Chapter: kW DEMAND vs kWh consumption. How LEDs and solar PVs are rather ineffective

[ggunn]

Actually, that one happened to be a valid point.

For some definitions of "large", I guess. Most residential PV systems will never backfeed as much power at any given time as the home's peak usage is when the PV is not operating, and almost never will there be a net flow into the grid over time. For the majority of the time the PV system's effect on the current through the meter is a reduction of power to the load, not a backfeed. The same is true of most commercial PV systems.

Utility scale systems are of course another matter because there usually is no significant local load, but these days most inverters built to service that market are being manufactured with grid stabilization features built in to them.

 

[JRW 70]

Scale

Scale

In our system (if most "non-peaking" plants are shut down),
there is still a little over 9.2GW in capacity. Granted that is
the approximate max. in conventional generation, but even
some of the largest P.V. systems I have seen specs. on is
a mathematical rounding error in the system at large.
There are always phase imbalances out in the system.
On the P.V. systems:
Pumped storage may be a good way to deal with this
"excess" just like we do currently. During the summer,
it helps keep the coal fired and the nuclear plant from
massive swings in output. And pumped storage is one
of the most viable and efficient (compared to other
methods) out there to take in the P.V. output for
later use.

JR

 

[iwire]

We balance the loads on the system. Changing the loads require re-balancing. Varying the load pattern makes it difficult to balance the system.

The loads are always changing just as the PV supply would always be changing.

Ideally. But the loads aren't ideal as they can be more unpredictable. It definitely complicates system load control, generation dispatch, voltage control, power quality, etc.

So really, its not a BFD, it just complicates things.


Don't get me wrong, I understand adding PV into the grids adds new issues but are these issues enough to justify not adding solar? I don't think so and believe time will show that to be correct.

 

[iwire]

Thermostat changed to less A/C load during the day, washing clothes at night, cooking in the morning and at night, etc. happens all across the country.

So all the folks that stay home during the day shut off their AC? Interesting concept.

My kids get home at about 2:30 the meter starts spinning.

You do not need a passport to travel the country you know .

I would have to be interested.

 

[mivey]

The loads are always changing just as the PV supply would always be changing.

Thanks Capt'n. It would be nice if both scenarios were as equal as you think.

it just complicates things.

And who should pay for the complication? Your neighbor who did not put in a solar panel but is being impacted?

Don't get me wrong, I understand adding PV into the grids adds new issues but are these issues enough to justify not adding solar? I don't think so and believe time will show that to be correct.

Don't see what time has to do with it as it is true now. Not adding solar is not my position.

Correctly allocating costs is my concern. Adding solar is not all moonlight and roses and some people get upset when you start talking about costs added to the system as they don't think solar has anything but positive effects.

There are issues that need to be worked through to minimize cross-subsidizing among rate payers and maintain a quality grid system. In general, a utility is going to pass the costs through with a margin so it could just not worry about the details of who pays what. However, the idea is to pass costs through fairly to the customers. Cost causation is a fundamental principle in cost studies and rate design.

 

[topgone]

Thanks Capt'n. It would be nice if both scenarios were as equal as you think.

And who should pay for the complication? Your neighbor who did not put in a solar panel but is being impacted?

Don't see what time has to do with it as it is true now. Not adding solar is not my position.

Correctly allocating costs is my concern. Adding solar is not all moonlight and roses and some people get upset when you start talking about costs added to the system as they don't think solar has anything but positive effects.

There are issues that need to be worked through to minimize cross-subsidizing among rate payers and maintain a quality grid system. In general, a utility is going to pass the costs through with a margin so it could just not worry about the details of who pays what. However, the idea is to pass costs through fairly to the customers. Cost causation is a fundamental principle in cost studies and rate design.

While most of the points mentioned are correct, I could see a faulty rationale why some sectors in power generation would get perks while others don't. Like what you said, those monies will be divvied up "fairly", but why does government have to take that route when things ought to be a level playing field--> a government responsibility towards businesses? Why do consumers be burdened with additional costs aka as "cross-subsidies"?
My stand is that if a technology cannot stand on its own, why force others to pay for them? Why can't market forces be allowed to decide which ones to live or die out? Just asking here.

