This might be the first best of/forecast article I have come across in 2021, which is a sign of the impending end times (of this calendar year). I can only read the abstract due to The Man’s “Intellectual Property Rights”, but here are a few things mentioned:

• satellite megaconstellations
• deep sea mining
• floating photovoltaics
• long-distance wireless energy
• ammonia as a fuel source

Most of these seem fairly self-evident, although I was not immediately sure how you would use ammonia as a fuel source. A quick web search reminds me that it is hydrogen rich, so if you have a chemical or biological process that can separate the nitrogen from the hydrogen without requiring energy input, you can produce hydrogen which you could then burn or use in a fuel cell. Both ammonia and hydrogen are fairly dangerous gases, so you would want to be kind of careful or do this in out of the way industrial areas (typically out of the way of the upper and middle classes, that is…)