Duniter is a cryptocurrency software supporting the concepts of a Universal Dividend and Web of Trust; and its Blockchain code is far more energy efficient.
F. Abel, J. Coi, N. Henze, A. Koesling, D. Krause, and D. Olmedilla. In 6 th International Semantic Web Conference, 2 nd Asian Semantic Web Conference, ISWC 2007 + ASWC 2007,of Lecture Notes in Computer Science, volume 4825, page 1-14. (2007)Springer.