Iin late November, a high-level meeting of European science ministers will meet in Paris. Their task is to determine the priorities of the European Space Agency (Esa), of which the UK is still a member, and one of the items on their list to be considered is a proposal to test the feasibility of building commercial power stations in orbit. . These large satellites would be exposed to sunlight, convert it into energy and beam it back to Earth to feed into the power grid. The proposed project, known as Solaris, will determine if the idea can contribute to Europe’s energy security in the future – or if it is all still in the sky.
If the study gets the go-ahead, it would be a homecoming for the local industry, which has always been at the forefront of solar energy development. A year after the Russians launched the battery-powered Sputnik 1 in 1957, the Americans launched Vanguard 1. This was the fourth satellite in orbit and the first to generate its power using solar energy. Since then, solar panels have become the primary means of powering spacecraft, which has helped drive research. Vanguard 1’s solar cells convert just 9% of sunlight into electricity. Today, efficiency has doubled, and continues to rise, while manufacturing costs have fallen. It’s a winning formula.
“Solar costs have decreased rapidly over the past 20 years, and faster than most players in the industry expected,” said Jochen Latz, a partner at management consultancy McKinsey & Company. So much so that, in the Middle East and Australia, solar power is now the cheapest way to generate electricity. According to Latz, as technology continues to develop, this will also be true in mid-latitude countries. “In 2050, we expect that more than 40% of the EU’s energy comes from solar energy – if the countries achieve their dedicated goals,” said Latz. That would make solar energy the largest energy contributor in the EU.
However, there are clear problems that need solutions if we are to fully utilize solar panels on Earth. First, what do we do at night? In May, Ned Ekins-Daukes, an associate professor at the school of photovoltaics and renewable energy engineering at the University of New South Wales, Australia, and his team of researchers demonstrated a solar cell that can generate electricity through infrared emission rather than emission. to be absorbed by the sunlight. This works perfectly at night because the Earth stores energy from the sun in the form of heat, which is then reflected back into space as infrared radiation.
The prototype device is based on the same type of technology used in night vision goggles and currently can only produce a few milliwatts of power, but Ekins-Daukes sees potential. “This is the beginning – it’s the world’s first demonstration of thermal energy,” he said, indicating that the team envisions a finished product that is “10,000 times more powerful”. At those levels, it is possible that the installation of such equipment on the roof, perhaps made in some way as an additional layer to the usual solar panels, will capture enough energy to power the house at night – that is, to store the refrigerator, wifi router and more. on the run. While that’s a small savings per household, multiplied by the country’s population, it’s significant.
Another obvious issue with solar power is that some days will be cloudy. To reduce this, the excess electricity generated on sunny days should be stored in batteries but the storage capacity is currently pathetic. “The EU will need about 200 gigawatts [GW] of battery storage in 2030, but as of 2021 there was only 2.4GW of storage space, so a big increase will be needed,” said Aidan McClean, chief executive of UFODrive, an electric car rental company.
To help with this shortfall, McClean is championing a system called vehicle-to-grid – V2G – which uses the battery in an electric vehicle (EV) to store excess energy produced by rooftop solar panels and then feed it back into the house when needed in the evening, or sell it to the National Grid at times of high demand. . “If V2G is widely adopted, the expected storage capacity of all EVs will far exceed any expected grid storage needs going forward,” McClean said. A recent V2G trial in Milton Keynes, Buckinghamshire, showed that participants are saving money and cutting their carbon footprint by using a “smart” charging system that adds batteries when renewables produce electricity.
Another way is to use solar energy to generate electricity but to produce sustainable fuel for vehicles. Virgil Andrei of the chemistry department at the University of Cambridge and his colleagues have developed a thin “artificial leaf” that is fueled by photosynthesis. In plants, photosynthesis takes sunlight, water and carbon dioxide (CO2) and convert them into oxygen and sugars. For synthetic leaves, the product is syngas, or synthetic gas. This mixture of hydrogen and carbon monoxide can be used to produce a number of fuels through various industrial processes. It is possible to produce gasoline and kerosene.
