How did San Francisco go from being in the technological vanguard of dog poop innovation to falling somewhere behind Boston and Phoenix? It’s a long story. Welcome, reader, to the second part of Mission Loc@l’s series on that which people pretend not to see but also look for carefully, so as to avoid stepping in it.

After the first part of the series, which touched on the delicate subject of humans pooping in the street (only illegal since 2002!), we got several letters from readers saying that humans were getting a bad rap. Look, they said, to the dogs.

Some of them cited arguments to this effect, which we checked. There are more dogs than babies in San Francisco? True. And babies rarely poop in the street? True. Dog pee is an acid that, in sufficient quantities, eats through bark and kills trees dead? True. Heartworm is on the rise in San Francisco, due perhaps to a correlation between those disinclined to take their dog to the vet and those disinclined to pick up their dog’s poop? Sure looks that way.

In the last article, I interviewed an idealistic toilet enthusiast in the process of applying for city grant to turn parking spaces in the Tenderloin into composting toilets. During that interview, a dim memory surfaced. Hadn’t the city done this before?

A little research led to this 2006 article on the National Geographic website:

San Francisco is believed to be the first U.S. city to explore the energy potential of pet waste.

In a pilot program to start this year, Norcal Waste, a garbage company that collects the city’s trash, plans to use biodegradable bags and dog-waste carts to pick up the poop in one of San Francisco’s most popular dog parks.

The waste will be run through a methane digester, a tank in which bacteria break down the feces to create methane. This biofuel can then be piped directly to a gas stove, heater, or anything else powered by natural gas.

Almost 10 million tons (9 million metric tons) of dog and cat waste is generated annually in the U.S., according to William Brinton, president of Woods End Laboratories in Mount Vernon, Maine. The lab specializes in analyzing compost and other waste.

“The amount of energy potential in dog and cat litter is higher than anything else because of the rich diet that we feed [pets],” said Brinton, who was consulted by Norcal to test the energy content of pet waste.

He estimates that 1 ton (0.9 metric ton) of animal waste could produce 50 gallons (190 liters) of diesel-equivalent fuel.

The project mentioned, in Duboce Park, never got off the ground. Another project, a plan to set up a small biogas digester at a nearby kennel and use the gas generated to provide energy for the building, was never funded, says Robert Reed, spokesman for Norcal Waste (which changed its name to Recology in 2009). When that plan got shot down, Recology continued to focus its biogas efforts on the most bang for the buck — the 300 or so tons of food scraps that the city’s restaurants generate every day. The city’s dogs can try, but they can’t come close to generating that much volume.

And then there was the matter of the bags. Recology has to shut down its machines several times a day in order to extract colonies of plastic bags that have migrated into any moving parts, winding themselves in further and further until the machine seizes up and a worker has to go cut off with a knife whatever has wedged itself in there. San Francisco’s plastic bag ban, passed in 2007, was viewed by Recology with unequivocal delight, but loopholes in the ban — exemptions for businesses that make under a million a year, and a loophole allowing stores to give away “reusable” bags, which plastic bags technically are, since they sure aren’t going anywhere — resulted in very little change in the number of bags showing up in Recology’s machinery.

Any notion of collecting waste from a dog park — where each turd in the trash barrel comes individually plastic-wrapped — did not go over well at Recology HQ. Biodegradable bags were dismissed on the grounds that most bags that are sold as compostable, like PLA bags, are not, really.

Despite all that history, Boston beat us. Matthew Mazotta, a conceptual artist working with MIT, persuaded the city of Cambridge to put a methane digester in the city’s Pacific Street Park. That’s how it goes, says William Brinton, who was a consultant for both the failed project in SF and the successful one in Cambridge.

“California gets all the attention,” says Brinton, who founded Woods End Laboratories. “But then the East Coast goes and actually does it.”

How did they do it? Well, they called it art, for one thing. The centerpiece of the project, which Mazzotta named Park Spark, was a gas lamp powered by the anaerobic digester, which Mazzotta would stop by the park every evening at dusk to light. (Alternate ideas that were, alas, rejected, featured a teakettle heated by the digester so that people could have hot tea in the park, and a popcorn popper.) The other critical point was to make the project temporary, since the city agreed to foot the cost of municipal insurance.

