Some months ago I started a
similar thread in the spanish subforum, and I came to pretty similar conclusions than you.
In my opinion, because of continuous energy input, these energy sources ensure the stability of the Bitcoin network, and no single force can tamper with the Bitcoin network. On this basis, more and more people have developed trust in Bitcoin, and can inject their wealth into the Bitcoin system, and value will be generated. The continuous supply of energy can maintain the stability of the Bitcoin network. The stability of the network can generate trust, and trust can generate value, and the value will ultimately be stored in the Bitcoin network.
While Wind_Fury is right that Bitcoin is not "a battery" (i.e. for the Bitcoin price it isn't relevant how many energy was put into mining in a certain point of time), I think this is actually a pretty good explanation for the
base mechanism which gives value to BTC, although it obviously only covers a part of the "value proposition".
Basically Bitcoin is "a medium I can trust to transfer value", because of the security provided by PoW, and because of the scarcity which ensures that my value isn't diluted. Like you wrote, there is consensus among the users regarding this part of the value proposition.
But then you can add more "items" which make up the whole value proposition. For example, you can mention some advantages which it has compared to the "fiat system":
1) No national barriers. It is a perfect medium for international transfers.
2) Transparency and non-reversability (important for businesses like merchants).
3) It gives new opportunities to make profit. This is not only a part of the "value proposition" for the hundres of thousands or millions of traders or holders, but also companies who build services upon it. This item is different from the base value proposition ("it has value because value is preserved"), because in this case, people expect to
benefit from it, not only to "store" value.
In my Spanish post, I related these factors to the network effect, which increases or decreases the base value. This is approximately what you mean with "consensus", I think.