From Andrew Ward, Wotton-under-Edge, Gloucestershire, UK
I am disappointed in your report of Elon Musk's planned battery in South Australia (15 July, p 6). It would be interesting to know what its capacity will be and its approximate efficiency.
The editor writes:
• The planned installed capacity is (460 gigajoules). Maximum output would, as we said, be 100 MW – enough to power 30,000 average homes. Efficiency depends a great deal on age and the “duty cycle”: of the car battery units to be used are typically in the range 80 to 90 per cent.
Is it that we took longer to become parents?
