Solar photovoltaic on the house as an investment

[ERD50]

Just a question to throw out...

How long does it take to get a coal plant running from cold

IIRC, my friend was talking like a day or two...

So, when you talk hours to produce I am assuming that it is from a running plant and you are talking increasing production....

I'd love to find some good data on this that is understandable to someone not in the industry. I've looked, and most of what I find is either too general and just descriptive (slow, long time, really can't change much, inflexible), or in insider terms that I can't follow, or specific to one installation that may or may not be typical.

From various sources, I get the impression that a coal plant can swing maybe 50% down from peak, at maybe 10% per hour? Something like that? But I don't know. Maybe someone can fill us in?

Coming from a complete dead stop? Yes, I would assume days - lots of thermal expansion and stresses to take into account, and I bet they need to make tests along the way. Not like firing up the furnace in fall!


-ERD50

 

[NW-Bound]

Locally, they have some peaker plants that run on natural gas. I think these are internal combustion engines (not steam driven) and can be fired up as quickly as starting a car, but I may be wrong.

I already told of a new rate structure here that will charge residential solar owners more for using power during peak times, such as after dusk when the panels are not producing. Yet, people with existing systems get grandfathered rights (not sure, but it may not be transferable to new owners). I read that it would cost a typical solar owner another $50/month, unless he does something to change his usage or tilt the panels westward.

So, if you want a solar system, get it soon.

 

[Texas Proud]

Locally, they have some peaker plants that run on natural gas. I think these are internal combustion engines (not steam driven) and can be fired up as quickly as starting a car, but I may be wrong.

I already told of a new rate structure here that will charge residential solar owners more for using power during peak times, such as after dusk when the panels are not producing. Yet, people with existing systems get grandfathered rights (not sure, but it may not be transferable to new owners). I read that it would cost a typical solar owner another $50/month, unless he does something to change his usage or tilt the panels westward.

So, if you want a solar system, get it soon.

It has been a long time since I had talked to my friend.... but he described a peaker plant that was basically powered by a jet engine.... (or maybe it was a jet engine.... who knows)....

 

[NW-Bound]

Again, Wikipedia comes to the rescue. Your friend is right. It's like a jet engine, but with an output shaft to drive the generator.

In the US peaker plants are generally gas turbines that burn natural gas. A few burn petroleum-derived liquids, such as diesel oil and jet fuel, but they are usually more expensive than natural gas, so their use is limited.​

But also,

Natural gas and diesel generators with reciprocating engines are sometimes used for grid support using smaller plants.​

 

[meierlde]

It has been a long time since I had talked to my friend.... but he described a peaker plant that was basically powered by a jet engine.... (or maybe it was a jet engine.... who knows)....

Actually most combined cycle gas plants consider of gas turbines (essentially stationary jet engines, surrounded by a water jacket and a big heat exchanger behind the turbine). The turbine provides a part of the energy and the waste heat absorbed by the water jacket drives a steam turbine. You can start a plant with the gas turbine in a short time, but it will take some time to get the steam cycle going. It should be noted that a gas turbine provides far more efficient conversion of heat to electricity than an external combustion steam plant. (Because the gases are far hotter than the steam) The best a super critical steam plant can do is in the low 40% with the water beyond its critical point whereas when running a combined cycle gas plant does 60%) Most current steam plants are in the 30% efficiency range because supercritical steam is a fairly new technology.
So besides the issues of mercury emissions and coal ash from a coal plant, if you are looking at energy in energy out a gas plant does better than a coal plant. It should be noted that nuclear is even less efficient due to the temperature limits that exist inside reactors.

 

[NW-Bound]

^^^^ Spoken like someone who worked in the power industry.

Anyway, thinking about the retail price that I pay (7c/kWh off-peak), I know that their efficiency must be very high (the 60% above), compared to what one gets from a small generator. For example, the Onan generator in my RV produces 4 kW at a burn rate of 0.71 gal/hr. That's a cost of $0.53/kWh (assuming $3 for a gallon), and a conversion efficiency of 17%, for a nice generator costing more than $3500.

