[bpodgursky]

Most transactions now do not involve cash, and credit card transactions are in fact far more energy-efficient than bitcoin transactions. And it is not just using energy to "create something of value"--it is an artificial waste of energy barrier.

Furthermore, there will be an energy cost to transactions even after no substantial number of bitcoins are mined, since just verifying transactions requires wasteful hashing.

The solar energy part is totally irrelevant--if you happen to have a solar panel sitting around, you could just as easily use it for actual work (and offset coal burning) rather than computing hashes.

[jafaku]

> credit card transactions are in fact far more energy-efficient than bitcoin transactions

Huh? You seriously think Visa/Mastercard are using less energy than Bitcoin?

> Furthermore, there will be an energy cost to transactions even after no substantial number of bitcoins are mined, since just verifying transactions requires wasteful hashing.

You can call it wasteful all you want, but if you don't see the value in creating/maintaining a global framework for storing and exchanging value, then I don't know what to tell you. Besides, you are comparing apples to oranges. Bitcoin is a currency. You can build things like Visa around Bitcoin.