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

Abstract

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

Suppression of Negative Sequence Current on HVDC Modular Multilevel Converters in Offshore Wind Power

“…Among them, offshore wind power, ocean energy and solar power are the main new energy forms in the world [2][3][4]. Offshore wind power has become an important part of the large-scale utilization of new energy because of its rich resource reserves, high power generation efficiency, low water consumption, small land occupation area and close to power load center [5,6]. The development of offshore wind power is helping to build a clean, lowcarbon, safe and efficient energy future, in order to meet the challenges of climate change and energy security [7].…”

Using Multi-Criteria Decision Making in Quality Function Deployment for Offshore Renewable Energies

“…To achieve the Sustainable Development Goals (SDGs) 7, 11, 13, and 14 from the 2030 agenda and net zero emissions by 2050, the transition to renewable electricity production must be addressed. In the study carried out by [4], the technical potential of offshore wind was estimated at 55,000 TWh/yr, wave potential 1000 TWh/yr, and tidal stream potential 180 TWh/yr. Advances in materials to manufacture devices such as tidal turbines have been challenging due to the technical requirements; however the efforts to improve the existing devices have the attention of stakeholders and engineers.…”