The management of waste at sea is often an environmental problem because that same waste is not seen as a resource. This shift in perspective can drive sustainable innovation and the search for solutions with a low environmental impact. And it can guarantee greater wellbeing for people, the marine ecosystem and the planet. Green Plasma reflects this change in approach: the plant transforms floating waste into clean energy. It was designed by the Piedmontese company Iris, which set out to help small organisations clean up beaches and other places overrun by waste. Iris was founded in 2012 with the aim of applying well-established industrial technologies to sustainable local growth. Engineer Manuel Lai founded it after nearly 20 years working at a well-known automotive company, bringing to bear the knowledge he had acquired there. To date, the project has involved many passionate young people and has developed partnerships with the University and the Polytechnic of Turin. The idea has the hallmarks of the circular economy: it recovers waste to generate new resources.

Engineer Lai, how does Green Plasma work?
The Green Plasma plant uses the technique of pyrolysis for the thermochemical decomposition of the organic materials present in waste. The process takes place at high temperatures with minimal amounts of oxygen. The large polymer molecules fragment, become gaseous and are able to carry energy. While the entire organic portion of the waste becomes gas, metals and composite materials made of plastic and aluminium are transformed into inert materials. One of the advantages is that Green Plasma can recover the moisture content of the waste exactly as it is at the time of collection, without further treatment and without sending anything to landfill or to a waste-to-energy plant.

Does it produce polluting emissions?
In the absence of combustion, no ash is produced and there is no need to dispose of it. This is a major difference compared to oxidation or combustion processes. The treatment of waste can, however, release critical substances into the air: chlorine, which comes from PVC used in electrical cables, for example, and sulphur, derived from rubber. For this reason, our plant includes a post-treatment process for the gas to remove sulphur and chlorine, as well as to eliminate particulate matter — the dusty particles carried by the gases through the plant. This treatment can be described as "intensive" because it makes it possible to purify the gas obtained in this way for use in a great many applications.

For example?
For example, in gas engines or in fuel cell systems. Under the right conditions — that is, working at sufficiently high temperatures and using oxygen to consume all the carbon present in the plant during processing — a mixture is obtained that is 50 per cent hydrogen gas and 50 per cent carbon monoxide and methane. With a generator set, which is an additional component beyond the plant we have designed, the hydrogen can be converted into electrical energy. In this case, all the sulphur must be eliminated, otherwise the electrodes do not function. This explains why we included the post-treatment described above. Fuel cell solutions that convert hydrogen directly into electrical energy also exist, and will be increasingly used in the future. We are working on this.

Is it energy-intensive — does it need a lot of energy to operate?
It operates at high temperatures, around 700°C, and is powered by electricity. To start up, the system uses a battery pack that can be charged with gas recovered from the previous cycle or with energy produced by renewable technologies. Once the batteries are charged, the plant starts up. For harbour installations, we favour the use of renewable technologies — we envisage a blue island equipped with solar photovoltaic panels and a wind turbine, where electric vehicles can be recharged, perhaps supplemented by energy produced from wave or tidal motion. To recover one tonne of waste per day, it consumes up to 25 kilowatts (kW), while producing around 125.

You have tested the plant both in the port of Ancona and in the port of Genoa — is Green Plasma ready to be launched on the market?
It is a prototype. We are following the innovative development pathway known as the technology readiness level (TRL), which assigns a value to the degree of technological maturity achieved. On a scale from TRL 1 to 9, we are at TRL 7, corresponding to validation in an operational environment. We expect to climb the final step and launch the plant on the market by the end of the year. We are already working with potential customers for supply. In addition, the Municipality of Ancona is interested in installing it in the port, while the Municipality of La Spezia is considering it for a vessel designed to recover waste at sea.

How much will the plant cost?
The plant, which is capable of treating one tonne of waste per day, occupies an area of six metres by two and costs around 250,000 euros. The cost is considerably reduced when one considers the immediate saving corresponding to the energy that no longer needs to be purchased from the grid operator. We made sure that operating and maintenance costs are as low as possible. Initially we had planned to use a graphite electrode to generate energy and drive the plant, given that this is a more technically efficient solution but a very costly one. We therefore opted for electromagnetic induction, which requires no replacement parts. We estimate that routine maintenance requires 400 hours per year.

Can it only be used to convert floating waste into energy?
Our plant is adaptable — it takes into account the specific nature of the waste, but can also be used to treat waste recovered on land. Our initial idea was to install it on board a vessel to allow it to remain at sea for longer and to carry out loading and unloading operations at the quay while reducing its environmental impact. We also considered installing it on the quay itself, so as to recharge electric transport vehicles with clean energy.

Furthermore, it can be useful in situations that might be described as critical. For example, in tourist destinations during peak visitor periods. Or, in this period of health emergency, for treating face masks — a type of waste that is small in mass but takes up a great deal of volume and places something of a strain on the conventional transport and waste management system. Moreover, Green Plasma is compact: it can be transported and shared between multiple companies.