Storing solar power increases energy consumption and emissions, study finds

January 30, 2017
Solarkraftwerk Waldpolenz, the first Solar 40-MW CdTe PV Array installed by JUWI Group in Brandis, Germany. Credit: JUWI Group

Homes with solar panels do not require on-site storage to reap the biggest economic and environmental benefits of solar energy, according to research from the Cockrell School of Engineering at The University of Texas at Austin. In fact, storing solar energy for nighttime use actually increases both energy consumption and emissions compared with sending excess solar energy directly to the utility grid.

In a paper published in Nature Energy on Jan. 30, researchers assessed the trade-offs of adding home energy to households with existing solar panels, shedding light on the benefits and drawbacks of adding storage considering today's full energy grid mix.

According to the Solar Energy Industry Association, the number of rooftop solar installations grew to more than 1 million U.S. households in 2016. There is a growing interest in using energy storage to capture solar energy to reduce reliance on traditional utilities. But for now, few homes have on-site storage to hold their solar energy for later use in the home.

"The good news is that storage isn't required to make solar panels useful or cost-effective," said co-author Michael Webber, a professor in the Department of Mechanical Engineering and deputy director of UT Austin's Energy Institute. "This also counters the prevailing myth that storage is needed to integrate distributed solar power just because it doesn't produce energy at night."

Webber and co-author Robert Fares, a Cockrell School alumnus who is now an American Association for the Advancement of Science fellow at the U.S. Department of Energy, analyzed the impact of home energy storage using electricity data from almost 100 Texas households that are part of a smart grid test bed managed by Pecan Street Inc., a renewable energy and smart technology company housed at UT Austin.

They found that storing solar energy for nighttime use increases a household's annual energy consumption—in comparison with using solar panels without storage—because storage consumes some energy every time it charges and discharges. The researchers estimated that adding energy storage to a household with increases its annual energy consumption by about 324 to 591 kilowatt-hours.

"I expected that storage would lead to an increase in energy consumption," Fares said. "But I was surprised that the increase could be so significant—about an 8 to 14 percent increase on average over the year."

The researchers also found that adding storage indirectly increases overall emissions of carbon dioxide, sulfur dioxide and nitrogen dioxide based on today's Texas grid mix, which is primarily made up of fossil fuels. The increase in emissions is primarily due to the increase in required to account for storage inefficiencies. Because storage affects what time of day a household draws electricity from the grid, it also influences emissions in that way.

If a homeowner is seeking to reduce his or her environmental footprint, adding storage would not make the household more green, but it shouldn't be dismissed either, the researchers said.

"Solar combined with storage is still a lot cleaner than having no solar at all," Fares said.

For utility companies, the benefits are more clear cut. Solar reduces peak grid demand by 8 to 32 percent and the magnitude of solar power injections to the grid by 5 to 42 percent. This is good for the utility because it can reduce the amount of electricity generation and delivery capacity required.

"However, if the utility is interested in reducing emissions, incentivizing home storage is probably not a good idea," Fares said.

In short, the analysis showed that storing today offers fewer environmental benefits than just sending it straight to the grid, because the lost to storage inefficiencies is ultimately made up with fossil-fuel electricity from the grid. "These findings challenge the myth that storage is inherently clean, but that, in turn, offers useful insights for utility companies," Webber said.

"If we use the storage as the means to foster the adoption of significantly more renewables that offset the dirtiest sources, then storage—done the right way and installed at large-scale—can have beneficial impacts on the grid's emissions overall," Webber said.

Explore further: Energy storage project to help homes be less reliant on grid

More information: The impacts of storing solar energy in the home to reduce reliance on the utility, Nature Energy , nature.com/articles/doi:10.1038/nenergy.2017.1

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humy
4 / 5 (8) Jan 30, 2017
Seems to me all the more reason to have a supergrid; problem solved!
Given his is the only current cost-effective answer we have, Why isn't there a huge pressure exerted by scientists and public on politicians and governments to make a supergrid happen?
gkam
2.4 / 5 (14) Jan 30, 2017
" This also counters the prevailing myth that storage is needed to integrate distributed solar power just because it doesn't produce energy at night."
------------------------------

Myth with whom? Most of us with PV systems already do this, and use the grid essentially as the battery. Those of us who will eventually get storage may be doing it for other reasons,.

