100% Renewable Energy Scenario 2050 for JapanJUST (Japan’s Union of the Concerned Scientists on Energy Mix and Climate Target),November 6, 2017
JUST studied 100% Renewable Energy Scenario 2050 and calculated the possible greenhousegas emission reductions amount under the scenario, based on the latest surveys on energy
efficiency improvement and domestic renewable energy sources in Japan. The results are as
follows,
1. Change of social and economic activity toward 2050
The largest change that shall happen is “Population Decrease”. In 2017, National Institute ofPopulation and Social Security Research showed that the population forecast for 2050 will be
101,920 thousands from 127,090 thousands in 2015. This is 19.8% decrease during 35 years. The
annual growth rate of GDP is 1% from 2010 to 2015, but the end use energy demand decreased
at the rate of minus 1.6% annually. The energy demand and economy already decoupled. We
assumed this trend will continue.
The level of social and economic activity will decrease along with the population change. And
we assumed it will affect the end use energy demand. Furthermore, we assumed the paper
consumption will decrease by penetration of electronic communication devises, the recycle ratioof steel will increase from 30% today to 60% in 2050, RE100% will demolish the oil refining andtransport of fossil fuels, and the production and possession of car will decrease by car sharing
systems with driverless vehicles
2. Improvement of energy Efficiency
Energy efficient devices such as LED, inverter controlled motors and heat pump will be widelyused. We assumed the energy efficiency in industry sector will be improved by 20% to 2050. Allof the passenger cars will be EV, and trucks will be EV and FCV by half and half. Buildings will
be highly insulated and be equipped with PV on the roof and wall. Many of ZEH (Zero energyhouse) and ZEB (Zero Energy building) will be built and they will reduce energy demand
drastically. We estimated the end use energy demand will be 4,442PJ (45.9% of 2015 level
11,853PJ) by combination of efficiency improvement and activity change as shown in Fig.1.

Fig.1

End use energy demandFig.2 Primary Energy Supply

3. Renewable energy 100％
Renewable energy will expand. The nuclear power and fossil fuel use will phase out toward2050. Renewable energy, such as hydro, photovoltaics (PV), wind, geothermal, solar heat andbiomass are domestic and self sufficient resources. They will supply to 100% of energy end use.
The electricity generated by renewable resources will be supplied to pure-electricity demand(lighting, motor, air conditioner, and electronic device).
Furthermore the electricity generation will expand to 160% of pure electricity demand. The
excess electricity will be used for fuel demand such as automobiles (EV and FCV), hightemperature heat and hydrogen for industry, and heat pump for low temperature heat. Biomass
will be used for aircraft and heating demand. EV will be equipped with rooftop PV which will
supply 20% of annual electricity demand of the vehicle. Ships will be driven by electricity andhydrogen. Solar heat will be used for low temperature heat demand. The scale of renewable energy
supplies is within the energy potentials surveyed officially.
Fig.2 shows primary energy supply. Fig.3 shows the structure of electricity supply. It shows thatthe electricity demand decrease for the beginning, but PV and wind will gradually increase tosupply excess electricity for fuel demands after 2020. The capacities of electricity generation are
PV 375GW, wind power 87GW, hydro power 46GW, geothermal 10GW, and wave power 10GWin 2050.
4. Greenhouse gas emission (GHG)
100% Renewable Energy Scenario 2050 of JUST shows zero emission of CO2 in 2050. But
some of the methane, HFC and other gas will remain as 64 million ton CO2 equivalent in 2050.
Fig.4 shows the transition of GHG emissions of JUST scenario. The Japanese Government
submitted the emission target in 2030 for INDC (Intended Nationally Determined Contribution)
under the Paris Agreement. It is 1,042 million ton CO2 equivalent, which is minus 26% from2013 level as shown in Fig.4. This number includes absorption by forest. Government already
decided to decrease GHG by 80% in 2050, but the INDC of Japan shows nothing about this fact.
Fig.3
Electricity SupplyFig.4 GHG emission

JUST
Japan’s Union of the Concerned Scientists on Energy Mix and Climate Target
http://justclimate.jp/en