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UK Electricity Generation
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Potemkin Villager



Joined: 14 Mar 2006
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PostPosted: Tue Sep 27, 2016 9:15 pm    Post subject: UK Electricity Generation Reply with quote

Carbon Brief have produced an interesting presentation on UK electricity generation that is worth a look.

https://www.carbonbrief.org/mapped-how-the-uk-generates-its-electricity
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clv101
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PostPosted: Tue Sep 27, 2016 9:33 pm    Post subject: Reply with quote

A key take home is that our electricity use peaked over a decade ago and has fallen a lot (twice Hinkley's C expected output). This is despite population and GDP growth. I'm often surprised by meeting clued-up, energy literate people that just seem to assume electricity demand has been and will continue to increase - it just ain't so.
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Potemkin Villager



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PostPosted: Tue Sep 27, 2016 10:07 pm    Post subject: Reply with quote

So what are all those electrical vehicles going to run on as they zip up and down the M1?
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adam2
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PostPosted: Tue Sep 27, 2016 10:57 pm    Post subject: Reply with quote

Firstly affordable electric vehicles are not ideal for motorway speeds and distances, not many will be "zipping up and down the M1".

Secondly I would anticipate that most electric vehicles will be charged overnight whilst the owner sleeps.
So doing will increase total electricity consumption, but should not have much impact on peak demand which is of greater concern.

In time, special tariffs for the charging of EVs will probably become available, in the interim use of economy 7 or equivalent off peak tariff would be sensible for most people.

And the more power that is used off peak, the easier it becomes for the grid to accept more wind power.
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PS_RalphW



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PostPosted: Wed Sep 28, 2016 11:04 am    Post subject: Reply with quote

Once real world range of affordable electric cars exceed 200 miles with 1 hour fast recharge time, long distance motorway driving becomes practical for a large number of drivers. 200 miles is 3 hours realistic endurance, and after 3 hours most drivers need an hour break.

Speed will need to be limited to 70mph to achieve that range, so it won't suit most travelling sales people Wink

The Chevy Bolt will be available in the US in a few months with 230+ mile real world range, at about the same price as the BMW i3. It is a 60KWh car so will recharge 40Kwh on a motorway fast charger in one hour, making at 350 mile drive possible in 6 hours including a one hour break. Unfortunately there are no plans to sell it in the UK.

In 5 years, electric cars will be a realistic option for most new mid-price car buyers, and the market acceptance will then really take off.
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PS_RalphW



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PostPosted: Wed Sep 28, 2016 11:16 am    Post subject: Reply with quote

At present it does not make sense for me to use economy 7 to charge my Leaf. What I would gain by cheap night time recharging is more than offset by the higher daytime tariff .

Also, the limited range means it gets used mostly for relatively short journeys and I need to recharge it after each one (plugging it in takes about 20 seconds) to make sure I don't forget and end up with less range than I need the next morning. I tried automatic overnight charging but the internet based app did not work reliably and I didn't want to risk a flat battery in the morning. The apps are a pain to use - poor software design.

Also, I am only charging the battery to 80% because leaving the battery at 100% for any length of time is said to shorten its life.

So I tend to end up recharging during peak demand hours.
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adam2
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PostPosted: Wed Sep 28, 2016 11:41 am    Post subject: Reply with quote

Charging significant numbers of EVs could well be a challenge, no problem at present, but looking to the future ?

The electrical industry allows for an average demand of about 5 amps per house, spread over a large number of houses.
Any one house can use a lot more, often up to 100 amps, but only 5 amps on average.

If one household in 10 slow charges an EV overnight then that has added nothing to the peak demand, and has only added about 1 amp to the off peak demand. No problem.

If however one household in ten fast charges an EV in the peak then that could be unfortunate, both for the local distribution system and for generating capacity.
Presume that a fast charger uses 30 amps, then that has increased the average load per dwelling from 5 amps to 8 amps which is significant.

We are at present a long way from any problem.
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PS_RalphW



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PostPosted: Wed Sep 28, 2016 1:40 pm    Post subject: Reply with quote

Thinking medium term we are probably looking at 50+KWh cars being charged primarily overnight. Demographically it will be in affluent suburbs and rural areas that the main load will come, because these are the areas that 1. can afford to buy and 2. have off road parking that is required to charge an EV.

Typically I assume that the cars will have 6KW+ chargers - less than this and it would be too slow even for overnight charging.

If the average car does 12,000 miles a year at 4miles/KWh that is 3000 KWh or about 10KWh/day a day allowing for charging inefficiency.

Spread evenly between the hours of 10pm and 6am that is about 1.2KW or 5 amps extra load.

So it would take close to 100% saturation of EV's in an area to overload the grid if they are charged primarily overnight. However, if every charger was programmed to come on at exactly 2.17am each day, a far smaller saturation would cause spikes in demand.
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Potemkin Villager



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PostPosted: Wed Sep 28, 2016 4:25 pm    Post subject: Reply with quote

PS_RalphW wrote:


If the average car does 12,000 miles a year at 4miles/KWh that is 3000 KWh or about 10KWh/day a day allowing for charging inefficiency.



30 million cars x 3MWh = 90 TWh per year and would represent a 30%
increase in demand (currently about 300 TWh per year).
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Potemkin Villager



Joined: 14 Mar 2006
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Location: Narnia

PostPosted: Wed Sep 28, 2016 4:32 pm    Post subject: Reply with quote

Not strictly relevant to this thread, but very interesting in comparison is their take on Germany.

https://www.carbonbrief.org/how-germany-generates-its-electricity
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PS_RalphW



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PostPosted: Wed Sep 28, 2016 4:46 pm    Post subject: Reply with quote

UK current vehicle Miles travelled is 250 billion for cars (not vans or HGVS).

At 4 miles/KWh that is 60 Twh or 20% of current UK production.

A lot, but it is going to take at least 15 years to replace the current fleet, even if we stopped selling ICE cars today, So, 30 years minimum real world.

It could be done.

It won't be done.
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clv101
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PostPosted: Wed Sep 28, 2016 4:53 pm    Post subject: Reply with quote

And we could cut electricity consumption by 20% in a decade to 'make room'.
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Last edited by clv101 on Wed Sep 28, 2016 7:30 pm; edited 1 time in total
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PS_RalphW



Joined: 24 Nov 2005
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PostPosted: Wed Sep 28, 2016 5:01 pm    Post subject: Reply with quote

Last year we produced 40TWh from wind power alone. This year will be more.
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Potemkin Villager



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PostPosted: Wed Sep 28, 2016 6:02 pm    Post subject: Reply with quote

I am still unsure which I find the most alarming,
the 30 million cars or the 250 billion miles.
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vtsnowedin



Joined: 07 Jan 2011
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Location: New England ,Chelsea Vermont

PostPosted: Wed Sep 28, 2016 8:04 pm    Post subject: Reply with quote

PS_RalphW wrote:
UK current vehicle Miles travelled is 250 billion for cars (not vans or HGVS).

At 4 miles/KWh that is 60 Twh or 20% of current UK production.

A lot, but it is going to take at least 15 years to replace the current fleet, even if we stopped selling ICE cars today, So, 30 years minimum real world.

It could be done.

It won't be done.
Why will it not be done once the era of cheap fossil fuel is over? The only reason for the low demand for EVs today is that ICE driven vehicles are cheaper and more reliable.
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