Research Today for DG Tomorrow

Today's researchers are investigating a range of options for distributed generation (DG) that could have a big impact on the building operations of tomorrow. Technologies being investigated could mean less expensive installation and significantly easier ongoing maintenance.

Thermionics revisited. One long-elusive goal for power engineers has been the conversion of waste heat into electricity without the use of a turbine. While devices capable of this do exist, their poor efficiency has made them unmarketable. However, researchers at the Massachusetts Institute of Technology and Salt Lake City-based Eneco, Inc., have developed a new approach to a longstanding design to boost efficiency significantly.

Using the principle of thermionics, two parallel conductive plates are separated by a vacuum gap in a high-temperature tube. Heat is converted to electricity as electrons boil off the first plate (the cathode), cross the gap and are absorbed by the second plate (the anode). In this version, however, the gap is replaced with a multi-layer semiconductor. The resulting "thermal diodes" are highly efficient and function at an acceptable 392ºF to 842ºF.

Reformulating fuels. The need to reformulate fuels other than hydrogen to power fuel cells may no longer be necessary if research at the University of Pennsylvania pays off. Chemical engineers there have developed a penny-sized fuel cell that runs on liquid diesel, without need of reformulation. The diesel is injected into the device in a manner similar to that used by fuel injectors in automobile engines. The eventual goal is a 5-kW fuel cell that could be used in residential or small commercial construction.

DG Hydro Power. Another promising DG development is a patent-pending device from Internal Command International, Inc., Tampa, Fla. The Energy Commander III converts water flow at typical residential or commercial pressures into electricity and pressurized air. The valve multiplies the existing municipal pressure to create energy that drives a small generator, without noticeably affecting the pressure of water coming out of the faucet. In a typical 2.5-person household, the device is said to generate 550 watts of power over a four-hour period.

From Pure Power, Summer 2002.