Sweet Radish
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The Final Report
🕑 Added 2024-01-01 18:19:32 +0000 UTCI decided it would be a good idea to copy and paste all the final report questions into my notes so I could write a really thorough and detailed report in my own time without worry about internet failure or accidental premature submittal. Upon copying and pasting my answers into the official online report form, I realized there was a word limit on each report question. Hours were spent into answering each question with meticulous thought. None of it needed. The whole process was set up for farmer's just trying to get a report in. This is what my answers looked like in the end:
Two bluetooth hydrometers in the air and soil which we track through an app on our phone, a child thermometer, mechanical pressure gauge and thermometer installed in the storage tank to monitor the temperature of the sub soil system.
Built a functioning hub, h2o storage and insulated growing space, extended our typical growing season, maintained a temperature of 40 degrees into December, canned and then delivered winter harvest grown on renewable energy to La Tiendita Food Pantry.
The solar heated hydronic system is most effective when it is well insulated. Renewable energy can be used more generously and without impact to the environment. Adapt, customize and join resources to create successes.
This project has created a space where we can grow produce year round which will increase our farm income. It helps our farm qualify to be a part of NRCS Conservation Stewardship Program by adding to our ongoing conservation initiatives.
We were able to send produce harvested to the La Tiendita Food Pantry which is the closest pantry location to the St. Benedict's homeless encampment. Our organic produce will be directly available and accessible to low income residents.
The process went much quicker than expected. The only difficult part was editing down our bounty of data and information to fit within the maximum words allowed for each question. The reporting process has been very easy.
For anyone interested here is the full final conclusion.
Solar Powered Hydronic Heated Greenhouse
Fieldwork Project: Final Notes/Conclusion
We used hydrometers installed in the air and soil on the interior and exterior of the building. We installed two bluetooth hydrometers which we track through an app on our phones. One hydrometer sits low at the stem growing base of the greenhouse and the other is installed directly sub-soil. They collect data on temperature, humidity and dew point 24 hours and are equipped with an alarm setting which alerted us to any severe temperature conditions within the greenhouse. We used a simple mechanical pressure gauge and thermometer installed in the solar storage tank to monitor the flow and temperature of the sub soil hydronic system. We also used a simple children’s forehead thermometer to check the closed glycol (antifreeze) loop which passively heats the water in the storage tank. We used data from the world weather system for Antonito to compare the overall outdoor temperatures. We monitored the plants inside the greenhouse daily, taking note of any stress. We measured our water conservation using an automatic solar pump drip system installed in a 5 gallon bucket. We started out on the lowest setting of watering every 48 hours and dispensing 5 minutes of needle drip directly placed in the soil at each plant. Our daily goal is to keep the soil between 70-90% humidity and the air 50-70% to achieve the best results from the heating system. Maintaining moisture content in the soil and air is important since heat is held in by moisture and it also helps us conserve water by keeping the greenhouse humid. We are using mulch to maintain soil moisture and temperature, focusing heavily on insulation. We use the hydrometer data to determine where there is heat loss and add mulch as needed. We are able to track the amount of solar/wind power we are generating each 24 hour period through our system controllers. This also gives us an idea of how much energy we need to produce and store in batteries on cold days/nights in order to maintain the temperature in the greenhouse. We are keeping a small worm farm inside the main planting bed who are very telling when it comes to temperature and humidity. The hydrometers would further confirm a drop in temperature overnight. We focused on the amount of heat we need to generate inside the storage tank on a short winter day to successfully keep the greenhouse warm overnight until the sun eventually rises and heats the greenhouse again. Since we cannot control the amount of heat the system can produce in a day we focused on optimizing the system by adding insulation as needed in the soil and walls of the greenhouse.
