide roosting sites.
In addition, the wind turbines are designed with automatic shutdown periods. This ensures that the rotors stop during the bats’ active phases. From mid-July to mid-September, the shutdown times are determined by the following parameters:

• when wind speeds at nacelle height are below 5.0 m/s
• when the air temperature in the wind farm is ≥10 °C
• during the period from 1 hour before sunset to 1 hour before sunrise
• when there is no precipitation
 

Wind turbines emit infrasound. These are sound frequencies that are so low that they are inaudible to the human ear. Bats, on the other hand, use ultrasound for navigation. This, too, is inaudible to the human ear, but because the frequency is particularly high. To ensure that bats are not adversely affected, wind turbines are designed with automatic shutdown periods. This means that the rotors stop when bat activity is expected. From mid-July to mid-September, the shutdown periods are determined by the following parameters:

• when wind speeds at nacelle height are below 5.0 m/s
• when the air temperature in the wind farm is ≥10 °C
• between 1 hour before sunset and 1 hour before sunrise
• when there is no precipitation
 

Part of the planning application is the so-called environmental impact assessment report. This report examines the impact on various protected resources, including the climate. The report concluded that the wind turbines have a positive effect on the global climate. No adverse effects on the local climate were predicted.

Modern rotor blades contain carbon fibres. In the event of a fracture, minute particles may be released and dispersed into the surrounding environment. Potential health risks have been investigated, including in a review study conducted by NASA.
If such particles enter the respiratory tract through inhalation, this can cause irritation. There is no carcinogenic effect. The particles are excreted within a few days to weeks via the body’s natural self-cleansing mechanism. Chronic exposure, however, could be problematic.

It is extremely unlikely that any significant concentrations of carbon fibre microparticles would result from a rotor blade fracture at all. Furthermore, any such exposure – for example, for rescue workers – would only be short-term.
In the event of a fire, toxic fumes may be released, comparable to those produced during the thermal decomposition of plastics. Compared with other technical installations, there is no increased risk. Furthermore, in the event of a fire, it would mainly be the nacelle that would be affected, rather than the blades.

This question depends on many factors and therefore cannot be answered definitively with a single figure. When it comes to felling, for example, it depends on what happens to the trees afterwards. If the timber is used in the long term, the carbon is not released as CO₂.

Furthermore, older trees store more carbon than young trees. The newly planted trees must therefore be allowed to grow for several years until they reach the same carbon storage level as the original forest. We must also bear in mind that we are clearing pine trees from a commercial forest, so trees are being removed and replanted here anyway.
In addition, during initial afforestation, a larger area is replanted than is cleared.

Furthermore, deciduous trees can store more carbon overall than conifers. As afforestation schemes primarily involve planting deciduous trees to replace the conifers that have been cleared, we anticipate a positive CO₂ balance overall, solely as a result of these forest conversion measures.

Irrespective of this, wind turbines have an excellent carbon footprint both overall and within the forest: according to the Stiftung Unternehmen Wald, on average one hectare of forest stores between 10 and 13 tonnes of CO₂ per year. [1] By contrast, each individual wind turbine that we are erecting in the Bliesendorfer Heide saves approximately 10,000 tonnes of CO₂ emissions per year (calculation based on the ‘Emissions Balance of Renewable Energy Sources 2017’ from the Federal Environment Agency and the CO₂ calculator from the BWE).

[1] https://www.wald.de/waldwissen/wie-viel-kohlendioxid-co2-speichert-der-wald-bzw-ein-baum/
 

Approximately 1,226 m³ of concrete and approximately 165 t of reinforcement are required for a foundation.

All the initial afforestation will take place within the Bliesendorf municipal area. One of the sites is situated more than 5 km from the nearest wind turbine. Another site for initial afforestation is located approximately 500 m from the planned turbines. In addition, there is an area designated for forest conversion in the immediate vicinity of the turbine sites. All these areas are shown on the ‘Wind in the Forest’ subpage. In addition, some areas within the forest will be cleared, but these will only be used during the construction phase. These areas will be reforested once construction is complete.

The decommissioning costs are determined by the building control authority on the basis of Decree 24/01.6 of the Ministry of Infrastructure and Regional Planning dated 28 March 2006. The decommissioning costs must be deposited as a bank guarantee with the relevant building control authority as security before work commences. For the type of plant applied for, a decommissioning cost of approximately €150,000 can be assumed.

The beech forest area was taken into account in the planning. As part of the planning permission process, an assessment was carried out to identify the tree populations within the forest and to determine the forest’s functions. On this basis, calculations are made to determine how much land needs to be reforested. Overall, more land will be reforested than cleared, thereby also taking into account the presence of beech trees within the planning area.