Blockchain technology and, more generally, distributed ledger technology (DLT) systems, face public scrutiny for their energy consumption levels. However, many point out that high energy consumption is a feature of (small block size) proof-of-work (PoW) DLTs, but not of proof-of-stake (PoS) DLTs. With the energy consumption of PoS systems being an under-researched area, we replicate, expand and update embryonary work modelling it and comparing different PoS-based DLTs with each other and with other non-PoS systems. In doing so, we suggest and implement a number of improvements to an existing PoS energy consumption model. We find that there may be significant differences in the energy consumption of PoS systems analysed and confirm that, regardless of these differences, their energy consumption is several orders of magnitude below that of Bitcoin Core.