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 on interlanguage fossilization are fascinating in that they contradict our basic understanding of the human capacity to learn. How is it that some learners can overcome interlanguage fossilization, even if they only constitute, according to Selinker, "a mere 5%", while the majority of second language learners cannot, "no matter what the age or amount of explanation or instruction"? Or is it perhaps not that they cannot overcome fossilization, but that they will not? Does complacency set in after second language learners begin to communicate, as far as they are concerned, effectively enough, in the target language, and as a result