Five-acres of photovoltaic solar cells supply much of the electricity to run pumps and climate controls. Thermal systems collect solar heat and warehouse refrigeration exhaust to warm the greenhouses on cool evenings. Together, the two systems generate 2.1 megawatts of electricity, enough to power 1,500 homes.
"We believe this is the first greenhouse in the world that is energy neutral," Houweling said.
Houweling envisions a day when greenhouses dot California's lush coastal plains, taking advantage of the abundant sunlight to grow thirsty crops such as lettuce and strawberries, using renewable energy to reduce their burden on the environment.
Until recently, that was a pipe dream. The cost of heating and cooling these structures was prohibitive for all but the highest-value specialty produce. The nation grows less than $1 billion worth of greenhouse fruits and vegetables annually.
But the rising expense of traditional farming is fast narrowing the cost gap. California farmers are coping with years of drought. They're also grappling with land degradation, an unstable migrant workforce and rising shipping costs.
"We are closer to parity than we have ever been," said Gene Giacomelli, a professor of agriculture and biosystems engineering at the University of Arizona in Tucson.
Houweling's greenhouses are at the leading edge of the type of facilities farmers will increasingly rely on for production, Giacomelli said.
Designed by Kubo Greenhouse Projects, a Dutch company, the temperature- and humidity-controlled glass-sheeted farm is expected to produce 482 tons of tomatoes per acre, 15% more than Houweling's previous generation of greenhouses. The plants live far longer than field crops and are replaced every six months.
Still, a shift to more greenhouse farming will be slow.
"Houweling is doing the demonstration," Giacomelli said. "He is going to have to prove to himself and his banker that this is the way to go."
Although they need just a fraction of the land taken up by conventional farming, greenhouses require far greater capital investment. The expansion to Houweling's Camarillo farm -- which includes the two greenhouses; the climate, energy and environmental technology; and a new packing plant -- amounts to about $1 million an acre, not including the land.
Houweling said he expected the investment to take as long as 10 years to pay off, depending on the price of tomatoes. More tomato-linked salmonella scares and bad weather during the growing season in Florida would shorten the pay-back period.
