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Page added on October 5, 2018

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Wind farms cause global warming

Wind farms cause global warming thumbnail

When it comes to energy production, there’s no such thing as a free lunch, unfortunately.

As the world begins its large-scale transition toward low-carbon energy sources, it is vital that the pros and cons of each type are well understood and the environmental impacts of renewable energy, small as they may be in comparison to coal and gas, are considered.

In two papers — published today in the journals Environmental Research Letters and Joule — Harvard University researchers find that the transition to wind or solar power in the U.S. would require five to 20 times more land than previously thought, and, if such large-scale wind farms were built, would warm average surface temperatures over the continental U.S. by 0.24 degrees Celsius.

“Wind beats coal by any environmental measure, but that doesn’t mean that its impacts are negligible,” said David Keith, the Gordon McKay Professor of Applied Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and senior author of the papers. “We must quickly transition away from fossil fuels to stop carbon emissions. In doing so, we must make choices between various low-carbon technologies, all of which have some social and environmental impacts.”

Keith is also professor of public policy at the Harvard Kennedy School.

One of the first steps to understanding the environmental impact of renewable technologies is to understand how much land would be required to meet future U.S. energy demands. Even starting with today’s energy demands, the land area and associated power densities required have long been debated by energy experts.

In previous research, Keith and co-authors modeled the generating capacity of large-scale wind farms and concluded that real-world wind power generation had been overestimated because they neglected to accurately account for the interactions between turbines and the atmosphere.

In 2013 research, Keith described how each wind turbine creates a “wind shadow” behind it where air has been slowed down by the turbine’s blades. Today’s commercial-scale wind farms carefully space turbines to reduce the impact of these wind shadows, but given the expectation that wind farms will continue to expand as demand for wind-derived electricity increases, interactions and associated climatic impacts cannot be avoided.

What was missing from this previous research, however, were observations to support the modeling. Then, a few months ago, the U.S. Geological Survey released the locations of 57,636 wind turbines around the U.S. Using this data set, in combination with several other U.S. government databases, Keith and postdoctoral fellow Lee Miller were able to quantify the power density of 411 wind farms and 1,150 solar photovoltaic plants operating in the U.S. during 2016.

“For wind, we found that the average power density — meaning the rate of energy generation divided by the encompassing area of the wind plant — was up to 100 times lower than estimates by some leading energy experts,” said Miller, who is the first author of both papers. “Most of these estimates failed to consider the turbine-atmosphere interaction. For an isolated wind turbine, interactions are not important at all, but once the wind farms are more than five to 10 kilometers deep, these interactions have a major impact on the power density.”

The observation-based wind power densities are also much lower than important estimates from the U.S. Department of Energy and the Intergovernmental Panel on Climate Change.

For solar energy, the average power density (measured in watts per meter squared) is 10 times higher than wind power, but also much lower than estimates by leading energy experts.

This research suggests that not only will wind farms require more land to hit the proposed renewable energy targets but also, at such a large scale, would become an active player in the climate system.

The next question, as explored in the journal Joule, was how such large-scale wind farms would impact the climate system.

To estimate the impacts of wind power, Keith and Miller established a baseline for the 2012‒2014 U.S. climate using a standard weather-forecasting model. Then, they covered one-third of the continental U.S. with enough wind turbines to meet present-day U.S. electricity demand. The researchers found this scenario would warm the surface temperature of the continental U.S. by 0.24 degrees Celsius, with the largest changes occurring at night when surface temperatures increased by up to 1.5 degrees. This warming is the result of wind turbines actively mixing the atmosphere near the ground and aloft while simultaneously extracting from the atmosphere’s motion.

This research supports more than 10 other studies that observed warming near operational U.S. wind farms. Miller and Keith compared their simulations to satellite-based observational studies in North Texas and found roughly consistent temperature increases.

Miller and Keith are quick to point out the unlikeliness of the U.S. generating as much wind power as they simulate in their scenario, but localized warming occurs in even smaller projections. The follow-on question is then to understand when the growing benefits of reducing emissions are roughly equal to the near-instantaneous impacts of wind power.

The Harvard researchers found that the warming effect of wind turbines in the continental U.S. was actually larger than the effect of reduced emissions for the first century of its operation. This is because the warming effect is predominantly local to the wind farm, while greenhouse gas concentrations must be reduced globally before the benefits are realized.

Miller and Keith repeated the calculation for solar power and found that its climate impacts were about 10 times smaller than wind’s.

“The direct climate impacts of wind power are instant, while the benefits of reduced emissions accumulate slowly,” said Keith. “If your perspective is the next 10 years, wind power actually has — in some respects — more climate impact than coal or gas. If your perspective is the next thousand years, then wind power has enormously less climatic impact than coal or gas.

“The work should not be seen as a fundamental critique of wind power,” he said. “Some of wind’s climate impacts will be beneficial — several global studies show that wind power cools polar regions. Rather, the work should be seen as a first step in getting more serious about assessing these impacts for all renewables. Our hope is that our study, combined with the recent direct observations, marks a turning point where wind power’s climatic impacts begin to receive serious consideration in strategic decisions about decarbonizing the energy system.”

