CitroJim wrote: ↑
28 Sep 2017, 06:47
...And there still remains a big worry that the UK's electricity infrastructure will be unable to cope with the charging demands if EV uptake was to soar...
I saw a piece on the BBC News Site a while back. Scottish Power raised the concern...
http://www.bbc.co.uk/news/uk-scotland-s ... s-41373466
There will definitely need to be some buffing up of electricity generation and distribution, mainly last mile distribution at a street level - there is no doubt of that, you can't shift an entire fleet of cars from petrol/diesel to electricity without some shift in infrastructure focus. The fact that it's possible at all shows how large the scale of the existing electricity infrastructure already is when you consider the bazillion gallons of petrol/diesel it is trying to replace.
However I think it's far from doom and gloom. From the article:
The estimate of a 20%-30% increase in demand for electricity comes after years of gradually declining power use, much of that due to growing energy efficiency and the closure of older, energy-intensive industries.
So what they're saying is that it would cause an increase in demand of 20-30% over our current electricity use...... and my response is so ? If the required demand was to have doubled or tripled our current electricity demand then I would have been very worried indeed. However 30% is an incremental increase, and in reality it would gradually ramp up over many years - probably 5-15 years when you take into account "grandfathering" existing ICE vehicles on the road which won't just suddenly come off the road all at once. It's not like millions of homes would dump ICE vehicles and switch to electric cars over night, especially those that drive old cars.
30% is well within the bounds of normal engineering upgrade work, and is no different to any of the other increases in demand for electricity of the last century as new energy intensive industries have come online such as aluminium smelting - demand increased and money was spent to build out the infrastructure to keep pace and everybody was happy. The tone of a lot of the news articles implies that we somehow can't do this upgrade work or that it will be left until it is too late - I don't think that will be the case.
Other interesting points - low energy light bulb adoption accounts for a large proportion of the decline in electricity demand in the last decade or so - if the switch hadn't been made then our current generation levels would most likely have already been 30% higher today than what it actually is - would we have been complaining about the extra infrastructure to keep up with the increase in demand then ?
The switch to energy saving bulbs has given a temporary respite to the gradual increase in demand but it was only ever going to be temporary - once they reached a high market penetration the trend was always going to go up again.
A lot of articles focus on peak demand - there is something like a 20GW difference between peak load in the early evening and the middle of the night in the UK - it has been calculated that the difference in demand between peak and off peak is enough to charge a country full of EV's without any increase in generation as long as they all charged off peak.
So you can either incentivise people to charge off peak (with a timer and cheaper rates etc) or you can build out a lot of storage capacity on the grid such that generation at night can continue at daytime levels going into batteries or other storage mechanisms and then released at peak times. So you don't have lots of power generation sitting idle at night time. We need this grid storage to move to majority renewable generation anyway as they are fluctuating sources of power. A combination of those two in theory would make it possible to charge all EV's with the current level of generation we have by tapping into the underutilisation in off peak hours.
The added challenge of cars is the change in technology from an eight-hour overnight charge to a rapid charge of 15 to 20 minutes.
This is somewhat irrelevant as rapid chargers are normally only used on a long journey (and that will certainly be the case when batteries get bigger) and most charging is still going to be done at home at no more than 7kW. Whether you charge quickly or slowly the total amount of energy in kWh is about the same and therefore the total generation required is the same. However in localised areas the grid would need to cope with higher peaks, something which could be buffered by a battery bank at a rapid charging site. But as far as total generation capacity goes, rapid charging is irrelevant.
If several car owners on a residential street plug those in at the same time, the system could not cope.
This is nonsense. Residential charging in the UK on single phase supply (which is the majority of houses) is limited to 7.2kW or 32 amps at 240v. Many cars still only charge at 3.6kW like my Ion.
Lets compare that to other large power users in a home - Electric Shower - 10kW, Electric hot water heating - 3kW or in some cases 6kW. Electric oven - 3kW. Kettle - 3.6kW.
So charging your car at 7.2kW is not as bad as turning on an electric shower in terms of instantaneous demand.... so if everyone in the street turns on their electric showers at about the same time in the morning the system can't cope with that either ? What if their hot water heater is on, the shower is on, someone is using the kettle and toaster, then what ? Lights out ?
Yes there will be places where the supply to a street is a bit under-provisioned and those will need to be sorted out, but 7.2kW from a house is really not that much of a problem, especially if most of that charging is through the night.
The article then goes on to conflate a "shift to electric heating" in the home with demand from EV's - where ? I don't see anyone rushing to switch to electric heating as it doesn't make financial sense...
More doom and gloom - if I were an engineer involved with the grid or generation in any way I would be thinking "These EV's are coming one way or the other, we better crack on and get the system upgraded in time to ensure a smooth transition and continuity of supply". Anything else would be negligence of duty.