Nanotechnology's image is sleek, modern and clean. But that's not its reality.
Turns out that designing and manufacturing materials so small that 100,000 of them can fit comfortably on the width of a hair strand absorbs tremendous amounts of energy and is anything but neat.
"You can make a very green product with a very messy process," said Mark Greenwood, a Washington lawyer and former director of U.S. EPA's Office of Pollution Prevention and Toxics.
That "very messy process" is a problem for nanotech researchers trying, among other things, to design more efficient batteries, higher-performing solar cells, more effective water purifiers and more sensitive pollution detectors.
Consider what it takes to purify a nanomaterial of unwanted chemicals. Traditionally, that has required the repeated use of solvents -- a lot of them, said James Hutchison, a professor at the University of Oregon.
"If you're washing with a solvent, you're wasting a lot of solvent," Hutchison said. "This is the biggest contribution to waste we've been able to see. If you think about a lifecycle analysis on this, you see what's the hot spot, and think about other ways to purify that don't require solvent."
Hutchison and others are trying to come at the nanotech problem with "green chemistry" techniques that emphasize materials, products and processes that reduce or eliminate hazardous substances and conserve energy and resources. His solution for the solvent waste: a nanofiltration membrane that separates nanomaterials from the rest.
Hutchison's work is part of a larger University of Oregon effort that researchers call green nanoscience. In 2005, Hutchison launched the Safer Nanomaterials and Nanomanufacturing Initiative, which is funded by the Air Force and aims to develop nanotechnology to ensure high performance without threatening human health or the environment.
Because nanotechnology is still an emerging field, scientists believe there are opportunities to make it environmentally safe. "Now's the time to think about how to make this stuff clean and green," said David Rejeski, director of the Woodrow Wilson Center's Project on Emerging Nanotechnologies.
But the technology is steaming ahead, and the opportunity is unlikely to last long.
"There is a real danger that we'll roll out a whole new infrastructure for nano and it won't be green," Rejeski said. "And it's not green now. Nanotech has been built on a brown production infrastructure ... and we're really underinvesting in that area."
The federal government spends about $1.5 billion a year on its National Nanotechnology Initiative, or NNI, a research and development effort launched in 2001. But Rejeski said the government is currently focused on assessing risk and less on avoiding risk from the beginning.
For his part, Hutchison points to a House bill that would strengthen environmental, health and safety research by requiring NNI to develop short- and long-term goals and gauge the funding needed to reach them.
"We haven't seen that investment yet," Hutchison said, "but we've seen the recognition that investment is important."
Not everyone is as convinced that green chemistry techniques can be applied effectively to nanotechnology, considering the number of unknowns that persist.
"We don't know what the toxicity issues are," said Roland Clift, president of the International Society for Industrial Ecology and a professor at the University of Surrey. "How can you apply the principles of green chemistry under a condition of ignorance?"
Bjorn Sanden, associate professor at Sweden's Chalmers University of Technology, said the challenges extend beyond nano-design because no one knows the fate of nanoparticles -- whether they biodegrade or how they interact with the environment.
"Even if you design the material to be environmentally benign, how do you know if you succeed?" Sanden asked. "Can you see all of the consequences down the road?"
To address those concerns, Oregon's initiative is focused on understanding how the structure of a nanomaterial affects its environmental or biological interactions.
To do that, researchers are examining the size, shape, composition and coating of various nanomaterials. So far, they have studied nine and surveyed hundreds more, Hutchison said. The goal is to develop a thorough understanding of each nanomaterial so it can be designed in a benign way.
Scientists also are looking for ways to design new materials to replace existing toxic ones.
"We still have a lot of work to do," Hutchison said. "Ultimately, we want design rules so you can design a material that has the function you want and is also green."
For green nanotech to really take off, companies will have to see an economic advantage in using a "greener" process, which is possible because that often means a more efficient process.
In academia, researchers have to take into account the economics of their materials and techniques, Hutchison said. Any process must perform better, cost less and be greener for the research to proceed.
"If we can't address those things, it could be a nice academic benefit, but it's not going to have an impact in the market," Hutchison said.
Many companies are also starting to recognize that green nanotechnology could be good for their bottom line, as well, Greenwood said. Most nano applications in energy, medicine and other advanced fields are still being developed in laboratories at universities and companies.
By contrast, simpler applications in consumer products are already being sold. There are more than 800 manufacturer-identified, nanotechnology-enabled items on the market, according to the Project on Emerging Nanotechnologies. And new nanotechnology consumer products are coming on the market at a rate of three to four per week.
Most producers of nanomaterials are considering the entire lifecycle of their technology, including managing waste streams that result from production, Greenwood said. That makes the idea of more efficient processes more appealing.
"If you can simplify," Greenwood said, "it's better."