Strongly inhomogeneous meteo-marine parameters in coastal waters: A high resolution spaceborn SAR study to assess the local ocean renewable energy potential

Abstract

Ocean renewable energies (e.g. ocean waves or currents) provide an opportunity to coastal regions to cost-efficiently cover their energy needs especially in countries that have only little fossil energy resources. To effectively exploit those energy sources, suitable locations have to be identified. Among others, coastal engineering aspects and estimates of the power potential need to be taken into account. On the one hand the acquisition of the necessary information for larger areas in the coarse site selection process can be challenging, on the other hand the high spatial variability of meteo-marine parameters near the coast demands high resolution data in order to obtain a good accuracy for a possible ocean renewable energy (ORE) facility site. Spaceborne Earth observation methods can largely meet both conditions. Over the past decades, spaceborne remote sensing has developed to a mature technology. It is now playing an important role in Earth observation due to its capabilities of global coverage, high temporal and spatial resolution, and advantages for long-term observations. Platforms like TerraSAR-X (TS-X), TanDEM-X (TD-X), RADARSAT-2, COSMO-Skymed or SENTINEL-1 with synthetic aperture radar (SAR) sensors, can provide two dimensional information about the ocean surface. The twin satellites TS-X and TD-X for instance can acquire images with a resolution of up to 1m. They are thus capable of giving wind and wave information for the ocean surface with unprecedented detail, while maintaining a large spatial coverage. A country that could strongly benefit from sophisticated methods to identify promising ORE facility locations is Indonesia, with an extended coastline, tidal channels between the individual islands and very limited fossil fuel deposits. The bilateral Indonesian-German project Science for the Protection of Indonesian Coastal Marine Ecosystems (SPICE) [1] has the overarching goal to address the scientific, social and economic issues related to the management of the Indonesian coastal ecosystems and their resources. One central research topic is dedicated to the estimation of the power potential from ORE facilities in Indonesia and to identify suitable locations. We evaluate the improvements of the TS-X wave algorithm XWAVE in a case study for a potential ORE site on the southern Java coast. We compare our data to both, fine-scale local wave model results and in-situ wave-rider measurements recorded during a dedicated campaign at the test site. We observe a good agreement between the SAR-based results and both, model and buoy data (Fig 3). Our findings indicate that the exploitation of spaceborne SAR data with the above methods can thus contribute to both, the identification of promising ORE potential on a regional scale along the extensive Indonesian coastline and to the small scale micro-siting process for possible facility locations.