See, this is what I get for having my head buried in code for days on end; interesting stuff just slips by without notice even when it’s begging for a post. Though in this case, circling back to the story now will actually add a fun twist. Basically, my former Skeptically Speaking sparring partner, George Dvorsky, wrote about making an honest to goodness Dyson sphere out of Mercury and attracted the attention of PopSci and a blogger at Forbes who dialed up the Bad Astronomer himself, Phil Plait, to do the math on whether this was or wasn’t a viable idea. Not surprisingly, their answer was no, but the odd thing is that the reasons why Dvorsky proposed an unworkable plan weren’t included in their calculations. Instead, they worked out that it would take so much energy to disassemble Mercury, that a 100% efficient Dyson shell of satellites would take us some 174 years to balance the energy budget. Now this would’ve been fine if we were talking about warp drives and negative energy/mass constructs, but we’re not, and even after having it pointed out that Dvorsky was proposing a very energy amortized bootstrapping scenario, Alex Knapp was still sticking to his energy balancing guns. So if we don’t need to balance energy the same way we need to balance a checkbook, what’s really wrong here?
First and foremost, the problem is that assumed 100% efficiency. As pointed out in a previous post in which I crunched the numbers on Dyson spheres, the amount of collected energy lost in transmission would be so high that the whole project may not even be worth it. When you do the math on beaming solar energy from the comfort of Low Earth Orbit, you find that you’d need a receiver stretching from the Earth to Saturn to get real returns on your investment due to the limitations on how powerful your beam can be and the diffusion of the photons in your microwave laser. If you really want to amp up the power, you’ll create a death ray and the swift release of energy will take down the grid for which you’re aiming, overwhelming your ability to deal with excess electricity now surging through the wires. Collecting energy isn’t like drilling for oil. You can’t put a lot of energy in a barrel and store it for future use for years on end in capacitor banks. This is why trying to work with efforts required to build a Dyson sphere and treating Joules like we’d treat capital investment and measure the rates of return in terawatt hours doesn’t accomplish much more than throwing big numbers around. The big point is that we’ll lose the vast majority of the energy being beamed back and without another incredibly precise mega engineering project, we can’t even beam that much power back without essentially zapping ourselves with an immensely powerful ray which will be illegal under the same treaty discussed in this morning’s post.
The second big problem? Cost. When we discussed putting up a sunshade to curtail global warming with some real numbers, we found that the optimistic cost for blocking out 1% of the Sun’s energy with a reflective solar sail comes to some $800 trillion. The global GPP hovers around $65 trillion, so in other words, blocking out or absorbing 1% of solar energy in space will cost an order of magnitude more than literally all the money in the world. Now, we can’t just multiply a bootstrapped project by 100 and declare that has what we could call an astronomical price tag of $8 quadrillion and call it a day. Certainly if we start small and take the recursively building nature of this endeavor, we’d be looking at budgets… in the tens of trillions? How? Why? Because all those initial robots and mining colonies won’t build themselves for free and will need human assistance for a whole host of issues since in space, a lot of things can go really, really wrong. This is why we lose missions; they break far away from humans who can fix them. Would we really want to start the absolute biggest project in all of human history by at least six or seven orders of magnitude to then be willing to lose it all when things go wrong and we can’t come and fix them? But it will all be worth it if we amortize this over many years and all the energy we’ll get will more than make up for our economic sacrifices, right? If you said yes, allow me to go back to the paragraph above and reiterate that we will not be beaming all that much power back.
Who would want to commit to a project that would last many decades, require tens of trillions of dollars to just get off the ground, and then be unable to beam back the monstrous energy it would be designed to collect for global consumption? And this isn’t even going into the politics of building this monstrosity and who would pull for what percentage of the energy generated and agree to find what part of all this. If we want access to clean, plentiful, cheap energy, we need to heavily invest in very efficient solar panels here on Earth and keep working away on fusion and its exotic power-generating applications. That’s what will grant us more energy than we’d even need, and those are projects with extremely high payoffs and to which we’re even closer than the robotic miners and energy collectors Dvorsky and his sources say we’re on the verge of building. Dyson spheres are great in science fiction but in practice, they would fail to do anything but barely sustain a species with no other seemingly viable options to survive and the money we’d have to invest in building one would be far, far better spent on at least a few thousand different projects that would do far more to secure our energy needs for the foreseeable future and beyond, while also making us a highly durable, long-living, space faring species, and it’s those projects in which we should be putting our money, time, and no pun intended, our energy.
[ illustration by Khang Le ]