I have seen discussions in the past looking at problems of locally overloading part of the distribution network. The load on a cable is usually monitored and controlled at the traditional source point, 800A fuses in the substation for example. A significant V2G source on that cable segment could allow an overload. A depot for EVs could be capable of sourcing a couple of hundred amps.

The principle you are suggesting, using V2G in a local part of the network to reduce the need for expansion of the wider grid seems to increase that chance of this without significant local monitoring.

Another point is that the CO 2 footprint of an EV is massive. Maybe 50K miles before it goes positive.

Plus the CO2 footprints claimed  never includes the upstream costs like transportation, manufacturing with Chinese coal fired power stations and mining of minerals by Conganese children and pregnant women. 

Built by slaves, maybe a 20% CO2 saving over 100K miles. Might need a new battery after 10 years, worthless second hand value. Why on earth would I want to own an EV. Definitely not to prop up a failing energy system.

Anything that say 'could' rings my BS bell.

And this from your link says all I need to know!

There is a slight risk that V2G could be used as an excuse not to invest in updating the grid 'properly', in terms of replacement transformers, thicker cables and so on. We have about a century of grid design experience design around centralized generation, and voltage drops that slope downwards towards the load, we have a similar length of time that has led to reliable design rules, like 1.5 -2 kW per house when sizing substations, and an arteries and branches approach to cables that means that the street main has an apparently oversized cross-section, when looking at those average loads, so that any one house can draw 100A for as long as it needs to. But no more than perhaps half a dozen houses in the street can do that at once, or the substation fuses pop ! And historically that never happens, and the design rules work OK,

A transition to electric heat pumps for heating and electric cars that need charging, at least if you expect cars to be charged at home, and not at dedicated charging hubs with their own substations, renders all those DNO design rules and assumptions obsolete, and replaces it with 'here be dragons'.

The ability to borrow a few tens of amps from the neighbour and save roasting the substation may initially look attractive, and allows some demand leveling, but then so does the far simpler measure of staggering the charging times that share a phase on a substation. At the moment, conventional  EVs are still a fairly niche thing - there are none in my street  for example but there are a few in total on the whole housing estate, so maybe less than ten per substation at the moment.

Equally I don't live in a street of detached houses where folk buy cars new from a main dealer - those that do will have a different perspective on 'normal' ;-)

I see that there is a lot of network reinforcement to be done before say every third house that currently has a car, can have an EV - V2G may be a way to shirk that.

Mike

https://youtu.be/K8Nz-4eEBTw

Mark P Mills gave this speech on the Economics and Future of Electric Vehicles on November 12.

Well.worth an hour of anyone's time to listen to him.

Hi Mike - some good thoughts.

I understand your view about V2G leading to risk of non investment in network upgrade.

I also like your thought about staggering charging - "smart" chargers could manage this recognising the capacity in the local network versus demand. People could be rewarded (with low cost) for scheduling their charging in advance (hence easing the management of the demand on the network). 

I'm thinking V2G may be a way of extending the lifetime of existing infrastructure such that the future investment could be optimised (e.g. prioritised based on the weakest points in the network.)

As solar and wind will play an increasing role in the future, and these are more distributed in nature than the centralised power station concept, I suggest that new investment would be optimised by recognising this de-centralisation rather then re-creating the centralised architecture of the past?

Stuart

I'm thinking V2G may be a way of extending the lifetime of existing infrastructure such that the future investment could be optimised (e.g. prioritised based on the weakest points in the network.)

quite, but if we only do that at the pace of the current system has developed, then it will take 70-120 years to complete, by which time the goalposts will have moved again.

Generally the  UK system either dates from when the house was built if post war, or from whenever the pre-war supply (if any) became inadequate for increasing load.

By way of anecdotal support for my 70-120 year figure.

I'm not sure how old the transformer that feeds your house is for example. but the one that feeds mine was installed at some point in 1969, and there is an adjacent unused pad for another to take extra load that has never materialized, and the street cabling is the same age except in a couple of places where the consac has gone bang and 6 foot lengths of plastic clad CNE between pairs of 'torpedo joints' bypass the blown out bits of SNE.

The transformer feeding my dad's place however went in during  the mid 1950s, and there is no room to upgrade it if that were ever needed without compulsory purchase of adjacent property or some seriously messy  building work- indeed by current standards of accessibility, it is already too small for the transformer it currently supports. The good news though is that the cable is PILC, not consac, and lead seems to be far more long lived than aluminium.

Here in town the pre-war houses have TT supplies coming in overhead on singles, and where they have failed, are replaced with concentric cable to the houses and ABC for the street mains. Transformers are an odd mix of H mounted pole pigs and things in brick sheds or ground mount fenced enclosures between buildings... Those transformers are mostly  50-70 years old and in terms of wear, in many cases barring an oil change and a rust inspection, in good shape for the the same duration again into the future.

(BSEN60076 Part 7, requires transformer insulation to be designed for 180000 hours of service (20.5 years) working at full load current and 98°C hot spot temperature - now the model predicts insulation lifetime doubles (or halves) with a ten degree change - so changes in load and seasonal load, are really critical to lifespan. In reality this is probably not as clear cut.)

