Can matter be reused according to the law of conservation of energy?

Question

Can matter be reused according to the law of conservation of energy?

Answer 1

Yes.  Matter and energy are interchangeable.

Answer 2

Energy can neither be created or destroyed.  But, it must be paid for.  Don't believe it, just look at your electric bill.

Answer 3

Only up to a certain point.

This is because most energy conversions lead to an increase in the entropy which is the dissipation of this same quantity of energy.

The best example is if you mix poisonous seeds and eatable ones... you still have the same amount but it is less usable.

Another example is a pool filled with water just 1°C warmer than the outside enviroment... it has potentially so much more energy as a difference of temperature than an AAA battery... nevertheless it is less usable.