Worldwide, between 1971 and 2018 world total energy supply increased 2.6 times, with fossil fuels at the end of the period still accounting for more than 81% of total energy production. With the increasing digitalisation of the modern world and the decarbonisation targets that most countries are adopting to challenge climate change, the attention of populations and politicians is shifting rapidly towards renewable energies. In 2019, annual net additions for renewable energy, especially solar and wind, outpaced installations of fossil fuels and nuclear for the fifth year in a row.
The Ocean Energy
While presenting a huge potential, ocean energy technology overall is still at an early stage of development. This is why it represents only a small share of renewable energies, with an estimated total installed capacity of 535 MW worldwide. This figure is negligible compared to the 2,600 GW of total renewable capacity installed.
Tidal barrage and tidal stream, wave energy, salinity and temperature gradient are the main forms of ocean energy. Tidal barrage technology accounts for most of the installed capacity, with almost 520 MW of the total ocean energy. When it comes to geographical distribution, 55% of this capacity is in Europe, 28% in the Asia Pacific region, 13% in Middle East and East Asia, with North America accounting for only 2%. Worldwide, the outlook for the next decades is of a sharp increase of the total capacity installed, with 10 GW expected in 2030 and 100 GW in 2050.
Most technologies are still in the prototype phase, so there is still a lot of innovation and research undergoing.
The Situation in Europe
Europe has been a pioneer in the development of ocean energy technology and is now a worldwide leader both in term of capacity installed and production. In the past 2-3 years ocean energy technology became a strategic pillar in the transition towards a carbon neutral economy in 2050: the goal is to produce 1 GW of ocean energy by 2030 and 40 GW by 2050.
The European commission is looking towards ocean energy because it can help the decarbonisation of the continent and the competitiveness of the European Union. There is a lot of support at EU level and a lot of work has been done in the past years to maintain the leadership, thanks also to the huge investments made by public and private entities. There is still a long way to go to meet cost reduction targets and bring the technology from pre-commercial state to full commercialisation in the next 10 years.
Ocean Energy Technologies
1. Tidal Energy
A distinction is made between tidal barrage and tidal stream technologies. Tidal barrage makes use of the height difference between high and low tide to harness the potential energy, while tidal stream makes use of the tidal currents. This technology is at a more advanced stage with respect to other forms of ocean energy and there is a clear path towards cost reduction. Over the past 4-5 years cost reduction was much faster than expected.
In 2019, tidal stream capacity in Europe stood at 27.7 MW, four times as much as the rest of the world, with the biggest share in the UK, France and the Netherlands. An estimated total of 4.6 GW of tidal energy project is in development and could be deployed by the end of 2027 in Europe.
2. Wave Energy
Since the technology is at the prototype stage, the focus is still much on R&D. An estimated 1.5 MW of wave technology is currently operational in Europe, with another 10.3 MW to be deployed in the near future on successful completion of testing programmes. The UK, Sweden, Denmark, Portugal and Spain are the countries with the highest installed capacity.
3. Other Sources
Ocean thermal energy conversion, salinity gradient and ocean current technologies are still in the research and development stages, with many barriers still to overcome. Nevertheless, they are expected to start picking up by 2030.
Space for Ocean Energy
While the ocean provides a huge potential for energy generation, there are important barriers that must be overcome to realise this in a sustainable and timely manner. Two key challenges facing the sector are lifecycle cost of the energy produced, referred to as Levelized Cost of Energy (LCOE), and impact on marine ecosystems. There are a number of ways in which space technology can help the sector tackle both of the challenges.
1. Identifying and characterising the suitability of sites during project development
Project development processes typically seek to quantify, at increasing levels of accuracy, the energy generation potential and development costs of a site. This process of investigation and design is progressed hand-in-hand with a process of defining and managing development risk. Geospatial data is at the heart of these processes. More effective use of satellite data can potentially reduce or inform in-situ data acquisition requirements, reducing overall development cost and supporting risk management efforts.
For example, data products derived from Copernicus Satellite data, such as wind and wave climatologies, can be used for broad scale regional assessments or to perform comparative analysis of sites during early stages of development. Long term climate quality datasets such as the ESA CCI (Climate Change Initiative) products can be used to understand regional climate risks including sea level rise and sea state.
All marine projects include land based elements, such as cable routing and landfall, and construction and operational support requirements. Earth Observation data enables rapid remote assessment of coastline features and historic rates of change, and can be used to map, for example, intertidal areas that can be challenging or costly to survey using traditional methods. Here optical and radar data are combined with tide gauge records or modelled tidal data and made available to users via web services or other platforms.
As projects progress to more detailed assessments involving hydrodynamic modelling and in-situ data acquisition, satellite data can be used to validate models, thereby reducing uncertainty, and using emerging techniques such as GNSS inferometric reflectometry (GNSS-IR), potentially significantly reduce the volume of expensive in-situ data required.
2. Providing geospatial data to inform environmental impact studies
Regulatory processes for managing development require extensive analysis of the environmental status of a site. Earth Observation provides data that can be used in synoptic analysis of a range of observable parameters including, for example, aspects of water quality, sea surface temperature and surface currents. In shallow water regions with good water clarity optical satellite data can be used to map bathymetry and benthic habitats in a rapid and cost-effective way. A better understanding of development sites at early stages of development helps improve decision making and help ensure data acquisition is highly focused and therefore cost efficient.
3. Supporting installation, operation and decommissioning activities
For the tidal stream and wave energy sectors projects are typically located in high energy environments which adds operational complexity and risk. Detailed understanding of weather windows for specific activities (for example during planned or unplanned maintenance work) is a vital input for cost effective and safe operations.
Satellite data can be used to drive or ‘force’ high resolution hydrodynamic models, to help assess operational efficiency and performance through ongoing characterisation of the resources, and can be used to remotely monitor, for example, using GNSS-IR, the sea state local to the project site before leaving the office. This can reduce the costs associated with mobilising vessels and people to perform activities in marginal conditions.
Christine Sams from the U.K. based National Oceanography Centre (NOC, Southampton), through the ESA Earth Observation Atlantic Regional Initiative, is working with the European Marine Energy Centre (EMEC, Orkney, Scotland, U.K.), one of world leading Marine Renewable Energy Test Centres, to develop innovative space applications while supporting sector uptake of satellite data. The partnership is focusing initially on the challenge of improving sea state characterisation in high energy environments.
