While emergency planning with my wife, I read this FEMA doc on food and water emergency. There's a section for shelf life for food, and instant coffee can be stored indefinitely. Pretty neat.
So it got me thinking, can you DYI instant coffee? You can but it takes a bit of effort and a contraption that freeze-dries it. The trick is freezing things ahead of time and then rapidly cooling brewed coffee in under 30 minutes.