Is it practical to generate all US power by solar PV?

[Salvador]

FFS , my long written and carefully edited last post to answer anorlundas assumption is deleted because the rulers of PF hate it :DOk well , nikkkom I don't understand your stance on ecology quite frankly , you seem to dislike nuclear power plants for being dangerous and some points you use for proof are actually rather slippery if not outright wrong , but when it comes to making thousands of tons of batteries for a energy storage system that atleast at current technology is simply no practical you then are ok with that.
To my mind batteries are some of the nastiest and toxic products in all of electronics , quite frankly a piece of an old turbine that has been in a nuke plant and has some small radioisotope residue on it is to my mind a million times cleaner than a trailer load of li-oh batteries.
All the energy used and toxic gasses produced at making them and then after a few years of intensive use one must recycle them , recycling probably being the hardest part , my friend works at a local recycling center near my town , even though it's small and they don't recycle the very basics they just prepare and split up the parts so that they can then be further refined at their destination and even then that smell in the air is one thing I will remember for a long time.

I think we are already deep under water in terms of how many small devices all rely on batteries , to think that we could also use them for massive mega amp energy storage I don't know seems crazy.Also as much as I know batteries like light loads under heavy constant loads they tend to fail faster and something go with a bang.

Flywheel in a vacuum could be an interesting thing but I assume it's energy density is just not big enough or the mechanical engineering and amount of metal would be over the top probably.

 

[Snerdguy]

There are two ways to look at it. Is it possible? Could it be done? Yes, I think it is technologically possible. But, certain things would have to happen. For one, Photo voltaic cells have to highly efficient, cheap enough and reliable which I think is doable. Secondly, we need to make some scientific breakthroughs with superconductors so that the energy can be distributed efficiently. That's because, to make a working system, it needs to be global so that there will solar energy available twenty-four hours a day.

The biggest problem is that, in order to provide energy just from photo voltaic cells, we would need global cooperation. All countries would need to work together so that everybody can tap into solar energy. That's not looking very likely for the foreseeable future. There's just too much inequality in the world right now. We have to over come that in order to use our resources wisely and if we ever want to have Star Trek sized achievements like interplanetary travel.

 

[Salvador]

You are correct about the "working together" which can help the civilization to achieve greater goals faster but as you know, not all people from the whole population are smart enough , capable enough or willing enough and some are plain idiots , some are criminals some are lazy , it's the choices we make that makes this world the way it is so let's look at this from the way it is.

Also as for the way it is science is the way it is and if I'm not mistaken which I hope you will kindly correct , superconductors require energy input to keep them superconducting because eventually heat will reach inside and destroy that state , not to mention the complexity of such technology , I have heard talks about superconductors uses for energy transmission but i think it's not practical atleast not now and I doubt also about the future.
HVDC line loss is already low enough even with our current switching substations , superconducting cables would really mean star trek level talking in this thread, not that I'm against it it's just that Stanley Kubrick will roll over in his grave , peace be with him he was a great director.

 

[OmCheeto]

I think the calculator let's you adjust tilt of the panels. it set mine at 20 degrees,

Me too.

I don't know whether that's off vertical or off horizontal...

Off horizontal.

and whether it's a simple default or some function of the local 35° latitude it used for local irradiance.
Might you try tilting for perpendicular to sun around winter solstice and see if winter output gets any better ?
Optimize for winter , accept a little less in summer when you don't need it ?

I'll probably experiment with tilts too, after some more cement work in the yard...

Good idea:

Om's system
4 kilowatt system
kWh generated per month
tilt ->_0°____20°___45°___90°
Jul___612___597___568___291
Dec___95___145___155___144​

Now everyone's situation is different, so my system won't work for you, and yours won't work for me.
But my idea was to have a mixed system.
Installing a vertical thermal collection system on the the south face of my house, I can generate 756 kWh for the month of December.
I checked the data for my energy use over the last year and have determined that my heating requirements are 700 kWh/month, for the winter months.

My lowest summer energy consumption over the last 25 years was last October, where I used 303 kWh for the month.
I checked my refrigerator, and it is rated at 790 watts. My guess is that it accounts for most of my summer electric bill.
Now, for a not small cost, I can pick up a refrigerator that uses 1/10th that amount. (Sunfrost RF19, $3500, 31 kWh/month)
So I'm thinking I could get away with only a 100 kWh/month solar voltaic system(1000 watts, $5000 professionally installed, $1000 if I do it), along with the 756 kWh solar thermal system (DIY construction and installation: $2000).

Now some people might claim that I've forgotten about the 7 day battery.
Not really.
I found a 2000 gallon swimming pool, for $59, that will fit in the crawl space of my house.
I've determined that if I heat it up to 190°F, it can store enough thermal energy to last me about 3 weeks.
So that far exceeds my thermal requirements.

