  The paper contains the online supplementary materials for "Data-Driven
Prediction and Evaluation on Future Impact of Energy Transition Policies in
Smart Regions". We review the renewable energy development and policies in the
three metropolitan cities/regions over recent decades. Depending on the
geographic variations in the types and quantities of renewable energy resources
and the levels of policymakers' commitment to carbon neutrality, we classify
Singapore, London, and California as case studies at the primary, intermediate,
and advanced stages of the renewable energy transition, respectively.
