More than half of the 15 trillion gallons of sewage Americans flush annually is processed into sludge that gets spread on farmland, lawns, and home vegetable gardens. In theory, recycling poop is the perfect solution to the one truly unavoidable byproduct of human civilization. But sludge-based as fertilizer can contain anything that goes down the drain—from Prozac flushed down toilets to motor oil hosed from factory floors. That's why an increasing number of cities have begun to explore an alternative way to dispose of sludge: advanced poop-to-power plants. By one estimate, a single American's daily sludge output can generate enough electricity to light a 60-watt bulb for more than nine hours. Here are the six most innovative ways that human waste is being converted to watts:
Digesters similar to brewery casks house anaerobic bacteria that eat sludge and belch out methane. This technology is the oldest, cheapest, and most proven poop-to-power method. Even so, fewer than 10 percent of the nation's 6,000 public wastewater plants have the digesters; of those, just 20 percent burn the methane gas for energy (the rest simply flare it off). Flint, Michigan, and several other cities use the methane gas to fuel fleets of city buses. The problem with anaerobic digesters is that they only reduce sludge's volume by half and capture a portion of its embedded energy.
Turd Cell Smashers
Destroying the cell walls in sludge—by heating it under pressure, zapping it with ultrasonic waves, or pulsing it with electric fields—boosts its methane production by 50 percent or more in anaerobic digesters. On the downside, researchers have found that some of these processes can unleash nasty odors and even a "chemical attack" on sewage machinery.
Last summer, Los Angeles began injecting sludge into a mile-deep well, where pressure and heat are expected to release enough methane to power 1,000 homes. The well also dissolves and sequesters carbon dioxide that the sludge would normally release, removing the equivalent exhaust of about 1,000 cars per year. "This renewable energy project is absolutely electrifying," Los Angeles mayor Antonio Villaraigosa told the LA Times. "It will save money and make money."
As a cheaper green option, some 50 waste plants in 20 countries have installed versions of UC Berkeley professor William J. Oswald's Advanced Integrated Wastewater Pond Systems Technology--large open-air ponds that primarily rely on anaerobic digestion and photosynthesis to break down sludge and convert it into a fertilizer or animal feed of nitrogen-rich algae. The algae in turn can be used as a feedstock for biofuels. Rich Brown, an environmental scientist at the Lawrence Berkeley National Laboratory, sees an obstacle in the ponds' huge footprint: "For rural areas it’s great," he says. "For San Francisco it wouldn’t work so well."
Sludge gasification plants are popular in Europe and especially Germany. A low-oxygen reaction transforms the solids in sludge into a carbon-rich "char" similar to BBQ briquettes. Next, the char is gasified in the presence of air to produce a syngas that can be burned for energy.
Last year, Atlanta-based EnerTech built the world's first commercial sludge "pyrolysis" plant in Southern California. Its patented SlurryCarb process converts sludge from a third of Los Angeles and Orange Counties into char pellets that replace coal at a nearby cement kiln; its ash is mixed into the cement.
One Small Poop for Man. . .
With billions in stimulus funds slated for wastewater improvements, is the time right for poop power? Such efforts, which reduce landfilling and emissions, have earned praise from some anti-sludge groups. Caroline Snyder, the founder of Citizens for Sludge-Free Land, calls it a "win-win situation."
The EPA says sludge power holds promise, but it's not ready to quit pushing sludge as a wonder fertilizer. This hasn’t deterred the sewage industry, which sees a chance to get into the renewable energy business and put a stop to the stream of health complaints and costly lawsuits. "After almost 40 years of working in biosolids," a sewage industry official wrote in a recent newsletter. "I never thought I’d say this: it is an exciting time for sludge!"
H/T to the State of Science Report: Energy and Resource Recovery from Sludge, published by the Global Water Research Coalition. Photo from Flickr user gtmcknight used under creative commons license.
With the price of oil in the bucket, environentalists have been acting as if Canada's speculative tar sands boom is all but dead. They shouldn't. A report released today by the energy consultancy IHS CERA predicts a nearly 80 percent increase in tar sands production by 2035, and that's assuming strong environmental regulation, weak growth, and low oil prices. Should things work out better for Big Oil, the tar sands will pump out five times the crude they do now and account for a staggering 37 percent of U.S. oil imports.
CERA suggests that this might not be such a bad thing. In an analysis of 11 previous studies, it found that "well-to-wheels" greenhouse gas production from the tar sands is only 5 to 15 percent higher than the average crude oil processed in the United States. Last year, I reported that a team of UC Berkeley researchers had calculated a 30 percent well-to-wheels difference. Either figure is significant when multiplied a potential tar sands output of 6.3 million barrels per day.
