Renewable energy requires constant backup from conventional power plants.
This system functions in Japan only because generation and transmission are integrated and utilities are bound by strict public-service obligations.
Once generation and transmission are separated, such costly balancing efforts would no longer be maintained.

2016-03-24
The following is a continuation of the previous section.
This commentary also sufficiently proves the correctness of my own argument.
Therefore, renewable energy must always be paired with conventional power plants that serve as backup.
When renewable energy output decreases, backup generation must be increased, and when it increases, backup generation must be reduced, meaning that a nearby thermal power plant is always forced to play this disadvantageous role.
This high level of adjustment capability exists only because, as in present-day Japan, power generation and transmission are managed as an integrated system.
If generation and transmission were separated, there would be no obligation to engage in such an irrational practice.
After all, they would be different companies.
It is only because electric utilities are currently imposed with strict obligations regarding power supply and demand as public-service entities that they perform this role.