Dined at Mario Batali’s famed Eataly recently? The oil used to cook your meal there is now powering homes and cars around the New York metropolitan area.

Grease Lightning, a company established in 2010, sends trucks around the city collecting hundreds of gallons of used cooking oil to recycle into biofuel.

They pick up the used oil from some of Manhattan’s best-known restaurants, such as Eataly and Balthazar, and trucks then ferry it to their two recycling plants in Newark and Hicksville, Long Island. There, the cooking oil — or actually, it’s just plain old grease — is converted into biodiesel to heat homes and fuel cars.

This may be just the start – Mayor Michael Bloomberg has aimed to eliminate the heaviest heating oils in the city in order to reduce soot pollution by 50 percent by 2013. Just last week, on June 13, Bloomberg announced more than $100 million in financing to help city buildings convert to cleaner fuels through the NYC Clean Heat program.

Grease Lightning works with about 3,000 clients, including Jean-Georges, Spice Market and Mercer Kitchen. In return for selling their oil, restaurants are paid part of the profits.

Cooking oil is better for the environment, said managing partner Jeff DeWeese, because vegetable oil burns more cleanly than fossil fuels like diesel or gasoline. In fact, DeWeese said he actually prefers to work with the oil discarded from fine dining establishments, as opposed to say, a corner burger joint.

“New York City is unique itself in that the restaurants tend to change their oil very frequently,” he said. “I think the reason is because there’s a very discerning customer in New York. If you don’t change your oil very much, you start to get a rancid taste.”

For example, restaurants that partner with Grease Lightening change their cooking oil about once every day or two, while others may change it just once every other week.

“The oil starts to break down over time,” he said. “The less you do that, the higher quality the oil.”

Anyone that uses an oil furnace to heat their home can use bioheat, DeWeese said. And with Bloomberg’s efforts, he hopes that many New Yorkers will choose to use cleaner fuel — anyone can request it from their local fuel distributor, he said.

Grease Lightening plans to open a third processing plant in Philadelphia this fall.

An employee at Grease Lightning’s plant in Newark, N.J. labels samples of used cooking oil from the day’s delivery.

A well-oiled recycling process

7 million gallons: Grease Lightning recycles more than 7 million gallons of used cooking oil each year.

6.5 tons: The company estimates that they have removed 6.5 tons of carbon emissions from the atmosphere

441 That’s the equivalent of removing 441 tractor trailer trucks from the road for an entire year, according to the company.

Grease Lightning worker moves hundreds of gallons of recycled waste oil.

Other restaurants that recycle

Transforming grease into gas isn’t the only way the city’s restaurants stay green:

Many restaurants choose to compost. The City Bakery in the Flatiron district separates their trash into waste, recyclable materials and food trash, then composts the food waste. Vegetarian restaurant Candle 79 on the Upper East Side also has a composting program, and separates food trash in the kitchen, saving it to get collected later. Their compost is processed in New Jersey, according to Green Apple Map, which tracks composting in the city.

The Maritime Hotel removes chunks of food waste from recyclables like paper and plastic waste, then sends those leftovers into its “garbage digester,” where the food is composted. The composting saves The Maritime Hotel garbage costs, and they also estimate it keeps 438,000 pounds of garbage out of landfills every year.

The New York Compost Company promises to pick up leftovers from restaurants by bike, delivering the leftovers to urban farms to compost.

Cleaned oil is kept under large white tents. The tents keep the oil cool during the summer and warm during the winter, to keep it from turning into sludge.