The energy that drives surface ocean currents such as the gulf stream comes from

Wind energy

Explanation:

The ocean surface water currents are generated due to the wind blowing over the vast ocean. The wind usually blows from a region of high pressure to a region of low pressure, and this is the main driving force for the ocean surface currents. This wind blows in a particular pattern due to the factors such as the rotation of the earth as well as the Coriolis force and is often affected at different latitudinal location. These ocean surface water in the northern hemisphere moves in a clockwise manner and anticlockwise in the southern hemisphere.

The Gulf stream carries the warm and less dense water from the lower latitude to higher latitudes, and during its transportation, the water in it undergoes evaporative cooling.

Thus, wind energy is the main mechanism that drives the surface water current in the large oceans.