Tokyo Tech is developing an ingenious seawall system that protects coastlines against destructive tsunamis while generating energy from the water's microtides.
If successful testing continues, the research could produce a self-powering movable barrier that also makes supplemental energy that can be stored for use during outages, the university's team said in a lab report.
"To our knowledge, there is yet no system in the world that uses movable seawalls to generate electricity and then uses that electricity to operate the system itself. In this sense, [it] is a completely new concept," Professor Hiroshi Takagi said in the article.
At issue is the Nankai Trough off the coast of Japan, an active geological trench known for creating powerful earthquakes every 90 to 150 years. According to Geographical magazine, a "megathrust" is due soon. This type of severe quake can cause terrible tsunamis that wreak havoc on coastlines. The Tohoku earthquake and subsequent tsunami in 2011 killed more than 18,000 people, for example.
Protection from rising waves is becoming increasingly important as planet overheating contributes to eroding coastlines, even in the States. Tokyo Tech's invention could be a safeguard against high water as we better cope with our changing weather — and it could do so while producing cleaner energy.
"Our findings outline a synergistic system between disaster prevention and the use of renewable energy," Takagi said in the university's report.
It works by placing self-elevating gates that activate from underground storage. When lifted fully, they serve as a protective barrier against storm surges and high waves.
The gates also produce a difference in water elevation that makes an inflow, which the experts said can be used to generate electricity by powering small turbines.
The "microtidal" water movement is too small for large-scale tidal power generation. But it's enough to create and store electricity for the gate system and potentially for coastal ports during outages, per the research.
The Tokyo Tech team sees the system as a potential protector for some of the country's more than 3,700 ports (including major ports and fishing ports). The researchers tested the invention at 56 sites around Japan, 20 of which faced the troublesome Nankai Trough and were among sites deemed feasible for gate use. They made enough power to return the barriers underground after the test warning was over.
Several sites also showed promise in producing excess energy to be stored for use at a later time.
The potential for the system is an expansion for global rollout, though the Tokyo Tech report noted that technical and regulation hurdles need to be cleared first.
"If the technology of the proposed movable tsunami barrier, under the harsh disaster conditions in Japan, can be firmly established through this research, there is no doubt that a day will come when this technology can be exported and deployed overseas as a groundbreaking disaster prevention technology," Takagi said in the research summary.
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