The Hawaiian Islands are in the northern hemisphere, about 21 degrees north latitude. The common reference to their location is "Mid Pacific".

Honolulu, Hawaii is 21° north* of the equator and none of the Hawaiian islands are south of the equator.

* Links:
http://stable.toolserver.org/geohack/geohack.php?pagename=Honolulu&params=21.30895_N_-157.826182_E_type:city_region:US&title=Honolulu
http://stable.toolserver.org/geohack/geohack.php?pagename=Hawaii&params=21_18_41_N_157_47_47_W_type:adm1st_scale:3000000_region:US-HI

Hawaii has always been big on the alternative energy sources since gasoline is ultra-expensive there, but natural sources like geothermal, wind, solar and ocean-thermal are plentiful.

If you look up OTEC in wikipedia the picture is from one of the first operational OTEC sites in the world (although last time I was there, the real energy conversion was done in the buildings which have been cropped out on the left side of the picture).