Minature Jet Engines to Power Future Mobile Devices

New Scientist has an interesting article about a mob at Georgia Institute of Technology who have created a mini jet engine that works within silicon wafers. These guys have successfully created a small engine that produces enough electricity to power small mobile devices and this is using the research demonstration version. The key benefit of these microengines is that they take up less space than current fuel cell technology that is starting to appear in commercial applications. I am always for devices that can extend the life of my gadgets but what are the environmental issues of these microengines when compared with conventional batteries even though current batteries also contain highly toxic materials.

Links
New Scientist article on Miniature jet engines