Actions and Scenarios
for the Carbon Neutral Society
Kenji Yamaji
Senior Vice President/Director-General,
Research Institute of Innovative Technology for the Earth (RITE)■Abstract
Japanese Prime Minister Suga declared the goal of realizing a carbon neutral,
decarbonized society by 2050 in October 2020, and efforts toward a carbon neutral society
are moving forward. The Green Innovation Strategy Council was initiated in July 2020 toimplement the Progressive Environment Innovation Strategy announced in January lastyear, and the Committee on the Growth Strategy formulated a primary plan of the Green
Growth Strategy toward a positive cycle of economic growth and environmental protectionin December. Full-scale actions to realize a carbon neutral society that mobilize all possible
solutions from innovations, such as electrification and greening electricity, realization ofhydrogen society, and CO2 sequestration and reuse, to social implementation of thosemeasures as well as existing technologies have begun. With two trillion yen of Green
Innovation Fund created as a supplementary budget, concrete actions are now being
undertaken in each field.
A decarbonized society, or a carbon neutral society, is a society where the CO2 emission
is net zero. This situation was maintained in the pre-industrial era when CO2 absorption byphotosynthesis and by ocean, etc. were enough to offset the amount of CO2 emission as anatural process. Deforestation and large-scale use of fossil fuels, being accelerated rapidly
since the Industrial Revolution, have disrupted this natural balance, leading to the increaseof atmospheric GHG concentration and eventually global warming. A carbon neutral society
where net zero CO2 emission is achieved artificially through innovation, although it isdebatable by what time it should be realized, is appropriate as a long-term goal for global
warming mitigation. Furthermore, the fulfillment of 3E + S (energy security, economicefficiency, and environmental preservation on the premise of safety as the basis of Japan's
energy policy) and SDGs are also required in order to make the response to climate changesustainable.
In the context of these basic understanding, this presentation examines the outlook ofa carbon neutral society and the scenarios leading to its realization. As the measures
toward a carbon neutral society, the reduction of atmospheric CO2 will be necessary inaddition to conventional measures such as energy saving, non-fossil energy, and CO2
capture and storage (CCS). Many of the studies describing scenarios up to the end of thiscentury have shown that CO2 emissions from power supply will be negative at earlier timing.
There are various uncertainties around the global warming issue. A scenario for acarbon neutral society that is valid under such uncertainties is important. The reduction ofCO2 emissions in the baseline scenario is noteworthy although this has not been muchconsidered in the discussions of climate change mitigation so far. A scenario for climate
stabilization can be possible without relying on high-cost CO2 reduction measures if thedecarbonization led by private sectors through ESG investment emphasizing environment,society, and governance advances along with the development of a digital society (Society5.0) being promoted by the countermeasures against COVID-19. Long-term climate change
measures require technological and social innovation. Social innovation to achieve theSDGs (United Nations Sustainable Development Goals) lowers the baseline of CO2emissions, and technology innovation produces clean secondary energy such as electricity
and hydrogen without CO2 emissions and builds a more energy efficient system, which will
open up the prospect for the realization of a carbon neutral society.

■BiographyDr. Kenji Yamaji, Emeritus Professor of the University of Tokyo, is Senior Vice
President of the Research Institute of Innovative Technology for the Earth (RITE) since
July 2019 and Director-General of the research institute since April 2010. He served asPresident of the Japan Institute of Energy and as President of the Japan Society of Energyand Resources. Dr. Yamaji’s immediate past position was a Professor of ElectricalEngineering and Information Systems at the University of Tokyo. He obtained B.S., M.S.,
and Dr. of Engineering degrees in nuclear engineering from the University of Tokyo in
1972, 1974, 1977 respectively. During the earlier part of his career, Dr. Yamaji had been
extensively involved in the analysis of energy technology assessment, mainly at theCentral Research Institute of Electric Power Industry (CRIEPI) in Japan. He has publishedmore than 80 books as well as many research papers on energy systems, and he is also
serving in many advisory bodies on energy and environmental policy for Japanese
government. Dr. Yamaji contributed to Intergovernmental Panel on Climate Change (IPCC)
as a lead author for 3rd and 4th Assessment Reports of WG3.