## 3 Results and Discussion
### Reuse  
In this section, opportunities, advantages, and disadvantages of RFID tags reuse are discussed based on recent technology and standards that involve tags manufacturing and protocols. The key aspects that allow an RFID tag to be reusable during its lifetime are the possibility to be rewritable many times and its robustness, i.e., the capability to keep its electrical and mechanical integrity over time. According to the Electronic Product Code (EPC) and ISO18000 standards, as depicted in Table 4, not all the tags can be rewritten since they are manufactured to be programmed only once and are intended for Read-Only purposes. Figure 5: The Smartres s.p.a. inlay-less RFID technology. With regard to active and semi-passive tags, they are always rewritable and thus reusable. Usually, the package is made of rigid plastic or flexible protective material, allowing the device to be resistant to its usage over time. The only concern is the battery, which is a limited energy source and limits the lifetime of the tag. Solutions to this problem, referring to general purpose applications, consist of battery replacement or the employment of rechargeable batteries. As shown in Table 5, which refers to coin-size battery comparison with a capacity ranging from 40 mAh to 50 mAh, and without loss of generality, the employment of rechargeable batteries represents a higher initial investment with respect to non-rechargeable battery endowment. However, they can be recharged and, consequently, reused up to 2000 times, allowing the producer to ideally save over time around $500 in the worst case and around $5100 in the best case per each employed rechargeable battery. Active RFID tags are usually used for tracking high-value resources over a large zone. They could be used for tracking vehicles in a lot or for tracking valuable objects or equipment within a structure. They are most beneficial when items need to be firmly controlled. Consequently, the number of active tags usually employed is relatively small, compared to general-purpose passive tags that are used, e.g., in warehouses and distributions, retails and point-of-sale, inventory management, and supply chains. Therefore, reuse possibilities for passive RFID tags represent a valuable and relevant aspect within the EEE waste hierarchy in terms of economic and environmental impact. As mentioned for active tags, one of the crucial properties that an RFID device should have to enable the opportunity of reuse is the possibility to rewrite information. However, referring to Table 2, the majority of HF-UHF passive tags are intended to be Read-Only or WORM devices, invalidating any reuse chances, since there is no possibility to store new information into the recovered device memory. However, the new, second-generation of EPC Class 1 UHF passive tags, which is one of the most used in RFID systems, \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**EPC Class** & **Standard** & **Frequency** & **Power Supply** & **Memory** \\ \hline _Class 0 Gen 1_ & 900 MHz Class 0—RF & UHF & Passive & Read-Only \\ _Class 1 Gen 1_ & 13.56 MHz ISM Band Class 1 & HF-UHF & Passive & WORM \\ _Class 1 Gen 1_ & RF Identification & & & (Write once, \\ _Tag_ Interface Specification & & & & read many) \\ _860 MHz-90 MHz Class 1_ & & & & \\ _RF Identification_ & & & & \\ Tag RF andLogical Communication & & & & \\ _Heritage Specification_ & & & & \\ EPCglobal Tag Data Standards & & & & \\ Version 1.3 & & & & \\ Class 1 Gen 2 & Class 1 Gen 2 & Protocol Standard Version 1.0.9 & UHF & Passive & WORM \\ _Class 1 Gen 2_ & Class 1 Gen 2 UHF RFID & & & \\ _Conformance Requirements_ & & & & \\ Specification v.1.0.2 & & & & \\ _Class 2_ & EPCglobal & UHF & Passive & Rewritable \\ _Hardware Action Group (HAG)_ & & & Active & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: RFID EPC classification.