There are a few (ok, many) meanings of the phrase. If by "waste" we mean using too much of a scarce commodity, no, we do not and cannot waste energy. Useful1 energy is wonderfully, recklessly abundant - like sand, or grass, or rabbits in Seattle. Our World in Data puts humanity's total energy consumption rate at about 165,000 TWh per year, or 19 TW. Compare that to what's radiated from the sun, which provides a power density at the Earth's distance of roughly 1.4 kW / m2. The Earth's cross-section is about 1.3e14 m2, which means we could be capturing ~ 1e17 W = 100,000 TW, four orders of magnitude above our current usage, just on this planet. If we were to put a little bit more pep in our collective step, and collect everything the sun emits, the relevant surface area would be 4π * (1AU)2, getting us up to 4e14 TW, or thirteen orders of magnitude (a factor of 10,000,000,000,000) above our current usage. And that is completely ignoring all sources of (non-solar) nuclear energy! We couldn't waste it if we tried - the scale far exceeds our civilization.2
It's worth stressing the point about physical abundance, because access to useful energy determines what we regard as doable. Every action we take must meet some minimum energy requirement; a sufficiently large supply unlocks new activities so wonderful as to lay outside the realm of intuitive possibility. Do you want to literally move a mountain? Engineer the perfect climate? Explore new solar systems? You can, if you supply the necessary energy. Things that today sound like science fiction are repainted in new psychological hues when it is granted: "it's just an engineering problem". If it were too difficult to harness our energy in a useful form, abundance might remain a theoretical joy only - but at this point you can just throw some cheap silicon on the ground and electricity falls into your lap. We live in unintuitive times.
Frugality in energy is positively dangerous, because it trades against things that are very valuable. Technology development is one, as nascent devices are often both inefficient and hard to distinguish from toys. Your time is another - unlike useful energy, it actually is pretty scarce.3 You can trade energy to get more of it, by flying rather than driving to get somewhere quicker, having an AI automate paperwork, or using air conditioning to be productive when it's hot outside. Right now you get at most a century of life - why exchange this for something that is almost comically plentiful?4 Thrift can be a virtue, but only if we apply it to the right things.
Anyway, so much for physical energy scarcity - let's consider other notions of waste. Is it reasonable to speak with moral authority of wasting energy on "luxuries"?
It is not. This line of argument is just rhetoric, based on the premise that it is possible to decide globally, for all people, what are "needs" and what are "luxuries". This cannot be done. Apart from the practical impossibility, any attempt to do so would run counter to one of the core moral principles of a free society, namely, that a citizen ought to be allowed to spend their money and time as they see fit, as long as they are not harming anyone else. This commentary from the Guardian is a good example of how accepting the notion of luxuries leads to error:
... there is no argument for the able-bodied to be using air-conditioning at home, just so that they are more comfortable during our short-lived warm spells.But this is an argument, a good one - an air conditioner buys you comfort, which is to say, the ability to focus on things other than your immediate physical environment. Do you need air conditioning? How about electrical lighting? Indoor plumbing? Hot food? Etc, etc. That's not to say it's impossible to be a fool - it makes sense to speak of waste when someone is spending resources and not obtaining any desired effect as a result. Perhaps they turn on the AC and open the adjacent window. The point is that this carries no moral weight - it is their own money they are choosing to burn.
Now, there are externalities in carbon-based energy production, in the form of CO2 emission and its consequent climatic effects. As long as we are producing a net carbon flux from the crust, could we be "wasting" some energy in the sense of "using up too much of a limited emissions budget"? Well, logically, no - the externality lies not with the energy itself, but with a specific mode of its production; not with the quantity of emission, but with its effect on the climate. It is important not to confuse these, lest we throw out a whole fleet of babies with the bathwater. None of our staggering abundance is predicated on carbon, and as a means of electricity generation its days are numbered.
But putting that aside - for as long as that externalized cost of energy exists, is it worth it? Is it worth growing ever larger? Yes, emphatically yes - even were all the growth from carbon-heavy sources. The benefit of energy in unlocking new technologies and extending human prosperity is sufficiently great.5 As an example of the former, planetary climate control itself is "just an engineering problem", one which we can solve with a bit of thought and plentiful energy. If we want to reduce temperatures, we can make the atmosphere more reflective, and if we want to decrease the atmospheric CO2 concentration, we can remove it directly. Frugality in energy is the last thing we want for the job!
Another notion of "energy waste" arises in design or aesthetic considerations - we can critique a device or method as "wasteful" if its energy usage far exceeds the physics or engineering limit, simply because we know it could be done better. This type of waste is certainly possible, and identifying it is part of good taste. But it is just one of several criteria that influence a designer working on a specific project, and not a general economic or moral guide. It also does not mean the "wasteful" thing should not exist. We run trillions of floating point operations in a GPT query to synthesize intelligence - is there a better way to do it? Yes. But what is it? This is wonderful creative fodder for programmers,6 but it is not a reason to throw the thing away before we have a better one.
The final notion of "energy waste" that I can think of is a sort of converse: waste in the sense of untapped resources, rather than oversubscribed ones. This actually describes our civilization's current physical situation pretty well. Remember how little of the sun's power output we are touching, the trillions of trillions of watts that are streaming uselessly7 into the void, feeding no life nor industry, laughter nor intellect. Consider the quiet corners of our solar system still unlit, the cold unmapped rock waiting for the architect and the engineer to command it, the other stars which beckon over lightyears of wilderness. The raw material for a civilization of surpassing beauty is just sitting out there unused, marking the time with radio static and the occasional crater.
This is a massive wasted opportunity; it will not remain wasted for long, I think. A future with
vastly more people, in vastly more space, is better,8 and now that we know enough physics to know
it's doable, the sense of unrealized potential is too keen to forego it. Your children will leave this planet,
to meet the immeasurable bulk of human
history waiting to be enacted out there in the cool starlight and rippling dust. They will do
so with fantastic energy expenditure, and none of that will be wasted.
Thanks to DL and RR for reading drafts.