Solar power plants in the Mojave Desert also plans to build other large solar plants in the Mojave Desert. The southwestern United States is one of the world's best areas for insolation, and the Mojave Desert receives up to twice the sunlight received in other regions of the country. This abundance of solar energy makes solar power plants a cleaner alternative to traditional power plants, which burn fossil fuels such as oil and coal. Solar power stations provide an environmentally benign source of energy, produce virtually no emissions, and consume no fuel other than sunlight. Some groups are also encouraging more distributed generation, or rooftop solar. In
Interlanguage fossilization language learners can only eliminate with considerable effort. Moreover, it has also been noticed that this occurs particularly in adult second language learners' interlanguage systems. Selinker suggests that the most important distinguishing factor related to second language acquisition is the phenomenon of fossilization. However, both his explanation that "fossilizable linguistic phenomena are linguistic items, rules, and subsystems which speakers of a particular native language will tend to keep in their interlanguage relative to a particular target language, no matter what the age of the learner or amount of explanation or instruction he receives in the target language" and his hypotheses