Examining the Potential of Marine Renewable Energy: A Net Energy Perspective

It is often claimed that marine renewable energy alone could meet the electricity demand of current and future human societies. However, such claims are based on highly uncertain estimations global potentials sources (including tidal, ocean currents, wave, offshore wind salinity thermal gradients), do not take into account embedded technologies. To better understand effective potential energy, we conducted a literature review its gross, technical, economic sustainable potentials, as well return investment (EROI), estimated net potential. We found all technologies provide maximum surplus 57,000 TWh/yr. This figure goes down to ∼5000TWh/yr when excluding wind. The previous figures include contribution from for which no reliable estimates EROIs be obtained. Due high upfront costs environmental impacts low social acceptance, additional tidal range capacity expansion envisioned. Similarly, combination EROI makes large-scale exploitation gradients unlikely with Including technologies, average ∼20, but reduces ∼8. While did consider sustainability constraints some sources, our estimation primarily relied technical factors legal constraints. Therefore, results presented here should interpreted an upper bound actual mix.