Where does the energy come from to drive them?

His relentless energy drove the waiting troops into a fever of anticipation.

The absorbed energy can drive further reactions and ultimately dissipates as heat.

This new energy drives the movement to the coda, which closes the symphony.

The same restless energy drove both men toward invention.

Besides, the radioactive elements whose energy had driven the process were giving out.

On the other hand, dark energy drives the universe towards increasing rates of expansion.

The stored energy of the compressed spring then drives the bolt back forward into firing position.

They had hoped that his testimony would provide fresh grounds and new energy to drive President Clinton from office.

"He certainly relayed that passion and energy which I think helped drive the process forward."