Historically, wholesale power prices for Northern and Southern California tracked closely with one another, indicating minimal market differences between the two areas. However, after the shutdown of SONGS in early 2012, the relatively inexpensive nuclear generation produced by SONGS had to be replaced with power from more expensive sources. Consequently, since April 2012 Southern California power prices have persistently exceeded Northern California prices, with the spread averaging $4.15/MWh, or 12% of the Northern California price.

This hypothetical graph shows how daytime and nighttime temperature vary in the vicinity of a large city. Notice how daytime temperature is higher over heat-reflecting buildings and lower over a water body. The urban heat island effect causes cities to run warmer than surrounding rural areas, especially at night. Development produces heat islands by replacing vegetation, particularly forests, with pavement and other urban infrastructure.

The lack of skills remains a major problem because technologies become increasingly sophisticated and some countries lack the technical and economic capacities. That threatens economic growth and social development.

In most countries the gender differences are usually smaller than other gaps. In the case of the US, the difference in the rate of users among men and women is almost irrelevant, only around 2%