Fuel cell of pollution (other than ) for every 1,000 kW·h produced, compared to 25 pounds of pollutants generated by conventional combustion systems. Fuel Cells also produce 97% less nitrogen oxide emissions than conventional coal-fired power plants. One such pilot program is operating on Stuart Island in Washington State. There the Stuart Island Energy Initiative has built a complete, closed-loop system: Solar panels power an electrolyzer, which makes hydrogen. The hydrogen is stored in a tank at , and runs a ReliOn fuel cell to provide full electric back-up to the off-the-grid residence. Another closed system loop was unveiled in late 2011
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