I couldn't find anything for Greenpeace, but I did find Friends of the Earth (which like Greenpeace, also split from Sierra Club), was split off "because of the [Sierra Club's] positive approach to nuclear energy. The founding donation of $500,000 (in 2019 USD) was provided by Robert Orville Anderson, the owner of Atlantic Richfield oil company." [1, 2, 3]
[1] https://en.wikipedia.org/wiki/Friends_of_the_Earth
[2] https://www.forbes.com/sites/michaelshellenberger/2019/03/28...
[3] https://atomicinsights.com/smoking-gun-robert-anderson/