Tesla's Powerwall stores 6.4 kWh, so that's only good for two days.
hmmmm...
I hear the Tesla Model 3 will have a 60 kWh battery. That would keep my food cold for 20 days.
And I'll probably have to hack into it to extract the energy.

U of Florida did research on thermal collectors forty-five years ago
and concluded a DIY'ers can't beat flat plate collector with intimate contact between plate and tubes.
They used copper sheet with copper pipes soldered to it on 12" centers
because the average home handyman can solder copper but he can't weld aluminum.
4 X 12 feet makes plenty of hot water for a family of four in Florida.
Does it ever freeze where you live?

[edit]
According to this website, 26 days a year.

Month___<=32°F___40°F
January_____8______24
February___6_______20
March______3______18
...
November__2______14
December__8______26
Year_______26_____118​

If not , consider replacing your water heater with a flat plate collector & elevated tank for thermosiphon .
View attachment 100130

Zero moving parts, zero maintenance.
Doesn't make kilowatts but displaces them with zero complexity. No electronics.
At a conservative 100kwh/month for two people(most water heater estimates are twice that see https://www.keysenergy.com/appliances.php )
and 15cents/kwh = $15/month
a thousand dollar homebuilt would pay back in 5.5 years vs ten for PV

this is not a hijack - a kwh saved is 3412 BTU's earned.
Save that beautiful electrical energy for more noble things than heating water - like posting on PF.

old jim

I have lots of bilge pumps. I ain't afraid of no movin' parts!

 

[jim hardy]

I have lots of bilge pumps. I ain't afraid of no movin' parts!

IN THAT CASE
you don't have to use thermosiphon, meaning your thermal collector panel can be mounted above the hot water storage tank.
Running a DC circulation pump from a pv panel built into the collector would save running conduit and housepower to it...
Just install a flapper valve to prevent nighttime thermosiphoning of hot water back up to the collector , for your BTU's will re-radiate back into outer space...
...unless you electroplate the whole collector with blackened nickel and that's another story...
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770013623.pdf

old jim

 

[Snerdguy]

You are correct about the "working together" which can help the civilization to achieve greater goals faster but as you know, not all people from the whole population are smart enough , capable enough or willing enough and some are plain idiots , some are criminals some are lazy , it's the choices we make that makes this world the way it is so let's look at this from the way it is.

Also as for the way it is science is the way it is and if I'm not mistaken which I hope you will kindly correct , superconductors require energy input to keep them superconducting because eventually heat will reach inside and destroy that state , not to mention the complexity of such technology , I have heard talks about superconductors uses for energy transmission but i think it's not practical atleast not now and I doubt also about the future.
HVDC line loss is already low enough even with our current switching substations , superconducting cables would really mean star trek level talking in this thread, not that I'm against it it's just that Stanley Kubrick will roll over in his grave , peace be with him he was a great director.

After I tried to explain it in detail, I found an article that explains it better than I can...with photos even. http://www.extremetech.com/extreme/...es-the-way-for-billions-of-dollars-in-savings

 

[OmCheeto]

IN THAT CASE
you don't have to use thermosiphon, meaning your thermal collector panel can be mounted above the hot water storage tank.
Running a DC circulation pump from a pv panel built into the collector would save running conduit and housepower to it...
Just install a flapper valve to prevent nighttime thermosiphoning of hot water back up to the collector , for your BTU's will re-radiate back into outer space...
...unless you electroplate the whole collector with blackened nickel and that's another story...
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770013623.pdf
View attachment 100219

old jim

Nickel plating! Perhaps you aren't aware of my budget for these types of experiments.

solar thermal collector hardware costs

$11.98 1/2 in. x 100 ft. Distribution Tubing for Drip Irrigation (thermal collection)
$9.99 1/2 in. thick, 4 ft x 8 ft aluminum backed styrofoam (insulation & reflection)
$70.00 2 x 2 ft x 8 ft x 1/4 inch polycarbonate thermal sheets (so everything doesn't freeze at night)
$10.00 wood frame (holds everything together without duct tape)
$0.00 5 x bilge pumps (5 boats, 5 bilge pumps)
$0.00 3 x 50 watt solar panels (dad bought them back around 1990, for probably $500/panel. He died in 2005. I got em)​

I balked at the $70 for the polycarbonate insulation, but knew it wouldn't work without it.
But then, when December rolled around, I knew this was one of the stupidest scientific investments I'd ever made...

View from my front porch in the middle of winter:

Those are all my neighbor's non-deciduous trees, so I really don't have much say in the matter...​

But it made my sister happy, and that's worth a lot.
And I think I can pawn off the panel to one of my friends, in exchange for boat rides.
She has a new houseboat, with a huge deck, and all of us, um, huge fans of summer, have been trying to talk her into installing a hot tub.

"It's going to cost a fortune to heat that thing!"
"Not with a "free!", OmCheeto solar water heater it isn't".