On top of the above, the 53c cost of the small generator is just operating cost, while the 7c is net retail.

 

[meierlde]

^^^^ Spoken like someone who worked in the power industry.

Anyway, thinking about the retail price that I pay (7c/kWh off-peak), I know that their efficiency must be very high (the 60% above), compared to what one gets from a small generator. For example, the Onan generator in my RV produces 4 kW at a burn rate of 0.71 gal/hr. That's a cost of $0.53/kWh (assuming $3 for a gallon), and a conversion efficiency of 17%, for a nice generator costing more than $3500.

On top of the above, the 53c cost of the small generator is just operating cost, while the 7c is net retail.

Ah yes the efficiency problem of gasoline engines (and diesel to some extent although because combustion temps in diesel are higher, thus a diesel car gets better mileage on diesel than the same weight gasoline car). Carnot's cycle strikes again. Here is a post on cars they deliver 18 to 25 percent of the energy in the gasoline to the wheels. 68 to 72% of the heat generated goes to pay Carnot. Recall it is the difference in temp between the heat source and the heat sink (the environment) that drives the efficency which is 1-(cold temp in Kelvin (absolute temp)/hot temp in Kelvin

 

[NW-Bound]

Due to the discussions in this thread, I have been examining my electric usage, and observe things that should have been obvious.

In early summer when I do not need cooling, my usage during the daylight hours is about 12 kWh, and that includes the pool pump and the water heater for morning showers (I can see their effects clearly on the hourly charts).

In the peak of summer, I can use up to 53 kWh during the same hours, or more than 4 times when it's cool.

Yet, if I had a solar system, I would be putting out more power during April/May than during Aug/Sep because PV panels lose efficiency when they are hot. No wonder the utility balks at having to pay for solar power when they do not need it. If more and more people have solar, the problem will get worse. Lots of power when nobody needs it, and not enough when they do.

This problem looks tougher to solve, the more I understand it. Of course, right now it's not a problem, but we cannot have the entire country going solar.

 

[Another Reader]

BTW, my next project is to research to cost to put in a well before California regulates ground water. I pay more for a month of water than I do for a month of electricity. With this 'drought', I will soon be unable to buy the water I want to use at any price from the utility.


I'm pretty sure you don't own the groundwater rights if you live in a standard City subdivision. And the well permitting process is arduous in places where they are allowed. I would be tempted if I could. The lawn is already gone. Trying to save 26 year-old trees is going to be a challenge. The proposed fines for watering are just too rich for the local government water agency to pass up.

 

[skipro33]

BTW, my next project is to research to cost to put in a well before California regulates ground water. I pay more for a month of water than I do for a month of electricity. With this 'drought', I will soon be unable to buy the water I want to use at any price from the utility.


I'm pretty sure you don't own the groundwater rights if you live in a standard City subdivision. And the well permitting process is arduous in places where they are allowed. I would be tempted if I could. The lawn is already gone. Trying to save 26 year-old trees is going to be a challenge. The proposed fines for watering are just too rich for the local government water agency to pass up.

Fortunately, I do own the ground water rights. We live in a rural part of a rural county on acreage; El Dorado County, in California. Wells are easy enough to get a permit for. To get a well installed will cost me around $7,000 to $8,000 complete. It will take about 7 years to break even on the cost. I plan to run the pump on it's own solar panels and install a cistern to store water instead of an on-demand pumping scheme.

