"If it takes 10 years to pay off, you still have 15 years of free energy coming in," he says. In theory, a 50-kilowatt vertical-axis wind turbine - which Enviro Energies is currently developing - could power a five-storey office building, Mr. Rowan says.
But skeptics argue that these performance claims are questionable because no standardized tests exist that could confirm the firm's power output estimates.
"Will [these turbines] produce a lot of electricity? I would say no," says Paul Gipe, a Bakersfield, Calif.-based renewable-energy industry analyst and author of the book Wind Energy Basics. Mr. Gipe points to a 2009 report by Britain's Energy Savings Trust, which monitored 38 building-mounted wind turbines for a year and found that they "exhibited generally poor output" due to inadequate wind speeds.
It boils down to a problem of physics that has consistently plagued small wind turbines, adds Tim Weis, a Gatineau, Que.-based engineer and director of renewable energy and efficiency policy for the Pembina Institute, a renewable energy advocacy group.
"If you try to put something on a rooftop or on top of a house, you get into areas where there are low winds and the physics dictate there's only so much energy there," he says.
In Mr. Weis's view, horizontal-axis wind turbines, which rely on long, slender blades mounted on tall towers to generate electricity, are a far more efficient means of producing renewable energy. He also points out that in jurisdictions such as Ontario where energy is relatively cheap, and where the feed-in tariff program pays more than five times the amount for solar power than wind energy delivered onto the provincial power grid, the former is a far more cost-effective investment.
These are criticisms that Mr. Rowan has heard time and again, and he says that delays in getting his turbines to market are partly due to time spent responding to each. He counters that Enviro Energies's technology is designed precisely for low-wind, high-turbulence rooftops and feels that successful third-party testing by Livonia, Mich.-based Roush Enterprises, as well as significant foreign investment, is proof that it works.
"Take our wind turbine and put it in straight-line wind conditions and the other turbines will outperform it. But we'll outperform them in turbulent wind conditions every time."
The man who once gleaned inspiration from a documentary program boldly proclaims that it could one day eliminate power bills for businesses up to the size of small manufacturers:
"We're not there yet," he says, "but give me another year and I'll have a solution operational that will do that."
