A residential electric-car charger spends most of its time just hanging around unused.

That underutilization looked like a opportunity to Val Miftakhov, CEO of the smart charger startup eMotorWerks. On Tuesday, the company launched a beta test of a distributed, peer-to-peer charging marketplace in California that lets drivers pay each other for use of their home chargers.

If successful, this concept could drastically expand the population of readily available EV chargers, at least in places with a high density of home charging stations. That reduces range anxiety, promoting more EV ownership and potentially generating a virtuous cycle.

For a charger company like eMotorWerks, this is part of a broader strategy to move from selling hardware alone to offering software that generates value beyond the initial purchase.

"The value of this flexibility will surpass any type of hardware margin we can generate in this market," Miftakhov said.

The peer-to-peer concept relies on blockchain, one of today's hottest trends in energy, to verify the transactions without a central regulator.

EMotorWerks uses the Share&Charge platform developed by MotionWerk, a startup which spun out of the innovation hub of German energy company Innogy SE. Share&Charge harnesses the Ethereum blockchain to track the charging transactions and exchange payment between customer and host. It's already being implemented in Germany.

Let's say a participating EV driver is looking to park and charge while picking up a poké bowl for lunch, and all of the public chargers in downtown Mountain View are taken. This driver could tap into the network, see an open charger in a driveway a few blocks away, and plug in there. The homeowner sets the rate and the blockchain verifies how much the driver owes and settles up digitally between the parties.

EMotorWerks won't be taking a cut of these transactions; the company sees this as a way to make its JuiceBox chargers more attractive and affordable. To participate as a host, you need one of those chargers, or a JuiceNet-enabled charger from a selection of partner companies, or a JuicePlug smart charging adapter.

For this marketplace to work, homeowners, at least, need to profit from the endeavor. Those who can afford both a house in Mountain View and a Tesla Model S might not be willing to go out of their way to chase a few spare bucks here and there.

But the economic incentive is not trivial, Miftakhov said. Typical public charging rates amount to $3 to $5 per hour, he said, and the typical EV owner in California spends $1,000 on charging each year. The revenue from renting out a charger could zero out that customer's annual EV fuel bill.

EMotorWerks customers respond to less tangible motivations, too, Miftakhov added. In this case, that means feeling good about playing a role in better local air quality, lower greenhouse gas emissions from transportation and reduced reliance on overseas oil.

Participants are also helping to tackle the public charging infrastructure shortage. The California government counts more than 10,000 Level 2 chargers and 1,500 direct-current fast chargers deployed, but 300,000 battery-powered vehicles have been sold in the state thus far. If blockchain opens up a fraction of those customers' home chargers to other drivers, it will drastically enlarge the roster of options.

"People like the idea that they can help fellow drivers to reduce range anxiety," he said.

Plus, getting to say that you're using blockchain is cool.

A few years ago, the notion of a stranger parking in your driveway and plugging into your personal charger would not have been cool; it would have sounded horribly invasive. Times have changed, though, and some people are happy to let strangers come into their homes and live there via Airbnb, or hop into their cars for a ride with Lyft or Uber.

"There's less and less of a psychological barrier there," Miftakhov said. "Letting someone use your driveway in a busy neighborhood where people park on the street anyway all the time is not such a big leap."

Whether or not this creates a thriving, long-term marketplace is a different question.

Over time, EV range has gotten longer and public chargers have proliferated. As those trends continue, they're likely to diminish demand for a peer-to-peer charging network. For most, the Tesla Model 3's 310-mile range comfortably rules out the need for a midday charging session, outside of long car trips.

"This is indicative of the niche blockchain applications coming to the market now, but that’s not where the market’s heading," said GTM CEO Scott Clavenna, a close observer of blockchain technology.

In the long term, more sweeping and transformative platforms beckon, he noted, like a blockchain-based digital ID to enable instantaneous vehicle charging transactions while roaming across the country, or smart contracts that moderate and compensate vehicle-to-grid operations between driver and utility.

An even more revolutionary vision would relegate the current retail utility to a software "layer" that rides on top of the physical distribution infrastructure and uses blockchain as the means to assign value to electricity and enable and record transactions among consumers and generators.

So far, though, energy blockchain has been big on possibility but light on shovel-ready projects. If there's anywhere that would be receptive to piloting a blockchain-enabled Airbnb platform for electric-vehicle charging, it's the Bay Area.