Environmentalists and nanotechnology haven't always been soulmates. From scientist Eric Drexler's suggestion that out-of-control, self-replicating nanotechnology could turn the world into "grey goo" — which Drexler has since described as a highly unlikely "worst-case scenario" — to more specific concerns about the health hazards of very tiny particles, worries about unintended effects have been a thorn in the young discipline's side almost since it began.

But nanotech also promises some environmental benefits. A number of researchers and some commercial businesses are working on ways of using it to reduce greenhouse gas emissions, generate and use energy more efficiently and even clean up existing contamination.

The intersection of nanotech and the growing "clean tech" industry is important for the nanotech sector and could become equally significant for clean tech, according to Duncan Stewart, head of Canadian research at Deloitte Consulting.

Stewart says environmental applications are "the engine that is fueling much of the growth in nanotechnology. If clean tech didn't exist, nanotech would still be in the doldrums."

As it is, it's not yet booming. "I'm not trying to get across the idea that this is a trillion-dollar industry that nobody's noticed," Stewart says. Rather, he argues, 2008 will be an inflection point — in five years or so, we'll look back and realize that this was the year when nanotechnology really started to have an impact on environmental products.

'If clean tech didn't exist, nanotech would still be in the doldrums.'—Duncan Stewart

Over time, that impact could be very significant, according to Arthur Carty, executive director of the University of Waterloo's Institute of Nanotechnology in Waterloo, Ont. Among the possibilities, he says, are nanoparticles that can act as catalysts to convert pollutants into useful — or at least harmless — chemicals.

University of Waterloo researchers are working on several projects aimed at using nanotech for environmental benefit.

Eric Prouzet, an associate professor of chemistry, is using nanoengineering to build ultra-fine membranes. One way these can be used is to extract carbon dioxide, a key contributor to global warming, from the emissions of fossil-fuel power plants.

Prouzet is part of an international consortium of academic and private-industry researchers called Nanoglowa that is seeking to use nanostructured membranes to capture carbon dioxide. This approach is much less costly than existing scrubbing techniques, the consortium claims.

Prouzet says this kind of international collaboration is vital to solving environmental problems using nanotech. He said he hopes the carbon dioxide extracted from fossil-fuel emissions using nanotech membranes can be fed back into another process that uses it to generate biodiesel fuel from algae. Waterloo's Centre for Advanced Photovoltaic Devices & Systems is working on ways to make photovoltaic solar cells more efficient using nanotechnology.

Siva Sivoththaman, a Waterloo professor of electrical and computer engineering and director of the centre, says the focus is on practical advances that can be incorporated into existing manufacturing processes at a reasonable cost. The shorter-term projects focus on silicon nanowires that will absorb sunlight more efficiently than existing technology and on silicon nanocrystals that promise both better sunlight absorption and more efficient conversion of light into electric current.

In the longer term, he says, other materials such as cadmium selenide will be able to provide better performance than silicon, but there is a lot of work to do in dealing with issues such as stability and toxicity and developing efficient manufacturing processes.

Sivoththaman believes the lab's silicon nanomaterials work can produce commercial results in the short term — within less than five years — while some of the other projects will yield results in five or more years. He expects it will take between five and 10 years for solar energy, aided by nanotechnology and other improvements, to become cost-competitive with traditional energy sources.

Nanotech printer toner could save energy, ink

While much of the work on nanotechnology and the environment today is being done in university laboratories, there is some activity in private industry, too.

MemPro Ceramics Corp. of Copper Mountain, Colo., is using nanotech in catalytic filters that can be used to clean exhaust from anything from small engines such as those on leaf blowers to coal- and natural gas-fired electricity generating stations, says John Finley, president and chief executive.

The products are based on extremely thin nanofibres coated with a catalyst that reacts with nitrogen oxides and other harmful substances. MemPro licensed the technology from researchers at the University of Akron in Ohio, Finley says, and is just starting to market it.

A new type of toner used in printers and copiers significantly reduces the amount of energy used in toner manufacture and also roughly halves the amount of toner needed to print a page. Toner — fine black or coloured powder that gets bonded to the page during the printing process — used to be made by grinding larger pieces of material to dust. A nanotechnology technique called emulsion aggregation builds up toner particles out of molecules.

Developed at the Xerox Research Centre of Canada in Mississauga, Ont., emulsion aggregation is how the toner for most of Xerox's colour office printers is made today, and the company plans to implement the method across its product line within five years, says Patricia Burns, laboratory manager for materials synthesis and characterization at XRCC.

Building up the particles this way uses 25 per cent less energy, she says, and because the particles are smaller, it takes half as much toner to print a page. Besides reducing energy consumption, this means less waste toner going into the garbage, Burns notes.

Nanotech isn't having a major impact on efforts to address environmental concerns yet, Stewart admits, but one or two significant breakthroughs, such as a really good storage battery or a technique for cleaning the exhaust from burning fossil fuels, could make all the difference.