Local researchers are using battery acid to turn your wasteful restaurant sludge into fuel

Next time you’re at a fast food joint such as McDonald’s, look for a manhole cover somewhere on the property. Those repositories are where commercial kitchens trap all the grease they’re using to cook up their dollar menu meals.

All that waste gets separated into “yellow grease” and “brown grease.” The first gets used to make biodiesel. The latter, also known as “scum grease” because it’s historically been considered to be a rancid, unusable sludge, ends up either incinerated or buried in landfills.

“We estimate that there is approximately half a billion gallons of brown grease generated in the United States every year,” said Don Wilson, a cofounder of Environmental Fuel Research (EFR).

The research firm, which Wilson started with chemical engineering professors Marilyn Huff (Penn) and Richard Cairncross (Drexel), recently landed a small business grant from the Environmental Protection Agency to scale their process of turning that brown grease into biodiesel by boiling it in alcohol with a small dose of sulfuric acid — the same kind of acid commonly found in car batteries.

Several companies have tried to turn brown grease into biodiesel, said Wilson. None have successfully commercialized the conversion process.

“There are a lot of companies that have tried to do this. All of them have failed. In my opinion, they’ve failed because they had come up with overly complicated technologies,” said Wilson. “Ours is very simple. It’s easy to operate. There’s no extreme pressures or extreme temperatures. It’s the kind of process we could show someone who’s already working at a plant.”

That’s why EFR is working on scaling their method at Delaware County Regional Water Authority treatment facility, where a pilot plant is currently under construction.

Water treatment plants are the most likely customer for EFR’s desired end product. They produce brown grease, too.

“When you wash your pots and pans or run the dishwasher — multiply that by all the people in the area — all that grease ends up at the treatment plant,” said Wilson. “They have tanks where they skim that grease off.”

The EPA grant funds a year of research. After that, said Wilson, they’ll expect to have to look for additional funding.

“If somebody could come up with what is most likely a pre-packedaged suite of technologies that would allow one to simply convert the grease into diesel fuel,” said Wilson, “it stands to reason that we could displace half a billion gallons of [brown grease].”