Tell them that Bitcoin is actually incentivising green energy, because it incentivices cheap energy. It is the only industry that has such a high priority on cheap energy that it is bound to be more efficient then any other industry.

The other principles of Bitcoin also outperform any other asset, making up for its energy use. It is freedom money, and its community is actually willing to help make earth a better planet.

And one of the reasons why they might not get much donations in Bitcoin is because they do not tell about it.