I'm posting this as more of a "fun thought" than anything else.
It's generally considered a fact that Linux, along with many other open-source software projects, are more efficient than their propriety closed-source counterparts, specifically in terms of the code that they execute.
There are numerous reasons for this, but a large contributing factor is that open-source, generally speaking, incentivises developers to write better code.
Currently, in many instances, it can be argued that Linux is often less power-efficient than its closed-source counterparts, such as Windows and OSX. However, the reason for this lies not in the operating system itself, but rather the lack of certain built-in hardware support for Linux. Yes, it's possible to make Linux more power-efficient through configuring things differently, or optimizing certain features of your operating system, but it's not entirely uncommon to see posts from newer Linux laptop users reporting decreased battery life for these reasons.
Taking a step back from this, though, and looking at a hypothetical world where Linux, or possibly other open-source operating systems and software holds the majority market share globally, I find it to be an interesting thought: How much more power efficient would the world be as a whole?
Of course, computing does not account for the majority of electricity and energy consumption, and I'm not claiming that we'd see radical power usage changes across the world, I'm talking specifically in relation to computing. If hardware was built for Linux, and computers came pre-installed with optimizations and fixes targetted at their specific hardware, how much energy would we be saving on each year?
Nanny Cath watching her YouTube videos, or Jonny scrolling through his Instagram feed, would be doing so in a much more energy-efficient manner.
I suppose I'm not really arguing much, just posting as an interesting thought.
Energy efficiency can be offset by extra computational ability though.
Eg Linux has a plethora of CPU and IO schedulers and allows you to tune the system to maximise performance for your particular workload. Getting more performance than with the generic CPU and IO schedulers provided in other OS's generally means more power consumption, unless you do some sort of "performance per watt" calculation to take that into account.
You're right in saying that. I might be wrong, but I'm fairly sure Parkinson's Law of Data Processing is the name for this concept?