bear pits. They were the open garbage dumps where tourists occasionally would try to
put their kiddies on the backs of hungry
wild bears in the hopes of getting that great souvenir photo, sometimes with unhappy results.
Turns out that calling our dumps bear pits was a misnomer. The proper name for what are
now officially sanitary landfills is money pits. Not only can municipalities reap substantial rewards from tipping fees of $90 a ton,
but they can also mine those mountains
of trash for valuable gasses and turn them into electricity.
Thats what R.G. Engineering Company of Webberville, Michigan is doing for
If a landfill is designed properly, that is. Lined first with a heavy plastic to prevent seepage into the ground water, all those goodies stay put, waiting to be harvested. In particular, what Jon Rabitoy, president of RPG, is after is trapped methane.
Were all familiar with methane. Its
the gas we generate ourselves after a meal
of bad chili or cauliflower. We dont generate enough to utilize other than to light as
a bachelor party prank, but a sealed landfill has plenty.
It works like this: gas wells are sunk from 30 to 90 feet in the landfill and a gentle vacuum sucks out the methane. It is then run through a battery of converters. Usually four are set up, with three always running while a fourth gets routine maintenance.
According to a confidential report from Rabitoys company, Neenah/Menasha, Wisconsin developed a landfill over a 10-year period. The landfill was filled, capped and a collection system was installed 18 months ago. Today the landfill generates and flares 1,000 ft3/min of landfill methane gas, where the gas temperature is 96 degrees F and is delivered at 1 psig pressure to the flare.
The electricity generated by this system is incredibly cheap, 2 cents a kilowatt hour created from the landfill gas which costs half a cent per kilowatt hour to recover.
The electricity is then sold for 5.5 cents a kilowatt hour, and the projects net revenue is estimated at $475,146, with a simple payback for the project of 9.25 years.
Other systems can recoup the initial costs in less time, 5.1 years. Even more rapid payback can be derived from animal waste.
My brother was once part owner of a pig farm where the noxious waste was turned into methane to provide energy. They generated enough electricity on the farm to provide all their energy needs. A feed lot may produce many tons of animal waste. Anyone whos lived within nostril range of one of those can testify to the noxiousness of that, but the electricity generated from that animal waste can recoup the costs of the installation in little over a year.
The electricity these systems generate is sold to the electric grid to supplement power generated by conventional plants. No wonder a landfill can turn into a profit for a municipality! They can collect at both ends.
Whats clear is that waste products from feed lots and city landfills can put a significant dent in our need for energy. I suspect that the Keweenaw bears are disappointed to no longer have easy pickings at our garbage dump, but if we go the way of Neenah/Menasha and other municipalities well not only get some extra income, but well utilize some of those infamous greenhouse gasses. Oh, and turn the stink to cash. You never knew the smell of money had an odor like that.