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Author Topic: Are we crazy ?  (Read 13000 times)
billi
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« Reply #45 on: February 27, 2014, 10:05:53 PM »

For Grid connected ideas ....

Simple as that ....http://www.victronenergy.com/blog/2013/11/16/hub-1-working/
Probably   another  controlling device needed to feed  the battery from the Grid as well in-case  the national Grid has too much  wind  / solar whistlie, and  as well to tell the battery to feed back into the Grid when needed  .... bingo

Yes we can ............ if we would want to  whistlie
« Last Edit: February 27, 2014, 10:07:26 PM by billi » Logged

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« Reply #46 on: March 31, 2014, 06:40:51 AM »

http://www.pddnet.com/news/2014/03/intelligently-managing-renewables


Quote
Experts have already conducted a test showing that this setup does indeed work reliably in practice, having combined numerous wind parks, biogas and photovoltaic facilities delivering a total output of over 80 MW in a virtual combined-cycle power plant. Because small providers work together, regional variations in wind and sun can be evened out via the grid or using biogas facilities that can be regulated according to requirement. Surplus energy is either stored or converted into heat. The result is a powerful network that remains decentralized but can still operate as a larger unit in energy trading markets.

 whistlie

I sometimes think we live in  the last century , and the multi media world has all , that the renewable world would need , .... money , gadgets , control ideas  , Apps , etc

by time , they start to think of ideas like this ...




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« Reply #47 on: March 31, 2014, 07:49:16 AM »

I sometimes think we live in  the last century , and the multi media world has all , that the renewable world would need , .... money , gadgets , control ideas  , Apps , etc

by time , they start to think of ideas like this ...
It all depends how much they had to provide by Biogas to balance the "grid". If it's more than a very small amount, it's no different from the current grid we have with the exception that the methane is derived from recent biomass rather than long dead biomass. After all, a virtual grid using 100% biomass would be no news at all. And funnily enough, they don't provide the numbers...
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billi
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« Reply #48 on: March 31, 2014, 10:50:24 AM »

surely , not much news , if several small de-central  RE suppliers combined ,  form a  stable power grid ...
Not that i am a total believer of that "Brave new RE World"...



But perhaps you remember the thread here "22GW of pv by 2020 will crash the grid !"   Wink ,  same in Germany with their 52 GW cap

Surely , if one  is a conventional Grid believer , than  one has to accept  those caps ....and keep on  talkin about indeterminacy  for decades ...

By time now , that PV (home) installs get more clever and play a bigger role   

Quote
Eguana Technologies announced that the Smart Grid Research Group of Germany's Fraunhofer Institute has selected Eguana's Bi-Direx inverter as the control platform to be used in developing creative control strategies that will allow distributed energy storage systems to contribute to load balancing strategies implemented by utilities and energy aggregators.

"Smart "edge-of-grid" power electronics will be a critical element of the system control strategies that will make decentralized residential and commercial storage capacity available to the power grid for load balancing in real time,"

http://utilitiesretail.energy-business-review.com/news/fraunhofer-institute-choses-eguanas-bi-direx-inverter-for-smart-grid-energy-storage-research-200314-4201658


Hopefully we see more intelligent PV soon   and  install far beyond  the set caps by the "big players "

Billi


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« Reply #49 on: March 31, 2014, 12:16:10 PM »

But perhaps you remember the thread here "22GW of pv by 2020 will crash the grid !"   Wink ,  same in Germany with their 52 GW cap
Surely , if one  is a conventional Grid believer , than  one has to accept  those caps ....and keep on  talkin about indeterminacy  for decades ...
I probably ought to, I seem to have written about half of it! From memory the big conclusions were that the grid wasn't even going to notice the effects of wind until it got to about 4-6x the annual generation it was at at the time (probably more like 3x now, due to the effects of falling coal prices and much more wind generation coming online). Most of the puffery about renewables crashing the grid doesn't stand up to even the briefest mathematical scrutiny.

