Energy efficiency is important because it is the multiplier different energies go through when they are actually used on board. What this means is energy densities are measured in theoretical energy contained per unit (volume or weight), however when the energy is consumed on board it is not the theoretical energy density that matters but the overall system efficiency. If energy has a high density but low efficiency it’s ‘Actual' or 'In Use' energy density is much lower. Batteries shine strongly here because they have high efficiency and therefore are not penalized as severely as other energy carriers.
We've put together an interactive figure that displays the energy density for several conventional fuels such as MGO, and Diesel, and some of the new fuels proposed for use in maritime such as Liquid Hydrogen (LH2) or Ammonia. As a twist, we have added the option to see what these energy densities look like on board when the energy is actually utilized (in a combustion engine or fuel cell, etc). Just click the box under Energy Density: Theory or Reality and select "Reality".
Beyond the density of the energy itself, system (Balance of Plant) weights and volumes are important but require design and operational specifications to compare these appropriately. Beyond energy and system densities are a number of key issues to be considered such as safety, cost, and fuel availability.
If you have a maritime project you'd like to explore zero emissions on, we're always looking to take on projects and offer advisory where we can add value
Do you want to learn more about electrolyser technologies? Check out our technology series: part 1, part 2 and part 3.