The manufacture of photovoltaic modules requires pure silicon. But it is scarce and costly. LuxChemtech has developed technologies to recycle silicon and other semiconductor materials and return them to the manufacturing cycle. The Saxony-based company was recognised as the national winner of the KfW Award for this sustainable innovation.
Dr Wolfram Palitzsch and Dr Ingo Röver stride through the large halls of LuxChemtech. Their path leads past conveyor belts full of shining, silvery pieces of silicon and metre-thick pipes of the exhaust system, all the while accompanied by the penetrating noise of the comminution plant, the crusher.
Today, a block of silicon has been produced in the crystallisation hall. It took five days to produce the 900kg grey block. To do this, crushed silicon pieces were heated to 1,500 degrees in a special mould and melted. Then the mass was slowly cooled from bottom to top, crystallising evenly to the surface. The special feature of this large block is that it is made from recycled material.
Wolfram Palitzsch explains how silicon is usually produced: “The input material is quartz sand. It is heated to around 2,000 degrees while carbon is added. However, this metallurgical silicon is still far too impure for applications in photovoltaics or microelectronics. So a complex process follows, using liquid intermediates until the purest silicon is finally produced.”
Metre-long columns or blocks – the silicon crystals – are formed from the liquid material. Large quantities of waste are generated during these production steps as some parts, such as the tips, the bottoms or sides, cannot be used. They are contaminated merely by contact with the mould. LuxChemtech reworks this scrap, chemically treating and mechanically crushing it. At the end of these processes, the material is as pure as new goods. Around 80 tonnes of silicon per month are recycled in this way and returned to the cycle.
Dr Wolfram Palitzsch and Dr Ingo Röver have patented the Saxon know-how worldwide.
The technologies are based on the founders’ more than 30 years of professional experience. Both have doctorates in silicon chemistry. As the technical manager of a chemical company, Wolfram Palitzsch dealt with the processing of semiconductors from used photovoltaic modules. There he developed some of the methods now used by LuxChemtech. Ingo Röver also brings extensive experience from his work in a solar company based in Freiberg. When it went bankrupt in 2018, the two scientists decided to join forces. They convinced a lender, bought the factory that was under threat of closure in a complex asset deal and took on 15 employees. In addition to their own innovative products, they now also want to promote recycling for silicon and other materials such as gallium or indium.
The industry must change its mindset
The time is ripe, and the market is demanding new solutions. The production of pure silicon requires a great deal of energy, which drives up costs. Most silicon is produced in China, but Asian supply chains are stalling. Prices for silicon from Norway are also climbing. However, our modern life is no longer possible without the valuable metalloid. It forms the basis for microchips, which are found in virtually all technical equipment – in smartphones, computers, cars and energy systems.
However, most of the silicon is required by the photovoltaic industry. Palitzsch places a used solar module on the table and explains its structure. “The blue square tiles are the cells made of silicon. The silver tracks conduct the generated electricity. The cells are laminated in plastic. And this type of composite material is a challenge for the separation process.” He then places several small bottles next to the solar module. They are each filled with components from the module, separated according to their type. It’s another of the company’s business sectors: recycling photovoltaic modules.
Solar power is an important building block for the energy transition. In order to become independent from foreign energy supplies, Germany is expanding photovoltaic solutions at a faster pace than before. Solar modules have become more modern in recent years. It can therefore be assumed that older solar systems will be replaced in order to generate more green electricity over the same surface area with more efficient cells. LuxChemtech aims to tap into these potential raw material sources from which the second-hand silicon and other valuable materials can be produced. At the same time, the founders expect the demand for recycled material to increase. This combination is an ideal prerequisite for their concept.
The next step: scaling up
The fact that LuxChemtech’s globally patented technologies work has been proven in Freiberg. Now, industrialisation is also on the horizon for photovoltaic recycling. To this end, the company is planning a plant in Tangermünde, Saxony-Anhalt, which is intended to accept and process significantly more residual materials. The location has been strategically selected. After all, any place that recycles tonnes of solar modules will still have 90% glass left over. In Tangermünde, this can be quickly returned directly to the surrounding glassworks.
It is an exciting and challenging time for the entrepreneurs. Their project requires space, machines, and a lot of capital. The coronavirus pandemic also affected their operations and disrupted their target figures. Wolfram Palitzsch said, “As an employee, I had a very good position, and my retirement was approaching. But now there is the opportunity to work again in a completely self-determined way and contribute all my knowledge. A circular economy is possible and benefits us all. I don’t want to miss out on the opportunity to make a big difference here.”
Published on KfW Stories: 25 October 2022