Wind Power Yield Under Climate Constraints: How Projections can Secure Long-Term Energy Production
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In 2000, wind power accounted for just 0.2% of global electricity generation. A quarter of a century later, production has surged by a factor of 1,000, with installed capacity growing at over 10% annually, outpacing all other energy sources except solar.
As a renewable and carbon-free energy source, wind power is a critical lever for reducing greenhouse gas emissions, achieving net-zero targets and mitigating climate change. Along with rapidly expanding solar power, it can help decarbonize and electrify emiting sectors like transport, industry and buildings. This transition also reduces reliance on fossil fuels and mitigates the economic risks exemplified by energy shocks since 1973.
Global Expansion of Clean Energy Amid Climate Change Challenges
Socioeconomic and geopolitical pressures are driving many countries to accelerate the development of renewable energy, particularly to secure energy independence from fossil fuels and producing nations. Onshore and offshore wind energy hold significant potential to expand global energy production capacity.
The global wind energy sector continues to experience rapid growth: new installations reached 72.2 GW in the first half of 2025, marking a 64% increase compared to the same period in 2024.
"The addition of over 72 GW of new capacity globally demonstrates the sector’s resilience and the trust that governments, investors, and communities continue to place in wind power as a cornerstone of sustainable progress." - Dr Irfan Mirza, WWEA President
By June 2025, total installed wind capacity reached 1,245 GW, meeting approximately 12% of global electricity demand. China, which has dominated the sector for over a decade, accounts for nearly half of this capacity and 72% of new installations.
China | 600 GW |
India | 3,5 GW |
United States | 2,1 GW |
Germany | 1,9 GW |
Brazil | 1,3 GW |
Top Wind Energy Producers by Intalled Capacity, 1st Half 2025 (source: WWEA)
With such rapid growth, the need for climate adaptation in the wind energy sector is more pressing than ever. Wind power production is inherently weather-dependent and vulnerable to extreme climate events, which can damage turbines or accelerate their aging. Wind projects, designed for a 30-year lifespan (or longer with repowering), must be prepared to operate in the mid-to-late 21st-century climate, not just today’s conditions.
Wind Power Yield: A Key Factor for Project Success
The core economic question for any wind energy project is straightforward: How much electricity will this wind farm generate over 20 or 30 years?
This question arises every time a wind farm is developed. Developers must estimate the amount of electricity the project will produce over its lifetime. This estimate, known as wind power yield, determines:
Project profitability,
Wind farm sizing,
Financing decisions and developer commitments,
Grid integration.
To calculate wind power yield, engineers analyze the meteorological conditions at the project location, particularly wind resources and simulate electricity production.
Wind yield evaluation involves converting variable weather conditions into a reliable forecast of power generation, based on the specific characteristics of the wind farm.
Traditionally, and still predominantly, these estimates rely on observed meteorological data: records from nearby weather stations, reanalysis and/or short-term in-situ measurements. However, this data has a major drawback: it reflects past conditions and may not accurately represent current or future climate.
In the context of accelerating climate change, this approach poses a significant risk for project operators and investors, as there is no guarantee that actual production will match backward-looking estimates.
Climate Projections for Wind Energy
Let’s consider a wind project launched in 2026. If feasibility and opportunity studies are based on the most recent 30 years of observed weather data (1996–2025), they reflect an average climate from around 2010.
In France, it takes an average of ten years for a wind farm to become operational. By the time of inauguration around 2035, the weather assumptions underlying the project will already be 25 years outdated compared to present climate, and this gap will only widen over the project’s lifetime. Yet, the meteorological conditions that determine wind power production, including wind patterns, can evolve rapidly due to climate change.
The scientific community and wind farm stakeholders (developers, investors, regulators...) are therefore confronted to a critical question:
How will wind potential evolve in a future climate?
To answer this question reliably, climate models capable of simulating atmospheric changes at global or regional scales, under various emissions scenarios, are essential.
Integrating climate projections into wind yield studies enables anticipation of potential changes in wind resources over decades.
Climate change affect athmospheric circulation with different impacts on wind patterns depending on the region, making local projections pivotal for calculating accurate wind power yield. Wind yield projections involve wind speed but also other key parameters such as:
Temperature,
Atmospheric pressure,
Air density.
How Wind Speed Impacts Wind Power Generation
To convert climate projections into electrical output, engineers use the power curve of wind turbines. This curve links wind speed to the power generated by the turbine and varies depending on the model.
Four distinct phases typically characterize the operation of a wind turbine:
Cut-in speed: Below this speed (usually 3–4 m/s), the turbine does not rotate and produces no energy.
Partial load operation: Once the cut-in speed is reached, power output increases rapidly with rising wind speed.
Full load operation: After the ramp-up phase, production reaches the rated power and further increases in wind speed no longer affect output.
