Comparative assessment of GHG mitigation scenarios for Japan in 2030

Discussion Paper
Comparative assessment of GHG mitigation scenarios for Japan in 2030

This study conducted a comparative assessment of 48 greenhouse gas (GHG) emissions reduction scenarios for 2030 reported in seven studies published since 2011 and based on bottom-up energy system analyses. This study conducted two sets of analyses. First, the scenarios were categorized into four mitigation effort levels and assessed the value ranges for GHG emissions (excluding land use, land use change and forestry) as well as the key underlying energy-related indicators for each effort level category. Second, a multiple regression equation was developed to predict GHG emissions with a few energy-related explanatory variables based on the data from the 48 scenarios. Using the derived regression equation, we calculated the levels of low-carbon energy supply and end-use energy savings required to achieve different levels of GHG emissions reduction in 2030.

Key messages:
-- For the scenarios that are categorized to assume the highest level of mitigation efforts including those consistent with a global 2 ℃ target, GHG emissions levels ranged between 16-39% below 1990 levels (23-44% below 2005 levels) with the nuclear power share ranging between 0-29%.

-- Taking into account the government’s plan to restart most of the existing nuclear reactors as well as the RE electricity deployment potential, GHG emissions reductions of more than 25% from 1990 levels (32% from 2005 levels) may be considered a minimum mitigation effort level required in the global efforts to achieve the 2 ℃ target.

-- To achieve the above-mentioned mitigation levels, strengthened pre-2020
efforts to reduce energy consumption in the end-use sectors are also
essential and the choice between coal and natural gas for fossil fuel-fired electricity generation is as equally important as the share of renewable electricity generation.


Final report posted on 1 May.