Lime pledged on Tuesday to make its entire fleet of electric bikes and scooters completely “carbon free.” The San Francisco-based company said it will purchase renewable energy credits from new and existing projects to ensure all of its dock-free bikes and scooters are carbon neutral. It is part of a new sustainability effort the company is calling “Lime Green.”

While bikes and scooters are certainly greener alternatives to cars, there is growing attention being paid to the proliferation of alternative modes of transportation in cities across the globe. Most of the focus has been on ride-hailing services like Uber and Lyft, but bike- and scooter-sharing companies also want to show they are making up for the electricity that is used to charge their devices. About 63 percent of electricity in the US is generated from fossil fuels, according to the Energy Information Administration.

63 percent of electricity in the US is generated from fossil fuels

Along with rival Bird, Lime is growing by leaps and bounds. The company operates in over 100 cities, including locations in Europe and (most recently) Mexico. It took 14 months in operation for Lime to hit a total of 11.5 million rides on its fleet of bikes and scooters. Less than a month later, that figure has grown to 13 million trips and counting.

Lime said it’s partnering with NativeEnergy, a firm that provides carbon offset and renewable energy credit services. Lime said it will help fund climate-friendly projects to displace the emissions from company operations, including the fossil fuels used by fleet management vehicles. These projects include an Iowa solar project and buying power from the Capricorn Ridge, an existing wind farm in Texas, in order to “green our fleet in Austin, Dallas and San Antonio,” Lime said.

There will be challenges, though. Lime relies on a loose network of freelancers (called “juicers”) to collect and charge its bikes and scooters each night. Many use their own vehicles — minivans, SUVs, and trucks, mostly — in order to “harvest” as many devices as possible. (Juicers earn a fee for each device charged, based on how challenging it is to find the bike or scooter.)

A spokesperson said the company plans to account for the electricity used by juicers to charge its bikes and scooters, but not for the vehicles used to pick up and drop off the devices. Lime hopes to cover these emissions sometime in the future, the spokesperson added.

Lime isn’t disclosing the amount of money it is budgeting for this entire project, but it won’t effect the price for consumers, a spokesperson said. Lime’s scooters cost $1 to unlock, and then 15 cents for each minute of riding. The company was recently valued at $1 billion after a big investment by Uber in a financing round led by Alphabet’s venture arm, GV.