Factor in devastation to Canada's boreal forests, streams, and native communities, and the swap of climate security for energy security seems even more faustian. Once we exhaust the tar sands, we'll move on to liquefied coal, which emits 80 percent more greenhouse gasses than regular oil, and then oil shale, which spews twice as much. When will it all end? And more important, what will the weather look like?
Strangely absent from the recent coverage of Pelosi's past knowledge of U.S. torture policies is any acknowledgement that this story is old news. Really old news. Way back in December, 2007, the Washington Post ran a piece headlined, "Hill Briefed on Waterboarding in 2002." It hit Pelosi with the exact same allegations that have been so breathlessly reported as of late:
In September 2002, four members of Congress met in secret for a first look at a unique CIA program designed to wring vital information from reticent terrorism suspects in U.S. custody. For more than an hour, the bipartisan group, which included current House Speaker Nancy Pelosi (D-Calif.), was given a virtual tour of the CIA's overseas detention sites and the harsh techniques interrogators had devised to try to make their prisoners talk.
So what's new? For one, Republicans are under intense moral and political threat and see a chance divert responsibility for their misdeeds back to Democrats.
To be sure, Pelosi should have taken action against U.S. torture policies as soon as she was briefed on them. And she's now paying the price for being too politically cowardly—or opportunistic—to address this issue head-on when the Post broke the story back in 2007. But it's disingenuous for the press and Pelosi's political rivals to feign outrage over what Pelosi knew and when. What did they know and when? Assuming they read the news, why didn't they make an issue of this back in 2007?
One politician did make an issue of the Post story at the time. Cindy Sheehan, the Peace Mom, ran a quixotic campaign against Pelosi for her House seat last year, and garnered 16 percent of the vote and very little press. Key to her electoral strategy was capitalizing on liberal outrage—surprisingly tepid outrage, it turned out—over what Pelosi knew. She even called for Pelosi to be stripped of her leadership post over the news. "I was appalled and really saddened," Sheehan told me at the time. "We can't be represented by a person like this."
With Sheehan's failed challenge in mind, it's hard to put credence in today's New York Timesstory on Pelosi's political fate, which quotes Bay Area resident Delphine Langille of San Ramon: "I'm very skeptical of what she's saying, Langille told the Times on the steps of San Francisco City Hall, "and when she goes to get re-elected, this could really damage her credibility." Yeah right. There's simply no way a Republican could ever mount a viable challenge in San Francisco, no way the Democratic establishment would ever try, and no way--as we've seen--that a third party outsider will take her down.
Politics is morally mushy business. The political climate was clearly more pro-torture back in 2002 than it is now. A braver politician might have spoken out sooner, but also might not have risen to the Speaker post. The interesting thing about San Franciscans is that they are politically sophisticated enough to entertain a race like Sheehan's while also voting for a pragmatist like Pelosi. And they can certainly distinguish between the moral clarity—or absolutism—of someone like Sheehan, and the immoral opportunism of liberal-come-lately Republicans. Let's hope the press and the rest of the nation eventually figure this out too.
IN AUGUST 1987, the National Park Service tore up the White House's South Lawn and tilled in heaps of a new, locally produced fertilizer. The weedy plot's transformation into a carpet of green caught gardeners' attention, and soon there was a waiting list to buy bags of ComPRO, a compost made from nearby wastewater plants' solid effluent, a.k.a. sewage sludge. Four years later, dumping sewage into the ocean was banned, and sludge went national. The Environmental Protection Agency launched a PR push to rebrand it as an all-purpose soil conditioner and fertilizer it innocuously called "biosolids." If sludge was good enough for the first family, the agency reminded us, then surely it was good enough for the rest of America. "The Clintons are walking around on poo," the EPA's sludge chief quipped in 1998. "But it's very clean poo."
Today, more than half the 15 trillion gallons of sewage Americans flush annually is biologically scrubbed, "dewatered," and processed into products with names like BioEdge, Nitrohumus, and Vital Cycle and spread on farmland, lawns, and home vegetable gardens. (The rest is incinerated or landfilled.) Recycling sewage is big business: In 2007 the Carlyle Group paid $772 million for the sludge-residuals company Synagro, whose products are the most popular on the market. Sludge could be the ultimate growth industry; as one trade publication observes dryly, "There will continue to be more wastewater solids to manage with every passing year."
San Francisco Supervisor Ross Mirkarimi wants the city to get into the drug dealing business by opening up a city-run medical marijuana dispensary. Though the law's as likely to pass as Cheech Marin is to sponsor a major public art exhibition--or something like that--it has at least been good for a chuckle: "The mayor will have to hash this out with public health officials," a spokesman for Mayor Gavin Newsom told the SF Chronicle. "It's the mayor's job to weed out bad legislation, and to be blunt, that sounds pretty bad."