I find it hard to believe electronics can't fully simulate physically rotating plant.

Posted By: barneya grid system designed for large scale generation, transmission, distribution and consumption - it handles voltage control and frequency stability very well, it is responsive to short term load fluctuations, medium term load shifts, fault clearing capability and a mix of generation types

is a great summary which aids understanding.

When you say 'distribution', looks like you mean load-balancing between regions/areas which are all reasonably self sufficient in supply, so it's just relatively minor balances that get redistributed, so the power transmitted/managed is relatively small? Different, as you say, from the total supply being transmitted from one one of the country/continent to the other.

Posted By: barneyNot Tesla again, Tom - surely you aren't reasonably suggesting that we use electrochemical storage ?

That indeed is the proposition that's been mooted for a long time, to use the national EV fleet's batteries as that, well dispersed towards point-of-use, as discussed in
http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14310&page=5#Item_6 .
The 'Tesla' one
http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14413&page=3#Item_5
is just an example of progress towards that. Do you think it's not just 'first steps' but fundamnentally rubbish?

Don't forget that the whole 'renewables' proposition, of which EV batteries are a sub-proposition, involves massive demand reduction - some say by 80%, which scales down the whole requirement on the grid. It's barking up a hopeless tree, to even think of renewables stepping into a 1to1 replacement for existing generation; likewise to think of a 'renewables' grid having to fulfil all its present duties unchanged.

Hello Tom

OK - We generate (big, in strategic locations), then we ramp up to very big voltages to allow long distance transmission (typically 275kV and 400kV)

A selected locations we start to drop that voltage to around the 132kV level - this is primary transmission - it's designed to move power around (not feed consumers directly (although very big consumers may connect at this point). This system is bidirectional

From this level, we then further transmit at 66kV and 33kV - this is secondary transmission - get the power roughly where it's needed - it may be bidirectional but is generally forward feeding.

Then we drop to primary distribution levels - typically 11kV (all those transformers you see at the back of shops, at the side of schools, up poles, at the end of your street) - from there we provide the 400V and 230V systems for small consumers - secondary distribution

Currently, each PV panel on a roof, the local farmer with a 200kW wind turbine, AD digester and the like is generating and connecting to the bottom end of distribution - ie pushing power the wrong way from which the system was designed

Now some people naively believe that we can continue to do this and everything will be just fine

So - this massive increase in generation from renewables in a region that was only ever a "consumer" can't be pushed around the grid as it causes overloads and overvoltages in distribution systems rather than transmission systems - the north of Scotland example above is a classic - it's also happening in Germany, Denmark and (from solar) in Spain

So now we have private developers raking huge sums of cash for building windmills we cant use without massive further investment that the public purse has to pay for - ditto for every field full of PV's you see all along the M4 and M5 corridors

Couple that with generation that is "unreliable" in output, not stable in operation until synchronised to something much bigger and not capable of control by the grid operators other than to dump it once it wanders out of spec, does the size of the problem begin to emerge

Look at the numbers above in terms of the storage capacity required - just how many of our Caledonian friends will need to have parked up EV's to match that level of storage

And I guess you have noticed that batteries are pretty chemotoxic things

We won't achieve 80% demand reduction - we'll be lucky to achieve 8% in the next 50 years if you still want to live in a westernised society with manufacturing industries

(as a side point, most windmills require permanent magnet alternators - the permanent magnet needs a few rare earth metals - who is digging these up)

So Tesla man is just marketing his hype, we can't operate a invertor based grid and rely on a few car batteries so we need massive investment along the scale of many tens of HPC's (HPC will do just 7% of UK demand, the barrage would be about the same)

The problem can be solved - but isn't it going to be so much easier to frack gas, burn that in conventional generation, pay the locals to shut up and proclaim that we need energy security first, low prices second (oh and we are rethinking green targets for sometime never)

Regards

Barney

In a nutshell, my point is that we cannot run a UK electricity supply on wind and PV alone regardless of wishful thinking

And at sufficient levels of PV and wind and insufficient levels of rotational high inertia generation we will have a grid crash

Regards

Barney

Tom: it is indeed the case that power electronics (linked to battery storage) can simulate rotating plant. And these can be (and are being) fully controlled by the grid operator (not things like the telsa powerwall, but utility scale battery storage).

I think we have to salute the efforts on the engineers on the ground, right now, going to work making distributed generation a reality. The lights are still coming on when you flick the switch.

There are real difficulties moving towards a grid with a large proportion of renewables, and this is going to require some changes to how things operate. I'm confident that in the several decades that this task will take that these issues will be addressed, and existing grid infrastructure (which needs to be replaced periodically anyway) will be upgraded appropriately.

There is a temptation to throw up ones hands and proclaim it all too difficult, but the progress is being made by people who refuse to give up.

We can't be seriously talking about battery storage, for all sorts of reasons

I'm just wrapping a project that has 3 data halls - we have about 2MVA capability in each hall (rack density is about 15kW per rack)

The whole lot is Tier 4 supported - it uses a combination of Diesel rotary UPS(DRUPS), conventional standby generation and battery supported UPS (NiCad)

For 15 minutes of support, the battery density is colossal - circa 70m3 per MVA

It's going to need an awful lot of parked up vehicles to meet that capacity

What's the expected lifecycle on a good quality VRLA or NiCad - 15 years ?

