Fuel cell fuel cells so efficiencies vary, but most are between 40% and 60% energy efficient. However, when the fuel cell's waste heat is used to heat a building in a cogeneration system this efficiency can increase to 85%. This is significantly more efficient than traditional coal power plants, which are only about one third energy efficient. Assuming production at scale, fuel cells could save 20–40% on energy costs when used in cogeneration systems. Fuel cells are also much cleaner than traditional power generation; a fuel cell power plant using natural gas as a hydrogen source would create less than one ounce
Interlanguage fossilization to learning second language, and the relationship of fossilization to the learner's communicative needs. Arguments have emerged regarding adult learners' general lack of empathy with target language native speakers and culture. According to Guiora et al., adults do not have the motivation to change their accent and to acquire native-like pronunciation. Unlike children, who are generally more open to target language culture, adults have more rigid language ego boundaries. Thus, adults may be inclined to establishing their pre-existing cultural and ethnic identity, and this they do by maintaining their stereotypical accent. Notwithstanding this, there is a lack of needed research,