On Thursday, September 12, 2013 8:52:52 PM UTC+1, The Natural Philosopher wrote:
snip
But as I said somewhere else, if all the households in the UK had a
100kWh battery* car all together they could run the UK grid for just 40
minutes.

That doesn't seem to add up to me - just over 26 million households with 100kWh gives a total of 2600GWh. Current demand about 40GW so around 66 hours (assuming 100% efficiency in conversion, of course)
But of course it's never going to happen with current battery technology...