Developers of a renewable energy pilot project in downtown Omaha plan to exploit a simple property of physics that they think will result in a complementary energy source for high-rise buildings.
Known as the stack effect, it’s the same principle that warrants revolving doors at the ground level of tall buildings. Warm air rises over cooler, denser air and, in a building, the resulting updraft can make it difficult to open swing-style doors at ground level.
Jess Baker, co-founder of GRNE Solutions, has seen it in action plenty of times during his construction career.
“We’ve learned mechanical systems must overcome the natural drafts in elevator shafts, so the question became how do we utilize these (drafts) to harness a local energy source in a building,” Baker said.
One possible answer can be seen in the aptly named Energy Column, a pilot project that Baker and company co-founder Eric Peterman unveiled Saturday at the Wire apartments at 19th and Dodge Streets.
It’s the first step in what the startup hopes will lead to widespread adoption of the concept as a renewable energy source — and to growth for the 2½-year-old company that counts five employees, all of whom are part-time.
Baker, 35, owns and operates Roca, Nebraska-based Wilderness Construction Inc., a custom homebuilding company. Peterman, 28, left a position as a pricing analyst for United Airlines to raise money for the Wire project and now works for a Chicago-based firm as a financial consultant to the health care industry.
Once financing was in place for the Wire project, the two combined their engineering expertise to bring the concept to life. In all, Baker estimates laborers have invested more than 1,500 hours of work into making a reality out of a concept that began as a rough sketch on the back of a church bulletin.
“My wife found (the bulletin) in a desk drawer where it had been sitting for nine months and (she) really encouraged me to pursue the idea,” Baker said.
That sketch is now a 14-story science experiment.
The 136-foot-tall structure is framed in stainless steel and is made of transparent sheets of polycarbonate plastic.
It resembles a small elevator shaft, except the only thing moving through it is air.
Air moves through the column on its own because warm air is less dense than cool air. When less-dense warm air is displaced by more-dense cool air, it has nowhere to go but up.
A turbine positioned in the bottom of the column spins as warmer air is displaced by cooler air. The motor attached to the turbine generates an electrical current, which is then sent to a converter that makes the electricity usable.
From there, electricity is either fed back into the building or is stored in a nearby bank of batteries.
Stand-alone structures known as solar updraft towers rely on the same effect, but significant upfront costs have been a barrier to proposed projects in Texas, Arizona and Australia.
Peterman said GRNE Solutions has bootstrapped financing for its pilot project, raising money mostly from friends and family.
Having financing in hand before the project started helped persuade NuStyle Development to give up space at its apartment development, the Wire, to test the idea, said Greg Rothermel, development director at NuStyle.
“I’ve never seen anything like this, but NuStyle is always looking at new options to make our buildings more sustainable or more energy-efficient, which is challenging with older structures,” Rothermel said.
Sustainability is a typical concern at NuStyle because the organization restores and upgrades historic properties while maintaining their original integrity. Its sustainability emphasis often turns its focus to energy-saving windows and roof structures, however, not features that actually produce energy.
“We’ve never done anything like that, and typically you can only do that with solar (panels) or a wind turbine on top of a building,” Rothermel said.
Now that the column’s turbine is spinning, Baker plans to test different blade configurations for higher- and lower-velocity drafts, measuring and interpreting results along the way. He will also evaluate additional turbines in different locations in the column.
But GRNE Solutions isn’t stopping at apartment complexes. The Wire project had to be retrofitted to work inside the existing structure, but the co-founders say a bigger building with a bigger column, in theory, would be capable of generating even more power.
So Baker and Peterman are soliciting farmers, co-ops and private grain elevators to install agriculture-themed iterations inside silos, where energy produced on-site could offset electrical costs.
“This project’s real intent is to prove the validity of the concept,” Baker said. “It’s a scaled-down version of what’s possible, but we’re using what we were given. It’s our intent that future applications will be far more substantial and will be a much bigger staple in the structure.”
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