111: How Wind Turbines Shape More Than Just Energy: A Closer Look at Their Environmental Impact
Could Wind Farms Become Ecological Architects, Designing Microclimates that Support Biodiversity and Climate Resilience? With an addendum on maximum theoretical limit of energy extraction.
In my last two posts, we’ve been diving into ocean exploration and the fascinating world of diatoms. That exploration continues, but today, I want to switch gears a bit. A dear friend of mine, Steve Boniwell, recently raised a question that piqued my curiosity: Can wind turbines actually alter wind profiles and impact the environment in ways we haven’t fully considered?
Initially reluctant to dive into this topic, I couldn’t resist after seeing the intriguing research. So here’s that exploration into the hidden impacts of wind turbines, drawing on findings from Baidya Roy’s study and the MOMENTA project.
Let’s dive in …
Wind Whispers: Unveiling the Hidden Ecological Impact of Turbines
We stand on precipice of dual environmental crises—climate change and biodiversity loss—our pursuit of renewable energy has led us to fill vast landscapes with wind turbines. Their towering blades cut through the air in a rhythmic, hypnotic dance, harnessing nature’s breath to power our homes and cities. But have we ever stopped to ask ourselves: What else might these towering sentinels of clean energy be doing? Could they be reshaping the very fabric of the ecosystems below?
Armed with state-of-the-art technology, a team of researchers took to the skies using the BOREAL unmanned aerial vehicle (UAV), a specialized drone designed to measure wind patterns in unprecedented detail. Their quest? To document the intricate wind wakes generated by turbines. What they discovered was far more complex than anticipated. The air beneath these turbines wasn’t simply being redirected—it was being sculpted into an entirely new microclimate.
These findings are part of the broader MOMENTA project, where scientists are combining UAV observations with wind tunnel experiments and numerical models to unlock the secrets of turbine wakes, hoping to optimize wind farm layouts. They’ve revealed that turbines not only create zones of wind deficit but also overspeed regions where wind races faster between turbine wakes. These invisible corridors of accelerated air could change the game in wind farm efficiency (Alaoui-Sosse et al., 2022). But could they also transform the ecosystems below?
A Manufactured Microclimate: The Dance of Wind and Turbulence
The results of these studies reveal an aerodynamic complexity that mimics the natural world. In the wake of each turbine, wind speeds drop significantly—by about 40%—while in the areas between these wakes, the air accelerates by up to 50%. It's almost as if these turbines are creating their own engineered weather systems. Researchers have observed this overspeed area, likely due to cumulative wakes from multiple turbines, in the wind farm used in the MOMENTA project.
The discovery of this phenomenon aligns with the findings of researchers like Baidya Roy, who showed that wind turbines don’t just redirect air but create turbulence that enhances vertical mixing of air, heat, and moisture (Baidya Roy et al., 2004).
This vertical mixing, akin to the processes found in natural ecosystems, could have far-reaching effects. In nature, vertical air movement helps distribute resources such as heat, moisture, and nutrients. Could it be that these turbine-induced wind patterns are altering the environment for plants and animals below? Is it possible that these wakes could influence soil moisture, temperature gradients, and even the distribution of seeds or spores?
In fact, this alternating pattern of slow and fast air isn’t just a curiosity—it forms the foundation of a whole new microclimate. Think of it as a manufactured version of the varied environments you'd find in a natural forest, from sheltered understory to windy clearings.
But what does this mean for the plants below? In the low-wind wake zones, we might expect to see changes in local microclimate conditions. Markfort et al. (2012) conducted wind tunnel experiments to study surface heat flux in model wind farms. They found that while the overall change in surface heat flux was small (about 4% reduction for a staggered layout), there was significant spatial variability. In the near-wake region close to turbines, they observed increased surface heat flux of up to 24%, while other areas showed decreased flux. This spatial heterogeneity could create a mosaic of microclimates within wind farms. Additionally, Armstrong et al. (2014) conducted a field study in a peatland wind farm in Scotland and found some intriguing results. They observed that wind farm operation affected the ground-level microclimate in measurable ways. During nighttime hours, areas around wind turbines were slightly warmer (by about 0.18°C) and more humid (by about 0.03 g/m³) compared to control areas without turbines. These subtle changes might seem small, but in ecological terms, they could be significant. The warmer, more humid conditions in turbine areas could potentially affect plant growth patterns, soil moisture retention, and even the behavior of small organisms.
