What incentive do you have to make sure a plastic bottle you use ends up in a recycling bin?

The answer is probably very little, unless you’re determined to get 5 to 10 cents per bottle at the recycling center or unless you happen to live in one of the few cities or states that have mandatory recycling laws or plastic bottle bans.

Recently, Istanbul devised a more direct incentive to boost recycling rates by installing "reverse vending machines" that allow people to trade recyclables for credit on Istanbulkart cards, which are used to pay for public transportation.

“With those smart machines, our waste management department and the municipality’s Smart City Technologies Company [İsbak] will contribute to the protection of the environment,” the municipality said on Twitter.

The machines, dubbed "Smart Mobile Waste Transfer Centers," are able to scan and assign a value to recyclables before crushing, shredding, and sorting the material. The Istanbul Metropolitan Municipality plans to install at least 100 of the machines in 25 locations by the end of 2018.

Shown above, Istanbul's reverse vending machines accept recyclables for metro fare.

Boosting recycling through reverse vending machines isn’t a new idea. The technology has already been installed or proposed in the U.S., China, the U.K., and Norway, where the recycling rate is 90%, largely thanks to reverse vending machines that have been in place since the 1970s. (Norway also adds an extra cost to its recyclable products that can be recouped later by recycling.)

In March, a leaked report estimated that the U.K. could increase its recycling rate from 60% to 85% by instituting a recyclable deposit scheme that includes reverse vending machines.

The success rates of other countries that have adopted similar schemes seem to support that claim, such as Lithuania, which increased its recycling return rate from 34% to 91% in the two years after implementing the plan.