5:15 PM - 7:15 PM
[MAG32-P01] Osmotic power generation as a renewable ocean energy -- its technical and economic potential assessment
Keywords:ocean energy, levelized cost of energy, blue energy, salinity gradient energy, osmotic pressure, first class river
Around the estuaries where rivers and coasts intersect, freshwater flowing out of the rivers mixes with salt-rich seawater. This mixing process generates enormous amounts of chemical energy, which is dissipated to the outside as heat. Can this energy, which is being lost day by day, be converted into a form that is useful to human society? What makes this possible is a power generation technology called osmotic power generation.
Osmotic power generation (OPG) uses the osmotic pressure difference between freshwater and seawater. This technology enables to extract the change in Gibbs energy of the solutions before and after mixing as electrical energy by manipulating the flow in and out of two different solutions using a semipermeable membrane. OPG enables us to collect electric energy at any time of the day near estuaries, regardless of the weather or time of day. Furthermore, the energy obtained is renewable since there is little concern that the resource will be depleted in the future due to mass consumption. Because of this promising outlook, the technical potential of OPG has been previously examined for various estuaries around the world. A common understanding deduced from the examination was that the more river water available, the more electrical power can be generated. From this perspective, Japan’s coastal areas will be geographically well suited for OPG. In Japan, about three-quarters land area is covered by forests and mountains, and there are abundant water sources in each region. In addition, Japan’s annual precipitation is nearly twice the world average. Furthermore, many rivers in Japan are shorter and have steeper gradients than those on the continent. Given these conditions, it can be inferred that Japanese rivers have sufficient flow capacity for OPG. This fact motivated us to evaluate what amount of electric energy can be obtained by OPG at estuaries in Japan. This is one of the main issue dealt with the present work.
Another main issue we have considered is to evaluate the levelized cost of energy (LCOE) of OGP. LCOE is one of the cost estimation methods for power plants, being a measurement used to evaluate and compare alternative methods of energy production. LCOE is defined as the total cost (e.g., construction and running costs) over the useful life of the plant divided by the total energy that can be supplied during the useful life of the plant. LCOE is also essential when examining the profitability of power plant construction plans themselves. Furthermore, LCOE analysis plays an important role in deciding whether to proceed with a given power plant construction project; the LCOE obtained will determine whether the project will break even or be profitable. If not, the company will not proceed with construction of the generation asset and will look for alternatives. Using LCOE to evaluate a project is one of the first basic steps taken when analyzing a project of this nature.
Based on this importance, we calculated the LCOE of OPG plants assuming that they are constructed at several suitable sites along Sea of Japan coastline where a large amount of electricity could be generated by OPG. In setting each parameter value, we referred to those deduced from the OPG system that will be operated in Fukuoka from the summer of 2025 by Kyowakiden Industry Co., Ltd. We also cited geographic data such as river flow rates from the geographic information database published by the Ministry of Land, Infrastructure, Transport and Tourism.
Osmotic power generation (OPG) uses the osmotic pressure difference between freshwater and seawater. This technology enables to extract the change in Gibbs energy of the solutions before and after mixing as electrical energy by manipulating the flow in and out of two different solutions using a semipermeable membrane. OPG enables us to collect electric energy at any time of the day near estuaries, regardless of the weather or time of day. Furthermore, the energy obtained is renewable since there is little concern that the resource will be depleted in the future due to mass consumption. Because of this promising outlook, the technical potential of OPG has been previously examined for various estuaries around the world. A common understanding deduced from the examination was that the more river water available, the more electrical power can be generated. From this perspective, Japan’s coastal areas will be geographically well suited for OPG. In Japan, about three-quarters land area is covered by forests and mountains, and there are abundant water sources in each region. In addition, Japan’s annual precipitation is nearly twice the world average. Furthermore, many rivers in Japan are shorter and have steeper gradients than those on the continent. Given these conditions, it can be inferred that Japanese rivers have sufficient flow capacity for OPG. This fact motivated us to evaluate what amount of electric energy can be obtained by OPG at estuaries in Japan. This is one of the main issue dealt with the present work.
Another main issue we have considered is to evaluate the levelized cost of energy (LCOE) of OGP. LCOE is one of the cost estimation methods for power plants, being a measurement used to evaluate and compare alternative methods of energy production. LCOE is defined as the total cost (e.g., construction and running costs) over the useful life of the plant divided by the total energy that can be supplied during the useful life of the plant. LCOE is also essential when examining the profitability of power plant construction plans themselves. Furthermore, LCOE analysis plays an important role in deciding whether to proceed with a given power plant construction project; the LCOE obtained will determine whether the project will break even or be profitable. If not, the company will not proceed with construction of the generation asset and will look for alternatives. Using LCOE to evaluate a project is one of the first basic steps taken when analyzing a project of this nature.
Based on this importance, we calculated the LCOE of OPG plants assuming that they are constructed at several suitable sites along Sea of Japan coastline where a large amount of electricity could be generated by OPG. In setting each parameter value, we referred to those deduced from the OPG system that will be operated in Fukuoka from the summer of 2025 by Kyowakiden Industry Co., Ltd. We also cited geographic data such as river flow rates from the geographic information database published by the Ministry of Land, Infrastructure, Transport and Tourism.