Cut-out speed: When wind speeds become excessive (around 25 m/s, depending on the turbine model), the turbine shuts down and the blades feather to prevent damage.
As a result, the relationship between wind speed and power output can be highly nonlinear: a change in wind speed can lead to significant variations in electricity production during the power ramp-up phase, or, on the contrary, have no impact during full load operation.
For this reason, a simplified approach to assess the impact of climate change on wind projects may involve estimating nonproductive hours based solely on cut-in and cut-out speeds, but more comprehensive methods are necessary to accurately predict future productions.
Adjustments Required for Reliable Wind Yield Estimates
Wind speed projections are not enough to get a reliable estimate of future wind yield, several other factor have a significant impact on electricity production.
Air Density
The electrical output of a wind turbine also depends on air density. For a given wind speed, power production will be lower if the air is less dense, due to factors such as temperature, atmospheric pressure and altitude.
In warmer climates, air density is lower, which can reduce wind power output. Conversely, in colder climates, higher air density increases output (source). Consequently, climate warming creates a global downward trend in wind power yield, assuming all else remains constant.
These parameters must therefore be considered when estimating a wind farm’s power yield. This significantly complicates the processing of climate projections, as it involves a multivariate assessment for which most bias correction methods are unsuitable.
Turbine Height
The height of wind turbines varies from one project to the other. Onshore industrial installations typically reach hub heights of 80 to 120 meters. Offshore wind farms, however, feature larger turbines, with hug height and blades often exceeding 150 meters. The size of a turbine thus depends on its intended use and the wind resources it is designed to harness (Kuczyński et al., 2021).
Climate models generally provide wind speed data at a reference height of 10 meters. However, wind turbine hubs are usually positioned much higher, between 80 and 180 meters above ground level. Scientists must therefore extrapolate wind data to the actual turbine height, accounting for environmental factors such as surface roughness.
Turbine Interactions
Within a wind farm, turbines slow down the wind behind them, creating a wake effect that reduces the power output of downwind turbines.
Optimizing the layout of wind turbines helps minimize losses caused by wake effects.
Capacity Factor: Measuring Wind Farm Efficiency
The capacity factor is a key performance indicator for energy production systems. It measures the actual energy output of a facility compared to its theoretical maximum output at full power and 100% availability. This metric is critical for the electrical system, as it directly impacts both the profitability of the installation and the sizing of infrastructure, including production, grid integration and flexibility.
On average, in France, the capacity factor of wind farm is:
Onshore wind: 25% to 40%
Offshore wind: 45% to 60%
The power output of a turbine, and thus its capacity factor, primarily depends on three parameters: Wind speed, swept area of the blades and air density. Turbines installed on taller towers or equipped with longer blades generally achieve higher performance (source).
P50 and P90: Managing Risk in Wind Energy Forecasts
In wind yield studies, lon-term forecasts can never be 100% accurate due to natural wind variability and climate uncertainties. To quantify the level of confidence, engineers rely on P50 and P90 indicators.
P50 represents the expected median production level: there is a 50% probability that the actual output of a wind farm will exceed this value. In climatology, the median is usully regarded as the "best guess" or the more likely outcome. This indicator is commonly used to plan a project’s average profitability and to structure baseline financing.
P90, on the other hand, provides a conservative estimate: it is the production level that will be met or exceeded with 90% probability. Banks, investment funds and investors typically use P90 to assess financial risks and ensure project viability, even under unfavorable conditions such as below-average wind years.
By combining P50 and P90, developers gain a comprehensive view of both uncertainties and likely performance for a wind farm. These indicators help account for risks related to meteorological fluctuations and seasonal wind variations. When calculated using reliable climate projections, they also reflect the potential impacts of climate change on future production. As such, they are a central tool for evaluating a project’s profitability and securing investments.
Conclusion
Estimating wind power yield can no longer rely solely on observed meteorological data or a general understanding of wind turbine technologies. In a changing climate, stakeholders in every project should integrate robust, localized climate projections to anticipate the evolution of wind resources, as well as other physical parameters such as air density, temperature and pressure, over the entire lifespan of wind farms.
This approach helps mitigate risks associated with inaccurate yield estimates, secures investments, optimizes turbine placement, and, more broadly, improves the planning of energy systems.
A deeper understanding of climate evolution and its impacts on wind installations could further refine yield estimates. In this context, Callendar, a startup specializing in tools to anticipate the impacts of climate change, is conducting a large-scale study focused on renewable energy projects and the influence of climate on their performance.
As part of this initiative, Callendar has studied the power yield of more than 50 major wind farms across all continents. For each site, localized climate projections were generated and analyzed using a harmonized methodology to ensure the comparability of results.
The findings of this study will be unveiled in April 2026 and will shed light on the impact of climate change on wind power production.
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