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Raytheon Technology Protects Crops From Frost
Date posted: 03/16/2009*
The Tempwave system uses Radio Frequency (RF) waves to deliver energy directly to the crop without heating the air.
As part of a strategy to apply existing defense technologies to solving some of humanity’s major challenges, Raytheon is taking the fight to the frost with a new system using radio frequency technology adapted from the company’s legendary radar systems. Raytheon’s Tempwave™ radiant heating system offers a more efficient way to warm crops and avoid the adverse effects of frost on the growing season. The prototype was installed and successfully operated in a California citrus orchard in February 2008.
The Frost Problem
When temperatures fall below freezing, sensitive crops can be damaged or destroyed and it happens in places not thought of as having cold climate. In January 2007, California experienced several successive nights of sub-freezing temperatures across much of the state, resulting in $800 million in crop losses. Navel oranges were hardest hit, but other crops like strawberries and avocados also suffered. Frost protection methods are widespread and consist of various passive and active techniques. These methods have been in existence and have evolved for more than 100 years. But in this particular event, they were not up to the task. In California, growers needing active protection methods generally resort to wind machines and irrigation, both of which work most of the time. Those systems have been installed in places where most of the freezing events are within the system’s capability. In other words, the capability of frost protection methods has defined where crops can be grown.
How It’s Done Today
Wind machines mix the stratified air present in a radiation frost, forcing the warmer air aloft toward the ground. This method is widespread and successful, although its effectiveness is limited by the energy available in the air at the ceiling height. Another technique is irrigation, which uses the latent heat of fusion to deliver energy to the crop. Sprinkler use can damage crops and water is often scarce, but the method works well. Fuel heaters are another technique not used much today due to high fuel cost. The fuel heaters heat the air, which then rises and creates an upward flow. Some of the energy is transferred to the crop by convection, but most of the energy is wasted.
The Tempwave Approach
The Tempwave system delivers energy directly to a crop without heating the intervening air. It works to prevent freeze damage in both radiation and advection frost events. It uses no water, emits no smoke (like fuel heaters do) and is silent in operation. Unlike a wind machine, Tempwave does not rely on environmental conditions for its effectiveness. It has the potential to redefine the way frost protection is delivered.
Tempwave Benefits
- Frost protection is guaranteed, limited only by input power.
- Frost protection is practical in advection events, opening new acreage for cultivation.
- Autonomous, intelligent computer operation reduces labor costs and improves performance.
- Complements irrigation methods and wind machines, providing flexibility in installation and operation costs; it can also stand alone.
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