But this situation is far from unique - almost every town in the land has miles of installations like this, and if the load profile is unchanged, it can carry on for many decades yet - and the number of DNO staff and rate of manufacturing of spares and many other things, reflect that pace.

Mike

Jon Steward said:

https://youtu.be/K8Nz-4eEBTw

Mark P Mills gave this speech on the Economics and Future of Electric Vehicles on November 12.

Well.worth an hour of anyone's time to listen to him.

Thanks for the link, I did listen to Mark P Mills speech…

I'll start with the positive points:

He highlighted 2 key challenge areas: the production of the EV battery and the need to upgrade the network to support the additional load.

Relating these challenges back to the message of my original post - both can be eased with a "bi-directional charging" (V2G) approach as this could:
(i) reduce the demand for house batteries
(ii) maximally leverage the investment in the EV's battery (for energy storage as well as transport)
(iii) ease the peak load on the network as a consequence of the energy storage (and hence reduce / defer the network investment need).

However, his views on EV battery end of life are simply wrong: "when the battery is exhausted it's garbage because its electrochemistry is just exhausted".
I know from personal experience (15 years ago as General Manager of a metals recycling venture) that Lithium Ion batteries can be recycled with high (>95%) recovery rates to produce high quality materials ready to manufacture new batteries.
Just taking a "common sense" view of this, why would anyone "throw away" a concentrated source of strategic materials when these have a high value?

I was also very concerned about his view of CO2 emissions: "if you burn oil you make carbon dioxide that's the point of burning it … it's not a pollutant it's an objective of the activity".
Despite claiming to understand climate science, he doesn’t seem to understand that there is a need to reduce CO2 emissions.

In summary, nothing he said detracts from the potential role V2G could play in support of EV rollout - but I won’t be wasting any more of my time following his thoughts.

Stuart

Hello Jon:

I watched the speech by Mark Mills yesterday and while it had some excellent points it does failed to mention the current economic situation in the US - high personal debt loads, overpriced new car prices, high insurance (both property and auto) costs, and high interest loan rates..

Peter Brooks

Hello Mike:

When one lives in an area which is prone to have annual hurricanes and tornadoes the power company has active ongoing programs to harden the complete interstructure (example replacing wooden poles with concrete). The local pole based transformers feeding houses in my area only have a life of about 15 years and take less than 2 houses to replace.

Peter Brooks

Peter Brooks said:

When one lives in an area which is prone to have annual hurricanes and tornadoes the power company has active ongoing programs to harden the complete interstructure (example replacing wooden poles with concrete). The local pole based transformers feeding houses in my area only have a life of about 15 years and take less than 2 houses to replace.

When I visited the states I was amazed/bewildered by their system of overheads, even in suburban areas - massive wooden poles but with just about everything hanging off them - HV, LV, phone lines, street lights, road signs, traffic lights the lot all one the same set of poles. Watched one crew replacing a pole which seemed to be done by letting all the cables dangle and lots of careful manoeuvring. I couldn't understand, especially given the extreme weather, why they didn't underground most of it, as is common elsewhere.

   - Andy.

Peter Brooks said:

When one lives in an area which is prone to have annual hurricanes and tornadoes the power company has active ongoing programs to harden the complete interstructure (example replacing wooden poles with concrete). The local pole based transformers feeding houses in my area only have a life of about 15 years and take less than 2 houses to replace.

When I visited the states I was amazed/bewildered by their system of overheads, even in suburban areas - massive wooden poles but with just about everything hanging off them - HV, LV, phone lines, street lights, road signs, traffic lights the lot all one the same set of poles. Watched one crew replacing a pole which seemed to be done by letting all the cables dangle and lots of careful manoeuvring. I couldn't understand, especially given the extreme weather, why they didn't underground most of it, as is common elsewhere.

   - Andy.

Hello Andy:

When one buys a house and the land on which it stands, one gets a legal drawing showing the external dimensions of the house and it's orientation relative to the boundary of the lot.

It also shows the power line easement (usually 10 ft from one of the boundary lines).

If one places a pool on ones property and the power cable would cross over the pool water on its way into the house then the LV line is rerouted from the power pole using an underground cable.

When repairing the lines the people use special safety blankets draped over the active lines.

The overhead HV power lines provide a perch for the migrating birds when they fly south to escape the cold fronts this time of the year.

Peter Brooks

Palm Bay Florida USA 

you need to visit the 220V bits of South America for the ultimate in pole re-use and scary wiring generally - North America is a bit of a tangle, but has nothing quite in comparison ! 

I have somewhere some pics from Brazil with 20kV overhead , 220V/380 3 phase transformers, and 3 phase _ N LV and underslung all manner of telecoms and cable TV cables. 

Worse the HV is earth-referenced as they make use of Single Wire Earth Return, to isolated farms and so on, so there is no 'big RCD' on the HV, so if an 18kV  line comes down it is probably still live as it hits the ground - unlike the UK, where if an 11 or 33kV line breaks, it usually isn't. (not sure about the USA on this - I think California has neutral free HV, but other regions do not seem to )

The funniest photos are a couple of chaps leaning bamboo ladders on the LV lines to climb up and work on the telecoms,

rgds,

Mike