 

[Mark Harder]

Yes, putting all that capacity in one geographic area seems foolhardy. What if it were distributed, as some have suggested, on rooftops? How many homes would be required to serve our total need? If every home devoted 25 m² to solar cells, and 897,000 km² = 8.97*10¹² m²was required, that's over 35 Billion homes, no? Methinks we should be thinking of consuming less. That's our eventual fate anyway.

As for the problem of storage of excess power, could it be used to hydrolyze water, store the water for times of excess demand and use it as fuel for fuel cells or generators driven by internal combustion on site? Locating the plants in a remote desert is out of the question, but what if they were built near existing hydroelectric projects? A reservoir provides a ready supply of water and a natural container for waste water. But then I haven't estimated the quantity of water required...

 

[nikkkom]

Photo voltaic cells have to highly efficient, cheap enough and reliable which I think is doable.

It is not "doable". It is DONE. We have cheap 20% efficient solar panels.

 

[nikkkom]

An all solar US is *not* practically possible using only battery backup, for exactly the reason you suggest (at least). This limitation has been addressed earlier in the thread. There is not enough lead, not enough lithium produced in this world to build the hundreds of TWh required, nevermind replacing it every half dozen years or so. Basic assumptions and facts: 336 billion kWh of storage required with 15 kg of Pb per kWh is 5 billion tons of Pb. Global reserves of Pb are 80 *million* tons.

Why would you use Pb batteries for this? Nickel-iron ones, for example, are cheaper, and they last 30-50 years. They are heavier, yes, but for stationary batteries it is not critical.

 

[nikkkom]

To my mind batteries are some of the nastiest and toxic products in all of electronics , quite frankly a piece of an old turbine that has been in a nuke plant and has some small radioisotope residue on it is to my mind a million times cleaner than a trailer load of li-oh batteries.

I don't know what "oh" is, but Li is not a right material to build stationary large-capacity batteries. Too expensive.

 

[nikkkom]

In an Hour for 1sq.mt solar panel will generate around 200W,
so for 5 hours/day will generate 1000W or 1KW/day,

Your units are off. Watts are power, not energy. W is Joule/second, so KW/day is nonsense.

1 sq.m. of 20% efficient solar panel generates some 30 Watts daily average in a sunny, southern US state.

for 10m wide road, it will generate 10KW/day,
for 1KM long road, it will generate 1000*10 = 10,000KW/day or 10MW/day,

1km x 10m road is 10000 m^2, so you may hope to generate 300kW daily average from it. You'd need 3333 km of such roads to generate one gigawatt of power (roughly equal to one todays powerplant).

 

[Salvador]

whoever here said about the superconducting lines I think we are still far away from them because that article that was given doesn't tell the story about how much energy will be lost maintaining the liquid nitrogen running through the cable.
So for a nationwide grid one must then count the losses and the extra complexity and materials for a current superconducting technology VS HVDC for example, surely a tough task to calculate here so I will just leave it at that.

 

[jim hardy]

it'll generate around 3050 MW per KM per Year

I know nothing about electric rates or costs of capital and labor in India.
In US, to wholesale that power at even $50 a megawatt-hour
https://www.eia.gov/electricity/monthly/update/wholesale_markets.cfm

3050 mwh/yr is $152,500 a year.
Can you finance, build and maintain it for that ?
I think instead your politicians will do what politicians in Florida and Colorado did -
install license plate cameras and have the computers send everybody who drives past one a bill for about ten bucks.

 

[jim hardy]

I did my calculation as per google search for solar power output per day,

i think the complaint is that you(and the author of that solar roadway article) confused power (kw) with energy(kwh)

that wipes out credibility even if the arithmetic is right , because the physics is wrong.

Sadly journalists do not have to know a thing about science and shouldn't write about it if they don't.
That author and his editor did their publication a disservice, their inattention to that detail got them dismissed as enviro-babblers.

I checked your and Nikkom's numbers . You only disagree by your 1000 vs nikkom's 720 watt-hours per square meter per day.

old jim

 

[nikkkom]

I did my calculation as per google search for solar power output per day, below are some of the links, kindly check,

http://www.theecoexperts.co.uk/how-much-electricity-can-i-generate-solar-panels
"The standard solar panel has an input rate of around 1000 Watts per square meter, however on the solar panels available at present you will only gain roughly 15-20% efficiency at best. Therefore if your solar panel was 1 square meter in size, then it would likely only produce around 150-200W in good sunlight."
For example: 2 square meter panel x 1000 = 2000 x 0.20 (20% efficiency panel) = 400. 400 x 5 hours of sun hours = 2000 Watt hours per day.

https://livingonsolarpower.wordpress.com/2013/03/23/basic-solar-energy-math/
Under clear skies and good sunshine each square meter is receiving about 1000 watts of solar energy. At typical 15% panel efficiency, a 1 sq m area will generate 150 watts of power.

Which is roughly equal to what I said. ~30W of power from 1 m^2, when you average it over 24 hours.

