CSR Zhuzhou, China, has unveiled what it claims is the world's first 100% supercapacitor-powered low-floor tram.

The LRVs will automatically recharge an onboard bank of supercapacitors during stops at stations and CSR says the vehicles will draw sufficient power during a 30-second stop to operate independently for up to 4km. The supercapacitor provides power to the traction system for acceleration and also draws current from the regenerative braking system, which can recover up to 85% of braking energy for reuse. 

Read more at http://www.railjournal.com/index.php/light-rail/csr-unveils-100-supercapacitor-powered-tram.html