The Kinetic Energy Budget of the Atmosphere (KEBA) model 1.0: A simple yet physical approach for estimating regional wind energy resource potentials that includes the kinetic energy removal effect by wind turbines

Mapping Intimacies ◽

10.5194/gmd-2020-77 ◽

2020 ◽

Author(s):

Axel Kleidon ◽

Lee M. Miller

Keyword(s):

Kinetic Energy ◽

Wind Energy ◽

Energy Budget ◽

Wind Turbines ◽

Large Scale ◽

Energy Resource ◽

Wind Farms ◽

Energy Yield ◽

Wind Speeds ◽

Kinetic Energy Budget

Abstract. With the current expansion of wind power as a renewable energy source, wind turbines increasingly extract kinetic energy from the atmosphere, thus impacting its energy resource. Here we present a simple, physics-based model (KEBA) to estimate wind energy resource potentials that explicitly account for this removal effect. The model is based on the regional kinetic energy budget of the atmospheric boundary layer that encloses the wind farms of a region. This budget is shaped by horizontal and vertical influx of kinetic energy from upwind regions and the free atmosphere above as well as the energy removal by the turbines, dissipative losses due to surface friction and wakes, and downwind outflux. These terms can be formulated in a simple, yet physical way, yielding analytic expressions for how wind speeds and energy yields are reduced with increasing deployment of wind turbines within a region. We show that KEBA estimates compare very well to the modelling results of a previously published study in which wind farms of different sizes and in different regions were simulated interactively with the WRF atmospheric model. Compared to a reference case without the effect of reduced wind speeds, yields can drop by more than 50 % at scales greater than 100 km, depending on turbine spacing and the wind conditions of the region. KEBA is able to reproduce these reductions in energy yield compared to the simulated climatological means in WRF (n = 36 simulations; r2 = 0.822). The kinetic energy flux diagnostics of KEBA show that this reduction occurs because the total yield of the simulated wind farms approaches a similar magnitude as the influx of kinetic energy. Additionally, KEBA estimates the slowing of the region's wind speeds, the associated reduction in electricity yields, and how both are due to the depletion of the horizontal influx of kinetic energy by the wind farms. This limits typical large-scale wind energy potentials to less than 1 W m−2 of surface area for wind farms with downwind lengths of more than 100 km, although this limit may be higher in windy regions. This reduction with downwind length makes these yields consistent with GCM-based idealized simulations of large-scale wind energy resource potentials. We conclude that KEBA is a transparent and informative modelling approach to advance the scientific understanding of wind energy limits, and can be used to estimate regional wind energy resource potentials that account for the depletion of wind speeds.

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The Kinetic Energy Budget of the Atmosphere (KEBA) model 1.0: a simple yet physical approach for estimating regional wind energy resource potentials that includes the kinetic energy removal effect by wind turbines

Geoscientific Model Development ◽

10.5194/gmd-13-4993-2020 ◽

2020 ◽

Vol 13 (10) ◽

pp. 4993-5005

Author(s):

Axel Kleidon ◽

Lee M. Miller

Keyword(s):

