Frequently Asked Questions

Historically it has always been seen as too expensive, but recent developments in low-cost launch, maturing technology and more modular space-based solar power concepts are changing the economics. The global imperative to decarbonise economies is also prompting nations to invest in clean energy technologies.

A number of factors have encouraged a resurgence of interest in the concept, including:

• The cost of space launch reduced by 90% from $20,000/kg to under $2,000/kg, with that trend set to continue.
• Advances in semiconductor technology leading to improving efficiency for space use.
• New modular Solar Power Satellite designs (SPS Alpha, CASSIOPeiA) are much lower in mass and production cost.
• Increased concern about climate change has led to a renewed imperative by governments to study all clean energy technologies.

Space-based solar power can provide continuous base load and dispatchable power, day and night all year round, irrespective of the weather. It thus overcomes the intermittency of terrestrial renewables. space-based solar power could offer competitively priced baseload energy. Baseload energy generation is essential for grid stability.

A Solar Power Satellite in GEO can see the sun for well over 99% of the time. It is only in the earth’s shadow for a few hours each year around the spring and autumn equinox. Using a suitable microwave frequency such as 2.45GHz, the transmitted energy can be beamed through the atmosphere with negligible loss, even through clouds and rain.
Existing studies of space-based solar power economics claim that the Levelised Cost of Electricity could be around £50/MWh, which is competitive with intermittent renewables, and considerably less than nuclear power.

Intermittent terrestrial renewables place an additional burden on the grid to ensure security of supply. Analysis carried out for the Climate Change Committee estimated the cost of these measures to be £10/MWh to £25/MWh for generation mixes with 50% to 65% of variable renewables, rising to £25 to £30/MWh for a system with 75% to 90% of variable renewables.

A space-based solar power programme will provide the market demand for development of a vibrant competitive reusable launch market.

Any space-based solar power programme, national or more likely international, needs very substantial low cost – and hence fully reusable – space lift requirements, in the order of many times the current global launch capacity. SpaceX has led the way in reusable launch, and it is likely that this will spur competition from other providers. A space-based solar power programme will provide the market demand signal for these capabilities to be developed, though it may also need government support to develop the underpinning technology for reusable spaceplanes.

Already there are two fully reusable heavy lift launchers in development – SpaceX Starship and Blue Origin New Glenn. RocketLab has announced the development of the Neuron fully reusable launch vehicle. Reaction Engines is developing the SABRE airbreathing engine which is designed for a future reusable single or two stage to orbit spaceplane. This is in the absence of a declared space-based solar power programme, and these efforts would only accelerate if space-based solar power were pursued with a substantial and well-funded programme.

No, the independent techno-economic assessment by Frazer-Nash Consultancy (summary report attached), concluded that a development programme would cost around £17Bn, including the first of a kind commercial power station in space. Thereafter the capital cost of the subsequent production systems is about £3.6 Bn for a 2GW system, or about one quarter of the cost of an equivalent nuclear plant.

No, it doesn’t, and efficiency is not the only measure of practicality.

Because the energy source (the sun) is limitless and free, the efficiency only matters because it affects the size, mass and cost of hardware. There are losses in energy conversion down the energy chain through the Collect, Convert, Transmit and Receive elements. This governs the size of the Solar Power Satellite, and hence its production and deployment cost, but not the practicality of operation of the system.

Overall efficiency from sunlight to AC power into the grid is therefore a notional 18%. Accounting for these factors, cost modelling analysis by Frazer-Nash shows that the LCOE (levelized cost of electricity, used to compare different methods of electricity generation on a consistent basis) falls between £37 and £74/MWh, which is competitive with terrestrial renewable technologies.

The utilisation (another broader measure of ‘efficiency’) of space-based solar power is nearly 100%, delivering power day and night year-round, compared to an average of 11% for terrestrial solar farms and 47% for offshore wind farms in the UK. Moreover, SPACE-BASED SOLAR POWER delivers baseload power, improving grid stability and reducing the need for other energy balancing systems on the grid.

For a given area of land or sea, space-based solar power produces 2.4 times more annual mean power than terrestrial solar farms and 12 times more than offshore wind farms.