GCC: Harvard team finds large-scale US wind power would cause warming that would take roughly a century to offset

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GRA

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http://www.greencarcongress.com/2018/10/20181005-wind.html

All large-scale energy systems have environmental impacts, and the ability to compare the impacts of renewable energy sources is an important step in planning a future without coal or gas power. Extracting energy from the wind causes climatic impacts that are small compared to current projections of 21st century warming, but large compared to the effect of reducing US electricity emissions to zero with solar.

In the journal Joule, Harvard researchers report the most accurate modelling yet of how increasing wind power would affect climate. They find that large-scale wind power generation would warm the Continental United States 0.24 degrees Celsius because wind turbines redistribute heat in the atmosphere.

  • Wind beats coal by any environmental measure, but that doesn’t mean that its impacts are negligible. 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.

    —senior author David Keith, an engineering and public policy professor at Harvard. . . .

To compare the impacts of wind and solar, Keith and Miller started by establishing a baseline for the 2012-2014 US climate using a standard weather forecasting model. Then they added in the effect on the atmosphere of covering one third of the Continental US with enough wind turbines to meet present-day US electricity demand. This is a relevant scenario if wind power plays a major role in decarbonizing the energy system in the latter half of this century. This scenario would warm the surface temperature of the Continental US by 0.24 degrees Celsius.

Their analysis focused on the comparison of climate impacts and benefits. They found that it would take about a century to offset that effect with wind-related reductions in greenhouse gas concentrations. This timescale was roughly independent of the specific choice of total wind power generation in their scenarios.

  • The direct climate impacts of wind power are instant, while the benefits accumulate slowly. 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 is enormously cleaner than coal or gas.

    —David Keith. . . .

More than ten previous studies have now observed local warming caused by US wind farms. Keith and Miller compared their simulated warming to observations and found rough consistency between the observations and model. . . .

[list]In terms of temperature difference per unit of energy generation, solar power has about 10 times less impact than wind. But there are other considerations. For example, solar farms are dense, whereas the land between wind turbines can be co-utilized for agriculture.

—Lee Miller. . . . [/list]

Keith and Miller's simulations do not consider any impacts on global-scale meteorology, so it remains somewhat uncertain how such a deployment of wind power may affect the climate in other countries. . . .

This research was funded by the Fund for Innovative Climate and Energy Research. David Keith is a board member and acting chief scientist at Carbon Engineering, a clean energy company that aims to make carbon-neutral transportation fuels from wind and solar power.
The bolded quote is something I've been emphasizing since I was designing and selling off-grid equipment and systems. Every tech or approach has an impact, you make choices based on the advantages and disadvantages of each and your priorities. TAANSTAAFL.
 
I think the take away from this is that there's no such thing as "guilt-free" power generation. All the known ways have their downsides, even if we are not aware of them at first. For example, before this article, there was concern about large wind turbines killing off birds. Another power generation method that has been known to kill birds (literally in mid-air) is the concentrated solar method like at the Ivanpah plant outside of Las Vegas.

I've heard people talk of hydroelectric as "clean" electricity and while that is true from a fuels standpoint, it's got its own considerable environmental impacts. And of course, nuclear power generation has a lot of its own impacts, and concerns about safety.
 
GRA said:
SageBrush said:
This sounds like heat re-distribution.
Uh, yeah:
They find that large-scale wind power generation would warm the Continental United States 0.24 degrees Celsius because wind turbines redistribute heat in the atmosphere.
It is an important distinction to make. E.g., the oceans are not involved. And as wind is sited higher up the effect diminishes. Nor does it affect the ice masses.
 
Did I read that correctly?

Did their study conclude that wind generation is worse for global warming than burning coal or natural gas in the short term? And it only works out as better than coal or gas in the 100 to 1,000 year view?

I can see solar being better than wind in that regard. But I find it hard to believe that the operation of a wind turbine is going to cause more heat per unit of energy produced than burning a fossil fuel. Also, burning that fossil fuel needs to be burdened with the production impacts to extract it, transport it, refine it, and transport it again to where it will be burned.

Please tell me I misread that.
 
DarthPuppy said:
Did I read that correctly?

Did their study conclude that wind generation is worse for global warming than burning coal or natural gas in the short term? And it only works out as better than coal or gas in the 100 to 1,000 year view?

If you look only at the USA Midwest surface only... Wind power changes local climate, not global climate. And not by heating the air, rather by mixing the air better.
 
LeftieBiker said:
Harvard is known for being a factory for industry-friendly studies.
Tossing in an ad-hominem fallacy adds nothing to this discussion.

In addition, let's not lose sight of the plain fact that the manufacture, distribution, and operation of wind turbines is, itself, a massive, growing industry.
 
GRA said:
http://www.greencarcongress.com/2018/10/20181005-wind.html

[list]In terms of temperature difference per unit of energy generation, solar power has about 10 times less impact than wind. But there are other considerations. For example, solar farms are dense, whereas the land between wind turbines can be co-utilized for agriculture.

