It's a bird. It's a plane. No, it's a Bird—the electric scooter brand, that is.

As people grow tired of congested commutes, many are opting to zip around cities on dockless electric scooters. Several brands have already sprung up to meet their needs, including Bird and Lime.

With lower carbon footprints than cars, electric scooters are seen as a good choice by some eco-conscious consumers. The transportation sector recently surpassed the power sector as the country's biggest source of greenhouse gas emissions.

The climate benefits of e-scooter rides aren't entirely clear.

"If people are replacing a cab or an Uber or Lyft drive with a scooter, from an emissions standpoint, that's obviously a better choice," said Dana Yanocha, senior research associate with the Institute for Transportation and Development Policy. "But if we're pulling people from walking or biking to scooters, then it gets a little bit more complicated, because the scooters do get charged. And the electricity from that charging could be coming from a renewable source. But it's likely coming from a non-renewable source."

What's very clear: The rise of e-scooters has caused headaches for city officials around the country who are still grappling with how to regulate them.

"They do sort of require a different type of regulation that a lot of cities don't already have in place," said Yanocha. "I think a lot of cities are really unsure of how they'll be able to manage these companies that are operating using public space, you know, city sidewalks and streets."

Some of the biggest regulatory debates are playing out in California, where transportation accounts for more than 36 percent of the state's greenhouse gas emissions.

In Los Angeles, city officials are working to craft regulations that would encompass both e-scooters and dockless electric bikes. But there have been a few speed bumps.

The city was in the process of negotiating with Bird in June when "they just dumped a bunch of Birds downtown," Los Angeles Mayor Eric Garcetti told The Wall Street Journal.

A Bird spokesperson said in an emailed statement to E&E News, "We work closely with the cities in which we operate so that Bird is a reliable and affordable transportation option for people who live and work there."

Oliver Hou, a transportation planner at the Los Angeles Department of Transportation, said the city is still working to impose a cap of 3,000 scooters allowed within city limits.

"We're going to have an initial cap to the fleet size to begin with before we review their operation and make sure that the companies are in compliance with everything else," Hou said.

The city is also considering allowing an additional 2,500 vehicles if they're deployed in "environmentally disadvantaged areas," such as those located near air-polluting highways, he added.

In San Francisco, scooter companies are vying for up to five permits that the city plans to award. Observers are waiting to see whether Bird and Lime make the cut.

"Bird officially applied for a permit with the city of San Francisco so that we can continue to offer our affordable, environmentally friendly transportation solution to the people of San Francisco," the Bird spokesperson said.

"In compliance with the process, we also removed our vehicles from the streets," the spokesperson said. "We are waiting to hear more about the status of our application and are hopeful that we can once again provide our traffic and carbon emissions-reducing vehicles to San Francisco."

Hal Harvey, CEO of San Francisco-based energy and environmental policy firm Energy Innovation, said the scooters there have caused quite the stir.

"The reaction is downright comical," Harvey said. "San Francisco is one of those cities where [officials] went into freakout mode because there were scooters on the sidewalk."

He added, "This is an amazing technology. It offers a lot. But you have to put guidelines on it."

All told, at least seven cities have impounded scooters due to violations of guidelines, according to The Wall Street Journal. In Denver, scooters were recently impounded after they were dropped into the city without a permit.

"Back in June, Denver Public Works removed scooters that were left unattended in the public right of way as our resources allowed," said DPW spokeswoman Heather Burke-Bellile in an email. "We provided the companies notice that they were in violation of an existing ordinance, which states it is unlawful to utilize any street, alley, sidewalk, parkway or other public space for the storage of goods, wares or merchandise."

The city department has since unveiled a pilot program that would cap the number of scooters at 250, she added.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.