Nowadays, marine energy accounts for only a tiny proportion of the electricity produced from renewable sources. However it is forecast to represent a very sizeable share of the overall global supply by 2050, complementing other renewables such as sun and wind. To achieve this result, various technologies that are currently at the research or testing stage, in the form of small single elements or of arrays of elements, will have to be developed to full scale systems and projects deployed on a worldwide basis.
It’s all there, just waiting to be tapped
Oceans contain 97% of the earth’s water and cover 71% of its surface; they are sources of huge kinetic energy from waves and swells, currents and tides, and of thermal energy in the form of the heat they harness from the sun. The difference in salinity between seawater and fresh river water creates a chemical pressure potential (salinity gradient power) that can also be used to generate electricity.
All these approaches could, in theory, provide a sizeable share of the world’s energy needs. However, currently they only make up a tiny percentage of the energy extracted from renewable sources. Of this, 90% comes from two tidal range barrages: one in France (240 MW), operational since 1967, the other in the Republic of Korea (254 MW), in operation since August 2011.
Marine energy is still in its infancy, with many technologies still at a research or testing stage aimed at finding the best possible systems for converting the various types of marine energy.
Marine energy conversion is still at an early stage of development and faces a number of challenges. International Standards will prove essential to the expansion of the industry.
IEC TC (Technical Committee) 114: Marine energy – Wave, tidal and other water current converters, prepares International Standards for all these converters. Its work programme includes assessment of various parameters such as resources, performance, measurement and testing.
The future of the marine energy sector does not depend on technological solutions alone, but also on environmental and economic concerns.
The environmental impact of marine energy converters, which may be deployed in sensitive marine environments, must be low. This is the objective of thorough risk assessments that cover various aspects such as the impact turbine blades may have on marine mammals and fish and the effects of the acoustic output of turbines or of changes in water flow and energy removal. The results of surveys so far are encouraging, showing that marine mammals will avoid large, slow moving turbines and that fish are largely unaffected.
However, more research is required and environmental concern may slow, or even prevent, the installation of marine energy converters in certain zones.
As costs for developing technologies are often a matter of concern and uncertainty, marine energy conversion, like other renewable energy sources, will certainly require financial support from governments and interested stakeholders, such as utilities. This support may take the form of direct investment, subsidies, cost-levelling mechanisms or guaranteed feed-in tariffs, as the cost of electricity produced by marine energy conversion initially will be higher than that produced by other means, including well-established renewables like solar and wind. As worries about large subsidies for renewable energies mount, funding may prove an issue in the future.
The overall return of marine energy conversion is likely to translate into large volumes of additional clean energy resources in coming decades. The IEA forecasts that “by 2050 ocean energy will have grown to 337 GW of installed wave and tidal energy capacity”, from well under 1 GW today. This expansion will be made possible in no small part by the pioneering standardization work carried out by TC 114.
Written by Morand Fachot for our e-tech Magazine. To find out more check out our e-tech article.