Atmospheric 'sunshade' could reduce solar power generation

Atmospheric 'sunshade' could reduce solar power generation
The world's largest solar power facility, located near Kramer Junction, Calif., consists of five Solar Electric Generating Stations and covers more than 1,000 acres. (Credit: Department of Energy/National Renewable Energy Laboratory)

The concept of delaying global warming by adding particles into the upper atmosphere to cool the climate could unintentionally reduce peak electricity generated by large solar power plants by as much as one-fifth, according to a new NOAA study. The findings appear in this week's issue of Environmental Science and Technology.

"Injecting into the stratosphere could have unintended consequences for one expected to play a role in the transition away from fossil fuels," said author Daniel Murphy, a scientist at NOAA's Earth System Research Laboratory in Boulder, Colo.

The Earth is heating up as fossil-fuel burning produces carbon dioxide, the primary heat-trapping gas responsible for man-made . To counteract the effect, some geoengineering proposals are designed to slow global warming by shading the Earth from .

Among the ideas being explored is injecting small particles into the upper atmosphere to produce a climate cooling similar to that of large , such as Mt. Pinatubo's in 1991. Airborne sulfur hovering in the stratosphere cooled the Earth for about two years following that eruption.

Murphy found that particles in the stratosphere reduce the amount and change the nature of the sunlight that strikes the Earth. Though a fraction of the incoming sunlight bounces back to space (the cooling effect), a much larger amount becomes "diffuse" or .

On average, for every watt of sunlight the particles reflect away from the Earth, another three watts of direct sunlight are converted to diffuse sunlight. Large power-generating solar plants that concentrate sunlight for depend solely on direct sunlight and cannot use diffuse light.

Murphy verified his calculations using long-term NOAA observations of direct and diffuse sunlight before and after the 1991 eruption.

After the eruption of Mt. Pinatubo, peak power output of Solar Electric Generating Stations in California, the largest collective of plants in the world, fell by up to 20 percent, even though the from the eruption reduced total sunlight that year by less than 3 percent.

"The sensitivity of concentrating solar systems to stratospheric particles may seem surprising," said Murphy. "But because these systems use only direct sunlight, increasing stratospheric particles has a disproportionately large effect on them."

Nine Solar Electric Generating Stations operate in California and more are running or are under construction elsewhere in the world. In sunny locations such systems, which use curved mirrors or other concentrating devices, generate electricity at a lower cost than conventional photovoltaic, or solar, cells.

Flat photovoltaic and hot water panels, commonly seen on household roofs, use both diffuse and direct sunlight. Their energy output would decline much less than that from concentrating systems.

Even low-tech measures to balance a home's energy, such as south-facing windows for winter heat and overhangs for summer shade, would be less effective if direct sunlight is reduced.

Source: NOAA

Explore further

AT&T to put 8,000 natural-gas vehicles on road

Citation: Atmospheric 'sunshade' could reduce solar power generation (2009, March 11) retrieved 18 August 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Mar 11, 2009
Assuming you buy the whole AGW argument to begin with...well so what?

So we use nuclear power instead (like we should be anyway).

Mar 11, 2009
Adding these particles into the atmosphere would be a severe risk as it may cause unexpected effects which are more dangerous than global warming.

Modernmystic - I disagree, the main drawback of nuclear power is that there is waste and it relies on non-renewable uranium resources. Renewable sources of power like Hydro and Wind are much better.

Mar 11, 2009
Modernmystic - I disagree, the main drawback of nuclear power is that there is waste...

The "waste"(slightly used nuclear fuel) is a resource if you allow it to be used.

... and it relies on non-renewable uranium resources.

There's no such thing as renewable energy(see the second law of thermodynamics for reference). There's enough uranium and thorium(if used judiciously, not if you use it to 0.5% and go to great lengths to prevent using the 99.5% remaining, labeling it as waste) for the remaining ~1 billion years the surface of the Earth will be habitable by humans.

Renewable sources of power like Hydro and Wind are much better.

Hydro is a lovely powersource(if you don't care too much about environmental impact), but it's very limited in the size of the resource.

There's no such thing as wind power; it's just a marketing tool by the natural gas an coal industry(it probably slightly reduces the consumption of natural gas and coal, but even that's questionable when simple cycle gas turbines must be used rather than CCGT).

Mar 12, 2009
-- just posing an argument to the wind issue... Granted -- IT is true wind produces very little power --- but if you placed a lot of those suckers you could generate a heck of a lot of power -- you just can't get it very far from the source - but hey almost all of our power neeeds would dissapear today if superconducting wires could be used for energy transmission.

