When the mercury drops, farmers may soon have a new tool to protect their valuable crops.
The tech company Raytheon has developed a 30-foot high antennae that emits low powered radar waves tuned to water molecules.
“This is essentially a radar that doesn’t detect anything,” said Larry Faria, a project manager who helped develop the Tempwave crop warming system. “Tempwave delivers energy to the crops, which is absorbed, and freezing is prevented.”
Currently farmers have several options to protect crops. Large fans can mix warm air across the crops. Sprinkler systems can surround fruit with a protective layer of ice. As a last resort, farmers can start bonfires and then circulate the hot air past freezing crops to prevent individual cells in the fruit from freezing and bursting.
To test the Tempwave’s effectiveness at warming crops, Raytheon, working with a large citrus grower, Paramount Citrus, recently tested the Tempwave system on a quarter acre plot of naval oranges near Visalia, Calif.
During the course of several nights, the temperature in the orange grove dropped to 28°F. Raytheon’s team placed one Tempwave antenna on each corner of the four-acre plot and let them run through the night.
Without any system to warm the fruit, the oranges would have frozen and become unsellable. The naval oranges made it through the night unscathed.
Each of the four antennae emit low powered radar waves tuned specifically to water molecules. Much like a microwave, the radar waves cause water molecules to vibrate and heat up just enough to keep them from freezing.
“We aren’t trying to keep the fruit at room temperature here,” said Faria. “We are just trying to shine enough energy on them so they don’t freeze.”
This winter’s test was small scale. In a full-scale system one antenna would provide enough energy to heat one acre. While the Tempwave system provides just enough energy to stop it from freezing, it’s completely safe for humans to work around.
Among other civilian applications, Raytheon engineers are also investigating whether radio wave heating could be used to incubate chicken embryos inexpensively, instead of using heat lamps. Last year Raytheon developed a similar heating system to heat oil locked inside shale, making it easier to retrieve.
“We are trying to look at world problems, and see if we can adapt core Raytheon technology to develop solutions that can address those problems,” said Faria.
Source: Eric Bland, Discovery News