I am amazed these folk have just started thinking about this.
kujarvis
2.7 / 5 (7) Jan 30, 2017
Storage pro.
Without storage, if the grid goes down you still have no power.
Duh
WillieWard
2.3 / 5 (6) Jan 30, 2017
Most of us with PV systems already do this, and use the grid essentially as the battery.
Fossil fuel power plants in the grid as battery. Great! Why nobody thought it before? It's quite simple, hide intermittency on a supergrid fueled by natural gas/fracking. It's a win-win game. This is the reason why fossil fuel industry loves the faux-greens.
gkam
2.5 / 5 (12) Jan 30, 2017
kujarvis, that is why I also have a standby generator, to provide the frequency standard for the PV system if the grid is down.

Duh.

gkam
2.6 / 5 (13) Jan 30, 2017
It IS win-win, Willie. All the power I produce replaces the dirty stuff made by fossil and nuke power. Every kWh counts. When we put it directly into the powerlines, we do so in the distribution system, where it is needed. Everybody wins.

I am now considering the roof spots for the next set of panels for the next car.
Eikka
2.2 / 5 (10) Jan 30, 2017
"This also counters the prevailing myth that storage is needed to integrate distributed solar power just because it doesn't produce energy at night."


It's not a myth because the grid can't accept unlimited amounts of solar power directly.

It's very simple: when the solar panels start to generate more power than the instant demand, the excess needs to go into storage or it is wasted. The solar peak is only a couple hours and everyone's generating power at the same time, so a relatively small amount of solar energy overwhelms the grid.

Why isn't there a huge pressure exerted by scientists and public on politicians and governments to make a supergrid happen?


Because at some point they have to explain to the public how absolutely ridiculously expensive it's going to be, and what a great risk to energy security it becomes to build your whole system on continent-wide power lines.
humy
4.2 / 5 (10) Jan 31, 2017

Why isn't there a huge pressure exerted by scientists and public on politicians and governments to make a supergrid happen?


Because at some point they have to explain to the public how absolutely ridiculously expensive it's going to be, and what a great risk to energy security it becomes to build your whole system on continent-wide power lines.


How do you know it will be "ridiculously expensive" compared to off-the-grid energy storage?
I once heard that it was calculated that it would be cheaper.
And where does the "great risk to energy security" from continent-wide power lines.come from? What is the nature of this 'risk'?
humy
4.1 / 5 (9) Jan 31, 2017
It's quite simple, hide intermittency on a supergrid fueled by natural gas/fracking.

WillieWard

If we had a supergrid, the electricity from renewable can be easily be made to collectively be continuous and uninterrupted (the sun is always shining somewhere and the wind is always blowing somewhere and there is always hydroelectric somewhere etc) and then we would have no need for natural gas/fracking, moron.
antialias_physorg
5 / 5 (6) Jan 31, 2017
shedding light on the benefits and drawbacks of adding storage considering today's full energy grid mix.
...
based on today's Texas grid mix, which is primarily made up of fossil fuels.


Note that this is always by *today's* energy mix. The energy mix of Texas is changing (even if by nothing else than more and more people getting solar on their roofs). Having starting to add storage is sensible in a long term approach to the issue (i.e. a slow transition that is independent of the policies of big energy producers)
WillieWard
2.3 / 5 (6) Jan 31, 2017
If we had a supergrid ... sun is always shining somewhere and the wind is always blowing somewhere and there is always hydroelectric somewhere etc) ... natural gas/fracking, moron.
Meanwhile, in the real world:
"Expansion of renewable energy cannot by itself stave off catastrophic climate change, scientists warned"
"Renewables can't deliver Paris climate goals: study" - January 31, 2017
https://phys.org/...als.html

