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Tadashi Narabayashi

【#735(Special)】Nuclear Power Required for Achieving Decarbonization by 2050

Tadashi Narabayashi / 2020.11.09 (Mon)

November 5, 2020

In his keynote policy address on October 26, Japanese Prime Minister Yoshihide Suga declared that his government would aim at realizing net-zero CO2 emissions, or a decarbonized society, by 2050. No opposition party can rebut the basic policy. Suga also vowed to promote a nuclear energy policy while giving top priority to safety. He thus indicated that nuclear power plants would be necessary to achieve decarbonization and that the 2050 decarbonization target could lead to the new construction and expansion of safe nuclear power plants.

Misguided praise for renewable energy

The world might have plunged into an illusion in which renewable energy is praised and understood as covering all electricity demand. The illusion is quite wrong. Solar photovoltaics panels can operate only for six hours per day or a quarter of a day. Japan’s sunny probability, though differing by region, is roughly 50% on average. This means that the capacity factor of solar PV panels is limited to 13%, or half the quarter. In the remaining time of the day, fossil fuel and hydro power plants must generate power to make up for the absence of generation from solar PV panels. The capacity factor for wind power generation, another major renewable energy power source, is limited to some 20%. Although the factor for offshore wind farms located in strong wind zones is given as 30%, shallow seas in strong wind zones for offshore wind farms are limited in Japan.

Gas turbine combined cycle (GTCC) power plants combining liquefied natural gas-fired and steam turbines are used to complement intermittent renewable energy power sources. Cutting-edge coal-fired power plants gasify coal for GTCC power generation to emit 17% less CO2 than conventional coal plants.

To achieve net-zero CO2 emissions, however, fossil fuel power plants must be replaced with CO2-free power sources. Even one typhoon can leave solar PV and wind power plants inoperable for as long as a week due to heavy rains that block solar light and strong winds that force wind power generator to stop to avoid damage from the wind. In such case, fossil fuel or nuclear power plants must make up for the absence of operable renewable energy power plants. Germany, which some in Japan see as its model, uses massive coal and nuclear power generation for that purpose.

Rejecting nuclear power plants would cost high

Solar PV panels in Japan will increase their capacity to the level for 63 nuclear power plants at the end of next March but account for only 8% of the nation’s total annual power generation. Renewable energy surcharge paid by consumers monthly in addition to electricity bills would be used to pay 60 trillion yen to solar PV power generation companies over 20 years. If renewable energy power plants cover 80% of power supply, ten times as much as the current level, with the remaining 20% being provided by hydro and biomass (such as wood and palm oil) power plants, some 600 trillion yen would be required. Facilities to store surplus electricity generated during the daytime would also be required, costing 400 trillion. The total sum of 1,000 trillion yen amounts to Japan’s national budgets for 10 years.

Such huge investment would be difficult, leading Japan to have no choice but to use nuclear energy while giving top priority to safety. All automobiles would have to be electric or fuel cell vehicles. Electric furnaces would have to replace shaft furnaces and hydrogen would have to replace coke for steelmaking. Then, zero CO2 emissions would be achieved.

Tadashi Narabayashi is a specially appointed professor at Tokyo Institute of Technology and a director at the Japan Institute for National Fundamentals.