In this case, says Brinton, the project had an advantage that San Francisco’s didn’t have — the backing of a powerful local university, MIT, instead of a waste company. Nonetheless, in order to get a single poop-powered lamppost approved, Mazzotta had to meet with seven departments and agencies, including union trash crews dubious at having a giant metal poop box added to their collection route.

Methane digestion was pioneered in India and China in the late 1800s (where it was mostly used in individual homes, to power cook stoves and lamps), and has since acquired a small following among DIY enthusiasts and your more progressive type of dairy farmer or water treatment plant supervisor. “I don’t understand why everyone is overlooking it,” says Brinton. “Except that it’s so simple. Not taking advantage of it is the equivalent of taking a gasoline can and pouring it down the drain.”

Brinton first encountered a digester when he went to Costa Rica to deliver a series of lectures on composting. At one dairy farm, he saw what looked like an enormous black sack lying on the ground. “I looked over and said, ‘What is that?’” he recalls. “And they pulled out a cigarette lighter and lit it at the opening and there was this big, beautiful flame. ‘We use this to run the dairy refrigerators,’ they said. It was so simple. There wasn’t even a switch.”

That said, Brinton adds, “I’m sure if I announced that I was converting the septic tank at Woods End to methane digestion, every agency in state would be on me.”

Biogas, which is mostly methane, is created as a byproduct when anaerobic bacteria eat things. It’s an old process — the natural gas buried under the ground was created when anaerobic bacteria devoured the organisms of the past — and it’s a process that goes on all around us (99 percent of the bacteria in our digestive systems is anaerobic, which is why fraternity boys can set their farts on fire).

Like many things that make things go, methane, when it builds up in a confined area, also makes things explode. “The biggest concern was safety,” says Brinton. “It took months to negotiate with the fire marshals. They were concerned that someone could have lit a cigarette and thrown it into the digester, but we tested that on several. It’s hard to ignite them.” In order to gain approval for the project, Mazzotta wound up buying a flashback arrester, which ended up being the project’s single most expensive piece of equipment.

And the final critical point? Social engineering, even more than the technical side. Mazzotta, who was traveling and could not be reached for an interview, appears to have approached the civic power structure with a verve that most people would associate with high-stakes geopolitical negotiations. “Matthew would always use engineering language when technical people were in the room,” says Brinton. “And being very nice also helped in these projects. No matter what they said against the project, he said, ‘Well, tell me what I can do so that I can work with you on this.’”

“I’m beginning to realize,” says Brinton with the air of a man who has been negotiating with local municipalities for decades, “you can have a great idea, but the complexity of society … you have to work on seven different levels to make it work.”

There’s also, Brinton says, a bias in the United States in favor of complex machinery. We’re just so unused to simple technologies that people line up in opposition to them. The new joke among engineers is that when the energy crisis really hits, the Third World will coast and we’ll be suffering.

Recently Brinton has noticed German companies quietly registering biogas-related patents with the United States patent office. “One German company has eight U.S. patents for methane energy,” he says. “It’s a smart business move on their part to move in and lock it up.”

The Park Spark project is now de-installed and in storage at Woods End. A team of engineering students at Arizona State Polytechnic are designing their own version at the behest of a city councilwoman who heard about the Cambridge project and decided it was the perfect thing for the local dog park.

Robert Reed, the Recology spokesman, says that the most ecologically neutral thing your average San Franciscan can do to deal with dog poop is to pick it up with toilet paper and flush it down the toilet. Reed himself is intrigued by other options, like a toilet manufactured by a company called Powerloo that is set at ground level and operated by a foot pedal. “It would be pretty inexpensive to run a pipe over from a sewer line,” he says. There are not, as of yet, any active plans to install the toilets in San Francisco.

However, Reed says, the dog poop can only be ignored for so long. The city has a goal of sending zero waste to the landfill by 2020, which is not exactly far away. “In order to get to zero waste,” says Reed, “eventually we are going to have to deal with this issue.”