A couple of years ago, Horner came to the Hill to pitch his drinkable yogurt bottled in compostable, polylactic acid containers. The House food vendor wasn’t much taken with the product. But staffers in the Office of the Chief Administrative Officer were intrigued by the idea of a compostable water bottle — the Hill goes through 100,000 a year — and told Horner as much.

He went back to work and returned to the Hill five months later with a prototype. And now, Green Bottle Spring Water can be found and purchased in each House and Senate office building.

Two years into its inception, the Green the Capitol office has become a place for green merchants to promulgate their products and probe the market. For some companies, like Horner’s Naturally Iowa, the Capitol is the launching pad. For others, the congressional campus provides a test market or puts products directly, and frequently, into the hands of decision makers — or, at the very least, makes for a good brochure line.

Plus, there’s always the chance of fortuitous, if entirely inadvertent, product placement opportunities.

Take Fabri-Kal, a large, Michigan-based manufacturer of custom plastic packaging, which has its Earth-friendly Greenware drink cup line in the House cafeterias.

When former Federal Reserve Chairman Alan Greenspan testified last fall in front of the House Committee on Oversight and Government Reform, Greenware cups just so happened to get prominent display in a New York Times photo of the hearing.

“At the time, it was like, ‘At least there is one good thing in this photo,’” says John Kittredge, the company’s vice president of marketing.

Green the Capitol’s six-person staff works out of a basement suite in the Longworth House Office Building. On a recent day, a racing bicycle was resting against waiting room chairs, and a few feet away, on a table, a handwritten placard encouraged visitors to partake of complimentary “Biodegradable Pens!” (It’s safe to assume that nowhere else on the Hill is it so written, let alone exclaimed.)

Perry Plumart, the deputy director at the CAO’s Green the Capitol office, says he gets pitched a couple of times a week. If you have a green product you want to hock, he’s a good person to know: a Hill staffer who wears hiking boots with a suit and tie.

“What we’re looking for is something that is not in the laboratory but not necessarily commercialized,” Plumart says, “something that’s in the beta-testing mode. What we want to show is the next generation of technologies. We want the first or second cell phone to show that these things are out there, that they provide jobs, that you can use energy more efficiently — or new off-the-grid kinds of things.”

Last Wednesday, right before he sat down with POLITICO, Plumart had a meeting with GreenGuard Associates, a Georgia company that makes a bio-composting reactor.

“It’s like putting solar panels on the White House during the Jimmy Carter administration,” says Greenpeace USA Research Director Kert Davies. “It’s symbolic, but I guess it depends on how a company plays it, and if a company plays it up. It certainly is not going to be a huge market for any one product, unless it’s like a recycled paper product.”

And it’s not quite like a bazaar — this is the federal government, of course, and the red tape is one thing that won’t be made from a plant-based biopolymer. The CAO has specific guidelines and a rigid procurement process.

Still, the green office remains hungry for the next best thing.

“A lot of these decisions become cascading,” says Plumart, a former staffer for House Speaker Nancy Pelosi (D-Calif.). “So, for instance, when you decide to ban plastics and Styrofoam in the cafeteria, then it’s like, ‘All right, what do you do?’ You go for the biodegradable and compostable” products.

As of now, Horner’s water bottle serves as the model. Plumart keeps a couple of the prototypes on the top shelf of a display case in his office. Naturally Iowa’s East Coast sales rep, Stephen Kay, says that the bottles are now in a federal agency (he won’t name which one), with others expressing interest.

Even large corporations are finding Congress to be an advantageous place to ply their wares. In the past few weeks, Coca-Cola has installed its line of climate-friendly coolers in the House cafeteria. Coke has placed about 39,000 of them around Europe, but it’s currently testing just a few in the United States to make sure they work properly when plugged into American electrical outlets.