  The enormous power consumption of Bitcoin has led to undifferentiated
discussions in science and practice about the sustainability of blockchain and
distributed ledger technology in general. However, blockchain technology is far
from homogeneous - not only with regard to its applications, which now go far
beyond cryptocurrencies and have reached businesses and the public sector, but
also with regard to its technical characteristics and, in particular, its power
consumption. This paper summarizes the status quo of the power consumption of
various implementations of blockchain technology, with special emphasis on the
recent 'Bitcoin Halving' and so-called 'zk-rollups'. We argue that although
Bitcoin and other proof-of-work blockchains do indeed consume a lot of power,
alternative blockchain solutions with significantly lower power consumption are
already available today, and new promising concepts are being tested that could
further reduce in particular the power consumption of large blockchain networks
in the near future. From this we conclude that although the criticism of
Bitcoin's power consumption is legitimate, it should not be used to derive an
energy problem of blockchain technology in general. In many cases in which
processes can be digitised or improved with the help of more energy-efficient
blockchain variants, one can even expect net energy savings.
