## 3 Results and Discussion
### Prevention
ones, are powered by a battery which lasts for almost 3-5 years. However, once the battery runs out, the tag (or at least the battery) must be replaced. The 125 kHz and 13.56 MHz tags, according to the ISO standards, are passive (without batteries), while for the UHF RFID technology, active, semi-passive, and passive TAGs can be employed. The active tags are powered by batteries. The semi-passive tags are powered by batteries only to keep the internal circuit part active, while for signal irradiation, they use a part of the energy received from the radio wave that also transmits the information. However, when the battery is present, it is not deeply integrated into the RFID system and can be removed. Since it is not possible to conceive an eco-sustainable design for the battery, the latter should be selected to have the highest energy capability per volume in order to extend the battery lasting. On the other hand, such a solution has some drawbacks related to costs and environmental impact for each battery technology. Therefore, a proper compromise should be considered while choosing the battery technology for the RFID device. In order to achieve the aforementioned target, the Lithium Thionyl Chloride technology for batteries is often used, since it offers promising performance in terms of energy density and costs (Table 3). The Lithium Thionyl Chloride offers the highest energy density compared to other chemistries, with an average lasting up to 10 years for low-power applications. These batteries are able to sustain extremely low temperatures, enabling their employment for many outdoor applications, and they also produce limited emissions under abusive conditions, which is an advantage over other battery chemistries that use liquid to produce a gas byproduct. In order to overcome the battery disposal problem from an eco-sustainable design point of view, an alternative can be found in novel, battery-less RFID technologies that rely on RF energy harvesting techniques [42; 43] to gather the required energy for the tag from the environment or directly from an additional reader signal [44]. This solution comprehends the usage of few active devices, such as diodes, passive electronic components, and ICs, which are much less hazardous compared to batteries and allow for a theoretical endless usage. Besides the power supply aspect, which involves only active and semi-passive tags, the crucial aspect for a sustainable design that allows waste and environmental impact prevention is the material choice involved for tag production. Nowadays, research and development (R&D) and industrial production include an extensive variety of electrical components that can be produced and directly included in low-cost manufacturing processes that mostly involve organic electronic components, conductive and semi-conductive materials-also known as green materials-being considered as a \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{\(\boldsymbol{\boldsymbol{\boldsymbol{\boldsymbol{\boldsymbol{\boldsymbol{ \boldsymbol{\boldsymbol{\boldsymbol{\boldsymbol{\boldsymbol{\boldsymbol{\boldsymbol{ \boldsymbol{\boldsymbol{\boldsymbol{ \boldsymbol{ \boldsymbol{ }}}}}}}}}}}}}}\) & & **Energy** & \multirow{2}{*}{**Cost [Wh/S]**} & \multirow{2}{*}{**Disposal**} & \multirow{2}{*}{**Proper Disposal**} \\  & & **[Wh/L]** & & & \\ \hline _Alkaline_ & No & 250–434 & 0.47 & Non-Hazardous & Trash (normal \\  _Carbon Zinc_ & No & 92 & 3.02 & Non-Hazardous & Trash (normal \\  _Lithium, Li-Ion_ & Yes & 560 & 2.68 & Hazardous & Recycle \\  _Nickel- cadmium_ & Yes & 100 & 3.22 & Hazardous & Hazardous Waste \\  & & & & & Collection Site \\  _Nickel Metal_ & Yes & 401 & 3.22 & Non-hazardous & Recycle or place in the \\  _Hydride_ & & & & waste & trash (normal \\  _Mercury Oxide_ & No & 300–500 & & Hazardous & Household Hazardous \\  _Lithium Thionyl_ & & & & Waste Collection Site \\  _Chloride_ & No & 1200 & 5.1 & Hazardous & Recycle \\ \hline \hline \end{tabular}
\end{table}