 

[electrofelon]

My stand is that if a technology cannot stand on its own, why force others to pay for them? Why can't market forces be allowed to decide which ones to live or die out? Just asking here.

Without getting too political: The counter argument is that people and businesses will generally do what is cheapest/most profitable for the short term and not take into account long term effects such as environmental, sustainability, etc. The government has in the past and continues to support/help/subsidize all sorts of things. How many billions has nuclear power received? It wouldnt even be here if not for uncle sam......

 

[topgone]

Without getting too political: The counter argument is that people and businesses will generally do what is cheapest/most profitable for the short term and not take into account long term effects such as environmental, sustainability, etc. The government has in the past and continues to support/help/subsidize all sorts of things. How many billions has nuclear power received? It wouldnt even be here if not for uncle sam......

I doubt if any plant here will be allowed to run and get away with it if the emission limits are exceeded.:happysad:
People also need to understand that with an erratic energy source, these plants require an equal size of conventional generation to fill the gap once the erratic power source wanes out. Simply put, a lot more startup/shutdown emission will have to be thrown up to the atmosphere when the ISO calls up a coal/diesel standby plant to run. The argument that holds these alternative sources more preferrable than the rest downright disregards the realities mentioned. I understand the regs do not penalize plants emitting beyond limits during startups for now, but the fact is that these things will be a common occurence in the future, even more often than it is now, with increasing distributed generations from PV units-->plus, we'll see what EPA says about the emission rules come May this year. IDK how our energy planners are doing, reconciling those things.

 

[ggunn]

Simply put, a lot more startup/shutdown emission will have to be thrown up to the atmosphere when the ISO calls up a coal/diesel standby plant to run.

FWIW, standby plants are very rarely diesel and never AFAIK coal. Virtually all are are natural gas powered.

 

[JRW 70]

Peaking Plants

Peaking Plants

None of our "standby" plants are coal, there is one
small (very small) diesel plant. People don't realize
that (or I should say the majority of the population)
doesn't realize some of our larger power boilers can
take three to eight hours from a shutdown state
before the temp. is up and the superheaters are
producing dry steam for the turbines. Like I said
above, the pumped water station will pull off
about 400MW and if that is not enough, the
generators at the hydro. plants are motorized
to take more off the system. When I first got
into this I thought what a terrible waste, but
it takes more fuel to bring a conventional station
on line than use the pumped storage (which really
can help in the summer months) than to keep the
coal fired plants and the nuclear plant in a constant
state of unnecessary load swings from day load vs.
night load, which also puts undue stress on the
mechanical systems.

JR

 

[mivey]

FWIW, standby plants are very rarely diesel and never AFAIK coal. Virtually all are are natural gas powered.

Some coal plants can run at reduced output and ramp up for peak demand. It wasn't much but I seem to recall about a 10-15% ramp-up. Smaller coal plants can do a larger percent but they are disappearing fast as they are being regulated out of existence.

 

[Electric-Light]

Some coal plants can run at reduced output and ramp up for peak demand. It wasn't much but I seem to recall about a 10-15% ramp-up. Smaller coal plants can do a larger percent but they are disappearing fast as they are being regulated out of existence.

http://www.technologyreview.com/news/531841/why-solar-is-much-more-costly-than-wind-or-hydro/

The high, high cost of solar PV

 

[Fulthrotl]

Some coal plants can run at reduced output and ramp up for peak demand. It wasn't much but I seem to recall about a 10-15% ramp-up. Smaller coal plants can do a larger percent but they are disappearing fast as they are being regulated out of existence.

natural gas peakers are pretty common. i've worked on a couple
of them outside bakersfield, calif. combined cycle units.

a huge gas turbine, with immediate throttle response, and a
massive heat exchanger to capture the exhaust heat and boil
steam....

http://www.energy.ca.gov/sitingcases/lapaloma/

 

[mivey]

natural gas peakers are pretty common

Probably the most common. So much so that they tend to set the market price.