By time now , that PV (home) installs get more clever and play a bigger role. Hopefully we see more intelligent PV soon   and  install far beyond  the set caps by the "big players "
I think intelligent PV is going the wrong way about it - it limits consumption to when PV is doing well on their roof, and when they can use it. Time of use metering, as enabled by smart meters seems a far better way to go about it - the technology is being rolled out now, and it'll be very easy just to have people switch their immersion heaters on when the price goes below a certain level (that of gas for instance). Smart meters strike me as both a simpler way of doing things and also a far more powerful one, as they can be imposed universally rather than relying on a small number of poeple to decide to adopt them, and can also apply to the big industrial users of energy.
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dhaslam
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« Reply #50 on: March 31, 2014, 12:36:14 PM »

Smart meters would be a little bit difficult to operate properly  so  does it just transmit the charge price and have an in house computer to decide what works or doesn't work?         
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« Reply #51 on: March 31, 2014, 01:05:40 PM »

Smart meters would be a little bit difficult to operate properly  so  does it just transmit the charge price and have an in house computer to decide what works or doesn't work?
That would be the most obvious way - people will have different priorities for when they want appliances to work. It also seems to be the way most appliance manufacturers are thinking - they're looking to smart appliances rather than smart plugs, and a price signal is the most obvious way of driving these.

Freezers for instance would be preferentially run away from peak hours with an override to keep them cold enough (for instance if someone puts several joints in it to freeze them during the middle of the day). Immersion heaters would only run when electricity is cheaper than the price of the alternative fuel (gas or oil). Washing machines would be set to run at the lowest price over the course of a night, to finish by the morning but taking the cheapest price available.

It would also dispose of the absurdity of people being paid to use up PV in immersion heaters at the time of day when demand is highest and the grid is currently at it's dirtiest - export prices should track import prices, at say 30-50% of them (to allow for the very high costs of running the grid) or set at the spot wholesale price less say 5% for admin costs.

The only reason it hasn't happened yet is VAT - the government's scared of losing out on it if prices change during a day.
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« Reply #52 on: March 31, 2014, 04:13:37 PM »

The only reason it hasn't happened yet is VAT - the government's scared of losing out on it if prices change during a day.

I don't understand that. Surely the electricity companies will be looking for the same income whatever so if they're charging less for some kWh they'll be charging more for others to compensate. 5% of the same will be the same.

(Separate issue is, of course, the question of whether domestic energy should be full-rate VAT.)
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pdf27
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« Reply #53 on: March 31, 2014, 04:26:38 PM »

I don't understand that. Surely the electricity companies will be looking for the same income whatever so if they're charging less for some kWh they'll be charging more for others to compensate. 5% of the same will be the same.
Makes no sense to me either, but I've certainly seen statements to the effect that VAT is the main reason they're worried about time-of-use metering. Sounds crazy to me - they manage it already with Economy 7 after all, so expanding it to more rates in future when smart meters are about sounds pretty easy to me. British Gas have already started talking about free electricity on weekends, so the concept shouldn't be beyond the wit of your average Treasury civil servant.
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« Reply #54 on: March 31, 2014, 05:27:58 PM »

That's crazy! Modern economics really is making a mess of so many aspects of evolution. Agree with everything you say here, pdf27.
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« Reply #55 on: April 02, 2014, 02:08:33 AM »

Quote
I think intelligent PV is going the wrong way about it - it limits consumption to when PV is doing well on their roof, and when they can use it. Time of use metering, as enabled by smart meters seems a far better way to go about it  

I think nothing can stop battery based PV systems  and why should one  ?? ( oh well , sure some  will try ....E.ON Germany profit  was halved last year and RWE  first time in history was loosing cash last year)

The prognoses  in Germany (as an example ) for the end user are  for the end of the decade  , no FiT payments (as we know them )  , PV will cost under 10 cent per kWh  and electricity imported  close to 35 cent

In the States they say  
Quote
Evans-Pritchard writes:

    The US Energy USEG +2.37% Department expects the cost of solar power to fall by 75% between 2010 and 2020. By then average costs will have dropped to the $1 per watt for big solar farms, $1.25 for offices and $1.50 for homes, achieving the Holy Grail of grid parity with new coal and gas plants without further need for subsidies.