The funny thing is; the water district that serves our area made us sign an agreement that we would not go and install a well as it would be too expensive to put in the water lines unless everybody out our way was on their system. When I called them to ask about putting in a well and how that would affect the agreement when they put in the water for our area, they were more than happy to cut us loose if that was our choice.
The reason is; they sell a water meter for hook-up to their system for about $20,000 for a 3/4" water line and about $40,000 for a 1" line to a residence. So, I said, I'll be getting back $40,000 when I give up my 1" meter. No, they say, you do not. And if I ever want to go back on their system, it'll be another $40,000 for a new 1" meter connection fee. In the meantime, just to have the meter and not use a drop of water is a flat $50 a month.
I paid $40,000 for the meter, I pay a flat $50 a month plus some amount for every 100 cu ft. of water, and if I want off their system, I give up the meter and don't get paid back what I bought it for, they sell it to someone else for $40,000 and if I ever want back on, it's another $40,000 from me to do so.
I should have put in a well years ago! I can drive in any direction from my house within a mile and see natural springs bubbling water to the surface, so I know there's water available.
California is a BIG state. Not everywhere is the desert you see on the evening news. May was 400% of a normal rainfall for the month is year in my area. We got lots of water, but the state treats everyone the same; from the deserts to the redwood forests. From the high alpine Sierra mountains to the fog enshrouded coast. It's the big ag that wants all the water, and it's the state's citizens who are made to pay the price. Big ag doesn't spend a dime on dams, aquaducts, etc. That's from taxes to residence.
Grrr......

 

[NW-Bound]

... To get a well installed will cost me around $7,000 to $8,000 complete. It will take about 7 years to break even on the cost. I plan to run the pump on it's own solar panels and install a cistern to store water instead of an on-demand pumping scheme...

That's cheap. My high-country neighbor faced the choice of paying $25K to extend the water mains to his lot, a distance of about 300 ft. He said that cost was about the same as for a well, so he went for the latter. Here, the water table is very low.

... California is a BIG state. Not everywhere is the desert you see on the evening news. May was 400% of a normal rainfall for the month is year in my area. We got lots of water, but the state treats everyone the same; from the deserts to the redwood forests...

Eh, we share. Remember how they built the LA aqueduct and sucked all the water from Owens River more than 100 years ago. When they finished the extension all the way to Lee Vining to get all the water that went to Mono Lake, the whole thing was more than 400 miles.

Heh heh heh... If you have water, you've got to share. They have very long straws. Big ones too. Heh heh heh...

 

[Another Reader]

I live down the road from you in the San Jose area. Not sure of the depth of the water table here, but wells are not allowed here anyway, as the water rights did not come with the house.


Wells in unincorporated rural Santa Clara County are more expensive than up where you are. There's some groundwater contamination because of the agricultural chemicals used. Most folks have not gone to cistern storage yet, but a few people I know are having water pressure issues now.


In San Jose, the City is encouraging very high density housing, over 60 units per acre where feasible. Thousands of units are being built, with no thought to resource consumption or traffic impact. The City touts its water recycling program, which is responsible for keeping the golf courses green.


The City provides potable water to some areas and a private company provides water to everyone else. The rationing method proposed by the private company is similar to LA County's. Reductions are so substantial they are impossible to meet and the fines are hundreds of dollars. Some folks could pay $800 a month or more to water the lawn once a week and take an occasional shower.

 

[skipro33]

Eh, we share. Remember how they built the LA aqueduct and sucked all the water from Owens River more than 100 years ago. When they finished the extension all the way to Lee Vining to get all the water that went to Mono Lake, the whole thing was more than 400 miles.

Heh heh heh... If you have water, you've got to share. They have very long straws. Big ones too. Heh heh heh...

When they tapped the Colorado River, they darn near ruined the whole eco system. To fix the leak, they had to build a railroad track to the sight, line up 100 rail cars and drive them off the end to plug it back up.

Owens Valley got screwed royally. There is hope though; that someday the whole LA area will fall off into the ocean when the big one down there hits.

People wonder about why the North part of the state wants to split off. State Of Jefferson. If that happened, they would be richer than the Arabs with their oil; selling water to California.

 

[skipro33]

When they tapped the Colorado River, they darn near ruined the whole eco system. To fix the leak, they had to build a railroad track to the sight, line up 100 rail cars and drive them off the end to plug it back up.