As predicted:
"Suggesting that renewables will let us phase rapidly off fossil fuels in the United States, China, India, or the world as a whole is almost the equivalent of believing in the Easter Bunny and Tooth Fairy." - Dr. James Hansen(climate scientist)
humy
4 / 5 (8) Jan 31, 2017
If we had a supergrid ... sun is always shining somewhere and the wind is always blowing somewhere and there is always hydroelectric somewhere etc) ... natural gas/fracking, moron.
Meanwhile, in the real world: ...

WillieWard

None of your following quotes and links contradict or in any way go against what I just pointed out and are completely irrelevant to what I just pointed out. So my assertion still stands; unlike what you were obviously trying to imply, a supergrid doesn't require natural gas/fracking, moron. A supergrid + going 100% renewable can entirely eliminate any need for that.
Anonym
2 / 5 (4) Jan 31, 2017
So, the idea is to use fossil fuels to run the grid when "renewables" are not available, for example the frigid calm of a clear winter night? That WILL be expensive because the cost of operating the backup generating plants that keep you from freezing to death in the dark must be paid whether they are generating or not. Their operating costs are fixed: the kilowatt price must go up if consumption goes down, if the utility is not to remain solvent.

And what is "storage?" Whole-house battery packs? What happens to those when they die? They become highly toxic garbage that is shipped to China for disposal. So green!

There is no free lunch. But the natural human tendency to freeload is evident in the ostrich-like stance of those deniers who promote part-time energy as a full-time solution. Electrical grids require a source of power that is continuous and constant. Part-time energy is a jury-rig at best --- at worst, random power surges can undermine the integrity of the grid.
Anonym
not rated yet Jan 31, 2017
typo: "if the utility is to remain solvent."
humy
3.9 / 5 (7) Jan 31, 2017
So, the idea is to use fossil fuels to run the grid when "renewables" are not available,

Anyone with reasonable intelligence who has thought through what we should do in the long run wouldn't propose that should be our policy in the long run.

And what is "storage?" Whole-house battery packs? What happens to those when they die? They become highly toxic garbage that is shipped to China for disposal. So green!

Using none-toxic rechargeable Mg-S batteries (just as one example. There are others) will mean that there will be no toxic chemicals in them and they can always be recycles into new Mg-S batteries after they are dead, no problem.

However, a more cost effective long-term solution would be to make a supergrid and gradually make it global.
humy
4.4 / 5 (7) Jan 31, 2017
. Electrical grids require a source of power that is continuous and constant. Part-time energy is a jury-rig at best --- at worst, random power surges can undermine the integrity of the grid.


Doable solution;

https://en.wikipe...per_grid
"...
the need for baseload generation is significantly reduced since intermittency of some sources such as ocean, solar, and wind can be smoothed...."

and then it can gradually made to extend over the whole globe and that will certainly remove need for off-the-grid batteries.
The only real thing getting in the way is shortermism and politics.
WillieWard
2.3 / 5 (6) Jan 31, 2017
supergrid doesn't require natural gas/fracking, moron. A supergrid + going 100% renewable..
poor eco-nuts, so delusional.
"Grid electricity is probably the least sustainable form of energy we have."
"Simply maintaining the electric grid is difficult...they fail catastrophically and interrupt services."
"The "Wind and Solar Will Save Us" story is based on a long list of misunderstandings and apples to oranges comparisons"
"Wind and solar are making extremely slow progress in helping the world move away from fossil fuel dependence"
"Our big need for energy is in the winter, when the sun doesn't shine as much, and we can't count on the wind blowing."
"Hydroelectric power is great for balancing wind and solar, but it is available in limited quantities. It too has intermittency problems, limiting how much it can be counted on."
"The "Wind and Solar Will Save Us" Delusion" - Jan 30, 2017
https://ourfinite...elusion/
gkam
2 / 5 (8) Jan 31, 2017
"Their operating costs are fixed"
-----------------------

Their operating costs depend on how much fuel they are using. If the load it great, the cost of generating it will go up.

