Can solar panels in space help power the Earth? ~~ Robin Mills

 https://asiatimes.com/2023/02/can-solar-panels-in-space-help-power-the-earth/

~~ recommended by emil karpo ~~

A criticism of solar power is that the sun doesn’t always shine – but it does in space

 

 NASA Integrated Symmetrical Concentrator solar power satellite concept. Image: NASA

Where is sunnier than the Middle East and North Africa region? Not many places on Earth – but in space, the sun shines eternally, and unhampered by clouds or dust. So it’s understandable that a desert kingdom would team up with a foggy island to harness this energy source.

Saudi Arabia’s Neom project, the futuristic new city in the country’s northwestern corner, has invested in Space Solar, a British company. The UK’s business secretary met the chairman of the Saudi Space Commission last month. Along with the UK, the US, Japan and China have shown serious interest in generating solar power in space.

Ground-based solar photovoltaic power has made tremendous strides in recent years, with the Middle East becoming home to the cheapest and largest systems in the world. Along with wind turbines, it has emerged as the favored workhorse for the new, low-carbon-energy economy that is essential to avoiding disastrous climate change.

 

But even in the best locations, solar’s capacity factor – the ratio of annual output to the maximum instantaneous generation – is only about 20%. Naysayers are fond of reminding us that the sun does not always shine, as if it were a new discovery.

There are partial solutions: using daytime solar to charge batteries or generate hydrogen for storage, or connecting different time-zones and latitudes with high-voltage cables thousands of kilometers long. One consortium plans such a link between Morocco and the UK. But “green” hydrogen is nascent and relatively expensive, and batteries have limited capacity to see a country through a long, sunless winter.

Not all countries have readily available land. Long-distance cables could be quite cost-effective, but present political and security vulnerabilities.

So the off-world concept is to put an enormous system of mirrors and solar panels into geosynchronous Earth orbit, where the sun is visible almost all the time. The generated electricity is converted into high-frequency radio waves, which are hardly absorbed by the atmosphere, and beamed to a ground station that converts them back into electricity.

The array can be redirected easily, so it could serve several widely spaced receivers, switching from one to another as night falls or demand increases.

 

A British government-funded report found that space-based solar power was technically feasible and affordable. Its potential viability has rocketed thanks to two major recent developments: the dramatic fall in the cost of solar panels, to the point of being the cheapest terrestrial source of electrons, and the declining cost of space launches facilitated by reusable systems such as SpaceX.

When I wrote about the topic in 2014, lifting material into orbit cost about US$10,000 per kilogram, and photovoltaic panels went for about 70 cents per watt. Now, SpaceX offers launches at just over $1,000 per kilogram, and PV panels are about 20 cents per watt.

By 2035, Space Solar hopes to have a full-scale operational system of 2 gigawatts. For comparison, this is the same size as the al-Dhafra plant under construction in Abu Dhabi, set to be the world’s biggest, and would generate about as much as a big nuclear reactor.

The government report more cautiously suggests 2040 as the starting date, and under conservative assumptions, it estimates an electricity cost of about 6 US cents per kilowatt-hour. This is significantly lower than new nuclear plants, hydrogen or natural gas with carbon capture, the other main contenders for continuous, low-carbon electricity.

A development program to advance to the first operating system could cost some $20 billion and would probably need substantial government support in the early stages. The basic components of the system are well understood.

 

The main technical challenge would seem to be mastering autonomous robotic assembly and maintenance in space. The panels would need to be as lightweight as possible, but also modular, easy to assemble, robust to damage from micro-meteorites, and highly efficient. The launch rockets should use zero-carbon fuels.

It’s not certain that space solar can be made commercially viable. But it appears easier than other futuristic energy options such as nuclear fusion. And it also seems a more practical candidate for the first large cosmic industry than another popular idea, mining asteroids for rare metals.

We might question why the Middle East – set to be a leader in deployment of terrestrial solar – should look to the skies. But if other countries are going to launch, it would be better to be on board. Locations with open land, closer to the equator, also make superior receiving sites. Ground-based solar, with its lower costs, could be a good complement to its orbital cousin.

The United Arab Emirates has its own active space program, sending an orbiter to Mars and a probe to the moon that should touch down in April. The research and development required over the next two decades to make the system a reality will have many technological spin-offs.

What was science fiction just a few years ago may quite soon illuminate even the Earth’s sunniest regions.