As with most little things that don't behave as we expect them to, nanocrystals pose unique challenges. Take gold, for example. We recognize this particular metal for its signature golden color. If you were panning for gold, you would recognize even a small fleck of gold by its color. Reduce this fleck to a nanometer, though, and you will not be able to recognize it (even if you could see a nanocrystal). It will turn blue-green or red because the nanocrystals, since they are so small, are almost entirely surface area. This greater ratio of surface area allows the metal nanocrystals to absorb colors instead of reflecting them [source: Boysen].
While this little fact may impress your friends at parties, this knowledge -- that nanocrystals follow different rules than other matter -- could also impact the world's fuel sources. Not only can nanocrystals take on different qualities than larger particles of the same material, but they react differently with other elements. The smaller the particle, the more atoms it has at the surface; the more atoms at the surface, the greater the surface area and the greater the ability to interact with other elements.
Think about it like this: You're swimming in a cylinder of water that is deep but not wide. You can touch the edges of the cylinder by simply outstretching your arms and legs like a starfish. Then you decide to swim laps in a shallow pool the size of a basketball court. All things being equal, you'll come into contact with more of the water's surface area if you paddle around the shallow pool than float in the deep cylindrical one. That's how nanocrystals work, too. Their many small particles have more surfaces exposed to other chemicals or elements, which can lead to a greater rate of chemical reaction
This greater surface area makes nanocrystals good catalysts, or substances that enable chemical reactions. When used as catalysts, nanocrystals can increase the rate of a chemical reaction without undergoing changes themselves. This means nanocrystals can convert raw materials into fuel at lower temperatures than other catalysts might. Conversely, nanocrystals make it possible to burn more fuel at a lower temperature.
Nanotechnology could make existing alternative fuel technology more viable. For example, corn is converted into ethanol, an alternative non-fossil fuel. But by the time the corn germinates and is irrigated, harvested, transported and then converted into ethanol, the process is not particularly cost- or energy-efficient. By using nanocrystals as a catalyst, an army of enzymes could efficiently and quickly dine on waste materials like wood chips or grass and convert them to ethanol [source: Understanding Nano].
There's just one problem, though. Nanoparticles, while naturally occurring, are more difficult to purposefully manufacture. Researchers haven't quite figured out a way to harness nanoparticles, let alone mass-produce them. When they do, we could have a renewable, efficient and inexpensive power source -- one that could potentially result in lower energy bills and vehicles with greater engine mileage.