I'll keep this updated throughout the day.
The Giants announced that the two generators at Tokyo Dome had to be turned on in order to help power the air conditioning units (to offset the warm outdoor temperatures) during today's game. Total usage at Tokyo Dome during the game was ~3,390kW, about 26% less than at peak times (~4,600kW).
The Swallows played their first night game of the season at Jingu Stadium today. In order to help conserve energy, they had 22% of the 6 lights banks turned down (particularly those pointing to the outfield). Ryoji Aikawa told reporters that he thought the light levels were fine while Norichika Aoki said the outfield felt a little dark.