California has long been the nation's leader in zero-emission vehicles, with initiatives dating more than two decades.

Now the Golden State is partnering with China, the world's largest car market, to accelerate that country's zero-emission goals.

The state announced a new initiative with China, in which they will work together to accelerate the deployment of zero-emission cars, trucks, and buses.

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The partnership will work under the China-US ZEV Policy Lab at the University of California, Davis.

The working lab was founded in 2014 to expand cooperation between California and the Chinese.

Now, it will have much bigger tasks ahead.

2017 Tesla Model S

2017 Tesla Model S

California wants to have 1.5 million zero-emission vehicles (ZEVs) on its roads by 2025, and 4 to 5 million by 2030.

To accomplish this goal, the state will work with Chinese automakers to guide development of new models and provide support for new makers to enter the U.S. market.

China, in turn, is expected to adopt a ZEV-credit policy modeled after California's.

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The country's future roadmap of new-car sales projects 7 million ZEVs by the year 2025.

Through the partnership, Chinese companies could also expand their domestic battery production into California if and when that market shows natural demand for battery-powered vehicles.

While there are benefits for both sides, the overarching goal is to reduce greenhouse-gas emissions and provide cleaner air in both locations.

2017 Chevrolet Bolt EV electric car at EVgo fast-charging station, Newport Centre, Jersey City, NJ

2017 Chevrolet Bolt EV electric car at EVgo fast-charging station, Newport Centre, Jersey City, NJ

In California, the state's transportation sector produces 40 percent of all greenhouse-gas emissions.

While roughly 20 battery-electric and hydrogen fuel-cell vehicles are now available in the state, companies also envision a cleaner transportation future in California for other sectors as well.

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Toyota's Project Portal semi truck features a hydrogen fuel-cell propulsion unit, ditching the diesel that's been the sole powertrain for heavy-duty trucks for half a century.

The Project Portal semi truck could point toward a major piece of Los Angeles and Long Beach California's Clean Air Action Plan.

Toyota 'Project Portal' proof-of-concept hydrogen fuel-cell powered semi tractor, for Port of LA

Toyota 'Project Portal' proof-of-concept hydrogen fuel-cell powered semi tractor, for Port of LA

The initiative looks to reduce harmful pollutants over the next 12 years.

In the announcement, Toyota and local officials hoped Project Portal could change the freight and transportation sector for the better.

The climate for zero-emission vehicles is lukewarm at best across the nation, but California is more focused than ever to produce real change.

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