 

[nikkkom]

yes there maybe plenty of land available but i try to reuse the existing land more efficiently,

Whereas what should be done is to use *money* more efficiently. You need to economize a resource only if it is scarce. In Japan, land is a scarce resource. Not in US.

transmission losses will also be less as compared to installing solar panels in remote areas & bringing that power to city

Calculate the savings. You may find out that they are unimportant.

maintenance cost for roads will also reduced

I seriously doubt that.

 

[Baluncore]

+ maintenance cost for roads will also reduced, as now there will be 24x7 shade over roads.

That will be a problem. The sunshine on the black bitumen heals the cracks that form. If it is always in shade you will need to change the composition of the road material to a softer material blend.
Take a look in a car park where there are wide white arrows painted on the road surface. Do you notice cracks formed in the surface where the white paint keeps it cool, but no cracks where it is black because it can heat, flow and so heal?

erashish14, are you the author of those web sites ?

 

[Salvador]

erashish14, are you the author of those web sites ?

That's Baluncore being funny :DOverall why don't we forget about the solar panel roads , they are even if possible not practical due to the simple fact that a road is under heavy stress from traffic and needs to be built on materials that last.The maintenance just would not be worth it.
Although maybe this idea could be used in cities in large car parks for example or in other areas were the speeds is low and stresses are low.
Just think about the load a typical highway sees you really think it would be practical to have some fragile solar panel semiconductor or whatnot material lying beneath the surface and the surface then would have to be anything other than bitumen or concrete because those two would kill all the sunlight coming through.

 

[jim hardy]

The utility electricity sector in India had an installed capacity of 298 GW as of 31 March 2016.[1][2] Renewable Power plants constituted 28% of total installed capacity and Non-Renewable Power Plants constituted the remaining 72%.

https://en.wikipedia.org/wiki/Electricity_sector_in_India

At 300 kilowatts per KM
to get 10% of total capacity by covering roads
you'd need to cover 298E9 / 300E3 = 993,333 km

. As of 2011, 54 percent – about 2.53 million kilometres – of Indian roads were paved.[2][3]

https://en.wikipedia.org/wiki/Indian_road_network
so you have enough roads for 10 or 20 percent. 993,333 km out of 2.53 million km = 39% .

 

[OmCheeto]

3050 MW per KM per Year

I think they must have their dimensions confused. That idea is a joke.
That amount of advertising space will depreciate the value of all advertising space.

I think that's supposed to be 3050 MWh per km per year.
I calculated it for my neighborhood and came up with 1027 MWh per km per year. (I measured the width of my roadway in front of my house yesterday at 20 feet)

But like solar surface roadways, I don't consider elevated solar roadway covers economically feasible.
Around here, they'd need to be designed to withstand sustained winds of 60 mph, and gusts of 120 mph.

...at Portland, Oregon's major metropolitan area, measured wind gusts reached 116 miles per hour (187 km/h) [ref]
​

And that person really needs an editor.

On the same Road, we can collect around 9,75,360[sic] Liters of Rain Water per KM, with 100mm of Rainfall (Average Rainfall in INDIA) & if we consider 700 Liters of Water for an Average Family...​

I'm pretty sure that's supposed to be 975,360 liters, as that yields a roadway width of 9.75 m (or 32 feet, for us yanks.)

 

[mheslep]

Why would you use Pb batteries for this? Nickel-iron ones, for example, are cheaper, and they last 30-50 years. They are heavier, yes, but for stationary batteries it is not critical.

Me? Pb acid is the most common rechargeable battery in the world today by kWh produced and for good reason. It's cheap and tough. The long life you cite for nickle iron is for stand by or shelf life, not the daily cycles required to back up solar. At that rate of use, any solid battery has at most a dozen years of life.

 

[nikkkom]

Me? Pb acid is the most common rechargeable battery in the world today by kWh produced and for good reason. It's cheap and tough.

And about two times lighter than Ni-Fe, for the same capacity. That's important in a car, and I guess one of the reasons why Pb batteries, not Ni-Fe, are used in cars.

For stationary applications, weight is not critical.

 

[mheslep]

And about two times lighter than Ni-Fe, for the same capacity. That's important in a car, and I guess one of the reasons why Pb batteries, not Ni-Fe, are used in cars.

For stationary applications, weight is not critical.

Right, solar backup need not be mobile, but mass matters for shipping and (frequent) replacement, especially when the mass is on the order a couple of mountains. There is no practical route at present to battery back up of a single large (GW) power plant for a week, nevermind an all solar US, not with batteries of kind.

 

[Baluncore]

"erashish14, are you the author of those web sites ?"

That's Baluncore being funny :D

No Salvador, it is a serious question. Both erashish14 and the site made many of the same mistakes.
I still wait for an answer from erashish14.

[edit] Now all erashish14's posts have disappeared from this thread. I guess that answers my question.

