Solar Energy for Sustainable Year-round Production

SUMMARY

The Santa Cruz Farm & Greenhouse team had an interest in environmentally healthy practices useful in its work and the current market for local, organic produce. In northern New Mexico, the team found it difficult to supply enough produce to its market during winter months to stay financially secure, so they went to work addressing environmental and financial interests.

The team built a solar energy system to use in its greenhouses, resulting in an increase in the team’s supply of organic fruits, vegetables and herbs during winter months through its use of solar energy and financial benefits. It also resulted in circumstances for the team to share its work and the system’s environmental and financial effects with the community.

The team made Santa Cruz Farm & Greenhouses a healthy producer for the environment, more financially secure and an educational resource for its community.

OBJECTIVES

1) Increase the farm’s supply of organic fruits and vegetables during winter months using solar energy.
2) Share results with the agricultural industry by presenting its solar energy system as a reference for others’ work.

RESULTS

The solar energy system implemented at Santa Cruz Farm & Greenhouses is a root-zone thermal heating system made from solar panels, an underground water tank, tubing for two closed-loop circulating systems and necessary pumps and gauges for coordinated circulation. The solar panels take in energy from the sun, which warms glycol fluid and water running through the panels. Glycol is the system’s anti-freeze substance used to keep the water running through the panels from freezing during the winter and steaming during the summer. Additionally, if any leaks occurred in the system, the glycol wouldn’t make the soil unhealthy or dangerous.

From the solar panels 190°-210°F glycol-water fluid passes through a closed copper tubing loop running into the underground tank storing cool water, which increases the water temperature in the underground tank to 180°F. The water in the tank then circulates through plastic tubes running under the greenhouses’ lifted plant beds, increasing the root-zone soil temperature from freezing to within 48°-50°F. This permits the plants to ripen and yield produce.

In addition to the heated water, there are two more insulating sources. The first is a cold frame structure used to shelter plants from wind and cool night temperatures. The second is an additional insulating technique requiring sheets of polyester lining spread over the plant beds at night to direct warmth near the soil’s surface.

Running without any direct fossil fuels, the greenhouse solar system is a clear advance for producers interested in self-sustaining practices. It requires a minimal amount of electricity to circulate the glycol and water through the system and is therefore healthy for the environment and financially sound. The first winter we used this solar system, we cut our fossil fuel expenses down from $1,900 to nothing, and our produce supply increased 30%.

We did encounter some difficult physical and financial issues. Building the system required a serious amount of physical work necessary in finding, repairing and mounting the solar panels, making a circulating pump for the system, digging out the space for the re-used water tank and setting the plastic tubing under the greenhouse beds. For the system’s plumbing and electrical elements, the team found it necessary to outsource to a plumbing and electrical specialist.

The solar system resulted in higher produce yields in the greenhouses during the winter timeframe and, in turn, higher supply to consumers and higher profits for Santa Cruz Farm & Greenhouses. We view this venture as an environmental and financial success.

BENEFITS OR IMPACTS ON AGRICULTURE

The clear and immediate benefit is the plentiful winter yields from greenhouse plants. With this system, the plants endured the entire winter and kept the team financially secure. Because the team had a successful first winter using the solar system, it is currently preparing to assimilate additional medicinal and cooking herbs into the existing 72-plant species in the fields and greenhouses.

The solar system’s additional benefit is its capacity to make rural communities financially viable in the US. It seems solar systems can actually assist in making it possible for men and women interested in agricultural ventures to succeed. The clear increase in plant yields using solar energy promotes higher earning for producers and lessens the amount of fossil fuels required to run greenhouses and transfer food from the greenhouse and fields to actual selling destinations.

PRODUCER ADOPTION

The solar system is so new and unique it is still in an assessment phase for the team and community. During the last nine months, we have led more than 250 guests and industry producers through our greenhouses in three educational tours. Many were interested in the venture and at least seven producers articulated serious interest in studying the system’s setup to discern if building solar energy systems would work in their greenhouses.

REACTIONS FROM PRODUCERS

From evaluations handed out during our educational tours, we learned that 21 farmers found solar-powered greenhouses “quite beneficial” to industry producers and “very beneficial” to the environment.

Specific comments include:

“Solar-powered greenhouses seem as environmentally beneficial as any other manmade structure, possibly more so.”

“I’m unsure I know enough about solar powered greenhouses but can see the applicability for some producers.”

“Startup expenses, initial capital could be a deterrent.”

“I think I will write a grant and try to put up a system myself.”

RECOMMENDATIONS OR NEW HYPOTHESES

Our team found it difficult to make it through our venture with the funds granted. We advise Western SARE to increase the amount of funding per project so seriously interested teams can build systems and actually maintain their businesses with fewer financial stresses.

We also encourage research in the following areas:

1) Making solar panels to cut expenses.
2) Using gravity to lessen the amount of electricity required to circulate water through solar systems.
3) Using photovoltaic sources for supplemental energy required to circulate water.
4) Further studying what plant varieties and species can withstand cool temperatures and intense sun.
5) Increase studying in different insulating techniques used to shield plants from cool temperatures and intense wind.
6) Increase studying regarding higher-efficiency planting and weeding equipment to use in cold frame structures.

OUTREACH

We have presented our solar system and 10,000 square feet of 100% solar energy winter greenhouse space in our “Alternative Energy for winter Food Production: A Tour” practicum series to 250 people. The tours addressed specifics for building the solar system, questions from attendees and advice regarding applying for Western SARE grants.

We have also reached out to the public through a steady stream of newspaper articles in the Santa Fe Reporter, the New Mexican and the Los Alamos Monitor and in a radio interview with KSFR Santa Fe in January 2006.

We have also spent time answering questions at the Santa Fe and Los Alamos farmers markets. Additionally, the team supplied lettuce to 13 schools within the Santa Fe school District and is working with students in youth gardens. The team technically devises and works specifically with the Chimayo Youth Conservation Corps in Chimayo, NM and the Sanchez Farm Project in Albuquerque’s southern valley.