Several cell disruption methods were tested on Nannochloropsis gaditana, to evaluate their efficiency in terms of cell disintegration, energy input and release of soluble proteins. High-pressure homogenization (HPH) and bead milling were the most efficient with >95% cell disintegration, +/- 50% (w/w) release of total proteins and low energy input (<0.5 kWh.kg(biomass)(1)). Enzymatic treatment required low energy input (<0.34 kWh.kg(biomass)(1)), but it only released +/- 35% protein (w/w). Pulsed Electric Field (PEF) was neither energy-efficient (10.44 kWh.kg(biomass)(1)) nor successful for protein release (only 10% proteins w/w) and cell disintegration. The release of proteins after applying HPH and bead milling always required less intensive operating conditions for cell disruption. The energy cost per unit of released protein ranged from 0.15-0.25 is an element of.kg(Protein)(1) in case of HPH, and up to 2-20 is an element of.kg(Potein)(1) in case of PEF. (C) 2017 Elsevier Ltd. All rights reserved.