By Matteo Ceriotti, Senior Lecturer in Area Techniques Engineering, College of Glasgow, writing in The Dialog.
The thought of space-based solar energy (SBSP) – utilizing satellites to gather power from the solar and “beam” it to assortment factors on Earth – has been round since not less than the late Nineteen Sixties. Regardless of its large potential, the idea has not gained enough traction because of price and technological hurdles.
Can a few of these issues now be solved? In that case, SBSP may change into a significant a part of the world’s transition away from fossil fuels to inexperienced power.
We already harvest power from the solar. It’s collected instantly by way of what we usually name solar energy. This includes completely different applied sciences equivalent to photovoltaics (PV) and solar-thermal power. The solar’s power can be gathered not directly: wind power is an instance of this, as a result of breezes are generated by uneven heating of the environment by the solar.
However these inexperienced types of energy era have limitations. They take up numerous area on land and are restricted by the provision of sunshine and wind. For instance, photo voltaic farms don’t accumulate power at evening and collect much less of it in winter and on cloudy days.
PV in orbit received’t be restricted by the onset of evening. A satellite tv for pc in geostationary orbit (GEO) – a round orbit round 36,000 km above the Earth – is uncovered to the Solar for greater than 99% of the time throughout an entire yr. This enables it to supply inexperienced power 24/7.
GEO is good for when power must be despatched from the spacecraft to an power collector, or floor station, as a result of satellites listed below are stationary with respect to the Earth. It’s thought that there’s 100 instances extra solar energy out there from GEO, than the estimated international energy calls for of humanity by 2050.
Transferring power collected in area to the bottom requires wi-fi energy transmission. Utilizing microwaves for this minimises the power misplaced within the environment, even by way of cloudy skies. The microwave beam despatched by the satellite tv for pc might be centered in direction of the bottom station, the place antennas convert the electromagnetic waves again into electrical energy. The bottom station might want to have a diameter of 5 km, or extra at excessive latitudes. Nonetheless, that is nonetheless smaller than the areas of land wanted to supply the identical quantity of energy utilizing photo voltaic or wind.
Evolving ideas
Quite a few designs have been proposed for the reason that first idea by Peter Glaser in 1968.
In SBSP, the power is transformed a number of instances (gentle to electrical energy to microwaves to electrical energy), and a few of it’s misplaced as warmth. With the intention to inject 2 gigawatts (GW) of energy into the grid, about 10 GW of energy will have to be collected by the satellite tv for pc.
A latest idea known as CASSIOPeiA consists of two 2km-wide steerable reflectors. These mirror the daylight into an array of photo voltaic panels. These energy transmitters, roughly 1,700 metres in diameter, might be pointed on the floor station. It’s estimated that the satellite tv for pc may have a mass of two,000 tonnes.
One other structure, SPS-ALPHA, differs from CASSIOPeiA in that the photo voltaic collector is a big construction fashioned by an enormous variety of small, modular reflectors known as heliostats, every of which might be independently moved. They’re mass-produced to scale back price.
In 2023, scientists at Caltech launched MAPLE, a small-scale satellite tv for pc experiment which beamed a tiny quantity of energy again to Caltech. MAPLE proved the know-how might be used to ship energy to Earth.
Nationwide and worldwide curiosity
SBSP may play a vital function to fulfill the UK’s net-zero goal by 2050 – however the authorities’s present technique doesn’t embody it. An unbiased examine discovered that SBSP may generate as much as 10GW of electrical energy by 2050, one-quarter of the UK’s present demand. SBSP gives a safe and secure power provide.
It’ll additionally create a multi billion-pound business, with 143,000 jobs throughout the nation. The European Area Company is presently evaluating the viability of SBSP with its SOLARIS initiative. This might be adopted by a full improvement plan for the know-how by 2025.
Different nations have lately introduced the intention to beam energy to Earth by 2025, transferring to bigger programs throughout the subsequent 20 years.
A large satellite tv for pc
If the know-how is prepared, why is SBSP not getting used? The principle restrict is the big quantity of mass that must be launched into area, and its price per kilogram. Corporations equivalent to SpaceX and Blue Origin are creating heavy-lift launch automobiles, with a deal with reusing elements of these automobiles after they’ve flown. This could convey the price of the enterprise down by 90%.
Even utilizing SpaceX’s Starship automobile, which may launch 150 tonnes of cargo into low Earth orbit, the SBSP satellite tv for pc would require a whole bunch of launches. Some parts, equivalent to lengthy structural trusses – structural parts designed to span lengthy distances – might be 3D-printed in area.
Challenges and dangers
An SBSP mission might be difficult – and dangers nonetheless have to be absolutely assessed. Whereas the electrical energy produced is absolutely inexperienced, the influence of the air pollution from a whole bunch of heavy-lift launches is tough to foretell.
Moreover, controlling such a big construction in area would require substantial quantities of gas, which entails engineers working with typically very poisonous chemical compounds. The photovoltaic photo voltaic panels might be affected by degradation, decreasing effectivity over time from 1% to 10% per yr. Nonetheless, servicing and refuelling might be used to increase the satellite tv for pc’s lifetime virtually indefinitely.
A beam of microwaves highly effective sufficient to succeed in the bottom may additionally hurt something that obtained in the way in which. For security, then, the ability density of the beam should be restricted.
The problem of constructing platforms like this in area could seem daunting, however space-based solar energy is technologically possible. To be economically viable, it requires large-scale engineering, and subsequently long-term and decisive dedication from governments and area businesses.
However with all that in place, SBSP may make a elementary contribution to delivering web zero by 2050 with sustainable, clear power from area.
This text initially appeared in The Dialog.
