December in the Geothermal
*Note the air intake in the back left and air returns to the right. See picture below for what the system looks like undergound.
Welcome to “Dirt in the Field,” our debut platform for producing insightful content about farming, home gardening, ethical food production, land conservation, our community, and so much more! Stay tuned every month for our latest content. Thank you!
For environmentally-conscious farmers and home gardeners alike, our experience provides us insight into striking a harmonious balance between nature and human production. At Orchard Hill Organics, we implement methods and technologies both ancient and modern to achieve this balance. One such modern technology is our geothermal greenhouse, where we capture solar energy throughout the summer to extend our shoulder season and reduce our carbon footprint!
The OHO Farm Crew
Earth’s soil acts as a vast thermal reservoir – for example, when cold air moves in over an area of previous warmth, the ground releases its heat to balance the new, colder ambient temperature. This process creates our morning fog! We utilize natural systems to minimize waste energy. Take for example, our geothermal greenhouse system.
The Earth Battery
There are 2 zones that compose the GHAT (Ground to air) greenhouse system. Pictured here was the first level of the air manifold system being installed. Hot air is moved into the system where the heat is transferred into the soil to be used at a future date.
In a typical greenhouse, heat from the midday sun is stored overnight, which raises the overall temperature and protects the plants. Now, imagine this concept over the course of an entire season. Geothermal greenhouses capture heat from the summer months, store it in the soil, and utilize it raise the overall temperature of the interior during the shoulder season. Geothermal greenhouses thereby extend the harvest season while reducing the need for fossil fuel heat and other environmentally degrading inputs!
Our geothermal greenhouse uses an earth battery system to capture and store heat. To put it simply an earth battery is a heat exchanger capable of moving thermal energy from one place to another, in this case via air that is circulated between the greenhouse and underground. During winter the temperature underground is higher than surface temperatures so when air flows down it returns warmer. In the summer the temperature underground is lower than surface temperatures so when air flows down through the system it returns cooler. By utilizing this natural temperature gradient, we are able to heat and cool the green house in a way that’s much more efficient and sustainable than traditional heating and cooling systems.
In addition the system is capable of storing massive amounts of energy from the sun during the growing season, like a battery, rather than exhausting it via vents like most traditional high tunnels. We use this stored energy to heat the greenhouse during colder months rather than rely on fossil fuel. Insulation installed around the perimeter of the green house prevents this energy from leaking out of the system. Comparable systems can store millions of BTUs!
At Orchard Hill Organics, we explore new technology and revive ancient practices to strike our harmonious balance between nature and human production. See for yourself at our Orchard Hill Instragram, or taste for yourself by shopping at our Orchard Hill webstore and visiting us in person at our winter markets!
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