Curerntly, Bitcoin require huge electric power. That's because nonce calculation is core part to make consensus.
By thinking why nance calculation is necessary, we can understand how to reduce it.
Bitcoin's case
In the case of Bitcoin, nonce calculation solves majority decision of the blockchain fork in PoW consensus.
Bitcoin is secure because many miners provides calculation power, and a single miner can't dominate more than half power. Therefore huge electric power is necessary.
CodableCash's case
In the case of CodableCash, nonce calculation solves time delay. In trustless P2P system, we can't trust timestamp. PoW is one of the solution to solve in such environment.
In CodableCash, it uses ticket PoS. Therefore basically nonce calculation is not necessary. But actually there will be full nodes which neglect mining a new block. Then backup nodes have to calculate it instead of it.
On the backup process, backup nodes have to wait for current full node to mine it for a while. Then delay period is necessary. Then nonce calculation is used.
In addition to that, sometimes miners have to mine blank or little block, if memory pool has few transactions. Then delay time is necessary, because without it, too many blocks are generated.
Solution is to use calculation for delay time
PoW consensus uses nonce calculation for majority decision, so it needs huge electricity.
But by limit the usage of it in making delay time, P2P consensus can be made with least electric power.