 

[nikkkom]

In another PF thread it was proposed to build a centralized PV farm of 1000 gigawatts, which is the order of magnitude of US installed generating capacity. It'd cover 1/10 the area of New Mexico, Arizona and Nevada.

I only now read the intro sentence attentively.

No, I was not proposing to build a single, huge centralized farm. That's suboptimal. Let "evil capitalism" do its magic: let different companies build their own solar power plants as they see most efficient. Location, type of panels, type and capacity of energy storage, method of financing, permitting, ... all this should be decided by individual companies and local communities. This way, different ideas and techniques can be tried, and ones which are better will be found "experimentally".

 

[jim hardy]

Fair enough. That's what i thought you were suggesting though, from the mention of three southwestern states..
We have a big fossil station, "Four Corners" out there. Power from it goes as far as Denver.
http://www.wrcc.osmre.gov/initiatives/fourCorners/resources/FC_TransmissionLines.pdf

I think we looked into the practicality of geographically centralized vs distributed generation .
Here's an example of why distributed is more practical from a grid viewpoint:
https://www.nmlegis.gov/lcs/handouts/NMFA%20082613%20Item%209%20Transmission%20in%20NM.pdf

and see the Wikipedia article for a glimpse onto the legal circus
https://en.wikipedia.org/wiki/Four_Corners_Generating_Station

History
The Four Corners Generating Station was constructed on property that was leased from the Navajo Nation in a renegotiated agreement that will expire in 2041.[3] Unit 1 and Unit 2 were completed in 1963, Unit 3 was completed in 1964, Unit 4 was completed in 1969, and Unit 5 was completed in 1970.

Apparently the astronauts of the Mercury reported that they could see two human-constructed things from space: one was the Great Wall of China and the other was the "plume streaming from Four Corners Power Plant."[4]

In 1975, New Mexico enacted a tax on the generation of electricity and an in-state credit such that only electricity exported out-of-state was subject to the tax. Objections to this tax led to two United States Supreme Court cases. In Arizona v. New Mexico (1976), on a motion seeking to invoke the original jurisdiction of the Supreme Court, the court initially decided not to be involved and denied the motion, leaving the matter to the state court.[5] The owners of Four Corners filed an action in state court to declare the tax invalid, leading to the United States Supreme Court decision Arizona Public Service Co. v. Snead (1979), which held that the tax violated the Supremacy Clause of the United States Constitution.[6]

In November 2010, APS announced that it would purchase the SCE share of Units 4 and 5, add air pollution control systems to these units, and shutdown Units 1, 2, and 3.[3][7] Following the shutdown of Units 1 through 3, the capacity of Four Corners will be 1,540 megawatts. This proposed transaction is being reviewed by various regulatory authorities and should close in the last half of 2012.[3]

After a law suit by a coalition of environmental organizations, the plant owners and the plaintiffs reached a consent decree in 2015. According to the decree the plant will reduce emissions of nitrogen oxides and sulfur dioxide, pay $1.5 million in civil penalties and $6.7 million in healthcare and other mitigation costs for the people in the affected parts of the Navajo Nation. The law suit was based on pollution of Class I areas under the Clean Air Act in Grand Canyon National Park and 15 other areas of the National Park Service as well as hazardous conditions for health of neighbors of the plant.[8]

Bureaucracy... It's Mother Nature's version of "Roundup" , to keep us humans from paving the whole planet ! old jim

 

[IllyaKuryakin]

With respect to replacing ALL of our power production with PV, someone said, "I am sure it would be more expensive. The question is whether it's practically possible (and I might add, without drastic measures such as diverting entire world's lithium production into batteries production for decades, or making electricity permanently x20 more expensive, or something like that)."

I maintain that the answer is still no. Of course you could spend a few trillion in batteries and make it work, but the "practical" limit is the generation of a maximum of about 10% of power with PV. Look at it like a visit to the moon. Is it practical to spend a few hundred billion to visit the moon for a holiday? Possible, yes. Practical, no.

There is no technical reason why we can't generate ALL of our power with PV, and store all we need to get through nights and cloudy days. It's just that it's not cost effective, meaning electricity would have to cost many times it's current rate to generate it all with PV. Just the cost of generation and distribution would be about 4 times the current cost of power, but the cost of storage to overcome nights and cloudy days would run the cost up to about 15 to 20 times the current rates for electrical power. Perhaps we'll eventually have some sort of fusion power generation that can completely replace fossil fuels, but PV will probably never do it. Anyone who understands both the technical issues and the economics of electrical power generation and storage knew that all along.