THe day we can produce wuper high temperature superconductors is the day the world stops worring about how power is produced. --- Cause lets face it half of the energy produced is wasted overcomming the resistance to get it to the spot it needs to be used.

Mar 12, 2009
Atmospheric 'sunshade' could reduce solar power generation

My 8-year old told me this after I told him how they were studying partially block the sun to stop the planet from over-heating...out of the mouths of babes!

Mar 13, 2009
Wind power relies on fossil fuel or another secondary energy just to power it's ability to generate power.

However, once the turbines are made their reliance on fossil fuels is quite minimal. I do dispute their usage however, since they rely upon "unreliable" outside forces.
Other sources dependent upon tides and wave action would be much more reliable, and are not receiving the focus they deserve. Unless the moon is somehow destroyed, the tides will continue to rise and fall, like clock-work, as they always have.And the Gulf-stream will continue to flow, as long as this planet rotates.
Pound for pound water gives alot more bang for the buck, and it happens to cover 2/3'rds of this planet (and soon to be more....evidently :) )

Mar 14, 2009
That is blatantly false. Once the turbines are made their dependence on fossil fuels begins. You need coal, oil, or gas fired plants to generate the energy to keep the wind turbine spinning when the wind power is below threshold.

Perhaps you are talking about the smaller hybrid systems, used for off-grid applications ( ) ...Is this the they they are all made in YOUR country? Here in North America, they are not. You are blatantly misinformed.
You're stopping the tide by removing it's energy and utilizing it else where. Tides and waterways have a far greater effect of global temperatures than CO2 does.

And now we are able to actually stop the tides??? lol
Are you suggesting that a 1000m trough cut into a coastline would affect the temperature of the planet? If anything it would drop the sea level, which would be a GOOD thing.

Mar 15, 2009
Wind power must compete with conventional generation sources on a cost basis. Depending on how energetic a wind site is, the wind farm may or may not be cost competitive. Even though the cost of wind power has decreased dramatically in the past 10 years, the technology requires a higher initial investment than fossil-fueled generators.

The major challenge to using wind as a source of power is that the wind is intermittent and it does not always blow when electricity is needed. Wind energy cannot be stored (unless batteries are used); and not all winds can be harnessed to meet the timing of electricity demands.

Good wind sites are often located in remote locations, far from cities where the electricity is needed.

Wind resource development may compete with other uses for the land and those alternative uses may be more highly valued than electricity generation.

Although wind power plants have relatively little impact on the environment compared to other conventional power plants, there is some concern over the noise produced by the rotor blades, aesthetic (visual) impacts, and sometimes birds have been killed by flying into the rotors. Most of these problems have been resolved or greatly reduced through technological development or by properly siting wind plants.


Notice where the good wind sites are located? They are located too far outside of most cities for use. Thus, they would also be using fossil fuels to maintain them. Notice also their other disadvantages. They are not really worth it in many situations.

As to tides, a 1000 meter ditch would interfere with the energy involved in waves. Believe it or not, interfering with waves certainly will have an impact on climate as well as interfere with the life cycles of various forms of sea life.

Mar 15, 2009
There is a reason why the fossil fuel companies support wind power. I wonder what it could be.

It's something called "image management"...their core product, fossil fuel, has been demonized the world over, and they are now vying for our acceptance...nothing new there, and it doesn't take a genius to figure out why they support wind power. As long as they can maintain 3/4 of the market, and keep the environmentalists at bay, then that's good business.

That being said, however, I definitely agree that wind power is not the answer to our energy needs, and I would not accept having one of those noisy monsters installed near my house.
You armchair ecology nuts are all media and no science.

You have presented no scientific data to back up your claims, only off-the-cuff remarks. The fact that you previously thought that wind-turbines had to be fed fossil fuels to keep them turning whenever the wind stopped blowing would lead us to believe that you really don't know what you're talking about. Let us see your science!

Mar 15, 2009
Wind Power Equals Blight. Wind power's environmental benefits are usually overstated, while its significant environmental harms are often ignored.

Despite industry claims, promised air quality improvements have failed to materialize. Because wind is an intermittent resource, wind farms must rely on conventional power plants to back up their supply. Wind farms generate power only when the wind is blowing within a certain range of speed. When there is too little wind, the towers don't generate power; but when the wind is too strong, they must be shut down for fear of being blown down. And even when they function properly, wind farms' average output is less than 30 percent of their theoretical capacity.

Bringing a conventional power plant on line to supply power is not as simple as turning on a switch; thus most of the fossil fuel power stations required to supplement wind turbines are not "redundant," but must run continuously, even if at reduced levels. When combined with the CO2 emitted and pollutants released in the manufacture and maintenance of wind towers and their associated infrastructure, substituting wind power for fossil fuels does little to reduce air pollution.