In 1900 they built the Alamo Canal to tap the Colorado river and try to turn the Imperial Valley into an ag use area. It was not long before the Colorado River began to wreak havoc with its erratic flows. In autumn, the river would drop below the level of the canal inlet, and temporary brush diversion dams had to be constructed. In early 1905, heavy floods destroyed the headworks of the canal, and water began to flow uncontrolled down the canal towards the Salton Sink. On August 9, the entire flow of the Colorado swerved into the canal and began to flood the bottom of the Imperial Valley. In a desperate gamble to close the breach, crews of the Souther Pacific Railroadhttps://en.wikipedia.org/wiki/Southern_Pacific_Railroad, whose tracks ran through the valley, attempted to dam the Colorado above the canal, only to see their work demolished by a flash flood.https://en.wikipedia.org/?title=Colorado_River#cite_note-Alamocanal-195 It took seven attempts, more than $3 million, and two years for the railroad, the CDC, and the federal government to permanently block the breach and send the Colorado on its natural course to the gulf – but not before part of the Imperial Valley was flooded under a 45-mile-long lake, today's Salton Sea.

 

[Nords]

It should be noted that nuclear is even less efficient due to the temperature limits that exist inside reactors.

IIRC about 17% for a saturated-steam plant. The submarine force's superheated plants (and the liquid-metal primary coolant plants) were more efficient but a lot more trouble.

I plan to run the pump on it's own solar panels and install a cistern to store water instead of an on-demand pumping scheme.

I'd recommend a really really big cistern or a backup power supply for cloudy days.

Every January or February over the last decade we've had at least one three-day period when our solar water heater was unable to get enough solar heat to maintain the tank at higher than 90 degrees.

Of course when our teen was living at home we were usually aware of that issue by the end of the first day. These days I take more showers at the beach than at home.

 

[NW-Bound]

... California is a BIG state. Not everywhere is the desert you see on the evening news. May was 400% of a normal rainfall for the month is year in my area...

I see that you are in Placerville, a bit west of Lake Tahoe. We visited Lake Tahoe a few weeks ago. The water level was a few feet low, and some boat ramps were closed. This was nowhere as bad as I saw at some reservoirs like Eagle Lake, Honey Lake to the north. This drought is bad. At Olympic Valley, they said that last ski season was lousy, while as recently as 2011 it was near record snowfall.

 

[skipro33]

I see that you are in Placerville, a bit west of Lake Tahoe. We visited Lake Tahoe a few weeks ago. The water level was a few feet low, and some boat ramps were closed. This was nowhere as bad as I saw at some reservoirs like Eagle Lake, Honey Lake to the north. This drought is bad. At Olympic Valley, they said that last ski season was lousy, while as recently as 2011 it was near record snowfall.

Tahoe spilled it's natural rim a few weeks ago. Into the Truckee River, it's natural outlet. Not much, but It did.

The lake rim to spill is 6,223 feet. As of this morning, it's at 6222.95 feet.

Add gauge datum of 6220 to this chart for elevation;
(Looks like it stopped spilling on June 14th.)

 

[rayvt]

Well, I don't know about 'insurmountable', you can do a lot if you throw enough time and money at it!

The laws of physics are pretty unforgiving.
No matter how much time & money you throw at it, the wind doesn't always blow and the sun doesn't always shine. People have this habit of wanting heat and electricity when they want it, not when Mother Nature provides it.

the growth in installed capacity is real and the economics for the first time are beginning to be such that a homeowner will not need a subsidy to consider a pv system economically feasible. The other matter besides storage is the build out of the electric distribution system to move power from renewable rich areas to where the demand is.

Long time ago I rad an analogy: "Figuring out how to climb a tree is not a step in figuring out how to get to the moon -- even though you are closer to the moon once you get to the top of the tree."

The economics of solar and wind sucks. The power provided is a minuscule fraction of the need, and will never be a significant portion of the need. And the timing of the availability absolutely does not match up with the timing of the demand.
Electricity is very difficult to transfer for large distances. It's one of those problems which is easy -- as long as you don't know anything about it.

England got a good lesson about wind power a while ago, when the wind didn't blow for several weeks.

 

[ERD50]

Originally Posted by ERD50 View Post
Well, I don't know about 'insurmountable', you can do a lot if you throw enough time and money at it!

The laws of physics are pretty unforgiving.
No matter how much time & money you throw at it, the wind doesn't always blow and the sun doesn't always shine. People have this habit of wanting heat and electricity when they want it, not when Mother Nature provides it. ...