 

[mheslep]

All the money in the world (evil laugh here) would not buy enough battery storage to power a US powered only by PV

 

[jim hardy]

I'm glad we had this thread.
I didnt think it was even technically feasible, as you know i thought PV was tinkertoy technology but it's more capable than i thought.
So I've learned a lot from folks here as usual.
Not the least of which is - I've lived long enough to become a fossil ...

old jim

 

[IllyaKuryakin]

All the money in the world (evil laugh here) would not buy enough battery storage to power a US powered only by PV

Yes, but batteries aren't the only way to store power. Power can be stored by electrolysis and regenerated with a fuel cell for instance, or it can be stored by pumping water up a hill and regenerated with hydroelectric generators as it runs back downhill. In either case, theoretical efficiency is capped out at about 25%. Once again, it's technically possible, but it's just not practical.

 

[mheslep]

Yes, but batteries aren't the only way to store power. Power can be stored by electrolysis and regenerated with a fuel cell for instance, or it can be stored by pumping water up a hill and regenerated with hydroelectric generators as it runs back downhill. In either case, theoretical efficiency is capped out at about 25%. Once again, it's technically possible, but it's just not practical.

I suppose, though in the US what you describe implies enough hydro or gas-fired plant or fuel cell capacity to run the entire load for days. That is, the required capacity is the same size that the US already has in place of ~1 TW, with a big switch on the side to flip it all off for a few hours (why?) while the solar science project collects sunlight. As you say, technically possible, like traveling east round the world to get to the house next door to the west.

 

[anorlunda]

Yes, but batteries aren't the only way to store power. Power can be stored by electrolysis and regenerated with a fuel cell for instance, or it can be stored by pumping water up a hill and regenerated with hydroelectric generators as it runs back downhill. In either case, theoretical efficiency is capped out at about 25%. Once again, it's technically possible, but it's just not practical.

Pumped hydro is 75% efficient, not 25%. For example, https://en.m.wikipedia.org/wiki/Blenheim-Gilboa_Hydroelectric_Power_Station
Where did you get 25%?

But pumped hydro is not scalable much beyond what exists because of the rarity of suitable sites.

 

[sophiecentaur]

consider a piezoelectric roadway surface. The bigger the vehicle, the more juice you get.

Every Joule that your PZ generators would produce would have to come from a Joule of motive Energy supplied to the vehicle. The system cannot produce more energy than you put into it.
Such systems could 'pinch' energy from passing cars on a small scale - perhaps as a toll for using certain roads- but it is not a solution to national energy resources, I'm afraid.

 

[sophiecentaur]

I looked through this thread and (as usual) I can't find anyone suggesting that one good answer to the problem is just to use less Energy. Not a popular idea for any but the brown rice and sandals brigade (and me) but it could be enormously good value.
The latest 'Terraforming Venus" thread has just passed by and, again, no one introduced the idea of efficient use of any resources. They want it to be just like Earth and look where that is getting us all.

 

[anorlunda]

I can't find anyone suggesting that one good answer to the problem is just to use less Energy.

I agree with that 110% Sophie. But we wanted a thread more narrowly focused than, https://www.physicsforums.com/threads/you-fix-the-us-energy-crisis.42564/
To discuss energy in general, that tread is still open and it is the place to do it.

But since you mentioned less energy, I cut my own electric consumption to 0.6 kwh/day for 2 people (that's gross consumption, not net). A 200 watt PV panel supplies 100% of our needs except about 25 days per year when it has been too cloudy too long. And we don't live frugally, we live a luxury life on our boat. It can be done.

 

[IllyaKuryakin]

Pumped hydro is 75% efficient, not 25%. For example, https://en.m.wikipedia.org/wiki/Blenheim-Gilboa_Hydroelectric_Power_Station
Where did you get 25%?

But pumped hydro is not scalable much beyond what exists because of the rarity of suitable sites.

Yes! You are quite correct. Pumped hydroelectric storage cycle efficiency is 75% or better. Thanks for the correction. As you noted, suitable sites with the water and elevation are the constraining factors.

 

[sophiecentaur]

suitable sites with the water and elevation are the constraining factors

That's very true. I talked to a guy in the Sierra Nevada (Spain) and asked why there were not many more hydroelectric schemes. He replied that the mountainous terrain just didn't have enough useful valleys that could be economically dammed. I had never thought of that - I just saw all the mountains and the water rushing down the sides. I guess that small scale projects could have a part to play here, though. How does the size affect the efficiency? Much less than in thermal power stations, I imagine.

 

[nikkkom]

I looked through this thread and (as usual) I can't find anyone suggesting that one good answer to the problem is just to use less Energy.

We already do that. Almost every industrial activity looks at opportunities to optimize its energy usage.

At home, LED lamps use some x8 less energy than old incandescent bulbs!
Computers go to sleep when not in use. Thanks to demands of battery-backed phones, today's CPUs can go to sleep incredibly fast - some milliseconds! - after they finished with the tasks, and then wake up again when they need to work again. Ten years ago, they just run continuously.
Modern homes are much better insulated. Many older ones have better insulation added.

 

[nikkkom]

All the money in the world (evil laugh here) would not buy enough battery storage to power a US powered only by PV

Care to support that with numbers?