Kinetic Energy ◽

Wind Energy ◽

Energy Budget ◽

Wind Turbines ◽

Large Scale ◽

Energy Resource ◽

Wind Farms ◽

Energy Yield ◽

Wind Speeds ◽

Kinetic Energy Budget

Abstract. With the current expansion of wind power as a renewable energy source, wind turbines increasingly extract kinetic energy from the atmosphere, thus impacting its energy resource. Here, we present a simple, physics-based model (the Kinetic Energy Budget of the Atmosphere; KEBA) to estimate wind energy resource potentials that explicitly account for this removal effect. The model is based on the regional kinetic energy budget of the atmospheric boundary layer that encloses the wind farms of a region. This budget is shaped by horizontal and vertical influx of kinetic energy from upwind regions and the free atmosphere above, as well as the energy removal by the turbines, dissipative losses due to surface friction and wakes, and downwind outflux. These terms can be formulated in a simple yet physical way, yielding analytic expressions for how wind speeds and energy yields are reduced with increasing deployment of wind turbines within a region. We show that KEBA estimates compare very well to the modelling results of a previously published study in which wind farms of different sizes and in different regions were simulated interactively with the Weather Research and Forecasting (WRF) atmospheric model. Compared to a reference case without the effect of reduced wind speeds, yields can drop by more than 50 % at scales greater than 100 km, depending on turbine spacing and the wind conditions of the region. KEBA is able to reproduce these reductions in energy yield compared to the simulated climatological means in WRF (n=36 simulations; r2=0.82). The kinetic energy flux diagnostics of KEBA show that this reduction occurs because the total yield of the simulated wind farms approaches a similar magnitude as the influx of kinetic energy. Additionally, KEBA estimates the slowing of the region's wind speeds, the associated reduction in electricity yields, and how both are due to the depletion of the horizontal influx of kinetic energy by the wind farms. This limits typical large-scale wind energy potentials to less than 1 W m−2 of surface area for wind farms with downwind lengths of more than 100 km, although this limit may be higher in windy regions. This reduction with downwind length makes these yields consistent with climate-model-based idealized simulations of large-scale wind energy resource potentials. We conclude that KEBA is a transparent and informative modelling approach to advance the scientific understanding of wind energy limits and can be used to estimate regional wind energy resource potentials that account for the depletion of wind speeds.

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Estimating offshore wind power potentials that account for the kinetic energy removal by wind turbines: the Kinetic Energy Budget of the Atmosphere (KEBA) approach

10.5194/egusphere-egu2020-4988 ◽

2020 ◽

Author(s):

Axel Kleidon ◽

Lee Miller

Keyword(s):

Kinetic Energy ◽

Wind Energy ◽

Wind Power ◽

Energy Budget ◽

Wind Turbines ◽

Wind Farms ◽

Offshore Wind ◽

Offshore Wind Energy ◽

Offshore Wind Power ◽

Wind Speeds

Offshore wind power is seen as a large renewable energy resource due to the high and continuous wind speeds over the ocean.However, as wind farms expand in scale, wind turbines increasingly remove kinetic energy from the atmospheric flow, reducing wind speeds and expected electricity yields.Here we show that this removal effect of large wind farms and the drop in yields can be estimated in a relatively simple way by considering the kinetic energy budget of the lower atmosphere, which we refer to as the KEBA approach.We first show that KEBA can reproduce the estimated, climatological yields of wind farms of different sizes and locations using previously published numerical model simulations with an explicit wind farm representation.&#160; We then show the relevance of these reductions by evaluating the contribution of offshore wind energy in specific scenarios of Germany&#8217;s energy transition in the year 2050.Our estimates suggest that due to reduced wind speeds, mean capacity factors of wind farms are reduced to 33 - 39%, which is notably less than capacity factors above 50% that are commonly assumed in energy scenarios.This reduction is explained by KEBA by the depletion of the horizontal flow of kinetic energy by the wind farms and the low vertical renewal rate, which limits large-scale wind energy potentials to less than 1 W m-2 of surface area.We conclude that wind speed reductions are likely to play a substantial role in the further expansion of offshore wind energy and need to be considered in the planning process.These reduced yields can be estimated by a comparatively simple approach based on budgeting the kinetic energy of the atmosphere surrounding the wind farms.

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Supplementary material to "The Kinetic Energy Budget of the Atmosphere (KEBA) model 1.0: A simple yet physical approach for estimating regional wind energy resource potentials that includes the kinetic energy removal effect by wind turbines"

10.5194/gmd-2020-77-supplement ◽

2020 ◽

Author(s):

Axel Kleidon ◽

Lee M. Miller

Keyword(s):

Kinetic Energy ◽

Wind Energy ◽

Energy Budget ◽

Wind Turbines ◽

Energy Resource ◽

Kinetic Energy Budget ◽

Physical Approach ◽

Supplementary Material

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Review of the manuscript "The Kinetic Energy Budget of the Atmosphere (KEBA) model 1.0: A simple yet physical approach for estimating regional wind energy resource potentials that includes the kinetic energy removal effect by wind turbines"

