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 1) why fossilization occurs, 2) the precipitating conditions, 3) what kind of linguistic material is likely to be fossilized, and 4) what type of learners are more prone to fossilize. However, there has been almost no investigation by SLA theorists on the possibilities of preventing or overcoming fossilization, and little explanation related to those adult second language learners who overcome one or more "areas of stability" in interlanguage—those learners whose interlanguage does not fossilize, and who reach a high level of proficiency in the second language. One factor of obvious relevance is motivation, and studies have been conducted regarding motivation