This combined insight from controlled wind tunnel experiments and field observations gives us a more comprehensive picture of how wind farms can influence local microclimates. The spatial variability in surface heat flux observed by Markfort et al. aligns with the heterogeneous wind patterns we discussed earlier, while Armstrong et al.'s findings of slight warming and increased humidity near turbines add another dimension to our understanding of wind farm microclimates.
In the high-wind areas, things get even more interesting. Bohrer et al. (2009) observed that plants in windy zones, such as forest edges, can see up to a 30% increase in CO2 uptake. These conditions could be ideal for prairie grasses or crops that thrive in windy environments. Wind turbines may be sculpting more than just air—they could be creating habitats suited for a variety of plant species.
And it’s not just about wind speed. The turbulence from the turbines mixes the air vertically, potentially moderating temperatures. Armstrong et al. (2014) recorded nighttime warming of up to 0.5°C near wind farms. This vertical mixing could create more stable environments for plants, buffering them against extreme temperature variations.
Could Wind Turbines Shape New Ecosystems?
Let's ask an ambitious question: Could the wind patterns created by turbines foster entirely new ecosystems? What if these manufactured microclimates provide an opportunity to cultivate diverse plant species in ways we have yet to fully appreciate?
In low-wind wake zones, moisture-loving plants could thrive in the sheltered, more humid environments. In contrast, more resilient species like prairie grasses might flourish in high-wind areas. The MOMENTA project suggests these alternating wind speeds form microclimatic niches, offering diverse species the chance to thrive.
Now, imagine if we could intentionally design ecosystems around these wind patterns. We could create a mosaic of habitats: drought-tolerant grasses in the high-wind zones, shade-loving plants in the sheltered areas, and adaptive species in transition zones. For instance:
In wake zones (low wind, higher moisture):
Plant types: Shade-tolerant, moisture-loving
Examples: Ferns, understory shrubs
In inter-wake zones (high wind, drier):
Plant types: Wind-tolerant, high evapotranspiration
Examples: Prairie grasses, certain crops
In transition zones (variable conditions):
Plant types: Adaptive, edge species
Examples: Mixed shrubs, ecotone specialists
This strategy isn’t just limited to plants. Northrup and Wittemyer (2013) found that wind farms can support a diversity of wildlife. By thoughtfully designing plant communities, we could enhance biodiversity, creating wildlife corridors that follow these engineered wind patterns.
Wind farms, then, could evolve from mere energy generators into biodiversity sanctuaries—designed habitats that help species adapt to a warming world. Could this be the future of both energy and ecological resilience?
The Ripple Effects of a Manufactured Windscape
How do these turbine-induced wind patterns interact with the environment? Could shifting airflow influence moisture retention and create mini-oases in otherwise dry regions? The MOMENTA project and UAV studies suggest that wakes affect wind speeds and moisture distribution over vast areas. This could have long-term implications for soil health and habitats.
Baidya Roy’s research extends this impact to local meteorology, influencing wind speed, surface temperatures, and moisture distribution. Could this even alter precipitation patterns and hydrology? If so, wind farms might not just impact the air—they could change water sources for plants and animals?
Engineering Ecosystems for the Future?
As we contemplate the far-reaching implications of these findings, a tantalizing possibility emerges: Could we intentionally design ecosystems around wind farms? What if, instead of simply placing turbines in barren landscapes, we planted species strategically, using wind farms as tools for ecological restoration?
In the future, wind farms might serve not only as clean energy sources but also as ecological engineers. By deliberately choosing plant species that thrive in specific wind conditions, we could create resilient ecosystems in places that are becoming increasingly inhospitable due to climate change. Wind farms could become biodiversity hotspots, attracting wildlife that relies on specific wind conditions or microclimates to survive.
We are only beginning to scratch the surface of this possibility. As the MOMENTA project progresses, researchers are poised to deepen our understanding of how wind wakes interact with the environment. Future experiments with higher wind speeds and closer proximity to turbines will allow scientists to better quantify the effects of turbine wakes on everything from soil moisture to the spread of airborne seeds. These findings could revolutionize how we think about the role of renewable energy in ecological conservation.
As we've explored the complex interplay between wind turbines and their surrounding ecosystems, we've encountered a wealth of intriguing data. To help summarize these findings, let's take a moment to review the key numerical insights from the studies we've discussed.
These numbers tell a story of an intricate dance between technology and nature, hinting at the potential for wind farms to become not just energy providers, but architects of new ecological landscapes.