—Lee Miller. . . . [/list]

This is why I dislike "solar farms". There are many better uses for that land (including keeping it as wild habitat!) then large arrays of solar panels. Instead, solar should be focused on rooftop installations - that way the land has true dual-use. We are a long way from saturating the usable roof space.

Now a real impact of solar is the energy-intensive production process. I was told that the EROEI for my panels was almost 10 years. It may have gotten better since, but it will always be greater than zero for any energy generation.
 
GetOffYourGas said:
GRA said:
http://www.greencarcongress.com/2018/10/20181005-wind.html

[list]In terms of temperature difference per unit of energy generation, solar power has about 10 times less impact than wind. But there are other considerations. For example, solar farms are dense, whereas the land between wind turbines can be co-utilized for agriculture.

—Lee Miller. . . . [/list]

This is why I dislike "solar farms". There are many better uses for that land (including keeping it as wild habitat!) then large arrays of solar panels. Instead, solar should be focused on rooftop installations - that way the land has true dual-use. We are a long way from saturating the usable roof space.

Now a real impact of solar is the energy-intensive production process. I was told that the EROEI for my panels was almost 10 years. It may have gotten better since, but it will always be greater than zero for any energy generation.
EROI is about 2 years.

I've seen photos of ground mounts in Europe where they continue to use the land for agriculture.
 
SageBrush said:
GetOffYourGas said:
GRA said:

This is why I dislike "solar farms". There are many better uses for that land (including keeping it as wild habitat!) then large arrays of solar panels. Instead, solar should be focused on rooftop installations - that way the land has true dual-use. We are a long way from saturating the usable roof space.

Now a real impact of solar is the energy-intensive production process. I was told that the EROEI for my panels was almost 10 years. It may have gotten better since, but it will always be greater than zero for any energy generation.
EROI is about 2 years.

I've seen photos of ground mounts in Europe where they continue to use the land for agriculture.

Both good news. I'm impressed if we've really improved EROEI by a factor of 5 in only 7 years.

I've never seen a ground mount system in the US, where the land is used for anything else. I'm not saying it doesn't exist, but it is the exception in both the Northeast and the Southwest where I have seen large solar farms. I still think rooftop is our best option, since the buildings (and roofs) already exist.
 
GetOffYourGas said:
I've never seen a ground mount system in the US, where the land is used for anything else. I'm not saying it doesn't exist, but it is the exception in both the Northeast and the Southwest where I have seen large solar farms. I still think rooftop is our best option, since the buildings (and roofs) already exist.
I'm a rooftop fan too, but so far it is a lot more expensive than large scale ground mount with rotating arrays. I like the middle ground on this issue: ground mount for poor quality land or in a dual-use.

I also like to point out that the worse case use of good land for PV is still a whole lot better than growing crops for beef or ethanol.
 
GetOffYourGas said:
SageBrush said:
GetOffYourGas said:
This is why I dislike "solar farms". There are many better uses for that land (including keeping it as wild habitat!) then large arrays of solar panels. Instead, solar should be focused on rooftop installations - that way the land has true dual-use. We are a long way from saturating the usable roof space.

Now a real impact of solar is the energy-intensive production process. I was told that the EROEI for my panels was almost 10 years. It may have gotten better since, but it will always be greater than zero for any energy generation.
EROI is about 2 years.

I've seen photos of ground mounts in Europe where they continue to use the land for agriculture.

Both good news. I'm impressed if we've really improved EROEI by a factor of 5 in only 7 years.

I've never seen a ground mount system in the US, where the land is used for anything else. I'm not saying it doesn't exist, but it is the exception in both the Northeast and the Southwest where I have seen large solar farms. I still think rooftop is our best option, since the buildings (and roofs) already exist.
Rooftop gives the best power density and lowest environmental impact, but the amount of it is strictly limited. Smil's book on power density includes the results of a study of rooftop solar potential in the Tokyo Metro area, which is currently the world''s largest megacity and representative of forecasts for where most of the world's urban population growth will be concentrated between now and 2050, and looking at all available roofspace in that area, it's orientation etc., IIRR the conclusion was that no more than about 10% of the metro area's demand could be generated using rooftop PV only. Germany has the highest % of rooftop solar in the world (and 44.3 GW total PV, both roof and ground mount, as of July), owing to extensive subsidies (which have been and are being gradually reduced). Per Smil the size of the rooftop systems have been increasing, with more and more going on MUDs and commercial buildings rather than detached homes.

Unfortunately I had to return the book to the library (interlibrary loan), so I don't have the exact figures handy and am working from memory. Just to remind everyone who's interested in what the actual power densities of deployed renewables are, I highly recommend it (like I do all of Smil's books I've read, especially those on energy transitions and technological change):

Power Density: A Key to Understanding Energy Sources and Uses
https://www.amazon.com/Power-Density-Understanding-Energy-Sources/dp/0262529734

Re ground mounts, parking lots show how PV can allow concurrent usage, although whether the typical monopole supports count as ground mounting is arguable:
The Design Basics for Solar Parking Lots You Need to Know
https://www.designnews.com/material...lar-parking-lots-you-need-know/96305277745717

Still, if there's enough room to park cars under the panels there's enough room for grazing/horticulture/silviculture (xmas tree farms etc.) if the amount of light getting through and around the panels is adequate for photosynthesis, assuming the concrete pads for the pole bases are kept small. The tradeoff for allowing concurrent use for such mounts is that the tilt angle is normally kept quite low, reducing the capacity factor. Providing water to clean panels in desert areas may be a bigger issue.

