Brookline MA, No oil or Natural gas For New Construction

jumper

JUST DO SOMETHING? Unless everybody only eats what grows in their front and back yards and bikes to grandma's; world will need most (probably more) of that ~15 TWs even with improved efficiency.

In US most solar is **** backwards from engineering POV. Instead of solar electricity powering AC; Brookline type regulations insist that solar electric mess with the grid and then the grid powers AC which also messes with the grid. A whole new industry now provides partial solutions (power factor improvement, isolators, etc.) for those messes.

Icarus

jumper said:

JUST DO SOMETHING? Unless everybody only eats what grows in their front and back yards and bikes to grandma's; world will need most (probably more) of that ~15 TWs even with improved efficiency.

In US most solar is **** backwards from engineering POV. Instead of solar electricity powering AC; Brookline type regulations insist that solar electric mess with the grid and then the grid powers AC which also messes with the grid. A whole new industry now provides partial solutions (power factor improvement, isolators, etc.) for those messes.

Please explain...I don’t understand, can you please expand on what you mean by “solar powering AC”. How does “Brookline type regulations mess with the grid”?

I know a tiny bit about PF issues, but not much...

Icarus

jumper

Cannot explain. You need to study electric power engineering.
Roughly speaking each time a power source or consumer kicks in or out is a challenge for your utility's job of providing constant voltage synchronous in phase alternating current. Regulations requiring each home's photovoltaics to connect with the grid increases those challenges.
>>Please explain...I don’t understand, can you please expand on what you mean by “solar powering AC”. How does “Brookline type regulations mess with the grid”?<<

Icarus

You explained it well enough for me in this context. That said, the grid has/does a pretty good job of regulating itself both by loads and by production. I do understand (very little) PF issue, (that is also an issue with power supplies and LED lighting I understand). The fact is, every load (or added power source) added to or taken off line connected to the grid, has an effect on that grid. Looked at this way: If I am running a conventional 60hz. Gasoline generator (not an inverter genny) that runs at a multiple of 60 hz (900/1800/3600 depending on the genny winding) with no load, the genny will try to run at say 1800 rpm to maintain frequency. As soon as I put a load on that genny, it will slowdown possibly imperceptibly as the throttle opens to force more fuel to power the load. Put a big enough load on that genny and it will slow down noticeably or stall trying to pick up the load.

The same issue exists with the grid. If you live in an old(er) house and you add a big load (like a fridge air A/C compressor starting) the lights may dim until the grid (from you local transformer) picks up the load...all the way back to the generator. Grid managers and engineers need to know (and they do, generally), how much load to expect and how much production to expect at any given moment, and adjust production accordingly. Is that somewhat harder to do as the quantity of connected PV grows? Probably, but it is not a good enough reason to discourage disaggregated production. (Wind is marginally easier, as it is generally larger scale, and on more predictable locations, at least hourly).

So, if you can, please explain why adding disaggregated PV in local communities, tied to local as well as region micro and macro grids is a negative thing? Are you really trying to suggest that turning off (and not installing solar) and firing up either nat gas or coal is a better alternative in the net?

Icarus

Jamie Hall

I promised @jumper I wouldn't get back in, but... the problem with disaggregated power, such as every residence in some suburb having their own solar array, is synchronization. It -- and only if -- there is enough "rigidity" in the grid itself can this be managed. Otherwise, if the various little arrays are a wee bit out of phase, which they will be, the grid can absorb the completely wasted current going more or less at random though the power lines only if the grid itself can average all of those and absorb the net waste current. And that means either some very large capacitors and inductors at frequent intervals, or preferably, a large generating plant -- several orders of magnitude larger than the total of the little arrays -- which can just "bull through" and stabilize the system. Large rotating alternators such as are used in powerplants are very good at that. Utility scale solar arrays (say 100 megawatts and up) or wind farms can be fitted with inverters which take a pilot signal from the grid to control them, but these are not used in small arrays -- and even those, as noted, do require a pilot signal which is rock stable, which means that the inverter output power has to be significantly less than the grid capacity at that location.

It has been suggested that one could use the GPS (or similar) time signals for synchronization, and one could. The objection, of course, is that they can be turned off or degraded at will with a simple switch in Denver or Moscow or Paris, and it's unlikely that this would be acceptable on any utility scale project.

ratio

It's almost as if…

as if…

there are no technological solutions to non-technological problems?

The only viable, long-term solution is to use less, not more efficiently. Personally, it seems to me that a comma is missing, it more often goes use more, efficiently.

Icarus

Jamie,

Please indulge my ignorance here but...

If you had a large enough, disaggregated production capacity, wouldn’t that work in a similar way net/net to a larger production facility? For example, what would the fundamental difference be between 1mw solar in 1 concentrated location, and 1 mg distributed in one general neighborhood. They each would be subject to relatively similar vagaries in insolation due to clouds, time of day etc.

I hear a lot of “noise” about this issue, but I don’t hear a lot of it coming from actual grid operators. Now it one thing for a utility to “not like solar” as it “picks their pocket”, but quite another because it is problematic for their grid. Understanding that problematic for their grid is not quite the same as net/net a loss for their grid.