Thank you for joining me on this exploration of the hidden world of wind turbines. Until next time, may the winds of discovery continue to guide our pursuit of sustainable solutions.
Addendum: The Bigger Picture of Wind Energy Extraction
(Edit 1) After publishing this, a thought-provoking question from Steve Boniwell took the discussion in a new direction: Just how much wind energy can we realistically extract before it starts to influence the atmosphere on a large scale? Alpha Lo recommended I dig into Axel Kleidon’s research, which sheds light on the thermodynamic limits of wind energy extraction and its broader implications.
Kleidon’s work asks the big questions: How much energy can wind turbines take from the atmosphere before we hit natural limits? And what are the potential consequences when we scale wind energy production dramatically? Could the sheer number of turbines eventually influence not just local climates, but even global atmospheric circulation?
These are the kinds of questions Axel Kleidon's research begins to explore, offering key insights into the physical boundaries of wind energy extraction.
Highlights from Axel Kleidon's Paper on Wind Energy Extraction
Thermodynamic Limits of Wind Energy:
The atmosphere generates kinetic energy due to solar radiation and temperature differences, particularly between the tropics and poles. This energy drives global atmospheric circulation and produces winds.
Only a certain fraction of this energy can be harnessed before it significantly affects wind speeds and reduces energy extraction efficiency. Kleidon estimates that no more than 38% of this kinetic energy can be sustainably extracted.
Energy Dissipation and Surface Friction:
Most of the atmosphere's kinetic energy is naturally dissipated as heat through surface friction, primarily in the boundary layer near the Earth’s surface.
Wind turbines extract this kinetic energy, which would otherwise be dissipated through friction, converting it into electrical energy.
Global Wind Energy Potential:
Wind turbines extract energy from the boundary layer, which can impact local wind patterns and speeds.
The theoretical upper limit for wind energy extraction is about 38% of the kinetic energy dissipated by surface friction globally, a fraction of the total energy dissipated by natural friction processes.
Efficiency Declines with Increased Turbine Density:
As turbine density increases in a region, the efficiency of each turbine decreases due to reduced wind speeds.
There’s a non-linear relationship between the number of turbines and energy output, meaning that beyond a certain point, adding more turbines yields diminishing returns.
Impact on Global Circulation:
While large-scale wind energy extraction could slow winds at local and regional levels, Kleidon’s research suggests the overall impact on global atmospheric circulation would be minimal due to the vast scale of natural atmospheric energy dissipation.
The atmosphere dissipates approximately 12,500 TWh/year through surface friction, but wind turbines currently harness only a small portion (around 2.4%) of this natural energy dissipation.
Current Wind Energy Metrics (Based on Axel Kleidon's Paper)
Installed Wind Energy Capacity (Germany, 2021):
Germany had 56 GW of installed wind energy capacity across 28,230 turbines, generating around 90.3 TWh of electricity annually. This accounts for 16% of Germany's total electricity generation (570 TWh/year).
Wind Energy Potential:
By 2050, Germany aims to install between 150-200 GW of wind energy capacity, generating between 330-770 TWh/year to meet a much larger portion of its electricity needs.
Global Energy Dissipation:
The atmosphere naturally dissipates around 12,500 TWh/year through surface friction.
Wind turbines globally are extracting only about 2.4% of this energy.
Estimating the Maximum Number of Wind Turbines Globally
Let’s assume we aim to scale up wind energy extraction to the theoretical maximum limit of 38% of the atmosphere’s kinetic energy:
Current Energy Dissipation: The atmosphere dissipates around 12,500 TWh/year through natural friction.
Maximum Energy Extraction Potential: 38% of this energy would amount to 4,750 TWh/year.
Current Global Wind Energy Generation: Wind turbines are currently generating around 300 TWh/year (2.4% of total global energy dissipation through friction).
Scaling Up to the Maximum Limit: To reach the 4,750 TWh/year limit, wind energy extraction would need to increase by a factor of 15.8 times the current capacity.
Current Number of Wind Turbines Globally: There are approximately 700,000 wind turbines in operation worldwide.
Calculating the Maximum Number of Wind Turbines: If 700,000 turbines generate 300 TWh/year, then to generate 4,750 TWh/year, we would need approximately:
700,000 × 15.8 = 11 million wind turbines.
Thus, to reach the theoretical maximum energy extraction limit, the world would need to install about 11 million wind turbines globally.
