Because of the energy needed to pump the water and to run the anti-refrigeration (energy extraction) processes, an OTEC plant must be quite large, at least several megawatts, to run efficiently and overcome these so-called "parasitic" energy drains.
(the energy; needed; to pump the water and to run the anti-refrigeration (energy extraction) processes) (an OTEC plant; must be; quite large)
the energy an OTEC plant
needed must be
to pump the water and to run the anti-refrigeration (energy extraction) processes
quite large