Harvard.edu



12 Comments on "Wind farms cause global warming"

  1. rockman on Fri, 5th Oct 2018 10:11 am 

    And once again the false assumption that alt energy is required to supply 100% of US energy demand. Interesting they point out Texas in their model. Of course as I’ve pointed out many times no one in Texas has ever proposed our wind farms would replace any of our current energy sources. Such as our NG powered and especially large coal/lignite generation. In reality we’ve not replaced one Btu of our conventional electricity sources with our very big wind power build. Instead wind power has allowed us to NOT BUILD ADDITTIONAL coal/lignite and NG fueled power plants. Which would have been numerous given our past and future significant increase in electricity demand.

    They can model it anyway they want. But I doubt few would believe a fossil fuel power plant is a better environmental option then a wind farm. At least in Texas, by far the largest electricity consuming state in the country.

  2. Outcast_Searcher on Fri, 5th Oct 2018 2:24 pm 

    Let’s pretend that the imperfect is the enemy of the good. That way we don’t have to DO anything but blame everyone else as AGW worsens and the consequences come home to roost.

    Because, after all, BAU and ignoring consequences has always worked out so well in the past.

    And yes, if you missed it, I am being sarcastic.

  3. Antius on Fri, 5th Oct 2018 3:55 pm 

    David McKay calculated some years ago, that the maximum power density achievable using wind turbines is 2-3W/m2. The limit is set by wind shadowing. So a 1000km2 wind farm could generate a maximum time averaged power 3GW – More likely 2GW.

  4. Anonymouse1 on Fri, 5th Oct 2018 7:37 pm 

    It is even worse than many of you realize. If anything, Harvard.bs is understating the danger that wind represents.

    Wind power, could very well blow the Earth right out of its orbit. True. Watch and learn more…

    https://www.youtube.com/watch?v=F0UkH81NMTo

  5. Davy on Fri, 5th Oct 2018 7:52 pm 

    Wow, the gimp is talkative tonight

  6. Davy on Sat, 6th Oct 2018 1:27 am 

    “New Mexico Approves Pattern Energy’s 2.2 Gigawatt Corona Wind Projects Plan”
    https://tinyurl.com/yb89evhy

    “The New Mexico Public Regulation Commission has opened the door for Pattern Energy to begin construction on an estimated 950 wind turbines as part of its Corona Wind Projects which will boast capacity of 2,200 megawatts (MW).”

    “Set to be built near Corona in Lincoln County, New Mexico, and expected to be completed by the end of 2020, the projects are estimated to generate $3.8 billion in economic impact for the region, hiring hundreds of workers during construction and supporting approximately 100 jobs during operation.”

  7. Anonymouse1 on Sat, 6th Oct 2018 2:29 am 

    I am the davyturd is delusional tonight. And every other night, actually.

  8. Cloggie on Sat, 6th Oct 2018 2:56 am 

    David McKay calculated some years ago, that the maximum power density achievable using wind turbines is 2-3W/m2. The limit is set by wind shadowing. So a 1000km2 wind farm could generate a maximum time averaged power 3GW – More likely 2GW.

    https://en.wikipedia.org/wiki/David_J._C._MacKay

    Even if Mackay would be right with his 2-3 GW/1000 km2 (Dutch offshore windpark Gemini for instance is doing fine generating 0.6 GW in an area of 68 km2), a big if, the shallow 600,000 km2 offshore area available for wind (North Sea, Baltic, Irish Sea) would still be 600 x 2-3 GW = 1200-1800 GW.

    500 million EU average electricity consumption is 300 GW.

    Thanks mr Mackay for promoting wind energy for us.

    There is enough potential to generate the required kWh’s, if you include solar, onshore wind, hydro and biomass. The key challenge in 2018 is storage, not energy generation.

  9. Free Speech Message Board on Sat, 6th Oct 2018 7:26 am 

    Life is not really that dangerous, but Americans want to live in a police state because there MIGHT be danger.

  10. Dredd on Sat, 6th Oct 2018 12:39 pm 

    Oilah Akbar …

  11. Cloggie on Sun, 7th Oct 2018 4:31 am 

    “If your perspective is the next 10 years, wind power actually has — in some respects — more climate impact than coal or gas. If your perspective is the next thousand years, then wind power has enormously less climatic impact than coal or gas.”

    If your perspective is the next 10 years, wind power actually has — in some respects — more climate impact than coal or gas. If your perspective is the next thousand years, then wind power has enormously less climatic impact than coal or gas.

    The most important takeaway points.

  12. Cloggie on Sun, 7th Oct 2018 4:38 am 

    “Wind Power Does Not Cause Global Warming — Is One Of The Best Solutions”

    (And two Harvard researchers did not suggest it does.)

    https://cleantechnica.com/2018/10/06/wind-power-does-not-cause-global-warming-is-one-of-the-best-solutions/

    “Ørsted Completes Acquisition Of Lincoln Clean Energy To Form Onshore Wind Business”

    https://cleantechnica.com/2018/10/05/orsted-completes-acquisition-of-lincoln-clean-energy-to-form-onshore-wind-business/

    Danish wind energy giant taking over US wind company.

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