New sensors that see rubbish and gas

The SINTEF Group, in co-operation with the re-cycling company Tomra now goes beyond cash deposits for bottles and cans to recycling plastic, glass and metal. Newly developed, patented technology makes it possible to sort different types of plastic, different colours of glass as well as metal – easily, effectively and inexpensively. A new, inexpensive gas-detector that contributes to a better indoor climate, is another area of use.

Although many things can be recycled or reused, it is a major challenge to sort this rubbish. It is expensive and complicated, because it’s not easy to see which plastic type makes up the bottle, cup or can. If the plastic is to be reused, different types cannot be mixed. It requires “clean merchandise”!

But a little, gold-covered plastic chip – as easy to produce as a CD – can manage this work. The surface is holographic, reflecting light in a carefully programmed way. With the help of new software that interprets the spectrum of light reflected from or passing through different materials, each material’s “fingerprint” is read very accurately – whether solid material or gas.

“We are now able to produce this chip and associated electronics for well under 1,000 NOK (120 EURO),”explains Tomra research manager Andreas Nordbryhn.

Together with the research group SINTEF (Trondheim),Tomra has achieved the goal that the research and development project (Sensit) started more than two years ago. The results are now commercialised, beginning in two important areas: Rubbish sorting and gas detection. But the technology is suitable in all areas where spectrometry is used. Tomra is developing an entirely new recycling station business area. OptoSense takes advantage of the same technology with sensors that can determine different gasses. Tomra is the patent holder of the new technology that has been developed by SINTEF, but OptoSense and SINTEF have the right to make use of the technology within areas defined in the agreement, such as gas detection, as well as medical and food products. The fourth company that was involved in the project at the start, Titech Visionsort, was acquired by Tomra during the project.

“The project has been remarkably successful,” Nordbryhn states. “We have long wanted to expand our activities to include rubbish handling. The deposit market is limited – for example, only about 15% of all bottles consumed annually around the world have a deposit. And 85% of the bottles and most of the other packaging are only rubbish. All countries have large problems with the handling an enormous mountain of rubbish, not the least of which is packaging that modern society produces. There is close to an unlimited market for solutions to handle the challenge in a rational way. Increasingly, different countries’ authorities are adding fees for those who cannot document that their packaging is recyclable.”

“To be able to develop this new business area you need a sensor that in an easy, inexpensive, robust and reliable way sorts different packaging material– without the user needing to think about what he or she put into the machine. We started more than five years ago, and now we have made it,” states the Tomra researcher.

The first prototype is already mounted at the British supermarket chain Tesco. It is a complete recycling station that sorts and shreds packaging the public inserts. The new, more advanced stations, that are now in production, will be able to separate between seven different types of plastic that will fall into their own containers after being shredded. Glass will be sorted after colour, then broken and disturbed in containers. The same for metal – iron/steel will be sorted from aluminium.

“Because the machine sorts and shreds the packaging material, the need for storage area and transport are reduced. This gives a large environmental gain as well as a better economy. The solution we can now present for the market is the cheapest and best in the world,” Nordbryhn points out.

Furthermore, the company has access to technology that makes it possible to produce an inexpensive, precise gas detector, for, among other things, CO2.

This sensor can, for example, be used to control a ventilation system at the workplace. It sees when CO2 levels in the air are too high – which quickly happens when many people are in the same room – or needlessly low. The sensor can signal the ventilation system to raise or reduce air flow so that is continuously is at the desired level. This ensures a good indoor climate, and at the same time prevents over ventilation. This also means saving energy for heating, cooling and circulating air.

This also prevents the system from using power when it is not necessary, which saves energy. “This is environmental technology,” underlines Trond Melen of OptoSense.