Atmospheric Limits and Global Impact
Kleidon’s research highlights a key takeaway: while scaling up wind turbines to such an extent could slow local and regional wind speeds, the overall impact on global atmospheric circulation would remain minimal. This is because wind turbines primarily interact with the boundary layer, which constitutes a small portion of the total atmospheric energy system. However, adding as many as 11 million turbines could begin to influence regional circulation patterns, particularly in areas with high turbine density.
Snapshots
Global Wind Energy Dissipation: The atmosphere dissipates approximately 12,500 TWh/year through surface friction.
Maximum Extraction: Only 38% of this energy can be sustainably harvested before wind speeds drop significantly.
Turbine Efficiency: As more turbines are added, their efficiency drops due to reduced wind speeds.
Maximum Number of Turbines: To reach the theoretical limit, the world would need about 11 million wind turbines to extract 4,750 TWh/year of energy.
Kleidon’s insights give us a clearer view of both the massive potential and the physical limitations of wind energy. While the potential is vast, the atmosphere’s capacity to generate kinetic energy imposes natural limits on how much we can sustainably extract.
Why is 38% the Limit for Wind Energy Extraction?
The 38% limit for wind energy extraction is based on the balance between the kinetic energy available in the atmosphere and the rate at which it can be sustainably harvested. Axel Kleidon’s research uses thermodynamic principles to calculate this upper boundary, relying on the idea that wind turbines extract energy from the atmosphere similarly to how friction dissipates energy near the Earth’s surface.
The key equation comes from the kinetic energy balance, where wind turbines capture a portion of the momentum carried by winds. The more energy turbines extract, the lower the wind speeds become, eventually reducing efficiency.
Here’s the equation,
Where:
v0 is the initial wind speed,
η is the efficiency of the turbine (typically around 42%),
ARotor is the area swept by the turbine blades,
n is the number of turbines per unit area (turbine density),
Cd is the drag coefficient, reflecting surface friction.
This formula shows how wind speeds decrease as more turbines are added. The reduction in wind speed limits the amount of kinetic energy that turbines can convert into electricity. As wind speeds slow down, the energy extracted by each turbine becomes less efficient, resulting in diminishing returns.
By calculating the balance between the energy extracted by wind turbines and the natural dissipation of energy through surface friction, Kleidon concludes that only 38% of the kinetic energy available can be sustainably harvested. Beyond this point, the wind speeds would drop too much, significantly lowering turbine efficiency and energy output.
Why Even the 38% Limit is Negligible in Terms of Total Energy Available for Circulation
Now, even if we could operate at this theoretical limit and extract 38% of the available energy (about 4,750 TWh/year), it would still be negligible when compared to the total global energy available for circulation.
Here’s why:
Tiny Fraction of the Total Energy System: The total amount of kinetic energy dissipated by friction in the atmosphere is 12,500 TWh/year. While this seems like a substantial number, it's only a tiny fraction of the total 500,000,000 TWh/year of energy received by the Earth from the Sun. Wind energy is a small slice of an already small portion of the Earth’s energy budget.
Minimal Impact on Global Circulation: Wind turbines primarily operate in the boundary layer, which is the lower part of the atmosphere, close to the Earth’s surface. The large-scale global circulation that drives weather patterns and climate occurs higher up, in the free atmosphere, which is decoupled from near-surface processes like wind energy extraction. So even though wind turbines alter local and regional wind patterns, they do not significantly affect the broader, large-scale circulation systems.
Negligible in the Earth's Energy Dissipation System: The 12,500 TWh/year of kinetic energy that wind turbines tap into is already part of the natural process of energy dissipation in the atmosphere. This dissipation occurs through friction with the Earth’s surface, and wind turbines merely redirect a portion of this energy. Therefore, extracting 38% of the available energy represents only a small fraction of the natural energy flow, making its impact on global circulation minor.
In summary, even if wind turbines operated at their maximum capacity, harvesting 4,750 TWh/year, this represents a minuscule 0.001% of the total solar energy that drives the Earth's systems. As such, achieving the 38% limit for wind energy extraction would have a localized effect but remain negligible in terms of altering global atmospheric circulation.
Axel Kleidon had an interesting paper about why you can’t try and get wind energy from the atmosphere without damaging way atmosphere works
Additionally, I believe the materials to manufacture wind turbines contains BPAs. So BPAs micro-particles are being sprayed across the landscape which is toxic and affects the fertility of animals and humans.