All The Right Foods

by Anna Simet (Biomass Magazine) About 15 miles southwest of Baltimore, the town of Jessup is right in the heart of the Maryland Food Center Authority. Stretching across nearly 400 acres, the center includes the Maryland Wholesale Produce Market and the Maryland Wholesale Seafood Market, with a self-proclaimed mission of providing quality food products efficiently and inexpensively.

But inevitably, where there is perishable food, there is waste. And to Bioenergy Devco, the site was the ideal candidate for a food waste-based anaerobic digestion (AD) project. To date, the company has constructed over 250 AD projects in seven countries. “We have the largest market share in Italy and France for AD plants and biological operations,” says Shawn Kreloff, CEO. “A few years ago, we decided to bring the business to the U.S., which led us to our first plant in Jessup, and many others are under development.”

When evaluating sites for the company’s first U.S. plant, officials of Howard County, Maryland, were receptive of and enthusiastic about the concept, Kreloff says. “Once they understood what we were doing, they got really excited about it. We received a lot of support locally and we were able to get land from the state of Maryland. The plant is right in the middle of the Maryland Food Center Authority, which is state property, and there are about 20 to 25 different food processors and distributors within a 10-mile radius. So, it ended up being a great location. You have to have support, you have to have your feedstock, and you need the right place to put your gas.”

When trucks arrive at the Jessup facility, they drive over a scale while en route to the receiving building (they will drive over another scale when leaving, to calculate the weight of what was left behind). There, the door closes and negative air pressure assures the air is filtered prior to leaving the building. “We have quick-opening and -closing doors,” Kreloff explains. “As trucks come in the doors open, but there is a massive amount of air moving around the building, which keeps the air pressure inside—if there is any odor, and really there isn’t that much—it doesn’t leave the building.”

If the delivery is liquid waste, the truck’s contents are pumped directly into a pre-tank. If it is solid—i.e., fruits or vegetables—it’s dumped on the tipping floor and visually inspected. “We pride ourselves on the fact that once the material is tipped on the floor, it doesn’t stay there for long,” Kreloff says. “It goes right into the feed hoppers. If it spends an hour outside the tank, I would be surprised.”

Inspected feedstock is lifted by front loaders and tipped into the hopper where augers move the material to the next stage. If it arrives in packaging, there’s a solution for that, too. “We have our own depackaging equipment,” Kreloff explains. “It does several things—simultaneously depackages paper and plastic, and then slurries the organic material, creating kind of a liquid smoothie thickness.”

Food packaging is disposed of into a container and eventually hauled away. “We always try to make sure that it’s recycled,” Kreloff says.

From the initial pre-tanks, the slurry is custom-blended and sent into large digester tanks, where it is continuously mixed and kept at a steady temperature to optimize microbe performance. As biogas is generated, the double membrane at the top of the tank rises. Biogas is pumped out of tank and sent to a gas filtration skid to be filtered and cleaned for pipeline injection, and can also be sent into the facility’s combined-heat-and-power unit (CHP).

To help with the cost of the CHP unit, the Maryland Energy Administration provided Bioenergy Devco with $467,500 from its CHP Grant Program, funded by the Maryland Strategic Energy Investment Fund.

Finally, the solids left behind after the digestion process are pumped out of the bottom of the tank, dewatered and turned into digestate, and any remaining water is either recycled back into the process or filtered through the plant’s on-site wastewater treatment system.

As far as future plans go, Kreloff could divulge details of a couple of new projects—one with a poultry partner on the Delmarva Peninsula on the eastern shore of the Chesapeake Bay, and another in Middlesex County, New Jersey, to build a digester next to a landfill in order to repurpose the organic material destined for the landfill. Both projects will produce RNG. Kreloff says the incentives to make RNG right now are far better than those to make electricity, but if the U.S. EPA ever implements eRINs through the Renewable Fuel Standard, that could change things.

Kreloff adds that hydrogen from methane is also a possibility for the company. “Most of the hydrogen we have in the country right now is made from methane that has been steam reformed. Mixing steam with methane under the right pressure changes the methane into hydrogen, and we’re definitely interested in that. We’re in the R&D process right now to make it happen.” READ MORE