I think you’re confusing terminologies here. Nuclear is not renewable since it requires using a finite resource that has to be mined from the earth to create energy, however it is a nearly zero emission form of energy since it’s basically a giant tea kettle who’s steam spins a turbine to generate energy. That steam is just water vapor, the by products and spent fuel rods can be safely stored and processes or reprocessed. Wind, Solar, Geothermal and hydroelectric are renewable since they require no fuel to operate. All of the above could be considered green since they emit zero emissions unlike Coal and Liquid Natural Gas plants
I agree GNOME is resource heavy however that has nothing to do with Javascript being involved. The James Web Telescope uses Javascript for some of its core functionality (specifically managing its science modules), does that make it a web browser? I personally don’t like GNOME either, but most of it is written in C, it has its own GUI library which is written in C. The Javascript code likely just is used to simplify calling the underlying C functions and CSS is used for customizing the actual UI elements.