“Black Gold” Begins with Reams of Green: How Retired Dollars End Up as Compost

Money doesn’t grow on trees, but banknotes from the St. Louis Fed can certainly help trees grow.

Since 2012, the St. Louis Fed’s headquarters office has been turning “unfit” currency into compost via its vendor St. Louis Composting of Valley Park, Mo. In 2020, the St. Louis Fed’s Memphis Branch began composting currency via its vendor Compost Fairy.

How Does Unfit Currency Become Compost?

Shredded unfit currency is diverted from landfills to become a compost ingredient.

In 2023, those two St. Louis Fed offices diverted from landfills 115 million bills weighing 127 tons, ranging from $1 to $100 in face value. That figure is down from the 2022 amount of 136 million banknotes equaling 150 tons, said a cash operations manager at the St. Louis Fed.

The goal of the composting program is to make the St. Louis Fed more environmentally sustainable, the cash operations manager said.

“We try to do the right thing, and this is more sustainable and better than going to a landfill,” he said.

How Much Unfit Currency Does the St. Louis Fed Compost?

The path to compost begins with truckloads of currency rolling into the St. Louis Fed’s main office and Memphis Branch for sorting. High-speed machines take the first pass and separate out bills that are damaged or soiled as well as those that could be counterfeits, which are examined by human handlers. The machines can process 40 notes a second, checking them for authenticity, thickness (which indicates age), soil, graffiti, tears, and more.

The currency deemed unfit is fed to shredders in St. Louis or Memphis and cut up into strips the size of grass clippings. From there, it’s moved into a dumpster-sized compactor and removed by St. Louis Composting or by Compost Fairy in Memphis.

In the St. Louis area, vendor St. Louis Composting hauls the compacted shredded money to its facilities in Belleville, Ill., the city of St. Louis, Maryland Heights, Mo., and Pacific, Mo. Those facilities combine the shredded currency with food, trees, grass and other organic waste in long pyramid-shaped piles called windrows, said Laura Gale, sustainability coordinator for St. Louis Composting.

“The shredded currency is a useful part of composting as it adds additional volume and material and a unique element that we do not get from any other customer,” Gale said.

St. Louis Composting machines, including this one, churn material once a week to aid composting.

As nature goes to work breaking down the material, it gets a boost from large machines that churn the windrows once a week to keep air circulating and encourage decomposition. As the windrows are turned, steam wafts from the piles. Temperatures inside the windrows can reach 160 degrees Fahrenheit as a natural part of the breakdown, Gale said.

Three to six months later, depending on conditions and the material inside the windrows, a rich, dark soil amendment for gardens and landscapes results. St. Louis Composting and the Missouri Botanical Garden sell bags of the resulting compost, named “Black Gold,” to individual customers. Commercial customers such as lawn care companies buy compost in bulk for landscaping uses. The Black Gold Compost is the company’s most popular seller, said Sarah Wilcox, marketing manager at St. Louis Composting.

As a result, shredded currency from the St. Louis Fed is enriching gardens and landscapes in a 150-mile radius around the St. Louis region, Gale said.

So while there might be “black gold” in those hills, it’s possible that it started with greenbacks.