LOS ANGELES (Bloomberg) -- Nissan Motor Co., the most prolific electric-car maker, has begun selling green-car credits under California's clean-air rules.
The only automaker that had previously disclosed doing so is Tesla Motors Inc.
California requires large automakers to sell electric or other zero-emission vehicles in proportion to their share of the largest U.S. state market for cars and trucks.
Nissan has delivered enough of its all-electric Leaf hatchbacks that it has started selling excess credits, Executive Vice President Andy Palmer told reporters in Irvine, Calif., this week.
"We've got carbon credits to sell, and we're selling them -- California ZEV credits," Palmer said.
He didn't elaborate and the company declined to provide details about timing, price or purchasers.
U.S. demand for plug-in hybrid and battery-only autos has been pushed by California's requirement for such vehicles to ease emissions of climate-warming carbon dioxide and other exhaust gases and by federal rules aimed at doubling fuel- efficiency by 2025.
The state's target is to get 1.5 million zero-emission vehicles on the road by 2025.
Tesla, too small to be required to accrue the ZEV credits under California's pollution rules, has so far been the main seller.
Its first quarterly profit -- achieved in the first quarter -- was made possible in part by such transactions to undisclosed mass-market rivals.
In the first half the Palo Alto, Calif.-based company received $119 million, or 12 percent of its revenue, from ZEV credit sales. Including sales of credits for exceeding federal efficiency requirements, such transactions accounted for 16 percent of Tesla's total revenue.
Tesla's Model S, priced from $70,000 to more than $100,000, generates as many as seven ZEV credits, the maximum issued by California, because of its range of as much as 300 miles (483 kilometers) per charge and ability to be rapidly "refueled" by swapping its battery pack with a charged one.
Tesla CEO Elon Musk said the company will open its first such facilities by year end.
Musk has also said its ZEV credit sales will drop in the third and fourth quarters.
Each Leaf sold in the main U.S. electric-car markets, including other states that participate in the California program, earns three credits from the state's Air Resources Board, which manages it.
Regulators don't set prices for ZEV credits and the sales are negotiated directly between companies, said Dave Clegern, a spokesman for the Sacramento-based agency.
Nissan declined to elaborate on its credit sales.
"While Nissan has been approached by other automakers regarding emission-credit transactions, these discussions and the outcome of any transactions is held in strict confidence by all involved parties," said David Reuter, a spokesman for the carmaker.
Nissan has sold 75,000 Leafs globally since late 2010, and California is among the car's biggest markets, Palmer said.
The Leaf, priced from about $30,000, travels as far as 100 miles per charge.
CEO Carlos Ghosn has said electric vehicles will account for as much as 10 percent of the global market by 2020.
Buyers of Leaf or Model S receive $7,500 in U.S. tax credits -- separate from the credits traded among the companies -- and clean-vehicle rebates of $2,500 in California.
Nissan sold 11,703 Leafs to U.S. customers this year through July, up 230 percent from a year ago, and should deliver 20,000 or more for the full year, Jose Munoz, the automaker's head of sales for the Americas, said in an interview this week.
That would be more than double the 9,819 it sold last year.