Maybe it's semantics, but I read 'insurmountable' as 'impossible'. I don't think it 'impossible' to provide the storage (unless there aren't enough materials on earth to build it?). I think we both agree it is a really, really huge issue, and we are extremely unlikely to see it happen in our lifetimes, or even come close, if ever. I say 'if ever', because I think better solutions will come along, making it a moot point.

Long time ago I read an analogy: "Figuring out how to climb a tree is not a step in figuring out how to get to the moon -- even though you are closer to the moon once you get to the top of the tree."

I like that one!

... the growth in installed capacity is real and the economics for the first time are beginning to be such that a homeowner will not need a subsidy to consider a pv system economically feasible. The other matter besides storage is the build out of the electric distribution system to move power from renewable rich areas to where the demand is.

.... And the timing of the availability absolutely does not match up with the timing of the demand.

Electricity is very difficult to transfer for large distances. It's one of those problems which is easy -- as long as you don't know anything about it.

...

I like that one as well! I keep seeing these comments at various sites about every 'new' idea (like the 'air car' on Shark Tank recently. All these people chime in "What a great idea, why didn't the govt figure this out, the oil companies will squash it, and on and on".

They don't know (and won't listen) that compressed air driven vehicles have been around since the 1800's. They simply aren't efficient, there are better options. But none of this matters when you don't know anything!

-ERD50

 

[meierlde]

And the timing of the availability absolutely does not match up with the timing of the demand.
Electricity is very difficult to transfer for large distances. It's one of those problems which is easy -- as long as you don't know anything about it.
.

Actually in the western US we have a demonstation that long distance electricty transfer does work. It is the NW SW DC intertie between the Dalles Or, and Sylmar, Ca. Note that AC is a very poor way to send energy long distance due to the way AC current works, but a DC line works well. It does mean building big rectifier and inverter plants at the ends of the line. There is serious talk in the engineering community of lines under the Mediterranean from the Sahara where solar energy is in huge supply to Europe.
As with many things it is an issue of economics, and changing the way you think about a problem.

 

[meierlde]

An interesting piece from the IEEE spectrum on distributed solar in Az. Note the move to paying wholesale for energy from the home. Also note the solar power folks looking at distributed power, and finally that Arizona Public service is looking to install solar on 1500 rooftops with the output under the utilities control: Utilities and Solar Companies Fight Over Arizona’s Rooftops - IEEE Spectrum

 

[NW-Bound]

Tahoe spilled it's natural rim a few weeks ago. Into the Truckee River, it's natural outlet. Not much, but It did.

The lake rim to spill is 6,223 feet. As of this morning, it's at 6222.95 feet...

We were there on 6/3, and the water was a few feet low. So, it looks like there was some rain or inflow after we left.

Back on energy storage, the local utility SRP (Salt River Project), one mentioned in the IEEE Spectrum article quoted by Meierlde above, also manages the water shed of the Salt River. For energy storage, it pumps water upstream between a series of lakes. Its largest turbine used as a peaker is rated at more than 100 MW. That sounds big, but is just a fraction of the total power produced by SRP. And SRP is not the only electric utility serving Phoenix.

Geographical features allowing upstream pumping for energy storage like this do not occur often.

 

[skipro33]

Electric company I worked at will be building pumped storage as peaker power. We use wind generated electricity at night to pump water up hill to run through a hydroelectric plant during peak hours on hot afternoons.

It's called the Iowa Hill Project

Here is a short video explaining the project and how it will be accomplished

 

[NW-Bound]

What I am curious to know is the investment cost of pumped water storage systems. There's a large initial cost, plus some maintenance and operating costs. How's that relative to the current small-scale battery cost? I am sure the numbers are available, but just not accessible to laymen.

 

[skipro33]

I don't know what the Iowa Hill project will cost, but it won't be cheap. That is all going to be completely underground, the generator and the upstream 'lake'; none of it will be dectectable from above ground that there was anything built there. 400 megawatts of generation is a HUGE plant. What a cavern they are carving out of the mountain. Then a lake built under ground above it!! I think the lake above will be built, then covered.


I can't imagine a battery stack that could stand a 400 MW draw. That would be a site to behold.