What do you mean by "backed by"? When we say "paper receipt is backed by gold" it means you can get gold in exchange for receipt at any time. In case of Bitcoin, you are NOT getting back electricity in exchange for your bitcoins, blocks or transactions. Please clarify what you mean by this.
One definition of "backed by" is "guaranteed exchangeable for."
Another is "supported by." As in 'Bitcoin is supported by the scarcity of energy available from natural resources.'
"Backed by", I would step back and not assume the definition of exchanged for even though that is common nomenclature in the monetary world.
People should think of at least part of a coin as how much resources went into producing it through the mining and proof of work system. I believe miners these days have too look at that when they weigh how much that coins should be worth in purchasing power. I understand the open market exchanges determine the current price but I am taking the side of the miner who is looking to potential sell that coin into the market for covering mining expenses. At the moment, he would have a good idea much these coins were worth if he was keeping really good records on his daily mining reward.
Dalkore