北朝鮮は、なんと電力消費の制限にプリペイドカードを使うという。

"Suffering from the long term electrical supply shortage, they issued prepaid IC cards for electricity in North Korea. The card can be charged at the service center for the next month electricity. The excess use of the electricity will be cut off -- which would save the energy consumption."

→ プリペイド式　電力で省エネ