10.5194/gmd-2020-77-rc1 ◽

2020 ◽

Keyword(s):

Kinetic Energy ◽

Wind Energy ◽

Energy Budget ◽

Wind Turbines ◽

Energy Resource ◽

Kinetic Energy Budget ◽

Physical Approach

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Offshore Wind Energy Resource Assessment across the Territory of Oman: A Spatial-Temporal Data Analysis

Sustainability ◽

10.3390/su13052862 ◽

2021 ◽

Vol 13 (5) ◽

pp. 2862

Author(s):

Amer Al-Hinai ◽

Yassine Charabi ◽

Seyed H. Aghay Kaboli

Keyword(s):

Data Analysis ◽

Wind Energy ◽

Wind Turbines ◽

Energy Resource ◽

Wind Farms ◽

Offshore Wind ◽

Wind Data ◽

Offshore Wind Energy ◽

Offshore Wind Turbines ◽

Wind Potential

Despite the long shoreline of Oman, the wind energy industry is still confined to onshore due to the lack of knowledge about offshore wind potential. A spatial-temporal wind data analysis is performed in this research to find the locations in Oman’s territorial seas with the highest potential for offshore wind energy. Thus, wind data are statistically analyzed for assessing wind characteristics. Statistical analysis of wind data include the wind power density, and Weibull scale and shape factors. In addition, there is an estimation of the possible energy production and capacity factor by three commercial offshore wind turbines suitable for 80 up to a 110 m hub height. The findings show that offshore wind turbines can produce at least 1.34 times more energy than land-based and nearshore wind turbines. Additionally, offshore wind turbines generate more power in the Omani peak electricity demand during the summer. Thus, offshore wind turbines have great advantages over land-based wind turbines in Oman. Overall, this work provides guidance on the deployment and production of offshore wind energy in Oman. A thorough study using bankable wind data along with various logistical considerations would still be required to turn offshore wind potential into real wind farms in Oman.

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Simulation of Flow Field on a Large Scale Wind Turbine

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2008-55189 ◽

2008 ◽

Author(s):

I. Janajreh ◽

C. Ghenai

Keyword(s):

Flow Field ◽

Wind Energy ◽

Wind Turbine ◽

Wind Turbines ◽

Cross Sections ◽

Large Scale ◽

Wind Farms ◽

Operating Characteristics ◽

Cross Sectional ◽

Capital Costs

Large scale wind turbines and wind farms continue to evolve mounting 94.1GW of the electrical grid capacity in 2007 and expected to reach 160.0GW in 2010 according to World Wind Energy Association. They commence to play a vital role in the quest for renewable and sustainable energy. They are impressive structures of human responsiveness to, and awareness of, the depleting fossil fuel resources. Early generation wind turbines (windmills) were used as kinetic energy transformers and today generate 1/5 of the Denmark’s electricity and planned to double the current German grid capacity by reaching 12.5% by year 2010. Wind energy is plentiful (72 TW is estimated to be commercially viable) and clean while their intensive capital costs and maintenance fees still bar their widespread deployment in the developing world. Additionally, there are technological challenges in the rotor operating characteristics, fatigue load, and noise in meeting reliability and safety standards. Newer inventions, e.g., downstream wind turbines and flapping rotor blades, are sought to absorb a larger portion of the cost attributable to unrestrained lower cost yaw mechanisms, reduction in the moving parts, and noise reduction thereby reducing maintenance. In this work, numerical analysis of the downstream wind turbine blade is conducted. In particular, the interaction between the tower and the rotor passage is investigated. Circular cross sectional tower and aerofoil shapes are considered in a staggered configuration and under cross-stream motion. The resulting blade static pressure and aerodynamic forces are investigated at different incident wind angles and wind speeds. Comparison of the flow field results against the conventional upstream wind turbine is also conducted. The wind flow is considered to be transient, incompressible, viscous Navier-Stokes and turbulent. The k-ε model is utilized as the turbulence closure. The passage of the rotor blade is governed by ALE and is represented numerically as a sliding mesh against the upstream fixed tower domain. Both the blade and tower cross sections are padded with a boundary layer mesh to accurately capture the viscous forces while several levels of refinement were implemented throughout the domain to assess and avoid the mesh dependence.

