Electric air taxis aren’t a real thing yet, but a host of well-financed startups are out to change that. Chief among them is Joby Aviation, an electric aviation company based in Northern California that just posted a noteworthy video of its six-rotor aircraft completing an impressive 150-mile flight.

Granted, it doesn’t sound too impressive, but it’s actually among the longest flights ever performed by an electric aircraft. It’s equivalent to a trip between Seattle and Vancouver, or Los Angeles to San Diego — the type of regional trip conducted hundreds of times a day by regional partners to major airlines. Swapping out those polluting airplanes for a zero-emissions aircraft like Joby’s could be a major step toward the reduction of CO2 emissions.

The company, which is backed by Toyota and recently acquired Uber’s flying taxi division, has said that it plans to have a full-scale air taxi service in operation by 2024, including regional trips. The point of the 150-mile flight was to demonstrate how far its aircraft could fly on a single charge, to allay concerns about the vehicle’s range and battery. If you want to fly from New York City to Montauk, Joby wanted to show that it can get you there without running out of juice.

“We’ve achieved something that many thought impossible with today’s battery technology,” JoeBen Bevirt, founder and CEO of Joby, said in a statement. “By doing so we’ve taken the first step towards making convenient, emissions-free air travel between places like San Francisco and Lake Tahoe, Houston and Austin, or Los Angeles and San Diego an everyday reality.”

Rather than fly between two points, Joby’s aircraft flew in a 14-mile circle 11 times for a total flight time of one hour and 17 minutes. It’s an impressive feat, given the challenges of electric flight. The power-to-weight ratio is one of the biggest inhibitors. Energy density — the amount of energy stored in a given system — is the key metric, and today’s batteries don’t contain enough energy to get most planes off the ground. To weigh it out: jet fuel gives us about 43 times more energy than a battery that’s just as heavy.

But Joby says that its commercially available lithium-ion batteries have been specially adapted for aerospace uses:

An 811 NMC cathode and a graphite anode cell were selected, following internal testing, to deliver the optimal trade-off between the specific energy required to fly the aircraft 150 miles, the specific power to take-off and land vertically and the cycle life to deliver an affordable service. We have demonstrated in the lab that this battery is capable of more than 10,000 of our expected nominal flight cycles.

The team developing Joby’s energy system is led by Jon Wagner, head of powertrain and electronics, who previously led battery engineering at Tesla.

It helps that Joby is starting small with a five-seater vehicle. Higher capacity aircraft won’t come until the energy density in the current batteries improves. But Joby has a financial buffer, having just gone public via a reverse merger with a special acquisition company, or SPAC. As part of the deal, Joby will get $1.6 billion in cash, which it will use to continue to tinker and perfect its technology.

The question is: will it be enough to get the company to 2024?