FERRISBURGH — From a distance, the vertical green panels revolving in a back field at Boundbrook Farm in Ferrisburgh look more like an art installation than a piece of farm equipment.
But don’t be deceived: Come spring, the unconventional windmill will pump as many as 150 gallons of water a minute into farmer Erik Andrus’s 5-acre rice paddy, day in and day out.
The windmill is the final result of a project that started two years ago, when Andrus and his wife, Erica, noticed a spike in the farm’s energy usage when milling wheat to make flour for Good Companion Bakery bread, one of the many outputs of the diversified farming operation.
“We noticed this big increase in our electric bills,” he said. “I wondered if there was some way to use wind for this.”
A standard commercial windmill costs tens of thousands of dollars and must be installed in a suitably windy location in order to justify the cost. Even then, it takes years to generate enough electricity to offset the cost of even the smallest windmill, and, Andrus noted, if any piece of the windmill breaks, the owner can’t repair it alone.
Then Andrus stumbled across the “Savonius rotor,” a simple machine that’s more like a medieval European wind turbine than today’s commercial windmills.
In the Savonius rotor, the propellers rotate slowly around a vertical shaft, catching the wind with scoop-shaped arms. The design goes against the grain of much of the common wisdom on wind power — it’s low to the ground, heavy, slow moving and not very efficient. While similar machines are widely used across Europe as low-cost, low-profile forms of power generation, Andrus said they are virtually unheard of in the U.S.
“This is the kind of wind-engineering project that no one pays attention to,” said Andrus.
But where some qualities of the Savonius rotor looked like drawbacks, Andrus saw opportunity. The windmill didn’t have to use lightweight materials or expensive energy conversion mechanisms. It could use cheaper materials, and the construction and maintenance would be relatively simple.
“It’s all within the realm of the average individual to be the master of this technology,” said Andrus. “That’s why I like it.”
And the low-cost input and maintenance, Andrus realized, meant that the machine could pay itself off within just a few years.
So Andrus went to the Northeast Sustainable Agriculture Research and Education organization (NE-SARE), landing a $10,000 grant to research and build a prototype wind turbine suited to use on a farm.
That Andrus had no prior experience working with wind energy didn’t deter him.
“I like to mess around with machines,” he said.
Working with retired engineer Victor Gardy of Charlotte, the two came up with a workable model, and Andrus set out to build a full-sized version.
The project wasn’t without its hitches. Until just a few months ago, the series of prototypes Andrus had created were large, clunky rectangular boxes containing wooden propeller systems. Andrus presented the design at a couple of sustainable energy and agriculture conferences, but still wasn’t satisfied.
So after wrestling with the design, he went to NE-SARE for a grant extension and headed back to the drawing board.
This time, he came up with a lightweight wooden frame, 20 feet high by seven feet wide and anchored to the ground with guy wires, with steel propeller blades made of salvaged 275-gallon fuel tanks. The materials cost less than $1,000.
Andrus estimates that this turbine would produce about 1,750 kilowatt-hours per year in average wind speeds of about 10 miles per hour. Hooked to a generator, that’s the equivalent of about $400.
While 1,750 kWh is less electricity than a commercial wind turbine can make, Andrus said the real value in the turbine lies in the slow-moving mechanical energy it creates, which is most suited for applications that can use the energy directly, without converting it to electricity — things like powering a water pump, pressurizing an air compressor or running a band saw.
While this turbine won’t be milling flour, it will replace two gas pumps that used to supply water for Andrus’s rice project, which he will expand from one acre to five this spring. The turbine will power an “Archimedes screw,” an ancient mechanical device used to move water uphill, to lift the water out of a pond and pipe the water to the end of the rice paddy. To Andrus, this system makes far more sense than fueling and maintaining two gas pumps for the same job.
“There’s no reason I should be using a gas pump when I can pump water essentially for free,” he said.
“I grew up on a farm in Vermont, so I have an interest in on-farm energy,” he said. “I’m interested in the question of whether it would be good for someone handy to go out and build this themselves.”
And Gorton said the prototype is also a good educational tool as well because it is a simple machine that can create the same energy all homes and farms use.
“There’s a lack of energy literacy when it comes to how you actually make it,” he said. “We’re all so plugged into the grid.”
The report will be posted in February on the NE-SARE and UVM Extension websites and at goodcompanionbakery.com. Andrus said he’s done building windmills for a while, but that he hopes this prototype inspires others to try their hand at creating simple, low-cost wind projects.
“This sort of thing can really make a dent in our energy usage, as farmers,” he said. “Power is power, and you can use it in many different ways.”