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Two methods for estimating limits to large-scale wind power generation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1408251112 ◽

2015 ◽

Vol 112 (36) ◽

pp. 11169-11174 ◽

Cited By ~ 32

Author(s):

Lee M. Miller ◽

Nathaniel A. Brunsell ◽

David B. Mechem ◽

Fabian Gans ◽

Andrew J. Monaghan ◽

...

Keyword(s):

Power Generation ◽

Kinetic Energy ◽

Wind Power ◽

Energy Flux ◽

Wind Turbines ◽

Large Scale ◽

Wind Farms ◽

Wind Power Generation ◽

Flux Method ◽

Free Atmosphere

Wind turbines remove kinetic energy from the atmospheric flow, which reduces wind speeds and limits generation rates of large wind farms. These interactions can be approximated using a vertical kinetic energy (VKE) flux method, which predicts that the maximum power generation potential is 26% of the instantaneous downward transport of kinetic energy using the preturbine climatology. We compare the energy flux method to the Weather Research and Forecasting (WRF) regional atmospheric model equipped with a wind turbine parameterization over a 105 km2 region in the central United States. The WRF simulations yield a maximum generation of 1.1 We⋅m−2, whereas the VKE method predicts the time series while underestimating the maximum generation rate by about 50%. Because VKE derives the generation limit from the preturbine climatology, potential changes in the vertical kinetic energy flux from the free atmosphere are not considered. Such changes are important at night when WRF estimates are about twice the VKE value because wind turbines interact with the decoupled nocturnal low-level jet in this region. Daytime estimates agree better to 20% because the wind turbines induce comparatively small changes to the downward kinetic energy flux. This combination of downward transport limits and wind speed reductions explains why large-scale wind power generation in windy regions is limited to about 1 We⋅m−2, with VKE capturing this combination in a comparatively simple way.

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An Analysis of Wind Power Generation on the Electric Transmission System of Southern Vietnam

WSEAS TRANSACTIONS ON POWER SYSTEMS ◽

10.37394/232016.2021.16.21 ◽

2021 ◽

Vol 16 ◽

pp. 204-212

Author(s):

Minh-Hoa Nguyen ◽

Van-Tan Tran ◽

Tan-Hung Pham ◽

Thanh-Luu Cao

Keyword(s):

Power Generation ◽

Power Systems ◽

Power System ◽

Wind Energy ◽

Wind Turbines ◽

Wind Farm ◽

Wind Farms ◽

Wind Speeds ◽

Southern Vietnam ◽

Three Phase

Renewable energy is an emerging candidate in power generation for the compensation of the exhausted fossil fuel, in which wind energy plays an important role. However, how wind farms impact existing power systems has still been a subject on which many researchers are studying. This study has analyzed and evaluated the four wind farms consisting of Ca-Mau (300 MW), Bac-Lieu (99 MW), Soc-Trang (100 MW) and Tra-Vinh (33 MW) located in Southern Vietnam via using the commercial package, WAsP software. Ca-Mau wind farm has the highest planned rated capacity with 51.7% among the wind farms. Each wind farm is built from three different types of wind turbines (1 MW, 2 MW and 3 MW). The estimation has shown that all of the wind farms could produce 2,265 GWh annually, and the 3-MW wind turbines are the most efficient and give the smallest losses for producing wind energy. The wind farms, with respect to environmentally friendly aspects, could avoid 978,544 tCO2 emitted to the environment annually. Additionally, the ETAP program has also been applied to simulate the effects of the proposed wind farms on the national power system including the disturbances from wind speeds, three-phase bus faults, tripping off wind farms and three-phase line faults on the power system. The results show that the wind farms are only slightly impacted.

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