Ballast Water Management (BWM) and Energy Efficiency Introduction

Ballast water (BW) is essential to control trim, list, draught, stability and stresses of a ship. The impact of Ballast Water Management (BWM) on a ship’s fuel consumptions is not normally considered despite the evidence that, regardless of the management method established, the overall energy efficiency of a ship is affected by ballast water because, ballast exchange requires the additional use of the ballast water handling equipment and in particular pumps and treatment systems developed to reach standards requires the installation of additional energy consuming equipment on board ships.

Ballast water impacts the ship’s energy efficiency in two additional ways:

  • The change in ship displacement; thus, wetted surfaces and ship resistance. Generally, the more ballast water or ballast sediments are carried around, the bigger the ship displacement will be and the higher ship’s energy consumption and therefore emissions increases are also expected.
  • The change in ship trim: Trim optimization via the effective use of ballast water could lead to gains in energy efficiency (MariEMS 2017).