If a new machine is more efficient than the old model, it uses a ...

[londonang]

If a new machine is more efficient than the old model, it uses a smaller amount of energy to do the same task.
 
  Why hasn't the experience with all the electric machines over the 130 year history of commercial electricity sales produced a machine that is 100 efficient?

Question 2

Solar ponds store solar energy.
 
  What will be an ideal response?

[kristenb95]

Answer to Question 1

It is impossible to eliminate all causes of friction in machines. It will never be
possible to have a machine that is 100 efficient.

Answer to Question 2

The energy in solar ponds is stored in the gradient between the salt and fresh
water layers.