Energy Potential Metric for Rapid Macro-level Resource Assessment of Tidal In-Stream Energy in the Philippines Michael L. S. Abundo, MS EE Allan C. Nerves, PhD EEE Institute University of the Philippines Diliman, Quezon City abundo@ieee.org Ma. Rosario C. O. Ang Enrico C. Paringit, Dr. Eng. Department of Geodetic Engineering University of the Philippines Diliman, Quezon City Lawrence P. C. Bernardo Cesar L. Villanoy, PhD Marine Science Institute University of the Philippines Diliman, Quezon City Abstract—This paper presents preliminary efforts in developing a rapid evaluation tool for tidal in-stream energy (TISE) in the Philippines. We study the possibility of using an energy density metric based on the sea surface elevation (SSE) or tide height difference at the boundaries of a site of interest as a gauge for the TISE potential of that site. Results show good correlation with high potential sites and the proposed metric. Verde Island Passage was assessed, through a combination of DELFT3D simulation and Matlab-based power computations, to have four potential TISE sites with a total energy density of 271.90 kW-h /m 2 in a month. Keywords-Tidal Power; Ocean Energy ; Resource Assessment; Rapid Evaluation Tool; Tidal In-Stream Energy; Sea Surface Elevation; Energy Potential Metric I. INTRODUCTION Ocean renewable energy resources have been grouped into: tides, waves, tidal stream, ocean currents, thermal gradients, and salinity gradients by [1, 2]. To date, only the tidal barrage has reached commercial maturity and is being used in the U.K.[2]. Thermal and Salinity gradient technologies have not reached the pre-commercial maturity level. Ocean thermal energy conversion (OTEC) technologies are still very expensive and the lack of pilot sites with installed power systems harnessing this type of energy pulled away support from a number of investors worldwide. Wave energy conversion (WEC) and tidal in-stream energy conversion (TISEC) systems however have reached full-scale and are in the pre-commercial scales of maturity [2]. Given that the tidal energy resource is more predictable than wave energy resource, it is better to investigate the potential of harnessing the tidal resource at this stage for the Philippines. Numerous groups have studied various aspects of tidal energy. Global status reviews have given good growth potential of tidal power [1, 2]. A number of resources assessments have been carried out worldwide, some of which include Australia [4], Malaysia [5], the USA [6], Canada [7], and Europe [8]. Reviews have been done with regard to efforts that cover: resource assessment methods [1, 3], technology [1, 2], environment , and economics [1, 2, 9]. Generally, there are two ways of harnessing tidal energy: using the tidal barrage approach and using the tidal stream approach [1, 2]. In the tidal barrage approach, water is stored in a reservoir when the tide is high and is released when the site is at low tide. This storing-releasing cycle operates similar to a dam-based hydroelectric plant where water flow drives turbines with a significant amount of head. In the tidal stream approach, storage of water in a reservoir is not necessary but rather the energy from the flow of tidal current is extracted similar to that of wind farms. Tidal stream power has gained more interest in the past years compared to the tidal barrage approach since it is a more economical and environmentally benign option [1, 9]. The Philippines’ ocean renewable energy resource, including tidal, wave, and thermal energy, has been assessed in a general manner by Mindanao State University - Iligan Institute of Technology (MSU-IIT) to be around 150GW.The Philippines’ Department of Energy (DOE) benchmarks the ocean renewable energy resource of the country to be around 170GW [10]. Eight straits and channels were identified to be potential sites for tidal stream energy. These sites are those with high tidal current velocity but have not yet been assessed properly. In 2004, Blue Energy, a tidal stream energy company from Canada assessed the potential of San Bernardino Strait to be 2.2 GW using their TISEC device array (274 Ocean Class Davis turbines, rated at 7 to 14 MW each). Other sites still exist in the Philippines with TISE potential but, to date, there is still no published work assessing sites with relatively adequate tidal current velocities. There is a need, therefore, to assess, in a more methodical manner and with improved accuracy and reliability, the tidal in-stream energy (TISE) potential of the Philippines. Since the Navier-Stokes equation as mentioned by [3] are primarily dependent on the sea surface elevation as the pressure term to calculate for the current velocity, and since power is a function of velocity, we conjecture that the energy density of a site might be correlated with the summation of tide height differences of the boundaries of that site. This research is made possible by the Engineering Research and Development for Technology (ERDT) program of the Dept. of Science and Technology (DOST) of the Philippines. 978-1-4244-8782-0/11/$26.00 ©2011 IEEE