Mini Unit Generates Emergency Essentials

Aug. 30, 2006 — A power generator that not only produces electricity but also refrigeration and water could help fulfill basic survival needs when disasters such as Hurricane Katrina wipe out utility stations.

The heat-operated refrigeration system, developed by University of Florida engineers William Lear and Sherif A. Sherif, could offer a new paradigm for power companies that typically build large plants to service thousands of customers.

Instead, the closet-sized generators would produce power, water and air conditioning for smaller communities such as apartment complexes, hospitals and warehouses — even neighborhoods. It is compact enough to fit inside a military jet or large truck, and is designed for use in war zones, hurricanes or other disasters.

The generators would be owned by the local utility company and connected to the power grid. And unlike large backup generators that are turned on only during emergencies, the University of Florida machines would run regularly to augment electrical needs during peak load demands, such as in the summer, and also work as backup generators during blackouts.

"It's more integrated and more useful all of the time. And in an emergency it's doing it all," said Lear.

In the aftermath of Hurricane Katrina alone, as many as 2.6 million homes and businesses across Louisiana, Mississippi, Alabama, Florida and Georgia lost power. For the 10,000 crews that arrived to provide assistance, the lack of food and water significantly hampered restoration efforts, according to a Hurricane Katrina situation report issued by the U.S. Department of Energy's Office of Electricity Delivery and Energy Reliability.

A system that provides power and water as well as cool air and even ice could go a long way to support both survivors and emergency responders.

The compact power plant will be designed to run on hydrogen, conventional fuel and even biomass.

"You have a fairly efficient generator as it is, it would beneficial if the fuel source was from a renewable activity," said John Masiello, manager of energy delivery services at Progress Energy Florida, the electrical utility servicing parts of central and western Florida.

According to Masiello, Florida recently purchased a power plant that generates 130 megawatts from a liquid crude made from bamboo-like grass.

Lear's mini power plant works similar to a conventional gas turbine generator. However, he and his team added components to change how the air flows into the engine.

In conventional systems, the air flows in at outside air pressure and temperatures. The air is compressed, the fuel added and then both are ignited. The resulting hot gas expands rapidly to turn a turbine. The turbine turns a coil inside a magnet to create electricity. Excess heat and polluting emissions escape out the exhaust.

Lear's system compresses and cools the air before the fuel is added, which helps increase the machine's efficiency. The gas still expands and does the job of turning the turbine.

The excess heat is not spewed out as exhaust, though. Instead, it is sent  through a component called a vapor absorption refrigeration unit that cools and condenses it into water vapor.

The vapor can be collected as water and the cooled air is recirculated back into the system, which helps to significantly reduce polluting emissions.

While the new unit is efficient, it's certainly not a perfect solution.

Incorporating the units into a large power grid could be a challenge for utility companies, though, said Masiello, as it would add to the cost of maintenance and refueling.

And in a catastrophic emergency, such as a Katrina, which flooded utilities with several feet of water, even backup generation may be rendered useless.