March 11, 2014

Engine problem: Lack of sludge

A PERPETUAL PROBLEM with boats is the toilet system. Too often it smells; repairs are an unpleasant task; finding a place for storage of the sewage is never easy; and pumping out can be a disagreeable adventure.

Little surprise, then, that composting toilets are becoming more popular on boats.

Listening to public radio the other morning, I learned that Brooklyn, New York, is doing something very similar to composting toilets. They have eight huge, egg-shaped, steel tanks that contain millions of gallons of Brooklyn’s sewage sludge. The sludge is food for uncountable numbers of bacteria. The microorganisms inside the digester eggs make methane gas that can be used to heat homes or make electricity.

That same gas can also run internal combustion engines, of course. It’s comparatively simple to convert an engine from gasoline to methane gas. 

Which got me thinking that there is no reason why we shouldn’t capture the sewage sludge generated aboard boats and use the resulting methane gas to run the boat’s engine.

It’s such an elegant solution to so many aesthetic and environmental problems that I’m amazed it hasn’t been done before.

I dreamed last night that my new sailboat was one of the first with a methane-driven auxiliary engine.

We were coming back from a trip to the islands when the wind died on us. I switched on the engine but it died five miles from home.

The methane-gas gauge pointed to zero.

I motioned toward the toilet. “Quick,” I said to my wife, “we need sludge or we’ll be out here all night.”

“I beg your pardon?”

“No time for prudery,” I said. “We need sewage sludge to get home.”

“I don’t produce sludge to order,” she said indignantly. “What’s wrong with you? Why can’t you do it?”

“Can’t go,” I said. “I’m constipated. I think it was the cheese casserole you made last night.”


“And probably the hard-boiled eggs you served for lunch.”

“I’m not talking to you.”

“But you have to do your bit for the boat,” I said. “We’re stuck unless we can produce some sludge.”

But she wouldn’t be persuaded, so I called the boat-tow company.

“We’ll be there in a half-hour,” said the nice man.

“I just need some sludge for a methane engine,” I explained.

“No problem,” he said. “I have a case of baked beans ready to go.”
Today’s Thought
Waste brings woe.
— Robert Greene, Sonnet

A boy was sitting on the curb in Denver, Colorado, with with a marijuana cigarette in one hand and a hip-flask in the other.
A little old lady approached him and said: “Sonny, why aren’t you in school?”
”Jeez, have a heart, lady,” he said. “I’m only three.”

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)

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