It looks like affordable electric cars with 200 mile range will be available within 5 years, rather than the 10 I thought it was going to take.

The 200 mile range is I reckon the critical range, allowing about 3 hours of motorway driving, after which most will want a break anyway, allowing charging, and allowing you to go pretty much anywhere in the UK with just 2/3 stops.

I think that that means that electric cars could make up a big chunk of the total car market in 10 years, and we might have almost exclusively electric cars in 20 years’ time, much faster than I thought.

That’s exciting in itself, but here’s the potentially interesting bit for me. And this might be b*llocks, so interested to hear from people that actually know what they are talking about. It’s probably also been covered elsewhere, but I couldn’t find the thread...

The average daily car journey is 20 miles. Assuming a 200 mile range, this means that, on average, 90% of total car battery capacity is unused at any one time.

The average UK household uses 4kWh of electricity per day, and 14kWh of gas. Let’s assume in 20 years people are instead using heat pumps with a COP of 3.0. That’s an extra 5kWh of electricity. So 9kWh is enough to provide for an average household’s daily energy needs. Round up to 10.

Now these 200+ mile cars have battery capacities of 60kWh+. If only 10% is used each day, they’ll tend to use only 6kWh per day. That leaves enough to provide for 3 days total domestic energy use while still leaving a decent buffer in the car even if it’s used every day (3 days domestic energy use = 30kWh, 3 days driving = 18kWh = 48kWh, so 12kWh left).

I’ve always been worried about renewables intermittency and how we'd deal with a few straight -days’- in winter of weak sun and little wind. But if all households had cars with these capacities, they could use their spare battery capacity to provide for their own needs or sell their spare electricity back to the grid, until such time as the wind picks up.

Long story short, I’m no longer scratching my head about how we’ll deal with intermittency if we rely more and more on renewables.

What have I missed? What would need to happen to the grid for all the cars to be able to feed in their leccy when needed?

Will not work, sorry I need my car to be ABLE to go along way without preplanning…. And I don’t want my car to be out of power at the time the electricity cuts hit due to a long time of no wind……

However if the car was a hybrid with a 100 mile electric range, and I could tell the car the night before if I was going to be driving over 30 miles the next day….. (This still leave the issue that most cars will not be plugged in while their owner is at work.)

The only storage system I can think of that will have enough capacity (many weeks of power) is mains gas; the excess renewable can be used to generate gas to put back into the underground storage. But using electric cars to balance the grid could remove the need for “spinning reserve” and allow power stations to start from cold, even if it takes a few hours before they are generating.

If we can put back into the ground as much mains gas as we take out over a year, we could then use a lot of gas power fuel cells for CPH and for when the wind is not blowing. Tidal and wave power would help greatly, as they are more predictable. The electric cars will be able to fill in between the tides.

Posted By: ringiI need my car to be ABLE to go along way without preplanning

Posted By: ringi... and I could tell the car the night before if ...

Posted By: GarethCI think that that means that electric cars could make up a big chunk of the total car market in 10 years, and we might have almost exclusively electric cars in 20 years’ time, much faster than I thought.

You're aware that the Netherlands (I think, plus one other) plans to ban sales of new IC cars in 2025, and Austria the same but in 2020?

What have I missed?

If you use car batteries to supply the grid, they will wear out faster than their design life. Whether that can be engineered/costed around, I don't know.

Posted By: ringiWill not work, sorry I need my car to be ABLE to go along way without preplanning

Also don't forget that cars will be self-driving, so the notion of 'my' car may not be so relevant. In particular, it might be reasonable to own or share a car with a 'shortish' range and simply call a 'long' range car on demand as and when you need it.

Posted By: ringiWith cheap PV and short term storage, will it be best to design homes so that they overheat in the summer using AC to keep them cool, so that they will get more thermal gain in the winter?

That might make a lot of sense, I think, yes. Either PV plus a reversible heat pump or a solar-powered absorption chiller.

Posted By: fostertomRather, use the PV electricity to input the reqd heat.

There is too little PV in winter when the heat is required!

That mismatch is a fundamental problem in cold climates.

A good electric car needs about 200Wh to travel a mile, but in the UK this will almost certainly be greater (cold weather, more speed variations), so let us say they need 300 Wh/mile. So to do 200 miles they will need:
200 [miles] x 0.3 [kWh/mile) = 60 kWh.
That is about the same as a basic Tesla has (look up the mileage they can do, you will be surprised).

Now taking a small house that has a yearly electrical usage of 4,000 kWh/year and assume that this is split evenly during the year (not true as the usage can go up in winter but that can be adjusted for afterwards), so that will be:
4000 [kWh/year] / 365 [days] = 11 kWh/day
If we want to get a third of that from the car batteries, that will be about 3.5 kWh of spare storage needed (or a reduction in mileage of about 12 miles of the 200).