Re EROEI, ten years seems far too long, as even a decade or two back the number was around 3-4 years IIRC. However, even if it were 10 years, as the panels will be useful for 40 or more (with decreased output, to be sure) you're still well ahead.
 
Tokyo is an extreme case, Guy. And 2050 is several decades from now. Meanwhile, in 2018, most of the solar farms in the northeast reside in freshly deforested areas, and not high enough for anything to grow beneath them. In many cases, they are near large buildings with plenty of roof space. The trouble is that the panels cannot be seen from the road, so no one would know how "green" the business/college/etc is!

Parking lots are a great option, especially in hotter climates - the panels provide shade, keeping the cars cooler and reducing their energy usage for A/C.

Regarding the 10 year number, that was a number I was given. I didn't dig any deeper than that. The panels / inverters are warrantied for 25 years, so I'm sure I will end up ahead. Although, as Reg knows from another thread, my inverters have been failing at an alarming rate. I have lost 9 of the 16 inverters in the less than 7 years that my system has been operational. I'm currently running on 14 functioning inverters, while I wait for my installer to replace the most recently failed inverters.
 
You beat me to it. I was just about to say that Tokyo is a rather dense population city and therefore tilts toward rooftop solar being inadequate. The study would be quite a bit more enlightening if it looked at 2 extremes - say Tokyo vs. Los Angeles. In LA, we have tons of roof space for our population versus the roof space in Tokyo. Then for most cities, the results will be within that known range.

Also, rooftop solar is an excellent route to take until the rooftop space is consumed. If we can produce 30% of our solar that way, that is a lot less other land that has to be consumed for solar production.

One area of consideration I'd like to know more about is the merits of rooftop solar versus rooftop gardens. On Facebook, I recently saw an interesting article touting rooftop gardens and how some cities are moving in that direction. Both are clearly a better use of rooftops than most cities have in place. But which of these two uses is better?
 
DarthPuppy said:
You beat me to it. I was just about to say that Tokyo is a rather dense population city and therefore tilts toward rooftop solar being inadequate. The study would be quite a bit more enlightening if it looked at 2 extremes - say Tokyo vs. Los Angeles. In LA, we have tons of roof space for our population versus the roof space in Tokyo.

There's also the fact that Los Angeles gets much more sunshine than Tokyo:

average-sunshine-united-states-of-america-los-angeles.png


average-sunshine-japan-tokyo.png


LA's least-sunny months (Dec and January) are still better than Tokyo's most sunny. In fact, Seattle (despite its reputation for being eternally cloudy and rainy) actually sees more sunshine between mid-March and mid-September than in the sunniest months in Tokyo:

average-sunshine-united-states-of-america-seattle.png
 
Wow, I had no idea that there was that much of a difference in sunlight between Tokyo and LA. That further accentuates these two belong at the opposite ends of the spectrum. Tokyo has very dense population so less rooftop space per capita and less sunlight throughout the year vs. LA has lots of roof space per capita and pretty good sunlight to make use of that space.

Using these two as measurement points would do a pretty good job of establishing the relevant range into which many cities would find themselves. And that would be much more useful than a study of just one of them. A study that picks just one, and it is one that is an extreme case in one direction, raises doubts about the intent of the study.
 
GetOffYourGas said:
Tokyo is an extreme case, Guy. And 2050 is several decades from now. Meanwhile, in 2018, most of the solar farms in the northeast reside in freshly deforested areas, and not high enough for anything to grow beneath them. In many cases, they are near large buildings with plenty of roof space. The trouble is that the panels cannot be seen from the road, so no one would know how "green" the business/college/etc is!
It's an extreme case in that it's the world's largest megacity now, but megacities, especially in Asia, are going to see the majority of urban growth (which is to say the majority of population growth period) for at least the first half of this century (also the greatest number of car sales), and the power density demands of their tall tower blocks are high. Smil also discusses studies about actual power densities, available roof (and wall) areas of other cities, including in the U.S., and they are in the same order of magnitude. Phoenix is obviously better than Berlin, both because of insolation but also because of the types of buildings. Even so, no city can provide more than a minority fraction of its electricity use from rooftop PV - the power densities of variable renewables are too low, even though rooftop PV is the highest among them. I really can't type the details of the whole book in, even if I remembered them all accurately, so again I recommend people who are really interested to read it. His data is provided from numerous real-world systems.

In fact, let me give Smil's books (who's Bill Gates' favorite author, FWIW) a general recommendation, as so many of the subjects he writes about are of interest to people on this forum. I've got his "Should we eat meat? : evolution and consequences of modern carnivory" en route, but "Harvesting the biosphere : what we have taken from nature" might also be of interest, along with many of his other books.
 
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