Passive Solar Semi-Subterranean High-Tunnels

Having lived in Mediterranean climates, we have experience growing such amazing fruits like Avocado, Citrus, Kiwi, Persimmons and Pomegranates plus some subtropical fruit like Guava. A high tunnel gives the opportunity to bring that knowledge further north and make it possible to grow tender plants locally. Along with producing local produce, it would become a destination for people to visit, learn and host educational events.

Imagine: The hig tunnel ‘floor’ would be excavated down to 6’ to create a protected and insulated subterranean growing space while the top portion (the arched metal and plastic part) is built over the excavated area and at ground level. A rainwater catchment system of gutters would run along both sides of the greenhouse and empty into 2 sunken 1700 gallon cisterns located on either side of the tunnel. The cisterns would have solar pumps attached to plumbing for an automated drip irrigation system inside. The goal is to make the high tunnel completely off grid and self-sustainable regarding electricity, heating/cooling, and water in both the summer and the winter. Because it is subterranean, we’re taking advantage of the natural temperature control of the surrounding soil to reduce the need for electricity to heat and cool the growing area (the most expensive part of running a greenhouse).

In ground planting areas would be prepared using biochar and compost amendments. Planting would take on a sustainable and lower maintenance food-forest route to reduce need for outside fertilizing, herbicide and pest control. We’ll create a high-yield habitat for temperate and subtropical fruit. In addition, our honey bees will live in the protected environment of the high tunnel, reducing the likelihood of hive die-off during winter. The bees would pollinate the plants all year round (especially in the winter flowering months for citrus) while also having access to outside pollination in warmer months.

To have warmer climate fruits available as fresh fruit in a colder climate rather than shipped from hundreds/thousands miles away reduces GHG/unnecessary fossil fuel use and keeps it local. The transportation related GHG emissions alone associated with sub-tropical and warmer-climate fresh produce is significant; between 0.3/kgCO2e/kg and 0.7/kgCO2e/kg. Most produce transported throughout the US (especially inland areas) is done by truck. Not only would our methods reduce emissions, the local and seasonal aspect would reduce potential emissions.