[mirror_neuron]

> Even if you manage to find something that is somewhat relevant to the real world, like green energy research, chances are it might be something highly technical, abstract, and difficult to relate back to the final product.

As someone lucky enough to have found a programming job in an organization that is dedicated to something I believe in, I can confirm this perspective. The big picture mission helps keep me motivated, but my day-to-day is pretty abstracted from that mission.

My advice to OP would be to try to diversify your sources of fulfillment. That may be unsatisfying advice - I know that there was a time in my life that I would have rejected it - but from where I stand now, it is the most reliable path to overall happiness.