No free lunch, and few folk here who understand how electric grids and powerplants work.
gkam
1 / 5 (6) Jan 31, 2017
Want a secure future? Get into alternative energy or radiological remediation.

There will be jobs in Fukushima for over 40 years!
gkam
1 / 5 (6) Jan 31, 2017

Speaking of power technologies, here is some interesting news:

"Toshiba, Westinghouse Could Exit Nuclear Power Construction"

http://www.power-...on.html?
HeloMenelo
3.7 / 5 (6) Jan 31, 2017
supergrid doesn't require natural gas/fracking, moron. A supergrid + going 100% renewable..
poor eco-nuts, so delusional.
"Grid electricity is probably the least sustainable form of energy we have."
"Simply maintaining the electric grid is difficult...they fail catastrophically and interrupt services."
"The "Wind and Solar Will Save Us" story is based on a long list of misunderstandings and apples to oranges comparisons"
"Wind and solar are making extremely slow progress in helping the world move away from fossil fuel dependence"
"Our big need for energy is in the winter, when the sun doesn't shine as much, and we can't count on the wind blowing."
"Hydroelectric power is great for balancing wind and solar, but it is available in limited quantities. It too has **


just a monkey in disguise of one of his socks
gkam
1.9 / 5 (9) Jan 31, 2017
The headline is misleading, implying solar power results in higher emissions. It does not. The increase is in the addition of storage, which is evident to any technical person.

And those of us contemplating storage usually do so for other reasons than money. I live in earthquake country, the one caused by Nature, not fracking.
Uncle Ira
4.4 / 5 (7) Jan 31, 2017
The headline is misleading, implying solar power results in higher emissions.


You mean this headline?

Storing solar power increases energy consumption and emissions, study finds


So you think,,,,,,

It does not.


The increase is in the addition of storage, which is evident to any technical person.


So what does the "Storing,,," in the headline mean to any technical person?

gkam
1 / 5 (6) Jan 31, 2017
What kind of nasty emissions do we get from a 9,000 hp Diesel engine?
Uncle Ira
5 / 5 (6) Jan 31, 2017
What kind of nasty emissions do we get from a 9,000 hp Diesel engine?


About 1/3 as much as you get from the EIGHT 4,000 hp diesel engines you want to replace them with. (That's how much more efficient we are than rail.)
gkam
Jan 31, 2017
This comment has been removed by a moderator.
WillieWard
3.7 / 5 (3) Jan 31, 2017
Eco-nuts believe intermittent renewables are replacing fossil fuels everywhere, but transportation is massively dominated by fossil fuels, the only hope is if gskam discloses his technological technology of converting fibs into perpetual motion to power EV.
https://pbs.twimg...pg:large
http://energyliteracy.com/
TheGhostofOtto1923
3.3 / 5 (7) Jan 31, 2017
The headline is misleading, implying solar power results in higher emissions. It does not. The increase is in the addition of storage, which is evident to any technical person
-And we better damn well believe this because george kamburoff the flaming psychopath has a phd now.

So he can say anything he damn well pleases and theres not a damn thing we can do about it.

Hes got sickfuck tenure.
Uncle Ira
4.4 / 5 (7) Jan 31, 2017
Every bit helps.


So why are you advocate for doing away the 9000 hp towboats when the only thing you can replace them with is the rail? For an idiot, you are remarkably stupid.
gkam
1 / 5 (7) Jan 31, 2017
Once more, you are incorrect.. I never said anything about getting rid of your polluting boat for more polluting rail.

Show me.

You seem to have some kind of fixation which distorts reality around you.

This is about storing solar power, like others do, but not me yet. Mine goes directly into the grid for kWh credit.

What do you do? Burn oil?
eachus
5 / 5 (2) Jan 31, 2017
It IS win-win, Willie. All the power I produce replaces the dirty stuff made by fossil and nuke power.