Regards

Barney

Posted By: barneyWhat's the expected lifecycle on a good quality VRLA or NiCad - 15 years ?

Wouldn't it be more relevant to ask about various lithium-technology batteries, flow batteries, fuel cells or whatever?

Posted By: barneyFor 15 minutes of support, the battery density is colossal - circa 70m3 per MVA

That's to achieve the required power density, not energy density, presumably. I.e., to get 1 MW out you need about 1 MWh of storage as you typically don't want to exceed 1C discharge (i.e., the rate which would discharge the whole lot in an hour) so for 15 minutes you'd only be using about a quarter of the capacity.

Posted By: Ed DaviesI think the trick to getting anywhere (rather than stagnating and decaying) is to start (carry on?) the change in thinking as quickly as possible by concentrating on small changes while keeping the longer-term larger changes in the backs of our minds.

It's more tricky than that. You have to have a view on what the long term goal is to know whether the short-term change makes sense. Basically, the mass of people need to trust a leader that they believe has a good long-term vision. Small problem is engendering that trust. Large problem is finding anybody with those qualities. Winston Churchill had the ability. So did Lee Kuan Yew. Cameron, Miliband, Corbyn, et al, Trump, Clinton clearly do not.

Posted By: djhthe mass of people need to trust a leader that they believe has a good long-term vision

Trust in leaders is a trap that almost always is betrayed, or is revealed as mouldy years later. It's a poor substitute for what is so closely in reach, the secret, never-used weapon of the people, the downtrodden/repressed, Brexit voters etc:
https://www.amazon.co.uk/Empowering-Public-Wisdom-Practical-Citizen-Led/dp/1583945008/ref=sr_1_1?ie=UTF8&qid=1470692090&sr=8-1&keywords=empowering+public+wisdom

http://www.bbc.co.uk/news/business-37016120

"Failing to go ahead with the Hinkley Point nuclear project could threaten China's relationship with Britain, its ambassador to the UK has warned."

Bugger orf!

Posted By: barneyI'm just suprised that battery support would play a part in a green grid given the short life…

Remember that when a battery reaches the end of its as a battery it's not useless - it's a great resource to recycle into new batteries. I think this is true of most battery technologies being contemplated. The operating costs are not negligible but they're not like a complete write-off of the capital either. A few years ago the retail costs of batteries put energy storage costs at about retail electricity costs (around 12p/kWh then) assuming no end-of-life value. Now and at wholesale prices with commercial residual value to the batteries at end of life I'd expect them to be closer to wholesale electricity prices.

Batteries are only part of the game, of course. There's a whole range from super-capacitors for very short-term storage to batteries, to compressed air [¹], to pumped storage for longer term with plenty of overlap.

[¹] Yes, naive compressed air is horribly inefficient but there are companies working on solutions to basically store the evolved heat separately and put it back as the air is expanded.

Posted By: Ed DaviesYes, I was sort of assuming that those campaigning for some change would know what change they were campaigning for.

Posted By: djhBasically, the mass of people need to trust a leader that they believe has a good long-term vision.

That's a different matter. What I'm suggesting is that the goal, or at least the possibility, will emerge as short-term (and local) changes are made. E.g., people won't believe how little heating a house should need until they themselves visit friends or neighbours living in houses with minimal heating systems.

I think there's a contradiction between your first sentence and your third. You can't make [some/many] short-term decisions without a long-term plan and I think the best long-term plan is in many cases a matter of belief rather than 'evidence-based logic' at least until the plan is part-way developed. Hence the fundamental need for good leaders.

The boffins like it just fine - we test the hypothesis with hard physics then get beaten up because the answer isn't what was wanted - then the answer gets changed

History is full of examples

Barney

The grid is certainly complicated and not at all obvious in it's workings...

I live in central England. About 8km from us is one of the main north-south distribution lines for the national grid. It's important enough to show up on top level maps. You might think it's an ideal place to build generating capacity but it's not so simple....

The line runs right past a wind farm but the wind farm couldn't be connected to it. Instead it's connection to the grid had to go under a main trunk road and something like 4 miles underground through villages to a point where it could be connected to the local grid.

A second wind farm was granted planning permission after the first was constructed. This one is very close to where the first connects to the local grid. But it can't be built and connected yet because the first has used up the available capacity. These are only small wind farms of 3-4 turbines.

Posted By: CWattersThese are only small wind farms of 3-4 turbines.

Only a dozen or so (have seen the actual number but can't remember it off hand) of wind farms in the whole country actually connect to the grid. The rest are “embedded” - that is, they connect to the local distribution network not the grid. There's a lot of casual use of the word “grid” (e.g., what's called grid-connected PV on people's roofs) but when you start being careful about what's what the grid is a much smaller part of the overall network than many think.

The grid is owned by National Grid (at least in England and Wales, I think Scotland's different). The distribution networks are owned by the local DNO (distribution network operator). The interface between the two is typically a big yard full of transformers on the edge of a town.

Apart from the actual physical connection the difference between a grid-connected wind farm and an embedded one is how the grid operators see production and how it gets paid for. The grid gets real-time data on the grid-connected ones and they get paid at wholesale rates with all the contracts for differences stuff whereas embedded wind farms just have a total-generation meter like a domestic producer and get paid FiTs.

So you wouldn't expect a small wind farm to connect to the grid lines even if they were in the next field.