In terms of being "green" there are many miners turning to renewable energy to counter commercial costs of electricity.
I don't have specifics but i have seen a few saying their mining is 100%powered by solar energy or wind energy so it is possible in the right circumstances to be completely green.
I for one would like to explore this further as well at some point.
I'm sorry for ruining the party here, but how is solar energy 'green '??
When you get an idea of what it requires to produce, maintain and recycle those solar panels, and the impact of it on the environment, you realise it's actually a pretty hypocritical way to go 'green' especially for big countries with a huge economy that will happily pollute the less economically developed countries to make THEIR home more 'green'..
Same with the electric cars :exploiting rare metals and underpaid workers in poor countries to produce some lovely batteries that last a few years, and then get rid of them by burying them in the same countries where they were produced. :/
So the way to greener crypto mining is more probably to focus on LESS energy spent, or eventually other energy devices that are being totally ignored for now (magnetic). Not 100 % sure about the production of magnet either, though
That upx mining bike sounds awesome, though! =)