http://www.forbes.com/sites/williampentland/2013/08/21/could-the-cost-of-solar-power-fall-by-75-by-2020/

Seeing , how they try to  starve PV  to death  in Germany  and other countries in Europe  at the moment , there is no plausible argument in waiting on Grid structures  , and politics , that are unable to deal with the fact , that people can make their own intelligent power plant , without relying on big players , that are timewasters and struggle to make their profits  and only gain those, in squeezing  long term funding agreements  out of weak governments , that in the end We have to pay for ...


So again , "Are we crazy ?"  in not just install what we need , nevertheless what they want us to do ?
« Last Edit: April 02, 2014, 02:33:01 AM by billi » Logged

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« Reply #56 on: April 02, 2014, 12:56:05 PM »

I think the extended use of batteries is going to depend massively on the development of battery technlogy and chemistry.

Battery usage cycle will vary with size - the smaller the battery in relation to load, the more it will be used. So take as an example a 1kWh battery, and assume that it is 100% used every day. That saves 25 cents (20p)/day, based on your predicted electricity prices - just under 75 per year.

A LiFePO4 battery - currently probably the most promising future chemistry for this sort of thing - has a lifetime of ~2,000 cycles (6 years) and costs about 300 (best price I could find at short notice, from a Canadian supplier). Over it's lifetime it will save ~450 in electricity, so will be worth around 35/year in savings.
As the battery pack gets larger, it won't be fully used every night. A 10 kWh pack for instance (required if you want to guarantee the sort of reliability the grid gives you, and don't want a generator) would end up saving you ~250 per year in electricity (based on my own consumption) but costing 500 per year in depreciation. Allow for seasonal variation in PV generation, and you still won't end up being free of reliance on the grid for some generation.

That leads me to conclude that small batteries are quite likely in the near future, but unless there is an order of magnitude crash in prices (which seems unlikely given the cost of raw materials) people will still want a grid connection. Unless you plan to legislate to force the utilities to make a loss, they'll end up with high standing charges (to cover their costs to run the grid and the standby power stations) and leave the unit cost around where it is. You'll end up with plenty of PV, but the utility companies will still be there and still be running the grid.
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« Reply #57 on: April 02, 2014, 02:56:46 PM »

.... You forget  , that including a battery in a  say 16 A  limited or 3.6 kW PV  , it could be possible (theoretically) to install say a 10 kW PV with a constant  output  of 1.5-2 kW over 24 hours to the grid and or the house  @ current FiT  of over 14 pence

The present  structure of current PV Systems (PV + stupid GTI) is not the holy end grail of engineering ... it just happened  due to FiT and  a Grid that had/has space ....

We need  alternative ideas  and surely  , why shouldn't  there  some saved on only using a smaller GTI (or like said bidirectional offgrid units)   instead  one big one ?  Charge the battery on the DC side direct or via cheap MPPT .... , absorb even at home  windpower surplus for free  into the battery via smart grid ideas and sell it back  later ....

Whats the problem  Wink

Sure i am aware , there might not  be enough  lead for   cheap batteries  facepalm but again  a 40 KWh  battery will cost  about 1500  so  under 40  per kW  or  @ 1500 cycles   (80 % DOD)  (= 40kWh *0,8 =32*1500=48000 kWh- 20% systhemlosses = 38000 = 4 pence per kWh )

I am not fixed to lead acid batteries  nor to small household solutions  ,  just thinking  , all our effort at the present time has to wander towards a 100 % renewable future , and  for that we indeed need "intelligent PV "



Billi
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« Reply #58 on: April 02, 2014, 04:22:00 PM »

pdf27's argument rests on the assumption that, for LiFePO₄s, the lifetime decrease per cycle is independent of the depth of the cycle. I'm not sure that's the complete story but from the little I've read on the subject it seems likely at least partly true.