“We had the idea of using CO2 from air or other industrial processes and pouring into these types of processes to create green fuel. Instead of releasing more CO2 in the air, we have a circular carbon economy, says Andrei. In effect they will also release carbon-capture plants, which are deployed to use up CO2 from industrial processes, and “recycled” into sustainable fuels.
The team first created an artificial leaf in 2019 but it was a large glass and steel structure sitting on a bench. This year, however, the team announced the results of a small, leaf-like structure researchers traveled through the River Cam. The leaf was sealed inside a clear plastic bag with pre-gas and water and then left in the river for several days. The team then opened the bag and tested which gases were produced by photosynthesis.
The artificial leaves themselves are made of materials called perovskites. The archetypal perovskite is a naturally occurring mineral of calcium titanium oxide – known as calcium titanate – that was discovered in 1839 in the Ural mountains of Russia by the German mineralogist Gustav Rose and named after his Russian colleague Lev Perovski. Modern perovskites can have different chemistries and some have shown that they can work as solar cells.
Andrei says: “These tools are new and very exciting. Laboratory tests show it can be more efficient than the silicon used in conventional solar panels. Perovskites may replace silicon in the solar panels of the future as they can be easily made into thin, flexible layers. Another bonus is that these devices produce higher currents and voltages than silicon-based devices, allowing for more powerful systems such as the reactions that have been used in the study of artificial leaves.
As promising as all this sounds, however, there is one insurmountable problem when generating solar energy from the Earth’s surface: the atmosphere. The molecules in our atmosphere scatter about half of the sunlight in a direct current. This soft diffused light is what creates the familiar blue sky. In the sky, there is no air, so sunlight is not reflected. And as aerospace engineers at the beginning of the space race discovered, put a solar panel in orbit and it will automatically produce twice as much energy as an equivalent panel on Earth. Unsurprisingly then, engineers and visionaries have been dreaming of putting solar-powered satellites into orbit for decades.
The basic principle is simple. A spacecraft with large solar panels collects sunlight, before turning it into energy and then beaming that energy back to Earth. How do you distribute power everywhere without wires? Turns out we’ve been doing it for decades. Every communication satellite since the 1960s has used a solar panel to generate electricity, which is then converted into a microwave signal and sent back to Earth. On the ground, antennas convert the microwaves back into electrical energy and read the signals. “The physics involved in the whole chain is very similar to space-based solar power, but the scale is completely different,” said Sanjay Vijendran of Esa, who coordinates the proposed Solaris program to study the feasibility of space-based solar power. solar energy.
Every few decades since the start of the space race, the idea of a solar power station has been investigated. Every time, the story has been the same: the cost of launching large satellites is prohibitive. But now, things are different.
“In 2015, a miracle happened. “The Falcon 9 reusable rocket is flying for the first time,” said John Mankins, a former NASA scientist who is now president of Artemis Innovation Management Solutions. Mankins is an expert on solar energy satellites, having worked on many feasibility studies over the decades. With the advent of reusable rockets, the cost of sending weapons into orbit is coming down. Instead of costing around $1,000 per kilogram to start in the area, Mankins now expects the price to drop to closer to $300 per kilogram. “That’s the holy grail of solar energy. It doesn’t just happen one day – it’s inevitable in the next five or seven years,” he said.
Others have the same hope. In September 2021, Frazer-Nash Consultancy published a report to the UK government which concluded: “Solar energy is technically feasible, affordable, and can bring economic benefits to the UK, and can support the right infrastructure.” At the end of August, Esa released its own space-based solar energy studies, which reached the same conclusion across Europe. As a result, the agency will ask in November that its member states fund a three-year feasibility study on solar energy satellites to examine in detail whether such a program is commercially feasible. “Solaris is a bridge to see if this is really possible and can really help before we ask for billions of euros,” Vijendran said.
Even if such satellites enter orbit, there can be no doubt that solar energy is destined to dominate the energy landscape in the future. And as the current situation in Ukraine shows, that can lead to better energy security and lower carbon emissions.