RENEE MONTAGNE, HOST:
OK. Now, think for a moment about the millions of tons of food waste Americans throw away each year. What if we could use all those pizza crusts and rotten vegetables to heat our homes? In some places, this vision is closer to reality than anyone might think.
NPR's Joel Rose takes us to one unlikely laboratory in New York City.
JOEL ROSE, BYLINE: If you flush a toilet in Midtown Manhattan, there's a good chance the contents wind up at the Newtown Creek wastewater plant in Brooklyn. The jewels of the plant are easy to spot: eight huge, shiny, oval-shaped steel tanks known as digester eggs. Each one contains millions of gallons of black sludge that's roughly the consistency of pea soup.
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JIMMY PYNN: So what you see coming out is what we call black gold. It has a pungent odor to it. To most people it's like ugly, yucky stuff.
ROSE: This is Jimmy Pynn, the plant's longtime superintendent. Where others see foul and potentially hazardous black sludge, Pynn sees a source of energy, thanks to trillions of helpful bacteria inside the digester eggs.
PYNN: The digesters like to be fed like us, three times a day. They like to be kept warm, 98 degrees. And whether or not we want to admit it or not, we all make gas. And that's what we have these guys here for, to make gas.
ROSE: In this case, it's methane, which can be used to heat homes or make electricity. Right now, what these bacteria are digesting is mostly sewage sludge. But they're being introduced to a new diet - food scraps. The hope is that this plant will soon take in hundreds of tons of organic waste from houses and apartments.
Ron Gonen is New York's deputy commissioner for recycling.
RON GONEN: We could be taking all of Brooklyn's organics. And rather than paying millions of dollars to send it to landfill, right here in Brooklyn, converting it into clean, renewable energy.
ROSE: This is similar to what happens in your backyard compost heap - but here, the bacteria do their work without oxygen. Anaerobic digestion isn't a brand new idea. What is novel is the idea of adding food waste into the mix. That's already being done in Europe. A handful of cities in California and Canada are trying it. Even the Walt Disney World Resort in Florida, in conjunction with the local community, recently got a digester.
Paul Sellew heads Harvest Power, the company that built it.
PAUL SELLEW: Cardboard packaging, past-prime produce, rotten tomatoes, fats, oils, greases from fryers, you know, past-prime dairy products and loaves of bread - those are all great foodstuffs for an anaerobic digester.
ROSE: That sounds so disgusting.
GONEN: My microorganisms love that. That's their, you know, that their five-course meal.
ROSE: New York is a big opportunity for this growth-hungry industry. But there are still a couple of major challenges.
SAMANTHA MACBRIDE: Everything in New York City is like big scale when you're talking about quantities of waste.
ROSE: Samantha MacBride is a former New York sanitation official who's now a professor at the City University of New York's Baruch College.
MACBRIDE: Right now, it's all in its infancy. And it's a huge question mark about whether it can grow.
ROSE: MacBride says one of those questions is how to separate the organic material from the rest of the trash in a city as dense as New York.
MACBRIDE: Just think about it, when you're in an apartment building, to separate out food scraps, it requires a lot of dedication and attention. It doesn't have to stink, and it doesn't have to be inconvenient. But it takes extra work.
ROSE: There's an even bigger challenge looming in 2015. That's when restaurants in New York are required to stop sending their organic waste to landfills. And it is not yet clear where all that is going to go. For example, the digester eggs at Newtown Creek are just starting to take food waste. And Paul Sellew at Harvest Power says they can only handle a small fraction of what's coming.
SELLEW: It's the first, what I'll call the baby step, because ultimately, in New York City, just the restaurants alone, you're talking well over a million tons a year. So that's, you know, huge capacity is going to have to get built to handle that amount of organics.
ROSE: Sellew says this fledgling industry is trying to build more compost plants and digesters to handle all that waste. The costliest part may be finding good locations in or around the nation's biggest cities. The trillions of bacteria work for free, as long as you feed them.
Joel Rose, NPR News, New York.
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