Solar energy: from implants to the car without recharging, the most promising innovations
Curtains, subcutaneous implants, cars without recharging, photovoltaic panels with exceptional yields... Spotlight on current research projects around solar energy which suggest that the exploitation of this renewable energy only begin.
Usbek & Rica- August 31, 2020#Energy#MobilityWhen we talk about solar energy, we imagine rigid – and not very aesthetic – panels installed on roofs or covering vast surfaces in the middle of the desert, while emphasizing the low conversion rate between energy received and electricity generated. There is probably a bit of that, but not only. Photovoltaic panels are more versatile than it seems. Above all, several research projects on materials and solar energy suggest very significant progress in this area.
From the army to the streets
In 2020, you can find on the market solar watches (and even solar smartwatches), solar wireless computer keyboards, solar chargers, solar surveillance cameras, solar lamps, or even wireless and solar-powered audio headphones. We also see the appearance of hybrid objects, such as this SunTable, which is both an outdoor side table (for terrace or balcony), an audio speaker and a wireless charging station, all of which is not connected to the grid.
Another example: the company Pvilion, which manufactures "solar tents" for the American army in the form of semi-rigid, self-sufficient and easy-to-deploy structures: once set up, they shelter, light and regulate the temperature of the cabin. In other words, solar power is becoming commonplace in everyday life, in urban areas and even on military terrain.
Several research projects are also trying to create “solar textiles” by weaving together textile fibers and ultra-miniaturized photovoltaic cells. At the end of 2018, the University of Nottingham Trent showed a prototype of solar fabric, as flexible as a conventional thick fabric, which can charge a mobile phone and a Fitbit bracelet. In Germany, the Fraunhofer research center, which is actively pursuing this idea, presented in 2019 several prototypes of solar textiles, flexible and available in different forms, with multiple applications, from truck tarpaulins to blinds and curtains for offices, which should be on the market within the next five years.
Photovoltaic implant
It is even possible that one day we could power electronic components with light… inside the human body. In early July 2020, South Korean researchers presented a prototype implant with photovoltaic cells successfully tested on mice. A patch glued to the skin facilitates the conduct of light through the tissues, the light is then converted into electricity to operate the implant, without the need for a battery.
Today, there are also half a dozen more or less advanced projects for “solar electric cars” intended for general public use. The Dutch company Lightyear, after a new injection of capital at the beginning of July 2020, is preparing the marketing of its luxury solar sedan for the end of next year. In Germany, Sono Motors raised 53 million euros in a community way at the beginning of the year to produce the Sion, a spacious vehicle covered with 248 solar cells, planned for the beginning of 2022.
Are these projects supposedly green gadgets or truly disruptive inventions? Hard to say at the moment. What is certain, however, is that the contribution of solar energy will be less and less negligible. Sono Motors ensures that, even in a country with little sunshine like Germany, its vehicle benefits from an additional autonomy of 34 km only thanks to solar energy, while displaying “full self-sufficiency over short distances. »
Same observation for Hanergy, which also intends to enter the race for solar cars. At the end of 2019, the Chinese manufacturer published the test results on a prototype of a small electric city car equipped with its thin solar collector technology and used for 30 days without ever being recharged other than with solar power. “Throughout the test, after a daily 20km drive, the car still had 60-80% battery charge, meaning it could still drive 30-80km that day,” d According to Hanergy, who adds that “on the last day of the test, despite a period of eight days of rain, the battery still had 60% charge. »
Electric car without charging
Another new player, Aptera. After raising $2 million last June, the company also assures that its eponymous car, whose production is scheduled for 2022, will be “the first electric vehicle in the world that we never recharge. The statement is undoubtedly optimistic but, depending on the level of sunshine, this miniature car with a retrofuturistic look, two seats and on three wheels, could offer up to 60 km of autonomy without using an electric charging station. .
And big manufacturers seem to believe it too. In Japan, Toyota began road testing a prototype solar vehicle (a Prius covered in photovoltaic cells) in July 2019 and showed that the vehicle could benefit from solar energy from 44 to 56 km of additional range per day.
Heliogen, which intends to "replace fossil fuels with light", is the first company to market solar energy converted into high temperatures, usable by heavy industries. In Switzerland, Synhelion converts the heat of the sun into traditional fuels (diesel, methanol, kerosene). The company, whose plant has just been purchased by Zurich airport, intends to market the first "solar fuels" in 2023 (with a 50% reduction in carbon emissions), and hopes to be able, by 2030 , produce fuel for aircraft without rejecting the slightest emission, from CO2 recovered from the air, water and the sun.
Without even being limited to photovoltaics as such, solar energy can also be used for water treatment. Last year, Australia's Monash University presented a solar-powered seawater desalination device that removes almost 100% of salt and operates passively, without electricity. Solar desalination processes are also under development or already operational in several countries, notably in Saudi Arabia and Kenya. And the subject is also the subject of an American competition launched in April 2020 by the Department of Energy, with 9 million dollars at stake to reward the most innovative companies in terms of desalination based on solar energy.
Record yields
There remains the problem of yield. The conversion rate of light into electricity by the photovoltaic panels currently marketed rarely exceeds 20%. Most are based on silicon (or other rare metals) and their efficiency is necessarily - that is to say physically - limited (the theoretical maximum efficiency is for example 33% for so-called "single junction" cells "). But several research projects are trying to overcome these constraints. And the records follow one another, at least in the laboratory.
In 2016 in Australia, researchers achieved a record yield of 34.5%, beyond the theoretical limit of traditional technology. In April 2020, in the United States, the National Renewable Energy Laboratory (NREL) reached a new record with six-junction cells offering an efficiency of 47% (after artificial concentration of sunlight) and 39% in actual conditions. Through structural improvements, “efficiencies of more than 50% could realistically be achieved,” say the NERL researchers.
Whether new materials (such as the very promising perovskites, minerals likely to replace silicon, with which yields of 28% have already been achieved) or devices to better concentrate light (such as the panels covered with magnifying glass from the Swiss start-up Insolight, offering an efficiency of 29%), everything leads us to believe that we will one day achieve conversion rates of light into electricity much higher than those of today today.
Especially as new tracks appear. For example, at Rice University, carbon fiber solar panels are being developed whose purpose is no longer to convert the sun directly into electricity, but to absorb the heat from solar energy, transforming it into light (photons) and finally into electricity. Counterintuitively, with this additional intermediate step, the process proves to be extremely effective: by adding this principle to existing solar panels to recover the heat hitherto lost, the researchers estimate that their efficiency could theoretically be increased to 80%.
Another promising avenue, presented at the end of 2019 by the University of Houston, Texas: capture only heat, stored in the form of molecular energy. The process makes it possible to have solar energy day and night, the heat being returned at night with an efficiency of 80% and a temperature higher than that captured during the day.
Of course, it is difficult to estimate the overall energy and ecological impact of all these innovations. In particular, the production of photovoltaic cells is known to be expensive and accompanied by harmful emissions. As for perovskites, they are still unstable and difficult to use on large surfaces. But the innovations follow one another and the progress is very real. In any case, it seems simplistic to reason only in large masses, by opposing solar energy to other energy sources on the basis of global figures, a fortiori by only considering the yields currently observed. Solar is not limited to photovoltaics, nor to a few usage scenarios such as panels on the roofs of individual houses. Above all, photovoltaics itself is not limited, far from it, to a single technology. Solar is protean and it is reasonable to think that the exploitation of the main source of clean energy that we have, in infinite quantities, is only in its infancy.
Usbek & Rica- August 31, 2020Share on FacebookShare on Twitter