What that says to me is that for a larger off-grid store the battery should be split into multiple strings and an effort should be made to only cycle one or a few of the strings most of the time, leaving one more more strings at constant charge (LiFePO₄s having pretty low self-discharge) as a reserve - only cycled when there's an extended period of poor conditions or a particularly heavy load.

Previously I'd wondered about LiFePO₄s for day-to-day use with FLAs kept topped up most of the time as a reserve.

Hmmm, more thought needed.
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« Reply #59 on: April 02, 2014, 07:12:38 PM »

.... You forget  , that including a battery in a  say 16 A  limited or 3.6 kW PV  , it could be possible (theoretically) to install say a 10 kW PV with a constant  output  of 1.5-2 kW over 24 hours to the grid and or the house  @ current FiT  of over 14 pence
Sure it's possible. The real question is whether it is desirable. If we were in the situation we were in say 80 years ago with no grid then the answer would almost certainly be a big fat yes - you get much the same effect as building a grid for much lower cost. But we aren't in that situation, and we have a robust and effective grid capable of accepting as much PV as you want to generate, and finding customers for it.
Now, that plan would work for the current FIT structure, but would probably not provide sufficient power in winter if it was PV-only for most people's lifestyles - and would cost more for batteries than would be saved in import costs (especially as the FIT is paid for generation, not use or export).

The present  structure of current PV Systems (PV + stupid GTI) is not the holy end grail of engineering ... it just happened  due to FiT and  a Grid that had/has space ....
Indeed. However, the Grid isn't going away any time soon - people are naturally going to want a supplier of last resort, and there are plenty of people who can't even fit a small PV system let alone the 10kW monster you're suggesting. So the situation we're facing in the long term is an uncertain FIT, much the same grid situation (probably a bit more stressed, but with smart meters) and the possibility of people fitting batteries in their home.
To me that suggests that you're going to see most of the ingredients you've suggested, but put together in a different way. Grid tied PV, batteries, and smart meters which people use to charge up their batteries on cheap rate electricity (probably overnight) and then feed the power into the grid when demand is high (right now, peak demand matches peak PV generation - one of the many reasons that your suggestion to charge up batteries on PV during the day and extract it at night is a bad one - with a grid increasingly powered by wind, daytime electricity will be the dirtiest by far as we want to encourage export to the grid during the day and import from it overnight). Grid tying batteries also has the nice effect that the grid can easily absorb far higher slew rates in consumption (thus enabling us to build far more wind farms), and at the same time we can get rid of a lot of dirty and expensive peaking plant.

pdf27's argument rests on the assumption that, for LiFePO₄s, the lifetime decrease per cycle is independent of the depth of the cycle. I'm not sure that's the complete story but from the little I've read on the subject it seems likely at least partly true.
It's a deliberately crude set of assumptions, but probably close enough for our purposes. Since you guys don't pay me for my analysis, I'm not going to spend hours looking through charge depth versus lifetime calculations.

What that says to me is that for a larger off-grid store the battery should be split into multiple strings and an effort should be made to only cycle one or a few of the strings most of the time, leaving one more more strings at constant charge (LiFePO₄s having pretty low self-discharge) as a reserve - only cycled when there's an extended period of poor conditions or a particularly heavy load.
I think you're heading in the right direction there, but I'd add that it's worth considering the sort of strategy used to maximise life in flash memory - rather than cycling all the strings simultaneously, you look at keeping most of them at a constant state of charge and only cycling one or two, but you rotate around which one you cycle. It makes sense to replace an entire battery bank at the same time, rather than have mixed makes and styles of battery in the bank (at least for most people, who would fit new systems - ebay specials are always going to be mixed).

Previously I'd wondered about LiFePO₄s for day-to-day use with FLAs kept topped up most of the time as a reserve.
For off-grid use in the immediate future, that makes some sense. In the long run, I suspect LiFePO4 will come down in price enough that lead acid becomes an obsolete technology for everything except maybe cheap car batteries (given the large number of cranking amps it can put out). Either way, I suspect the grid will provide a better and cheaper reserve than batteries where it is available.
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