Icarus

PS to Ratio,

I don’t quite agree... I do however agree that conservation is job one. That said certain technologies can contribute significantly to either solving or exacerbating the issues.

I

ChrisJ

> @Jamie Hall said:
> I promised @jumper I wouldn't get back in, but... the problem with disaggregated power, such as every residence in some suburb having their own solar array, is synchronization. It -- and only if -- there is enough "rigidity" in the grid itself can this be managed. Otherwise, if the various little arrays are a wee bit out of phase, which they will be, the grid can absorb the completely wasted current going more or less at random though the power lines only if the grid itself can average all of those and absorb the net waste current. And that means either some very large capacitors and inductors at frequent intervals, or preferably, a large generating plant -- several orders of magnitude larger than the total of the little arrays -- which can just "bull through" and stabilize the system. Large rotating alternators such as are used in powerplants are very good at that. Utility scale solar arrays (say 100 megawatts and up) or wind farms can be fitted with inverters which take a pilot signal from the grid to control them, but these are not used in small arrays -- and even those, as noted, do require a pilot signal which is rock stable, which means that the inverter output power has to be significantly less than the grid capacity at that location.
>
> It has been suggested that one could use the GPS (or similar) time signals for synchronization, and one could. The objection, of course, is that they can be turned off or degraded at will with a simple switch in Denver or Moscow or Paris, and it's unlikely that this would be acceptable on any utility scale project.

What about a DC grid with SMPS for stepup and step down operations? Would certainly increase efficiency over transformers at 60hz no?

Jamie Hall

A completely disaggregated array -- such as, let's say, an upscale neighbourhood -- could be make to work well provided it had one inverter station. If it has multiple inverter stations -- such as each house has a grid feed of its own -- it is inevitable that there will be small phase differences between them. These will cause current to flow in the grid, but that current isn't useful -- all it does is cause a voltage drop and heat up the wires (and transformers). It's not a matter of power output, so passing clouds or what have aren't the problem. It's those small phase differences. 5 hundredths of a millisecond is enough to cause trouble.

Utility scale arrays get around this by having only one single feed (usually three phase, if not always) with the inverter piloted off the grid itself. Generally the inverter is set up for either a slight lag in voltage or a slight lead -- depending on what the grid needs for power factor at that location (power factor, basically, is a measure of the phase relationship between the line voltage and the line current -- at a factor of 1, they are in phase; at any other value one leads the other, and the kilowatts delivered are less than the kilovoltamperes measured -- and the difference is wasted in heat in the lines).

It should be noted that keeping the grid in phase is not just a problem with disaggregated systems -- it's also a problem and a very intriguing one to power electrical engineers! with any system with interconnected generators. Power companies really don't like out of phase systems -- even slightly -- or power factors not equal to one -- because the part of the current which is out of phase does nothing except make heat and cause transmission losses. Increasingly very large interties -- connections between two or more more or less stand alone grids (such as Quebec Hydro to New England) are done with extremely high voltage DC lines (500 kilovolts and up) as they are less expensive to install and eliminate the problem of phasing. There are losses associated with the AC/DC conversion at one end and DC/AC at the other, but they are of a similar order to the losses in AC aerial transmission, and less than buried AC.

A great deal of research has been done in Germany on this problem, as they ran into severe instabilities in their system after they closed their nuclear plants and tried to shift to distributed solar PV. They still haven't solved the problem, and now -- ironically -- they are relying on lignite fired powerplants for stability and stand by. Not, shall we say, a step forward...

I'm afraid I have to take gentle issue with @ratio , however, where he says "The only viable, long-term solution is to use less, not more efficiently. ". This is undoubtedly true, for a small fraction of the world's population -- even a relatively small fraction of the First World population. However, when one starts from a consumption of near zero -- as some of the communities in North America which I work with do, never mind most of the developing world and third world -- the injunction to use less, wherever one puts the comma, isn't really very helpful.

ratio

You're right, @Jamie Hall, & I need to find some way of incorporating that in what I say.

Icarus

Jamie. Thanks for a explanation that spells out the issue. Next thing we need to do is figure out a way to co-mingle AC and DC on the same conductor!

Given all that you said, (and what I have read about this isssue, particularly about power supplies and PF) it would seem to be a solvable problem in the grand scheme.

As I said, it may be a PITA for the grid operator, but not so much as to make disaggregated production valueless.

Icarus

ChrisJ

Icarus said:

Jamie. Thanks for a explanation that spells out the issue. Next thing we need to do is figure out a way to co-mingle AC and DC on the same conductor!

Given all that you said, (and what I have read about this isssue, particularly about power supplies and PF) it would seem to be a solvable problem in the grand scheme.

As I said, it may be a PITA for the grid operator, but not so much as to make disaggregated production valueless.

Icarus

This has been done for a very very long time.
For example the Atari 5200 and Nintendo NES automatic TV switches.
DC triggers to switch while AC is the signal

In the Atari 5200 case the DC actually powers the computer as well.