One of the biggest promises of smart technology is smart cities, which use data-collecting devices to manage utilities and traffic patterns, drive policies and coordinate services.

Ideally, all this is done while making the city’s resource use more efficient.

As a result, technology could reduce waste and make cities more sustainable.

However, there is also evidence that while the tech may look green on the surface, it could ultimately be bad for the environment. Concerns over e-waste have environmentalists worried that smart technology could create as many problems as it solves.

How Smart Cities Can Improve Sustainability

Proponents of smart cities believe technology could make them more eco-friendly. Smart tech and sensors are already being used to adjust city utilities and systems so fewer emissions are produced and less resources are used.

For example, a city with smart sensors that detect traffic flow and can tweak signal timing can use that combination of information and systems automation to streamline traffic. The system could automatically redirect drivers away from accidents, or speed up signal cycles to reduce the amount of time drivers spend idling at lights.

Implemented well, drivers will spend less time waiting — and, as a result, less time producing emissions. Similar technology — like street lamps that dim when there’s no foot traffic — can be used to adjust and optimize energy usage, which could have additional positive effects. Electric power generation is responsible for up to 41% of water withdrawals in the U.S., meaning that cutting back on energy use could improve municipal water use, as well.

Other smart city solutions could encourage sustainable habits — like new electric vehicle charging stations.

As a result, smart city technology would lead to more sustainable cities by virtue of reduced consumption of valuable resources.

Why Smart Cities May Not Be So Sustainable

While smart tech may make cities more sustainable, however, there’s evidence to suggest these devices may come at a steep environmental cost.

One of the most significant concerns environmentalists have is in how smart technology could contribute to the growing problem of e-waste. Smart sensors, like most computer technology, aren’t always built to be easy to recycle and may not be long-lasting. Once they begin to fail, cities’ only option is to throw them out and purchase a replacement.

As cities become smart, they’ll also need more devices to collect data. These sensors will naturally need to be replaced over time as equipment degrades. Worse, if cities want to keep their smart sensors cutting-edge, they’ll need to replace them even more frequently, generating additional waste.

Many of these smart devices are also wireless and powered by rechargeable lithium-ion batteries, which have a lifespan of three years at most. While these batteries can be recycled once they burn out, most are sent to landfills, instead. In the U.S., only about 5% of lithium-ion batteries get recycled.

The problem is made worse by lithium’s tendency to react violently under heat or pressure, potentially leading to landfill fires that can release toxic chemicals into the atmosphere.

Studies also show that higher use of smart technology leads to significantly elevated energy use. This increased consumption may offset any gains made by smart city optimizations.

Smart Cities Offer Mixed Results on Sustainability

Smart cities are one of the most significant possibilities created by technology. Proponents hope they will reduce resource consumption and emissions production, making them more sustainable.

Some environmentalists, however, fear the waste created by smart technology — in addition to the increased energy consumption associated with smart tech — easily outweighs any potential benefits. The pros and cons are something officials need to be aware of as they plan for the future.

Emily covers articles in sustainability and green technology. She is also the creator of Conservation Folks. You can follow her on Twitter to keep up with her latest work.