The Kardashev Business

Can profit be made from solar energy in space, and used to bootstrap our interplanetary civilisation through capitalism?

Almost all spacecraft these days are powered by solar energy. Absent the Earth’s atmosphere, the power collected is about 50% greater, there is no disruption due to weather, and the eclipse of each orbit is always far shorter than a terrestrial night - or almost entirely absent in geostationary orbit. For decades it’s been proposed that this power be transmitted back to the Earth for use here, using microwaves, but this has not yet been realised. In his book The High Frontier, Gerard O’Neill proposed it as the means to finance large free floating colonies in space, so its worth looking into whether or not it is viable.

A few years ago Casey Handmer published his views on why the concept is so much inferior to terrestrial power that it can never possible be viable. Dale Skran of the National Space Society published a rebuttal questioning the technical details. The main points of disagreement between the two are in the thermal management of the system, the practicality of the transmission and reception of microwave energy, and the cost of the hardware in space. Why is a rectenna in a field better than a solar farm, when the latter doesn’t require expensive supporting space infrastructure? Yes, the solar farm requires substantial battery back up if its going to be your main source of power, but is that still going to be cheaper than sending stuff into space?

The consultancy Frazer-Nash published a report in 2021 which claimed that space based solar would be commercially viable as part of the UK’s Net Zero strategy, giving a levelised cost of electricity (LCOE) of £50/MWh. The LCOE is the lifetime costs divided by the lifetime production of a system, so includes all upfront costs for building and launching the power satellite. This value is competitive with other sources in the UK - but we have expensive energy already. It would not be competitive in the US market which has cheaper energy.

The report answers the technical questions well enough, but notes the low TRL of several key enablers (including thermal management and transmission). The credibility of the economic case Frazer-Nash present still depends on how the engineering case turns out as the technical issues are worked on, so at present this is still not a solid business case for conventional space based solar power.

There are other approaches though - a startup Aetherflux seeks to commercialise power beaming from LEO instead of GEO, using compact infrared lasers that can be aimed at smaller receivers. While this may overcome some of the above issues, the company is not aiming to provided the baseload power promised by traditional SBSP schemes, rather niche applications for remote areas and military bases. The business may be profitable but won’t be transformative of our energy situation.

The reason space based solar power was first proposed was as a driver of colonisation though. Ultimately, as we ascend the Kardashev scale and begin to colonise the solar system, we will undoubtedly consume much more of the energy output of the Sun and put it to work for mankind - but in the near term, we would like a business model where every kilowatt of extra solar energy we harvest in space has a clear return on investment, in order to drive that colonisation effort.

Using the Energy in Space

The best means we have of turning solar energy in space into money at present is data - Starlink being a prime example. I estimate, very roughly, that SpaceX have deployed about 150,000 square metres of solar panels from the constellation, which if 20% efficient and spend half of the time in eclipse would give about 20MWe in total. Encoding people’s data on the radio waves beam back to Earth yields a lot of profit from this relatively modest amount of power. Given an annual revenue of $6.5 billion, SpaceX are effectively charging $37/KWh, 2-3 orders of magnitude more than domestic (unmodulated) electricity is sold for.

This is great business, but doesn’t help with the general problem of utilising solar energy at scale, as even in the most optimistic possible scenario Starlink can only scale its revenues by a factor of 1000 or so if it served every internet user on the planet. Scaling up the constellation naively would still only require the power of a mid sized European nation.

If beaming energy to Earth is dubious and beaming data to Earth is capped, then perhaps we should look for more ways to use the energy in space.