京都大学 白眉センター

｜　ENGLISH　｜

Bahareh Kamranzad

　Commercial exploitation of fossil fuels began with the industrial revolution in the 19th century. Since then, fossil fuels (petroleum, coal and natural gas) have been the primary source of energy in the world, while the energy demand has been increased with the increasing human population. However, today, the negative impacts of using fossil fuels have been very well known:
　I) Excessive Green-House Gas (GHG) emission and consequently, global warming and climate change. Climate change has caused warmer atmospheric temperatures, ocean acidification, glacier melting, sealevel rise, etc.
　II) Geopolitical wrangling over the control of oil and gas reserves and their price, which has led to many conflicts and all-out wars in the last decades
　III) Decreasing reserves of carbon fuels. Although fossil fuels are continually formed by natural processes, it takes millions of years for them to be formed. Hence, they are classified as non-renewable resources. Studies have shown that it has been estimated that oil and gas resources will be depleted by 2042 and Coal reserves will become the only type of fossil fuel left on Earth until 2112 when all fossil fuels will cease to exist [1].
　After Kyoto Protocol in 2005 and Paris Agreement in 2015, a priority has been given by the countries to zero net anthropogenic GHG emissions to be reached during the second half of the 21st century. Hence, the development of clean, green, and renewable energy resources has become a priority for decisionmakers, investors, developers and researchers. The government of Japan has announced on October 26, 2020, its target to achieve net-zero GHG emissions by 2050, too, which sets Japan on a course to become carbon neutral in 30 years.
　Oceans hold about 96.5% of all Earth's water and around two-thirds of all the human population lives within 100 kilometers of a coastline. Hence, Ocean Renewable Energies (ORE) (such as tidal, current, osmotic, ocean thermal, wind and wave energies) can be a promising alternative to provide part of the energy demand in the areas adjacent to open water bodies and exposed to vast ocean energy. This would be more crucial for remote islands where providing the energy sources for the growing population is a challenge. In addition, usage of OREs is in line with three of Sustainable Development Goals (SDGs) adopted by the United Nations as global priorities, i.e., Affordable and Clean Energy (goal #7), Climate Action (goal #13) and Life Below Water (goal #14).
　Wave energy as an endless source, has the highest density among all OREs. In addition, it has other advantages such as predictability, low visual and environmental impacts, broad geographic viability, conservation of terrestrial resources, and adding to the diversity of the renewable energy mix [2,3]. Furthermore, as well as power generation, wave energy converters (WECs) can be used for desalination, hydrogen production, pumping and heating processes and coastal protection. Plus, wave farms are typically floating structures and hence, can be naturally adapted to sea-level rise (e.g., Fig. 1). It is interesting to know that the modern scientific pursuit of wave energy was introduced by Yoshio Masuda -a former Japanese naval commander and the father of modern wave power technology- in the 1940s.
　One of the main challenges in using OREs is the uncertainties in resource assessment and their sustainability. Although the OREs are promising alternatives to fossil fuels and their usage is aligned with SDGs, their available resources are highly affected by climate change. Hence, their sustainability must be investigated while planning for their usage. The sustainability concept can be assessed within two different time scales: in short-term (e.g., seasonal/ monthly variations) and in long-term (e.g., decadal or long-term changes due to climate change). Recent studies have shown that the areas with lower potential of energy, but higher stability in available resources (lower variability) are more appropriate for wave energy exploitation [5]. The long-term changes in available resources are investigated using two approaches, including past trends and future projections. For the past trends, long-term measurements or re-analysis simulation are used. For the future projection, Global Climate Models (GCMs) with different Shared Socioeconomic Pathways (SSPs) as future scenarios provide the future projections for simulating future available energy.
　East Asia, with some of the highest populated countries (e.g., Japan, China, Indonesia, Philippines, etc.), has one of the highest population densities in the world [6] and vicinity to open ocean and usage of OREs can be a solution for providing the required energy resources. Hence, recently, we have been working on the sustainability of wave energy resources in East Asia, in two projects funded by JSPS Grantin-Aid for Scientific Research (C), Japan and State Key Laboratory of Hydraulics and Mountain River Engineering (SKHL), Sichuan University, China. We developed a Sustainability Index (SIp) for the first time to detect suitable locations for future planning. The factor considers both short-term variation (in monthly scale) and long-term change (for 5 decades), as well as the amount of the available energy [7]. However, additional considerations are required for the selection of a suitable location for wave energy extraction. For instance, the ideal depth for most types of WECs is about 60 m, and distance to the coast is also important considering the Operation and Maintenance (O&M) costs. Hence, recently, we have proposed novel criteria with more detailed technical considerations taking into account the sustainability of available resource. The proposed methodology provides an applicable solution for detecting the suitable locations and technologies at the same time [8].
　In summary, OREs and especially, wave energy can be a promising resource for providing clean and green energy supporting net-zero emission as committed by many countries. However, climate change impacts cannot be neglected, and the long-term stability of the resources is required to be investigated for sustainable development. Having the opportunity to work with different groups and discuss my research with researchers from different backgrounds and disciplines, I learned that the future focus of this work will be on multi-disciplinary research, and alternative solutions for reducing the uncertainties in climate projection and resource assessment.

References

1. [1] Shafiee S, Topal E, When will fossil fuel reserves be diminished? Energy Policy, 2009, 37(1), 181-189. https://doi.org/10.1016/j.enpol.2008.08.016
2. [2] Zheng CW, Wang Q, Li CY, An overview of medium- to long-term predictions of global wave energy resources. Renewable and Sustainable Energy Reviews, 2017, 79, 1492-1502. https://doi.org/10.1016/j.rser.2017.05.109
3. [3] Pecher A, Kofoed JP (Eds.), Handbook of Ocean Wave Energy, Springer International Publishing, 2017, https://doi.org/10.1007/978-3-319-39889-1
4. [4] http://www.emec.org.uk/about-us/wave-clients/pelamis-wave-power/
5. [5] Portilla J, Sosa J, Cavaleri L, Wave energy resources: wave climate and exploitation. Renewable Energy, 2013, 57, 594-605, https://doi.org/10.1016/j.renene.2013.02.032
6. [6] https://neo.sci.gsfc.nasa.gov/view.php?datasetId=SEDAC_POP
7. [7] Kamranzad B, Takara K, A climate-dependent sustainability index for wave energy resources in Northeast Asia. Energy, 2020, 209, 118466. https://doi.org/10.1016/j.energy.2020.118466
8. [8] Kamranzad B, Lin P, Iglesias G. Combining methodologies on the impact of inter and intraannual variation of wave energy on selection of suitable location and technology. Renewable Energy. 2021, 697-713. https://doi.org/10.1016/j.renene.2021.03.062

Fig. 1. Pelamis wave energy converter. Source: EMEC website [4]


Panel Discussion: Artificial Intelligence (AI) gamechangers for the Earth-challenges, risks & future opportunities, AI for SDGs conference, Tokyo, Japan

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