[Proposals to use reversible computation, which in principle consume no energy, elided.]
There’s a contradiction here between the computer science and economic parts of the problem being discussed. What gives a digital coin value is exactly that there is some real-world expense in creating it.
For some definition of “digital coin.”
An alternative design where all coins are double-spend checked against on-line infrastructure belonging to the issuer don’t have this constraint. Though they have different properties. For example, anonymity might then depend on trusting mixmaster-type networks to exchange coins the issuer knows you have for coins that the issuer doesn’t know you have, but that might make anonymity entirely impractical. But then, how practical are POW coins anyways?
I suspect most people in the formal sectors of most economies would gladly live with digital credit/bank cards most of the time and to heck with digital coins.
Jerry LeichterSo, how do you tie the cost of a token to power? Curiously, something of the sort has already been proposed. It’s been pointed out - I’m afraid I don’t have the reference - that CPU’s keep getting faster and more parallel and a high rate, but memories, while they are getting enormously bigger, aren’t getting much faster. So what the paper I read proposed is hash functions that are expensive, not in CPU seconds, but in memory reads and writes. Memory writes are inherently non-reversible so inherently cost power; a high-memory-write algorithm is also one that uses power.
Clever!
Nico