Future Energy: LA crystals turn cars into energy source
Los Angeles is the car capital of the world with traffic a part of daily conversation as people estimate how many hours they will be stuck in a jam on their commute home each night.
But what if the cars they spend so much time in could be used to generate electricity using crystals embedded in tarmac that can capture energy via the vehicle's vibrations?
It may sound like a typical La La Land idea but in fact the California Energy Commission is investing $2m in two pilot studies of the technology.
It is part of a wider effort towards cleaner air in the state, which currently has a goal to provide half of the state's energy supply via renewable electricity by 2030.
Piezoelectricity is not new technology - one of the most common applications is electric cigarette lighters which use piezoelectric crystals to create a flame. The electric lighters for barbecues use the same technology.
And microphones in laptops also used such crystals to convert the sound vibrations in voices into electrical signals that can be processed by the computers.
Piezoelectric crystals generate an electrical charge when compressed and scientists estimate that if they were positioned on a 10-mile stretch of highway they could generate enough electricity to power the city of Burbank, which has a population of more than 100,000.
Currently the technology is used on a much smaller scale.
Since 2009, all the displays at the East Japan Railway Company's Tokyo station have been powered by people walking on floor tiles that utilise piezoelectricity.
And start-up PaveGen has put similar technology beneath the floor of a football pitch in one of Rio de Janeiro's most notorious favelas to offer night-time floodlights powered by footsteps. It means children can play at night rather than hang out in gangs.
It is now installing the tech on a street in central London to provide street light and has similar schemes in Washington.
Mike Gatto, a Californian legislator, is pleased that the value of the technology has finally been acknowledged.
"California is criss-crossed with roads and our car culture is both a blessing and a curse," he explained.
"No society can be 100% solar and so energy needs to be procured from a variety of different sources and I think that this has tremendous potential."
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Mr Gatto actually proposed a similar scheme back in 2011 which was vetoed by the state governor.
"Six months later I got a call from one of his aides saying that they had got it wrong and were going to get the State Energy Commission to look into it," he told the BBC.
Money has been awarded to The University of California, among others, to investigate the potential of the tech.
Mike Gravely, from the California Energy Commission, explains why it is pursuing the technology.
"California has an aggressive renewable energy policy and we have a lot of cars. They roll by and the energy is lost, so if we could capture that energy if would be another type of renewable to meet the future policy goal," he said.
Crystals will be embedded into a device the size of a coin which will be laid along a stretch of highway a few millimetres apart.
The pilot programmes will run in about 18 months time and will assess how many of the devices are needed, how deep into the concrete they need to be embedded and what the best location for them will be.
Mr Gravely said that if the pilots prove successful, they could be rolled out more widely.
"When roads are extended or repaired will be the time to do it to avoid tearing up the highway," he said.
"There are some people who would like us to do it for all the roads in California but we don't know if it will work yet."
It might not just be energy that the devices capture.
"One of the contractors is looking at using them to capture information to help with road management," he said.
Critics might say that the move away from fossil fuel should mean fewer cars, not a scheme to utilise the vast amounts of traffic on California's roads. But Mr Graveley points out that California wants to introduce 1.5 million zero-emissions vehicles by 2025.
In April 2017 the American Lung Association reported that LA had hit its lowest levels of particle pollution ever. Despite that, Southern California remains the most polluted region in the US and is ranked the worst nationally for ozone pollution.
A study from New York University revealed that better air quality in the state could prevent more than 3,000 deaths a year from pollution-related conditions.
Some people remain sceptical about what a crystal energy scheme can achieve.
Peter Calthorpe is an urban architect who has long been campaigning for greener cities via lifestyle changes.
"I am pretty cynical about fancy gadget solutions. There are lots of these technologies that capture a bit of energy here and there but it is not the answer.
"Everyone loves a solution that doesn't change their lives, but this is about the way we live," he said.
He wants to change the landscape of cities in Southern California, taking lanes from the arterial roads which criss-cross the state and converting them specifically for public transport while making suburbs more connected via high-speed rail and locating shops within walking distance of people's homes.