Wind farms are also land-intensive and unsightly. In Europe, wind power is growing at an even faster rate than in the United States. Wind Power Monthly , the British magazine for wind industry enthusiasts, has reportedly recognized that wind power's popularity is decreasing due to the industry's portrayal of wind farms as "parks" in order to trick their way into unspoiled countryside in "green" disguise. Wind farms are more like highways, industrial buildings, railways and factory farms. Often, the most favorable locations for wind farms also happen to be the current location of particularly spectacular views in relatively unspoiled areas.

Wind farms that produce only a fraction of the energy of a conventional power plant require 100 times the acreage. For instance:

* Two of the biggest wind "farms" in Europe have 159 turbines and cover thousands of acres; but together they take a year to produce less than four days' output from a single 2,000 MW (million watt) conventional power station - which uses one percent as much space.
* A proposed wind farm off the Massachusetts coast would produce only 450 MW of power but require 130 towers and more than 24 square miles of ocean.
* A comparison of "footprints" is telling: to produce 1,000 MW of power, a wind farm would require approximately 192,000 acres, or 300 square miles; a nuclear plant needs less than 1,700 acres, or 2.65 square miles (within its security perimeter fence); and a coal powered plant takes up about 1,950 acres, 3.05 square miles. [See the figure.]

In addition, regular wind-tower maintenance requires miles of paved roads, increasing runoff and reducing soil moisture absorption. The damage to wildlife habitat is often greater than that from technologies associated with conventional fossil fuels.

("Wind Power: Red Not Green" URL: Accessed 3-15-2009)

Mar 16, 2009
unbelievable that scientists are contemplating injecting particulates into the stratosphere to combat AGW. UNBELIEVABLE. Someones getting clever in finding new ways to WASTE research grant money.

Mar 16, 2009
oh, and wind power does pollute the environment, but in a differently way - ITS UGLY. Does anyone think that visual pollution doesn't matter? Does anyone mind 100s of windmills dotted along beautiful mountain or ocean vistas? Take a drive through the mountain pass on your way to Palm Springs California, home to one of the worlds largest wind farms and behold the wonders of "green" energy.

Solar energy is the future, once we get a big improvement with efficiency. give researchers another 10-20 years, and wind power on a large scale will seem pretty silly.

Mar 16, 2009
dont blame big oil. when theres a better way to generate power, no one's going to stop it. it just takes time...

Mar 17, 2009
Funny, I thought the whole burning tires to stop global warming was just a joke and my burning tire pile in the back yard was just a punchline. Go figure someone actually takes these stupid ideas seriously.

While the impact on solar power plants is irrelevant since the power supplied to them without said particulate sheilding is still insufficient, the real threat of the particulate cloud is the loss of plant life and subsequently animal life that would take place.

I think the bigger story is the 20% drop in solar power that no one noticed. tells you the actual production and usability of those plants.

Vel, I think you are bashing big oil. You strike me as just the kind of guy who despises have those horrible conditions like lighting, air conditioning, computers, and modern medicine forced upon you. ;)

Mar 19, 2009
You have presented no scientific data to back up your claims, only off-the-cuff remarks. The fact that you previously thought that wind-turbines had to be fed fossil fuels to keep them turning whenever the wind stopped blowing would lead us to believe that you really don't know what you're talking about. Let us see your science!
No I didn't. The wind turbines need to be fed electricity to continue spinning when at a zero generation state. That electricity is generated via fossil fuels, and that is fact.


In addition, wind farms also have on site Generation systems that run on fossil fuels to keep the facilities viable because they do not produce power more than about 30% of the time overall during the year. Wind farms do not remove the use of fossil fuels and require their use in order to be viable. If turbines are left in a non-moving state for too long they freeze up and require costly maintenance to free their mechanisms. Thus, electricity from the onsite generation system powered by fossil fuels is used to cause the turbines to spin slowly during zero wind conditions.

Mar 19, 2009
That's 3 people and a linked reference article for you to peruse DG. Wind is no where near the "clean" source of energy you're thinking of.

So what is YOUR suggestion V for cleaner energy sources? (one that DOESN'T require a single drop of fossil fuel to obtain)

Mar 20, 2009
Hey why not a Traveling Wave Reactor while we're at it...

There are other, much less exotic (and costly), possibilities as alternate energy sources, such as Solar Towers and ocean-based thermo-electric plants, which don't take decades and billions upon billions of dollars to build. And while we still have the sun at our disposal, a free resource, ready to be harvested, we would be irresponsible to not use it.

In the event of an impending, long term, "nuclear winter", due to a large asteroid strike or volcanoes, then we would need to look at the "nuclear solution".

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more