UK startup Renew is taking smartphone tracking to London's streets with the help of its Wi-Fi-enabled trash cans. Already outfitted with advertising screens, a handful of the city's 100 Renew Pods are now equipped with new "Renew Orbs," which use Wi-Fi to track the proximity and speed of people walking past and identify the maker of their smartphone. As GigaOm points out, Londoners might be shocked to find they are being tracked, but many will be unaware that it's happening without their permission.

Renew installed Orbs in the square-mile City of London, home to the highest concentration of professionals in Europe. The marketing company allows clients to use its smart trash cans to conduct their own statistical analysis on "trending demographics" in high profile locations. For example, if there are lots of iPhone or Galaxy S4 owners walking past a Pod, a retailer can work out how many consumers are likely to be in the area and range smartphone accessories to cater for them.

It can track your speed, proximity, and even your smartphone model

Renew's approach is likely to attract attention — both UK and EU privacy laws require companies to notify consumers they are being tracked and allow them to opt out. Even if the company fixes notices around its trash cans or uses digital signage to warn people walking past it, Renew isn't able to provide an easy way for them to immediately tell the company that they don't wish to participate. However, because the system utilizes Wi-Fi to gather information, personal data cannot be obtained and is purely for research purposes only. Retailers across the world are using similar tracking techniques to learn more about their customers. Armed with anonymous data, store owners can tune layouts, offer discount coupons, or reward frequent buyers, much like their online counterparts.