New Mexico Grower Saved by the Sun

Perched at the edge of the Sonoran desert, Don Bustos' family farm has always been endowed with ample sunshine and daylight. However, the New Mexico grower had long been bedeviled by cool temperatures that limit the growing season to four or five months. With the short season and rising fuel costs threatening his ability to support his family, Bustos decided to tap nature's own unlimited and free energy source: the sun.

Heating a greenhouse with solar power was a logical choice for Bustos, who incorporates principles of sustainability throughout his three and a half acres of certified organic land in the small town of Santa Cruz. "I wanted to be more light on the earth and use energy more consciously," said Bustos, who grows more than 72 varieties of horticultural crops.

Bustos also had a powerful economic incentive: One winter, he received a $700 gas bill for one month's heat for the greenhouse. Thanks to a SARE grant, Bustos was able to test a root-zone thermal heating system.

To minimize costs, Bustos picked up recycled solar collectors from a building demolition site. Heating fluid runs from the panels through a closed-loop system of buried copper tubing to an underground tank just a few feet away from the panels. The tank's warmed water is circulated through plastic tubes under the greenhouse's beds, raising root-zone soil temperatures to a comfortable 48 to 52 degrees.

The first season was extremely successful, cutting annual heating costs from $2,000 to zero and increasing yields 30-40 percent over those from the standard cold frame. The only ongoing costs related to the solar heating system are a $5 monthly electricity charge for two water-circulating pumps.

Thanks to the solar-heated system, Bustos can produce a steady supply of vegetables and greens from October to March. During frigid nights, Bustos uses sheets of polyester to create heat-retaining igloos over the beds. The system even works in reverse: When the soil is too hot during summer, Bustos runs the pumps to circulate water now cooled by the geothermal properties of underground storage.

Bustos has a solid, local market for his winter crop thanks to a strong collaborative effort among the New Mexico Department of Agriculture, private citizens and farmers that permits the Santa Fe school district to buy directly from growers. This helps him cut transportation-related energy use and adhere to his philosophy of marketing his food within 28 miles of his farm. Bustos is investigating how to get entirely off the grid by increasing energy efficiency, expanding the solar panels to the house and filling his tractors with biodiesel.

For Bustos, the solar greenhouse and its economic benefits fit perfectly with his philosophy of keeping the land in the family. "We wanted the ability to retain our land for future generations and not have to develop it into houses," said Bustos.

Want more information? See the related SARE grant(s) FW05-011, Solar Energy for Sustainable Year-round Production.