Lumping all fossil fueled power together is a big mistake, same for lumping all nuclear power together. When it comes to fossil fuels, I've been against the worst, coal, for over fifty years. I grew up in Pennsylvania where you never saw the words "coal mine" in the newspaper headlines unless they were preceded by "Another," and followed by "disaster." To put this in perspective, during the 1970s to reduce the work of the federal mine safety commission, it was split in two coal, and everything else. An inspector for non-coal mine disasters campaigned in the early Reagan years to get his job eliminated. There were no non-coal mine disasters.

And of course, you have heard of Centralia, Pa. Bought up and evacuated by the US govt, because the fire in a coal mine under the city couldn't be put out.

Compared to coal, natural gas CC plants are very clean and green.
eachus
5 / 5 (2) Jan 31, 2017
As for nuclear power there are several different types of plant, with different fuel cycles. Modern PWRs (pressurized water reactors) are designed for very high fuel burn ups. The US Navy now puts reactors on subs that will not need refueling until after the sub is retired. Makes worries about high-level nuclear waste moot once (newer) commercial plants are built the same way. Even better resume building of MSRs (molten-salt reactors) now often referred to as LFTRs (liquid fluoride thorium reactors). These use thorium (Th-233) as a nuclear fuel, and are glad to use plutonium-239 to get the breeding cycle started. (One place to get this is the old fuel rods above.) What killed MSRs back in the 60s? The bomb makers wanted sources of Pu-239, not sinks.

There are other relatively new nuclear plant designs. As far as I am concerned PWRs and BWRs the most common type in the US are safe enough, but there are lots, now, that are much safer. Choose any, they are safer than coal.
Waaalt
3.7 / 5 (3) Jan 31, 2017
And those of us contemplating storage usually do so for other reasons than money. I live in earthquake country, the one caused by Nature, not fracking.


If you don't care about money, then you can skip solar variability and battery storage entirely. Go geothermal.

It's always available and extremely reliable. You don't need volcanoes or hot springs etc nearby for it, it works pretty much anywhere and is to large extent basically solar thermal. You can do either a vertical loop down into the ground or a horizontal loop over a large surface area.

You get power rain or shine, summer or winter. A binary cycle generator uses two working fluids that are entirely separated and is a very low maintenance sort of design.

Such generation methods are also much more environmentally friendly than solar power and batteries in terms of the materials they require and how those materials are produced(i.e. nothing special is required).
Zzzzzzzz
5 / 5 (2) Jan 31, 2017

Why isn't there a huge pressure exerted by scientists and public on politicians and governments to make a supergrid happen?


Because at some point they have to explain to the public how absolutely ridiculously expensive it's going to be, and what a great risk to energy security it becomes to build your whole system on continent-wide power lines.


How do you know it will be "ridiculously expensive" compared to off-the-grid energy storage?
I once heard that it was calculated that it would be cheaper.
And where does the "great risk to energy security" from continent-wide power lines.come from? What is the nature of this 'risk'?


He doesn't. He only claims he does.
Zzzzzzzz
5 / 5 (1) Jan 31, 2017
324 to 591 kwh is 8-14%? Only if the user uses less than 1/3 the electricity I use. I would consider that sort of energy investment in the ability to store quite reasonable.
gkam
1 / 5 (6) Feb 01, 2017

While we are making great progress with non-polluting resources, here is what is going on with other technologies:

http://www.asahi....073.html

http://mainichi.j.../007000c

http://www.the-ja...03493582

These are all bad news for the folk at Fukushima. They will have to re-figure the additional costs now to the projected cost of $190,000,00,000 to "clean up" these disasters - if we can develop the technology.

