Scenario Analyses

Topical working group
“Review of German and Japanese long-term scenarios (2050) and their evaluation mechanisms”

Duration: November 2018 – July 2020

The future of sustainable energy systems will always be uncertain. Scenarios are the best research based instruments to reduce uncertainty and to quantify the whole range of feasible energy futures. Germany and Japan have both been working on long-term energy transitions. Both also need further efforts to achieve their respective goals/targets (Germany has targets up to 2050, while Japan has targets for 2030 and aspirational goals for 2050). Evaluation mechanisms become more and more important when aiming to contribute as much as possible to long-term ambitious targets like decarbonization and risk-minimization and to narrow the gap between announced and actual national pathways towards the goals.

Research questions

  1. What kind of progress management is being implemented? How does it work?
  2. Any challenges in existing evaluation/feedback mechanism?
  3. Any good practices or useful method existing inside of Germany or Japan?
  4. Existing gaps between what has been achieved and the targets/goals for energy transition and climate change mitigation
  5. What will be the consequences regarding policy action to close any such gaps identified, and how can such policy action be advanced/secured?
  6. Areas that need to be addressed by monitoring and evaluation mechanisms in Japan and Germany in a long-term perspective


Jun Arima
Andreas Löschel
Felix C. Matthes


Climate & Energy PolicyTargets, Plans and Strategies – The Role of Monitoringand EvaluationMechanisms (Output Paper, 2020)
Authors: Felix Matthes, Jun Arima, Peter Hennicke, Andreas Löschel, Gerald Zunker



Study Program
“Energy transition as a central building block of a future industrial policy – Analysis of energy transition scenarios”


Duration: May 2016 – November 2017

The respective costs and the corresponding added value for tax payers, industry and the total economy are one of the main questions for the acceptance and willingness in implementing a national energy transition. An energy transition needs to cover strategies to decarbonize the energy supply with the help of various low-carbon energy sources according to the specific country conditions and to reduce the energy demand by energy efficiency. Energy security is also an important objective.

Title ST1

Development and deployment of innovative, disruptive and transformational technologies is likely a prerequisite for long-term deep GHG emissions reduction. Both countries are already on top international positions regarding development of and investments in innovative energy technologies. Based on some studies there is evidence that the German way of energy transition already shows that it can bring positive economic effects – including security of supply – and that it is connected to central low-carbon technology growth sectors. Several publications indicate this relationship. Japan is seeking its own ways of energy transition that is to pursue balanced development of energy security, energy efficiency and environmental affordability. Japan, as a technology and export-oriented nation, could further benefit from existing market opportunities.

Main tasks

  1. Identify the official national targets
  2. Identify the range of existing research-based, long-term scenarios including scenarios that back and/or go beyond the official national targets
  3. Identify the reasons behind the differentiatin of scenarios
  4. Draw implication of above mentioned analysis

Key findings

ST1 Bsp

Overview of the level of reliance on key energy transition strategies in selected scenarios for Japan and German until 2030

  1. Long-term energy policies in both countries are based on selected scenarios out of a range of projected energy futures.

  2. In Japan, there is an ongoing debate on the long-term (2050) CO2 reduction goal and ways and means for achieving it. Germany has decided on a CO2 reduction target range of 80-95% for 2050.

  3. A key difference are the expectations on future system costs and potentials of wind and photovoltaic (PV) energy: Germany expects high shares in energy supply due to low costs and high potentials, while Japan up to now expects higher costs and lower shares. In Japan, there is an ongoing debate on the future role of renewable energies. Up to now, Japan has decided on an electricity generation mix with a share of 20%-22% nuclear energy in 2030; Germany decided to phase out all nuclear up to 2022.

  4. Japan’s island nature restricts grid connection to neighbor countries as an available flexibility mechanism in the electricity system. The country therefore perceives different challenges from very high shares of variable wind and PV generation.

Discussion Papers

“Japan’s Energy and Climate Quadlemma”
Author: J. Arima (2017); Reviewer: F. Schafhausen

“Ambitious climate targets – the prerequisite for a successful, future-oriented climate change policy – A Comparison”
Author: F. Schafhausen (2017); Reviewer: J. Arima

Topical paper 1: “G20 states – Selected official energy and climate targets”
Author: GJETC Secretary (2017)