Sumitomo Mitsui Construction’s floating
solar power generation facilities, shown
here installed in Tokyo Bay, can adjust
easily to rising and falling water levels. By
comparing and verifying multiple systems,
the company aims to develop a low-cost
system for generating power.

SEA-BASEDSOLAR ENERGY:A NEW ANSWER TO CLIMATE CHANGE?

In a world that requires more solar power, finding the optimum place to install solar panels has become a pressing
issue, so the installation of systems that generate solar power at sea has drawn much attention. With its extensive
experience in a wide range of construction projects, Sumitomo Mitsui Construction Co., Ltd. is working to realize
the technology as quickly as possible, based on its excellent track record in constructing infrastructure in freshwater
environments.
Renewable energy is becoming more commonplaceas the world moves toward decarbonization. Solar
power, in particular, is gaining traction at anaccelerating speed, with large-scale power generation
facilities having been installed throughout the globe.
But that comes with new challenges, especially how
to secure enough land to situate power generation

facilities while protecting the natural environment,such as forests and other habitats. As a solution
to that problem, attention is being focused on
the development of new systems for solar power
generation, in which solar panels float on the sea.
TAKETOMI Yukio, director of Sumitomo Mitsui
Construction’s Business Creation Division—whichalready manages many floating solar power projects
in freshwater environments, including dams, lakes,
and reservoirs—explains that the benefits of building
such systems are not confined to merely expanding
the locations where solar panels can be used. For
example, while sunlight is essential, too much of it
can cause the surfaces of solar panels to overheat,decreasing their efficiency and paradoxically reducing
power output in the summer. However, overheating
can be prevented if the panels are located on a water
surface, the cooling effect of which allows them tomaintain their power output. Also, there is no need toworry about slopes and inclines with floating systems,
unlike in the case of land installations of solar panels.
Thus, thanks to the effective use of water surfaces—
normally hampered by limited usability comparedwith the land—larger-scale power generation
facilities can be built there more easily. Moreover,since the solar panels in the systems—which havefloats and anchor blocks fixed to them—simply reston the surface of the water, there is no need for anyof the preparatory construction work (foundations,etc.) normally required when installing such facilities
on land. That is why floating solar power systems
can be installed without reworking the naturalenvironment.
However, several new challenges emerge whenconstructing the installations offshore: enablingthem to withstand the motion of currents and waves
is of paramount importance. Sumitomo Mitsui
Construction is therefore looking to install thesystems first in coastal areas and inland seas where
the wave motion is relatively mild. Besides utilizing
the technologies it has cultivated in freshwater
environments, the company can also take advantage
of its expertise in the building of ports and othertypes of infrastructure. By doing so, it believes thatcosts can be lowered and the systems realized more
quickly.
The company’s technology was selected by theTokyo Metropolitan Government as a prior project
making use of innovative technology in the Tokyo
Bay eSG Project for sustainable urban development,with offshore solar power generation facilities
installed in Tokyo Bay in April 2024. Demonstrations
are currently underway to examine the mooringsystem, the amount of power generated, and theeffects of salt damage. Also, the company is said tohave already received several inquiries from various
countries regarding the system’s practical use.
Sumitomo Mitsui Construction has set a goal for
itself of achieving substantial carbon neutrality in
its own activities by 2030. To achieve that ambitiousgoal, it needs to minimize its CO2 emissions throughrenewable energy power projects. As Taketomi
emphatically states, constructing systems of floating
offshore solar power generation will be a major factor
in accomplishing that.
Lofty expectations have thus been pinned on seabased solar power systems, which seek to harness thepower of nature in its natural form. It is hoped thatthey will expand the potential of renewable energy,
helping the world solve the issue of climate change.

Top: (from left) NAKAJIMA Hirohisa, deputy general manager ofSumitomo Mitsui Construction’s Civil Engineering Design Department,
TAKETOMI Yukio, director of the company’s Business Creation
Division, and TSUDA Wakaki, general manager of its Civil Engineering
Design Department.
Bottom: Sumitomo Mitsui Construction’s floating system for solar
power generation is shown here installed in an agriculture-use reservoir
in Sakaide City, Kagawa Prefecture.