Talk about extreme makeovers.

A former dump site for human waste is poised to become home to one of the most advanced and promising forms of renewable energy currently in development.

Though they represent opposite ends of the spectrum, from sewage to the sun, both procedures include toxic materials and the potential for worrisome health hazards, which could lead to concerns about the land’s safety from contamination. The land is the once and future home of dangerous, deadly and, well, disgusting substances. Because the land in question is within a couple acres of the Poudre River, that is a major concern.

But officials say there are enough procedures in place to make sure the land, on the southwest corner of Prospect Road and Interstate 25, remains safe.

As part of a land swap Fort Collins City Council initially approved a couple weeks ago, a 143-acre chunk of land will be home to AVA Solar, Inc., a new company that developed an efficient process for manufacturing photovoltaic cells.

AVA officials said the process for making the company's cells, which convert the sun's light into electricity, will be safe, clean and as environmentally friendly as the product.

“We're going to set high standards for ourselves in terms of production and everything else,” said Russell Kanjorski, director of strategic planning for AVA Solar. “It would be a little ironic if we had a process that was not environmentally sound to make a product that is environmentally sound. So we intend on making the whole thing sound.”

Solar cells come in various forms nowadays in addition to the more common crystalline silicon kind, which is made of the same material used to make computer chips.

Many of the materials are toxic and even deadly, according to the National Renewable Energy Laboratory. The type AVA will use— a composite of cadmium and tellurium called cadmium telluride, or CdTe to its friends — is seen by some as a better use of already-existing dangerous substances.

Cadmium is a byproduct of the zinc mining process, and if it isn't needed, it is discharged into the environment or put in a pile at a mine.

“They can either leave it in the mine, or pull it out, and we get to put it in a very high value-added product and take it to market,” Kanjorski said. “This is a new use for it. It's a good thing to pick it up.”

The metal has such good conductivity that it's commonly used in batteries, often with nickel — anyone with a digital camera has probably heard of a “NiCad” battery. When those run out, however, they're often tossed into a landfill, where the metals can leach into the soil or groundwater. Cadmium compounds can cause kidney problems, fatal swelling of the lungs, and cancer, according to the Brookhaven National Laboratory, a U.S. Department of Energy program that has conducted extensive research into PV cells.

“If it doesn't go here, it goes into the batteries, which go into the landfill,” Kanjorski said.

AVA Solar's CdTe cells will sequester that harmful metal far better than any battery would, and they will provide much more energy, too, he said.

Cadmium telluride PV cells will have less cadmium than a C battery and generate 2,500 times the electricity, according to the Brookhaven lab.

Most concerns addressed in CdTe cell research center on what would happen if the material went into the environment.

“People have also looked at what happens if these things catch on fire, will it release the cadmium,” Kanjorski said.

It's not likely, because the compound's melting point is 1,041º C, according to the Brookhaven lab. The potential for that kind of heat would only happen in a huge industrial fire—and in that case, the fire itself would probably pose a bigger hazard than any potential emissions of cadmium or other PV materials, the lab said in a report.

To address concerns about the PV cells going into a landfill once they stop working, after about 20 years, AVA plans to create an end-of-life recycling program to get the materials back.

Part of the explanation for why the CdTe cells ought not to present a major public health concern is a matter of chemistry.

The CdTe cells are a 50-50 combination of the two elements, which are bound together as strongly as sodium and chlorine are in table salt, Kanjorski said.

“You take sodium and chlorine, and they're pretty harmful alone, but when you put it together, it becomes benign,” Kanjorski said. “Cadmium is bad, for sure, as a heavy metal … but you put those two together and it becomes, relatively speaking, benign. You lock the cadmium up.”

That's not to say that AVA doesn't treat it as a hazardous material, however. Employees have to wear masks around the material and it is isolated from workers as much as possible.

After the CdTe is processed into a thin film, it is encased between two layers of glass, which will prevent anything from getting in or out.

Even before talk of cadmium telluride and photons, the land AVA will one day occupy was used as a place to dispose of municipal waste, namely the galaxy of toxins, heavy metals, bacteria and pollutants found in sewer sludge, the byproduct of the city’s wastewater treatment facility.

Starting around 1980, Fort Collins Utilities started applying municipal sludge onto the 143-acre parcel in question, at the southwest corner of Prospect Road and Interstate 25.

The property, known as the Resource Recovery Farm, was originally 325 acres and was a working farm, primarily raising corn, according to information in city documents and on the city's Web site.

Treated biosolids are nutrient and phosphorous-rich, which makes good fertilizer for plants. But they also include toxic materials, including dioxin, pesticides, heavy metals and various kinds of bacteria and parasites, according to research compiled in a 1995 book, “Toxic Sludge is Good For You,” about the public relations industry.

Whatever goes into a wastewater treatment plant has to come back out, whether it has been broken down by bacteria, irradiated or otherwise disinfected. The materials that don't stay in the liquid remain in the sludge, and the practice of applying it to the land has remained a source of enduring controversy. Although the Environmental Protection Agency regulates the land application of municipal sludge, only a handful of metals and materials are required to be monitored. Wastewater utilities are not required to test for the presence of such ingredients as asbestos, dioxins or PCBs, which all pose serious human health threats.

The EPA estimates that about 7 million tons of biosolids are generated in the United States every year. As of 2002, about 60 percent was being applied onto land, according to the EPA. Fort Collins applies about 1,900 dry tons of sludge a year to its newer sludge application site, Meadow Springs Ranch, according to the utilities department.

The city bought that property, a 26,000 acre ranch 26 miles north of Fort Collins in Weld County that runs to the Wyoming border, in 1990 and began using it a while later. The land is leased to a cattle grazing association.

As Meadow Springs started operations, parts of the Resource Recovery Farm began being acquired by the city's Natural Areas program, to become part of Running Deer Natural Area. The most recent acquisition was in 2003, when City Council directed the Natural Areas program to acquire 151 acres in the interest of protecting open space near I-25.

Now, much of that land—118 acres, specifically—is now being traded to CSU, plus another 25-acre chunk, and that's where AVA will eventually be located. Thirty-three acres will stay in the city's hands, to protect Box Elder Creek and the Poudre River.

The rest will be home to a decidedly more advanced type of toxic-materials research and development.