The TMRO Science program recently had an interesting long-distance conversation with Paul Zaber, a scientist working with the EDEN-ISS project in Antarctica. The project involves operating a greenhouse in Antarctica to learn how foods can be grown more effectively in a closed-loop environment. This has applications for space habitation as well as for food production on Earth.
The goal of the EDEN ISS project is to advance controlled environment agriculture technologies beyond the state-of-the-art. It focuses on ground demonstration of plant cultivation technologies and their application in space. EDEN ISS develops safe food production for on-board the International Space Station (ISS) and for future human space exploration vehicles and planetary outposts.
Operating a greenhouse in Nebraska may seem to be a far less interesting challenge than doing so in Antarctica but growing tropical fruits and other warm climate plants in a region that often reaches -20°F (about -30°C) in winter is not a trivial accomplishment.
Retiree Russ Finch has developed a clever low-cost approach to keeping the inside of a northern latitude greenhouse temperate year round using underground warmth, i.e. geothermal heat. Rather than a complex and expensive system involving an anti-freeze fluid controlled with pumps and valves, he designed a simple low-cost system with fans blowing air through plastic tubes buried about 2 meters below the surface. The ground at that depth stays constant at about 50°F (10°C) year round. He grows oranges, lemons, and many other tropical fruits and vegetables in his greenhouse.
From the caption to the video:
… retired mailman Russ Finch grows oranges in his backyard greenhouse without paying for heat. Instead, he draws on the earth’s stable temperature (around 52 degrees in his region) to grow warm weather produce- citrus, figs, pomegranates – in the snow.
Finch first discovered geothermal heating in 1979 when he and his wife built it into their 4400-square-foot dream home to cut energy costs. Eighteen years later they decided to add a 16’x80′ greenhouse in the backyard. The greenhouse resembles a pit greenhouse (walipini) in that the floor is dug down 4 feet below the surface and the roof is slanted to catch the southern sun.
To avoid using heaters for the cold Nebraska winter nights, Finch relies on the warm underground air fed into the greenhouse via plastic tubing under the yard and one fan.
For more about Finch’s greenhouse designs, see Citrus In The Snow- Geothermal Greenhouse
Over 40 installations have now been built following Finch’s designs as outlined in his Citrus In The Snow Report.