In these days of high fuel prices, how about a little hope?
Vegetable oil can be used to heat greenhouses,
allowing operators to turn up the heat without blanching. It all
began three years ago at a Monk’s Café in Philadelphia, a
restaurant known for their French fries because they change the oil daily. One day Glenn Brendle, when delivering his farm-grown
produce to the café, saw 25 to 30 jugs of vegetable oil sitting in
the alleyway. He asked, “What are you doing with all that oil?” The
proprieter said, “Take it, take it!” A service used to take the
oil away, but now the café used so much oil that it was becoming cost-prohibitive.
Brendle, a self-described “piker,” said, “Maybe I can use it.”
For the last 20 years Brendle has grown produce for Philadelphia
restaurants at Green Meadow Farm, a small farm
outside of Gap, PA. He also directs a loose coalition of local
market farmers. He distributes their produce, cheese, and meat to
local restaurants and cafes, which love the fresh food. (Diners
love it too.)
Brendle’s two heated greenhouses covered 4,000 square feet.
He hated burning all that money every winter … especially
if he could get the fuel for free. First,
Brendle made a heater to burn the vegetable oil in one
greenhouse. Later, he experimented with a commercial waste oil
heater, but he was always having to tinker with it. Then, one
morning, to his astonishment, a huge hole was melted in
the side of his greenhouse. During the night the heater had
exploded and sent a fireball through the plastic. So, he decided
to bite the bullet and do it right. He found another waste
oil burner, modified it to burn vegetable oil, then
installed it inside a small shed he calls the heat house. The burner
heats the water to 180 degrees. A circulator pump sends the
heated water through pipes four feet underground to hot-water radiators in the house and the two greenhouses. In each greenhouse is a hanging radiator that’s about 2 by 2 ½ feet. A squirrel-cage fan blows the heated air over the plants. When the fan shuts off, the
radiator puts out very little heat. Any time the winter temperature
drops below zero, Brendle will turn on the oil burner for backup, but he’s had to do that only two times over the last year. The
heated water is constantly circulating, so it doesn’t freeze,
not even when the boiler shuts down completely, which has
happened. The vegetable oil doesn’t gel up because it’s stored in the
heat house, which always stays toasty. The vegetable oil burns
very clean, and the exhaust smells like French fries. When Brendle
first started using the vegetable oil, he kept thinking that
someone was cooking French fries up at the house until he realized the
smell was coming from the furnace. In summer, the heat house gets
very hot because the boiler’s always running in order to deliver
the hot water supply. Brendle’s making the best of this: he’s found
that the heat house is the perfect place to dry things. Since the
vegetable oil doesn’t stink as other fuels would, it doesn’t add odd
flavors to the food he’s drying. He plans to build slots with bread trays that slide out to dry tomatoes, herbs, even ham!
