Interesting Items...

[Black Hole]

Electronics Weekly, 8th July 2015:

 

[Black Hole]

Electronics Weekly, 14th October 2015:



"There are a number of limitations when dealing with ARM hardware and not everything that you would expect to work will be present, but users should have access to pretty much everything." Eh? That's self-contradictory.

"Previously designers wishing to run Windows applications..." Does this mean this OS can run Windows apps straight off??

 

[Ezra Pound]

Could I introduce you to the thumbnail option when uploading a image file

 

[Black Hole]

I am very well aware of the thumbnail option, as well you know. In these cases the image is the post, and I regard it as appropriate to include in full rather than type out the text from it.

Knowing that I know, you should know that it was a conscious decision not to use the thumbnail and therefore pointless you commenting.

 

[Ezra Pound]

Knowing that I know, you should know that it was a conscious decision not to use the thumbnail and therefore pointless you commenting.

The first part your comment seems to suggest that you know what I know (not sure how), the second part seems less certain what I know.

Thanks for the clarification anyway, should I have used your dictatorial format, e.g. User - place your text in code brackets

 

[Black Hole]

If you can't tell the difference you're less intelligent than I gave you credit for.

 

[Trev]

Oh stop it you two!

 

[Wallace]

Yes, it's getting rather tedious. Again.

 

[Black Hole]

Cars section, Daily Telegraph 14/11/2015:



Reading through the accompanying article, this blatant misuse (or misunderstanding) of statistics appears to stem from a statement "if you have 20,000 vehicles plugged into 50kW fast-chargers, that's the output of an entire nuclear power station".

 

[prpr]

But where IS all the energy going to come from to charge electric cars en masse? And how much power can the existing distribution systems handle? Not enough, I guarantee you that.

 

[grahamlthompson]

But where IS all the energy going to come from to charge electric cars en masse? And how much power can the existing distribution systems handle? Not enough, I guarantee you that.

The glaring error of course is not everybody fuels there cars at the same time. What would happen if we all try to fill up at garages at the same time ? Not sure where the 2.25 power stations comes from. It obviously depends on which power station. Typical 70s base load power station has 4 x 500MW turbo alternators and up to 4 x 25MW gas turbine units. So it's just over 1 for one of these. Drax has 6 x 66oMW units.

You can forget about the distribution system limit, there is no where near enough installed generating capacity to simultaneously provide 50Kw to 37 million cars. 37,000,000 X 50 = 1850 GW. The highest peak UK demand was 52.54 GW 20th January 2015. and there was little left in reserve.

 

[Trev]

20,000 cars times 50kW = 1 GW and it is only Sizewell B, Hartlepool 1 & 2, Dungeness 1 &2 and Torness 1 & 2 that exceeds this at present Here

 

[grahamlthompson]

20,000 cars times 50kW = 1 GW and it is only Sizewell B, Hartlepool 1 & 2, Dungeness 1 &2 and Torness 1 & 2 that exceeds this at present Here

Where did Nuclear Power Power and 2000MW come into it ? Nuclear power is only a small fraction of the total installed capacity.

Drax 3960MW. Ratcliffe On Soar 2000MW, West Burton 3270 MW, Cottam 2000MW, Fiddlers Ferry 1989 MW. These figures exclude the 17.5MW or 25MW emergency gas turbine units associated with each turbo alternator unit (Used for peak lopping, declutched for system voltage control and restarting without external auxiliary supplies).

 

[MikeSh]

Well, I've just done a little exercise from a different direction. I dug out some figures for annual fuel use in the UK for cars (petrol and diesel, excluding LGV, etc). I converted that into annual kWh (at 100%) and assumed electric cars will need half that. Comes to 123,000 GWh. Which is 14 GW of generation 24/7.
So allowing for charging not being spread through the 24 hours evenly you'd probably need to allocate 20 GW or more capacity to service a UK electric car system if all current car use went electric, which is ten typical (2000 MW) power stations.

(If I've done my maths, etc wrong this could out by a factor of 1000, or more, so I'll paste my workings in below for someone to check.
I have rounded in places - it's all fairly aproximate.
Petrol + diesel cars ~20,000,000 tonnes per annum = 20,000,000,000 kg
petrol = 0.72 kg/l, diesel = 0.83
Say 0.77kg/l avge
20B kg / 0.77 = 26,000,000,000 litres
petrol = 9.1kWh/litre, diesel = 10
say 9.5 kWh/l avge
9.5 x 26B litres = 246,000,000,000 kWh
= 246,000 GWh
Assume electric is more efficient, so uses half:
246,000/2 = 123,000 GWh per year
365 days = 337 GWh per day
= 14 GWh per hour = 14 GW generation.)

