Monday, November 1, 2010

Arizona Nature Conservancy Goes Solar

When it adds a swimming-pool-sized rainwater tank to its array of "green" strategies later this year, the Nature Conservancy will close the loop on its sustainable campus on East Fort Lowell Road.

It will harvest most of the rain that falls on the site while generating most of the electricity its offices need, partly from a new rain-catching shade topped with solar panels.

Signs around the 2.35-acre campus explain the various strategies used by the Nature Conservancy to conserve resources on-site.

Jim Cook, director of operations, said the organization's hope is that it will educate and inspire businesses, particularly nonprofits, to adopt sustainable practices.

The key to making this deal work, said Cook and Kevin Koch of Technicians for Sustainability, was finding a financial partner that could use the tax credits and accelerated depreciation schedules available for solar projects.

Otherwise, said Koch, nonprofits are "left out of the solar game when they can't take advantage of the tax credits."

The Nature Conservancy was able to take a donation of $130,000 and parlay it into a $542,000 photovoltaic system that, together with two smaller arrays already in place, will supply 93 percent of the building's power.

Using a lease-purchase agreement allowed the conservancy to add panels and upgrade their efficiency while keeping most of the site free for native plants - all for a monthly payment that is less than its current electric bill, said Koch.

"Their goals were to provide as close to 100 percent as possible from renewables without taking over the site, which they would really like to use as a demonstration of xeriscape and water harvesting and all the things the Nature Conservancy stands for."

That meant making triple use of the parking area where a 4,200-square-foot photovoltaic array now shades 14 parking spots while generating electricity. Rain that falls on the panels will be directed into a "mega-cistern," made of modular "milk-crates" of recycled material wrapped in impermeable plastic buried beneath the driveway. That 30,000-gallon reservoir will be installed by the end of the year, said Cook.

"It kind of rounds out the possibilities you want at a demonstration site," said Gary Woodard of the University of Arizona, who helped the Nature Conservancy land a grant to beef up its water storage in connection with the shade structure, a metal frame supporting 240 solar panels.

The grant, from the U.S. Bureau of Reclamation, was available for projects that demonstrate the connection between water and power. When you talk about energy use, you must include its water-cost for cooling, said Woodard, and when you talk about water supply, you need to account for the energy needed to move it.

"This reverses that water-energy nexus in a beneficial way," said Woodard, associate director of the UA center called Sustainability of Semi-Arid Hydrology and Riparian Areas, or SAHRA.

The reservoir will be less visible than the existing "iconic" cistern, an 18-foot tall corrugated metal tower that collects roof water for plants on the sides of the building. The added storage will supply water for the entire 2.35-acre campus.

Use of rainwater is augmented with smaller cisterns at a house on site and at the Barbara Mettler Dance Studio, now leased for dance and yoga classes. They are meant to demonstrate smaller, residential-scale water-harvesting techniques.

Passive techniques are also in play. Curb cuts on the North Cherry Avenue side of the campus divert storm runoff to street trees. Swales in the middle of the property and wells around the trees help retain water that falls on-site.

In the parking lot and driveways, rock covers a membrane that allows water to percolate into the aquifer.

The campus was planned, with help from UA landscape architecture faculty and students, to demonstrate sustainable practices, said Cook.

Cook said the conservancy wants to use its experience to help other nonprofits, small businesses and homeowners with their own sustainability plans. They will be able to tour the grounds and find more information in the building's lobby, he said.


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