Now to generate 3.5 kWh/day of renewable energy, at the same time of day that the car is at home is a tricky one, so why bother. Much easier to set up a windfarm that feeds into the grid (offset the generation though financial means).
The easy way to finance this is via the purchase of the vehicle (cost about £1,600). As soon as you are into large scale windfarms, the £/kWh drops quite a bit. Not hard, once though planning/legal hurdles/grid connection to install at £1000/kWp, which could yield around 2600 kWh/year at a capacity factor of 30%.
That would be enough to travel 8,700 miles, or almost power a small house or a mixture of the two.
This is really up to the car companies to sort out with the National Grid/Energy companies.
I think we sold about 2.2 million new cars last year (from memory), so if half of them were all electric and they needed 4000 kWh/year, then that would need:
1,100,000 [cars] x 4,000 kWh = 4.4 TWh/year of wind generation
This is equivalent to about 350, 5MWp turbines and at £5m/turbine installed £1.75bn (less than 10% of Hinkley Point).
It would add about £800 to the price of a new car.
To do 13,000 miles in a car that does 50MPG currently costs about £1,300.
So it is possible (just about and assuming I have not made a school boy error in the sums, which I had but hopefully now corrected) to create a financials system that allows a fast replace of IC vehicles to EVs without any government subsidies (other than normal ones i.e. training, relocation inducements etc).
So all that has to happen is that a 200 mile EV needs to be developed that can do 150,000 miles on a set of batteries, is about the size of a Focus/5 Series and costs around £15,000 on the road.

Now the but, you are still stuck with a car that can only do 200 miles on a 'tank full'. This could be overcome with some cooperation of the motorway service area people (I used to work for the biggest one). They could put two turbines on their land (no one can complain about the noise, the looks are something different, but a service are looks like a lorry park anyway), then they could have vehicle rental business that allows you to swap cars for longer journeys (and park your own up and be charged up). This would allow me to drive the 110 miles to my nearest motorway service area (Exeter M5) and swap vehicles, then just under 200 miles later at Oxford M40 swap again to a fully charged car for the last 15 miles to my Mother's. Then I could go and visit people I know before I go home. When I get to Exeter, my own vehicle would be fully charged (and maybe valeted for an extra 20 quid), then I can do the last leg without range anxiety.

(I reserve all rights to this idea)
I think I overestimated the generation capacity of a wind turbine, it should be 2,600 kWh/(year.kWp installed capacity, shall edit when I get home from work, think I have sorted it now, but maybe someone else (Ed) can double check it).

Ed
Might it not be more economical to recycle the high value car batteries. I assume that they can become batteries again.
We have a good system already for breaking and recycling cars.

Posted By: tonyIf we do see a big swing towards electric vehicles what influence will this have on the price of it. At present the government makes massive amounts from tax revenue on vehicle fuels.

Logic says we should have some sort of road charging, but would any goverment that tried remain in power for long enough to do it.....

Posted By: ringiNo need to swap cars etc at motorway service station, 200 miles is close to 3hr driving time, by that point you need a break and a fast charger can recharge in half an hour.

Some people like to get the journey done and dusted, I am one of them. I often drive the 300 miles 'up country' in one hit, and have gone further in the past. I hate stopping on a long journey.
Tesco 'K' energy drink comes in large bottles. It is great.

I expect that by the time batteries are good enough and cheap enough to make electric cars “normal”, they will also be cheap enough to use for short term power storage in their own right.

However smart charging of electric cars is needed, otherwise the evening peak will get worse, as that is when most cars will be plugged in.

Posted By: GarethC

Posted By: SteamyTeaNow taking a small house that has a yearly electrical usage of 4,000 kWh/year and assume that this is split evenly during the year (not true as the usage can go up in winter but that can be adjusted for afterwards), so that will be:
4000 [kWh/year] / 365 [days] = 11 kWh/day

Whoops, silly error in my numbers. Still doesn't kill the argument though.

How many miles -can- car batteries do currently?

Depends... (Temperature, traffic conditions, road surface, tyre pressure, driving style, hills etc etc) Same as an IC engine, but the time penalty for needing to refuel is much bigger at the moment. I think you need your 200 miles target to be 400 miles to guarantee the 200 range.

Sorry I meant how many miles total can car batteries do before they have to be replaced.

Posted By: djh: “You're aware that the Netherlands (I think, plus one other) plans to ban sales of new IC cars in 2025, and Austria the same but in 2020?”

Norway from 2025 it seems - very recent report (yesterday?):

http://electrek.co/2016/06/03/norway-gasoline-powered-car-ban-2025/

Says Netherlands is still not agreed.

I think the grid storage problem is more of a creation of anti renewable energy lobbyists than a reality. There was a study published at the start of this year showing that the USA could cut its greenhouse gas emissions by 80% without raising electricity prices by improving electricity transmission using Hvdc. By enabling electricity to be shared over such a wide area, most of the variability in supply and demand can be smoothed out. For example it may be sunny in Arizona while dark in New York or windy in Dakota while calm in Texas.

The same principle should apply in Europe and if the EU is going to be good for anything, I would have thought this would be something for it to do.

Ed

Should have said the USA could cut its GHG emissions from electricity generation by 80%.