 

[jim hardy]

I looked through this thread and (as usual) I can't find anyone suggesting that one good answer to the problem is just to use less Energy.

Too logical.

How does the size affect the efficiency?

Not greatly i believe. But when the fuel is rain, maybe return on investment is a better metric.
There's a 1925-ish 400 kw low head hydro plant near my home that's now a museum. It ran until 1972.
The $20 to $40 an hour revenue just doesn't make economic sense i guess. Somebody would have to tend to it , unless they spent a metric ton of money to rebuild it with modern controls so it could run unattended..
www.panoramio.com/photo/7324660
That is why i have a hard time accepting windmills and solar.
There do exist 60mw gas turbines that run unattended but were i a utility executive i'd be nervous about them. I think big machinery needs to be surrounded with loving, attentive eyes and ears. Economy of scale pays for that.
What they do with windfarms is instrument everything , telemeter it and pay a maintenance outfit to be those remote eyes and ears. Much like modern airliners.

As an "Old Guy" i don't handle change all that well. (see my signature line)

 

[The Electrician]

A current magazine article discusses an important ancillary issue associated with electricity generation: http://www.americanscientist.org/issues/feature/2016/3/energy-water-nexus-head-on-collision-or-near-miss

I've read the article and there are some facts about water usage in connection with power generation that are critical, and not well known.

 

[Baluncore]

For over 30 years now, it has been advocated that giving customers free high efficiency light globes and free insulation for their houses, is a lower cost option than building a new power station. In Australia the “Energy Efficient Homes Package” was implemented in 2009. That gave free roof insulation to uninsulated houses. Giving anything back to the people was a political anathema to the opposition of the day, resulting in a focus on the costs, with a complete failure to analyse the positive aspects of the scheme that the nation benefits from to this day.

A skylight is an efficient solar energy collector, but it does not use any form of storage. If we made skylights from laminated glass with a phosphorescent filler, then that would be solar energy stored for lighting. We would need to draw the curtains to turn of the light. It would be considered as solar power and storage, but it would not qualify as solar PV as in the title of this thread, so is off topic.

 

[OmCheeto]

I agree with that 110% Sophie. But we wanted a thread more narrowly focused than, https://www.physicsforums.com/threads/you-fix-the-us-energy-crisis.42564/
To discuss energy in general, that tread is still open and it is the place to do it.

But since you mentioned less energy, I cut my own electric consumption to 0.6 kwh/day for 2 people (that's gross consumption, not net). A 200 watt PV panel supplies 100% of our needs except about 25 days per year when it has been too cloudy too long. And we don't live frugally, we live a luxury life on our boat. It can be done.

This kind of floored me, when I saw this the other day. The average home installed PV system is 4000 watts.
Trying to figure how you did that, I compared where you and I live.
It started to make sense.

Blue: Om's electrical usage (Careful! I multiplied it by 10)
Green: Heating degree days where Om lives
Yellow: Heating degree days where Anorlunda lives​

You don't need any heat!

But I figured out the other day that I needed at least 1000 watt system, if I installed a solar thermal system.
So that had me scratching my head.
I thought that maybe you caught all your food off the side of your boat every day, and didn't need a refrigerator.
But I decided that was silly, so I researched refrigerators.
It would appear that the one I posted about the other day, isn't that extraordinary.

According to the Energystar website, my refrigerator: Oct 1988 19.0-21.4 Cubic Feet Side-by-Side
uses 2,623 kWh/year

I found a new refrigerator for $450 that uses only 382 kWh/year.
That's 7 times more efficient than mine.

Calculating the cost savings @ $0.118/kWh:

2623 kWh - 382 kWh = 2241 kWh/yr annual savings
2241 kWh * $0.118/kWh = $264 annual savings​

That fridge would pay for itself in less than two years.

And that also reduces the size of my solar system by a factor of 7.
1000 watts / 7 = 143 watts

That's starting to make my laptop look like a power hog: 44 watts.

hmmmm...
Do people still say "Jeez Louise"?

 

[dlgoff]

Trying to figure how you did that, ...

There are ways. Maybe something like this.

image compliments of http://www.tacticalsolar.com/rugged_solar_tents.php

 

[Baluncore]

I cut my own electric consumption to 0.6 kwh/day for 2 people (that's gross consumption, not net). A 200 watt PV panel supplies 100% of our needs except about 25 days per year when it has been too cloudy too long. And we don't live frugally, we live a luxury life on our boat. It can be done.

Do you have hot water?
Do you cook on the boat with electricity or fossil fuel?

 

[OmCheeto]

...
Modern homes are much better insulated. Many older ones have better insulation added.

My house was built in 1945. When I bought it, back in 1989, I discovered one of 3 reasons why it was so cheap, and had been on the market, empty, for 3 years.
It had no insulation!

