Closing the loop
Electric mobility is picking up momentum worldwide. All traffic lights around the globe have been switched to green for this “silent inovation.” Automotive supplier Schaeffler, for instance, expects that an electric motor will propel 70 percent of all new cars by 2030, either alone or as a component of a hybrid system. At that time, millions of vehicles will draw their power from millions of large traction batteries and since they have an estimated life of eight years, millions of old lithium-ion batteries will have to be sensibly recycled. Even the “second life” idea proposing that traction batteries would still be used for about another ten years as storage systems for electricity from renewable sources and to stabilize the grid – can only delay the scrapping of these batteries.
Raw materials are scarce
End-of-life lithiumion batteries have to be recycled in sensible ways for both environmental and economic reasons. If their components were not recovered, the enormous anticipated worldwide demand for cobalt, nickel and rare-earth elements could not be met by the available raw material supply. By 2020, there will be more than 100,000 metric tons (110,000 short tons)ofold batteries from electric vehicles, according to current estimates. And that would just be the beginning. That’s why research institutions and manufacturers are already developing efficient recycling technologies.
Tesla Europe has old traction batteries recycled in an ultra-high temperature smelting (UHT) process at Umicore in Belgium. During the incineration of the entire battery cobalt and nickel are extracted. The cobalt – transformed into cobalt lithium-oxide – is used again for batteries. The slag with calcium-oxides and lithium is used in concrete production.
Reducing the carbon footprint
There are other methods besides this high-energy technology. In the hydrometallurgical process of Duesenfeld GmbH, the battery is initially shredded mechanically. Subsequently, the metals it contains are chemically extracted. In this way, it is possible to salvage copper at rates of 100, manganese of 99, cobalt of nearly 98, nickel of 99, and lithium of nearly 96 percent for future uses. Compared with incineration, this technology reduces the battery’s carbon footprint by 40 percent. Duesenfeld is currently able to recycle 3,000 metric tons (3,300 short tons) of old batteries in this way.
In the electrohydraulic fragmentation (EHF) process of Fraunhofer Institute for Silicate Research (ISC), a shock wave generated by electrical discharges is sent through a medium – the process works with normal water. As a result, the material interfaces of the battery become brittle and the individual components can be easily separated without significant heating.
There are many international regulations that require battery recycling, but at this juncture nobody can tell which technology will prevail, plus batteries with other components may require different technologies.
A solution that eliminates the need for traction batteries and practically makes the disposal chain superfluous is the fuel cell. It generates electricity without any significant environmental impact even after the end of its life.
In the Irish Sea, in Europe’s largest onshore wind farm Markbygden in northern Sweden or in the countless wind farms sprouting up from the ground around the globe: In all of them, huge rotors are spinning, milling the energy out of the air, pumping electric current through the constantly hungry transmission lines into insatiable megacities and the machinery of manufacturing industries. Worldwide, hundreds of thousands of these systems are in operation, eliminating the need for coal-fired power stations and nuclear power plants, albeit even clean electricity will ultimately produce waste: aging on the one hand and progress and dwindling profitability on the other cause more and more wind turbines to reach the end of their service life and being decommissioned.
Performance and profitability pressures are high: Where possible, smaller wind turbines are replaced by more efficient larger systems as part of repowering processes. When government funding programs expire, if not earlier, the continuing operation of old, repair-prone systems is no longer considered to be lucrative, so they have to go. Dismantling them is routine technical work done with the same huge cranes that were used to erect them. Down on the ground, things of diverse uses are gathered: The nacelle including its technology, the tower segments and the foundation can be easily dismantled, shredded and 98 percent of them reused. The extremely long rotor blades are cut into transportable pieces at the site.
Rotor blades pose problems
But this is where the secondary raw materials chain stops moving: No further use has been found yet for the substances contained in the blades. The vast majority of the older rotor blades consists of composite materials that are practically inseparable. A viable sorting process for fiber glass reinforced plastic (FRP), balsa wood, resins and steel, in which all material fractions are generated in reusable form, is not available yet. Rotor blades will never turn into rotor blades again but are finely shredded in special machines and incinerated in the kilns of the cement industry. The ash is used as part of the raw material for cement.
Rotor blades of more recent generations with carbon components do not end up in the fire because the ash of carbon-fiber reinforced plastics (CFRP) clogs the filters of the incineration plants and is highly harmful. By means of thermochemical fission the organic compound of the fiber is separated from the thermally resistant silicon dioxide and recycled into production. However, this costly pyrolysis process is not economically feasible for the cheap first rotor blade generation and is used in just a few countries. For instance, in the United States and China, due to the high recycling costs and a lack of regulations, end-of-life windpower systems typically end up in landfills.
225,000 tons of waste
The recycling issue will soon prominently emerge and incineration has a poorer image than recycling of materials. The Danish research project Genvid expects some 50,000 metric tons (55,000 short tons) of plastic waste from old rotors being generated by 2020 and more than likely 225,000 metric tons (275,000 short tons) annually by 2035. Denmark is particuarly active in this area because as early as in 2017, 43.6 percent of the country’s electricity was generated by wind farms. Manufacturers such as Vestas and Siemens, Fraunhofer Institute for Chemical Technology ICT, TU Brandenburg, Aalborg University and the University of Nottingham are all intensively looking for a solution to prevent the positive potential of wind power from having to turn into ashes on the last mile.
They’ve long become a familiar sight. Whether in villages, cities or industrial parks, solar collectors shine on the roofs of houses, halls and production facilities. As a renewable source of energy photovoltaics has become mainstream and is virtually obligatory on new buildings in many countries like Germany. The solar future is the solar present, and will soon be the past: The first generation of solar modules reaches the end of its lifespan after 25 to 30 years and will be discarded. In 2017, as many as four million metric tons (4.4 million short tons) of modules were installed Europe-wide, resulting in 43,500 metric tons (48,000 short tons) of special waste. In 2050, 60 million metric tons (66 million short tons) of waste will be generated, according to the UK environmental portal GreenMatch.
“Waste,” though, is not really the right category in this case: The product design of solar modules allows for extensive recycling – with recycling rates of up to 95 percent. Based on GreenMatch’s calculations for the 2050 scenario, the recovered material worth 15 billion U.S. dollars could be used to produce two billion new solar modules.
Up to 100 percent recycling
In a cooperation project of manufacturers, research scientists and disposal companies, two methods for decomposing low-efficiency or defective solar panels have been developed. Silicon-based solar cells are disassembled by hand; their glass content can be reused at 95 percent and the aluminum of the frames at 100 percent. Heated to 500 °C (932 °F), the plastic components evaporate and serve as a source of process heat. Afterwards, the cell modules are dismantled and can be reused at 80 percent. The silicon is extracted by means of acid and can subsequently be recycled into the manufacturing process for new solar panels at rates of up to 85 percent.
Global regulations are lacking
A different method is used for thin-film modules (market share: about 10 percent). They’re initially shredded. Subsequently, the components can be separated mechanically, by floating and by vibration. As much as 95 percent of the semiconductor material and 90 percent of the glass can be recovered in this way.
In spite of practicable technologies, the recycling challenge for photovoltaics is far from having been resolved on a global scale due to a lack of returned modules. Across Europe, the PV Cycle industry association organizes the return and recycling of the modules but in
many industrialized countries such as the United States there are typically no specific regulatory disposal requirements, so that defective or worn out solar panels are just sent to landfills.many industrialized countries such as the United States there are typically no specific regulatory disposal requirements, so that defective or worn out solar panels are just sent to landfills.