 

[grahamlthompson]

Well, I've just done a little exercise from a different direction. I dug out some figures for annual fuel use in the UK for cars (petrol and diesel, excluding LGV, etc). I converted that into annual kWh (at 100%) and assumed electric cars will need half that. Comes to 123,000 GWh. Which is 14 GW of generation 24/7.
So allowing for charging not being spread through the 24 hours evenly you'd probably need to allocate 20 GW or more capacity to service a UK electric car system if all current car use went electric, which is ten typical (2000 MW) power stations.

(If I've done my maths, etc wrong this could out by a factor of 1000, or more, so I'll paste my workings in below for someone to check.
I have rounded in places - it's all fairly aproximate.
Petrol + diesel cars ~20,000,000 tonnes per annum = 20,000,000,000 kg
petrol = 0.72 kg/l, diesel = 0.83
Say 0.77kg/l avge
20B kg / 0.77 = 26,000,000,000 litres
petrol = 9.1kWh/litre, diesel = 10
say 9.5 kWh/l avge
9.5 x 26B litres = 246,000,000,000 kWh
= 246,000 GWh
Assume electric is more efficient, so uses half:
246,000/2 = 123,000 GWh per year
365 days = 337 GWh per day
= 14 GWh per hour = 14 GW generation.)

Excellent thinking, I will defer the calculation till tomorrow when the brain is a little refreshed

One thought, delivering the fuel compared to the delivery losses associated with the UK transmission system losses (England and Wales at the last published figures by National Grid) is around 1.65% of power delivered to the grid, needs to be factored in. The power factor of the technology used to deliver DC power to charge batteries could significantly increase the current required to support the charging network, which of course could significantly increase losses in the lower voltage distribution networks.

Add future fuel cell possibilities associated with yet undiscovered hydrogen generation techniques from surplus generation during overnight and periods of high wind and high solar activity.

Factor in the unpredictable contribution from renewables like wind and solar, really happy I do not have to predict long term UK demand trends. It's hard enough to do it for the next few hours, let alone the next 10yrs or so

There is of course no end of searches that could provide information.

Like


http://www.telegraph.co.uk/news/ear...inter-as-wind-power-slumps-to-its-lowest.html


http://uk.reuters.com/article/2015/04/09/uk-national-grid-outlook-idUKKBN0N018W20150409

Last time I sat in the loading desk of a CEGB control centre. planning the scheduling of plant required to meet the demand increase from overnight Sunday to a Monday morning, it was fairly complex involving matching the capability of synchronising plant to increase power and match the steeply rising demand curve. At least the parameters of the available plant was well known. Factoring in renewables must be a nightmare. Mentioning the CEGB should tell you it was rather a long time ago So long ago the system was purely manual (computers were in there infancy, and network analysis relied on analogue network models).

This wasn't that long after a experiment by control staff experimented by connecting isolated generation and demand systems together to create the first National interconnected system in the world.

When I retired (2000), we had sophisticated digital network analysis tools, despite this the capability to predict problems depends on lots of other factors (Remember the Micheal Fish there is no hurricane coming )

Then of course is the energy used in refinining crude oil into Petrol and Diesel. it's not that simple is it ?

 

[Black Hole]

The glaring error of course is not everybody fuels there cars at the same time.

Exactly. Fast chargers are supposed to be fast - charging from empty to full in maybe 2 hours? So even if everyone did that every day, the average demand would only be a twelfth of the quoted figure. Favourable tariffs would shift the demand to the dead of night, when the other demands on the system were at their lowest (but then peaking the vehicle charging demand again).

I grant that there is a pending problem, it's just not the magnitude of problem the article indicates.

Well, I've just done a little exercise from a different direction...

That's the way I would have done it.

I think hydrogen is the better way forward.

 

[prpr]

50kW is 200A or so. This is way more than most people's domestic supplies can cope with. It would mean massive amounts of recabling would be required both in the property and in the street all the way back to the substation... and probably further.

 

[Black Hole]

(Remember the Micheal Fish there is no hurricane coming )

As far as I know, that was a detachment of terminology. There was not, literally by meteorological terms, a hurricane in '87. What there was, was a very strong wind event of great rarity which was colloquially regarded as a "hurricane" by comparison with normal weather. It's the same as everyone around here referring to our hills as "mountains", when a geographer would not regard them as such because they are all under 3,000 feet (or whatever). To us, they are big hills and therefore mountains compared to the smaller hills.

Fish made the mistake of not recognising what the general population might regard as a hurricane.

 

[Black Hole]

50kW is 200A or so. This is way more than most people's domestic supplies can cope with. It would mean massive amounts of recabling would be required both in the property and in the street all the way back to the substation... and probably further.

So the majority will slow-charge, delivering the same amount of energy at a lower rate. Makes no odds to the generation demand.

 

[prpr]

Fish made the mistake of not recognising what the general population might regard as a hurricane.

It didn't really do him any harm as it raised his profile significantly.