I mentioned this one year, and one day ago, in the "Tesla Powerwall" thread. [ref]

...
For fun over the last few months, I've been transcribing my old electrical bills.
Between 1989 and 1995 you can see my winter energy use dropping every year.
This is because I discovered my first winter, that the house had virtually no insulation.
So each year, for 5 years, I removed the sheetrock from a single room, rewired, and insulated the exterior walls.
I also added insulation in the attic and crawlspace.

Those Powerwalls are starting to make more sense now.

 

[rbelli1]

I found a new refrigerator for $450 that uses only 382 kWh/year.
That's 7 times more efficient than mine.

Calculating the cost savings @ $0.118/kWh:
2623 kWh - 382 kWh = 2241 kWh/yr annual savings
2241 kWh * $0.118/kWh = $264 annual savings

In the US right now for some reason politically spending money to save or make money is anathema. I don't follow anything outside the US so your mileage may vary.

Many (US; other country?) politicians say you can't spend your way out of debt. Many (most?) businesses do just that. Look at any successful business venture and you will find debt as a large part of their balance sheet.

Your example does just that. Buy a more efficient appliance and you will save money in the minimal long term. Even doing that on the almost usurious rates of credit cards and you save money. This doesn't even consider externalized costs associated with electricity.

BoB

Edit: This is an off topic rant but it it the same logic that condemns solar (or other alternate energy) power. Buying a new TV on 30% interest when the old TV works perfectly well is a bad idea therefore spending on credit is always (100% no exceptions) a bad idea. Solar power will never be able to replace 100% (absolutely 100%; not candles no outdoor grilling) of our power therefore trying to replace any part (no matter how small) of our power is a bad idea.

 

[Salvador]

Well first of all I just couldn't help myself but to comment on sophie's posts here , yes surely being more efficient is a nice thing to do , also riding a bike to a place near your house at sunny times is both better for you and the environment but guess what most people have their "reasons" not to do that.that results in more energy consumption and shorter lifespan and on average more health problems which leads to more money spending and consumption etc.a circle that never ends.
Forgive my deterministic view but I think it's quite impossible to change human nature , all empires and political ideologies that tried it failed sooner or later , if it changes at all it happens in terms of centuries not decades.So the only way we can spend and consume less is to give the greedy civilization technology which gives them the same level and quantity of stuff and satisfaction. And many here already touched downed on that like more efficient fridges , house thermal insulation , more efficient lights etc etc.
Simply saying , Hey, stop using your pc so often or shower in colder water isn't going to work for the 21st century consumer.Not everybody collects his empty aluminum cat meal packs and other household trash like I do just to then take it to the metal recycling scrapyard.
This being said I think even with our more efficient appliances and housing we still won't be able to cut down our total annual energy usage simply because tech is spreading faster by the day and more people are using it also by the day and also more people are being born so I think we all can see where this is going.
Either we start killing portions of our civilization or greatly reduce birth rates like China did back in the day or we have to find some new stable ways of energy production that are also environment friendly and solar is just one rather small bit of that.as for what @rbelli1 said I don't think one can spend his way out of debt , the only way that could happen is if by spending the budget gets some boosted gain like for example being in debt but inventing something high tech which then is bought heavily and is also valuable and so gives some gain.
in modern times we face something Karl Marx wrote about back in the day , that most of labor would be replaced by technology simply because it's more reliable and cheaper and faster that way so capitalism and every sane person running a business would stick to that but this also means that the masses that we have become these days in terms of population size have nothing much left to do to earn their living so wages drop , the average person is not capable enough to be a high skilled worker or a lawyer or something like that so an economy that has advanced to this phase is somewhat in trouble.I think it's the US situation today (one of the reasons why Trump is so popular because of his bringing jobs back rant) , the spending hasn't gone down but the average income from the average person has declined , if not for some huge outside reason or huge resources that can be sold the average country is only as strong as its average citizen is in terms of his tax returns to the budget.
so if one decreases the income but keeps the spending he ultimately runs into debt and without changing the very core of this I have a hard time seeing how it can lead out of debt.

 

[sophiecentaur]

Edit: This is an off topic rant but it it the same logic that condemns solar (or other alternate energy) power. Buying a new TV on 30% interest when the old TV works perfectly well is a bad idea therefore spending on credit is always (100% no exceptions) a bad idea. Solar power will never be able to replace 100% (absolutely 100%; not candles no outdoor grilling) of our power therefore trying to replace any part (no matter how small) of our power is a bad idea.

The energy used in manufacturing can be much greater than the energy used by an appliance (including a Motor Car!). Can you think of anything more loopy than buying a brand new car on the basis that it will do another 10mpg? The whole automobile industry is selling cars (new ones) as a way of making itself money and not saving you money.
But to do anything about that would require a completely different slant to the economies of rich and developing nations. Economies rely on growth and expanding customer numbers. That is the real reason for our energy problems and it's a very hard nut to crack. Reducing consumption would, as it stands, result in people being put out of work.