WillieWard
3.7 / 5 (3) Feb 01, 2017
we are making great progress with non-polluting resources
Where? Not in Germany, not in California, and nowhere. Excluding hydro and geothermal, intermittent renewables are a fiasco in terms of decarbonization, a waste of taxpayers' money, and that just served to make the fossil fuel industry ever stronger and to disrupt untouched wildlife's habitats and destroy natural landscapes.
gkam
1 / 5 (6) Feb 01, 2017
Gosh, Willikins, because folk like me are generating our own electricity we are going to shut down California's last two reactors at Diablo Canyon, . . . named for the Devil himself.

Want to buy them? There are some units in the midwest you probably can have for free, if you take responsibility for their clean-up.
WillieWard
3.7 / 5 (3) Feb 01, 2017
...folk like me are generating our own electricity we are going to shut down California's last two reactors...
It is amazing! Congratulations! You really found out a way to power the entire state by converting your fibs into electricity. Please share it with the world, Ivanpah solar plant needs your technology.
"The behemoth Ivanpah solar power plant built with federal subsidies to combat climate change is using increasing amounts of natural gas, a greenhouse-gas-emitting fuel, state and federal data show."
"Ivanpah solar plant, built to limit greenhouse gases, is burning more natural gas"
http://www.pe.com...pah.html
gkam
1 / 5 (6) Feb 01, 2017
Gosh, there is hope for Chernobyl to be an exporter of electricity again. Check this out:

http://www.bbc.co...steland?
WillieWard
3.7 / 5 (3) Feb 01, 2017
Gosh, there is hope for Chernobyl to be an exporter of electricity again. Check this out:

http://www.bbc.co...steland?
Lamentable! Now that wildlife is flourishing there, the faux-greens want to cover all land with solar panels full of chemical carcinogens and arsenide worse than asbestos. With this kind of friends, Nature does not need enemies.
It is a good deal for Ukrainian/Russian fossil fuel barons that will keep lights on when sun is not shinning.

gkam
Feb 01, 2017
This comment has been removed by a moderator.
WillieWard
3.7 / 5 (3) Feb 02, 2017
It's shining in my heart...
Good news from Japan! Congratulations! Your fearmongering speech is driving carbon-free nuclear power out of the business, except that intermittent renewables are unable to replace reliable sources of carbon-free energy, but no problem, the fossil fuel industry is prompt to provide cheap backup solution.
"Japanese government planning to build 45 new coal fired power stations to diversify supply" - Fev 01, 2017
http://www.abc.ne.../8224302
gkam
1 / 5 (6) Feb 02, 2017
I did that? I ran the nuke folk "out of the business"?

Where is my medal?

It will only take one more nuclear disaster for The People of the World to stand up and throw you nuke folk out, . . . or into prison.
WillieWard
5 / 5 (2) Feb 02, 2017
nuclear disaster
a disaster where no one has been killed by radiation, while air pollution from fossil fuels(backup for intermittent renewables) kills thousands of people each day, millions each year, thanks to faux-greens fearmongers.
Where is my medal?
ask it to fossil fuel barons, they are very proud of you.
gkam
1 / 5 (6) Feb 02, 2017
Not me, Willie, my car is electric, and the "fuel" comes from my PV panels.

You are not still driving a polluter, are you?

BTW, this just came out:

http://www.bbc.co...38843691

"Fukushima nuclear disaster: Worker sues Tepco over cancer"
WillieWard
3.7 / 5 (3) Feb 02, 2017
Most of cancer has no direct correlation with radiation, it can be caused by viruses, chemical products, and mostly from natural cellular mitosis processes; and on the contrary, radiation can be used as the cure (radiotherapy).
But of course, any occurrence of cancer that has nothing to do with radioactivity is always a good opportunity/pretext to issue to take some money from a big company and to fabricate scaremongering fables to favor ever more the fossil fuel industry.
"Japan considers buying more U.S. energy as Abe prepares to meet Trump" - Feb 2, 2017
"Another idea is to offer to increase liquid natural gas (LNG) imports from the United States"
www.reuters.com/a...BN15H0NJ
Where is intermittent renewables replacing fossil fuels? Not in Germany, not in Japan, and nowhere.

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