We have successfully extended our typical growing season and maintained an air and soil temperature of 40 degrees into December. The caveat to that is that the system can only perform as well as it is insulated. The water systems and Solar Water Pump are fully operational and are providing a reliable stream of water into the storage tanks from the main solar water pump. The sensor works and effectively turns on the well pump maintaining the tanks at full capacity when cold or hot water is accessed externally. We installed a separate passive solar hot water system on the exterior which uses propylene glycol (non-toxic antifreeze) running through insulated black panels and into a heat exchanger unit. We modified the system to fit an existing copper coil inside a hot water storage tank. This gives us passive solar hot water that is freeze protected. We also installed a 1000 watt solar/wind hybrid system with batteries to run the circulation pumps on the hydronic system day and night to prevent freezing. Our lowest drop in the soil was 35 degrees which did not seem to affect the growing plants or the root system. We planted ever-bearing raspberries, dwarf apples, mint, onions, roses, asparagus and mullein so far as our test plants. There’s a good range of sensitive to cold hardy plants growing. The apples went into hibernation in November possibly because the upper canopy of the greenhouse is much cooler at night. Everything else continues to be green and the raspberries most recent fruiting was in November. We are hoping that adding as much insulation as we can and increasing the thermal mass barrier thickness on the exterior by at least a foot will compensate for the yearly -40 degree week we have in late winter.
On hot days the system regularly heats the propylene glycol to 105 degrees which we found will heat the 80 gallon hot water storage tank within 80-100 degrees by noon. The storage tank is insulated and designed to hold the temperature for 24-48 hours. With the system going in and out the soil there is some extra loss in heat. We observed that the tank cools down to around 40 degrees by morning which is perfect timing for the closed glycol loop to start warming up. With a minimal addition of external heat and thick insulation the soil will stay warm enough to grow during external temperatures as low as -5 degrees. We believe the system will work best in the future with an additional top soil heat source either via an electric heater connected to the existing hybrid system or by connecting a water heating element in place of the dump loader from the wind turbine to boost the tank temperature. The hybrid system tends to create an excess of energy especially on windy days. These days tend be the biggest days of heat loss. That extra energy can be redirected into an electric heater unit and/or also be dumping the excess wind load into the solar storage tank which has a hybrid heating element available. Heating the water versus the air still seems to be the ideal way to heat the area since it will hold the heat longer and help maintain the humidity year round. Heating the soil is very important and did maintain a suitable temperature for the low growing plants but in order to achieve optimal growing the upper canopy will also need to have an external source of heat on extra cold nights, which will be achievable by adding canopy level hydronic tubing into the sub soil system. Most days are sunny and no heat is needed during solar hours. We are measuring the success of the system based off the well being of the plants being grown/harvested and any observable wildlife still active. After performing this research we noted that the plants do not always need as much warmth as we initially believed to thrive, a well insulated growing space can be heated without the use of fossil fuels and wind creates a heat loss issue which can be solved by harvesting wind energy. We delivered our first harvest grown on renewable energy to La Tiendita Food Pantry. We processed and canned 24 servings into ready to eat shelf stable food. Sharing freshly harvested and processed organic food with members of our community in the middle of December was one of a few milestones we celebrated during this project. We believe the project is an ongoing success with a lot of trial and error and no real instruction manual.
The biggest takeaway from this project was that the heated hydronic system is only as good as the insulation around it. We learned at what point the frost will penetrate the greenhouse and affect stable growing temperatures and how much linear footage of hot water tubing is needed to create a rise in the temperature overall. It’s more cost effective and safer to use a variety of energy generating systems working in unison rather than installing a large high wattage system or fossil fuel operated system. The renewable energy can be used more generously and without impact to the environment. This is what we put together
1. Well Pump System Solar (operates the sensors and charges batteries for night access + pumps water up from the well)
2. Solar Hot Water System (Passive Propylene Glycol circulates through enclosed panels and transfers heat into a storage tank)
3. Sub-soil Circulatory Pump System (Hybrid Wind, Solar system circulates water and generates additional power for heat, lights, etc. Solves high wind heat loss issue).
We installed a special solar system dedicated to pumping the water up from the well which draws a strong current at 200’ depth. With the sensors and switches it was better to keep the well pumping system (Solar Pump) separate from the circulatory system (Hybrid wind/solar). The Passive Solar Hot Water system recirculates a non toxic antifreeze (propylene glycol) through insulated panels and transfers heat into a solar hot water storage tank inside the greenhouse. From this tank the water is circulated through the subsoil tubing and is accessible top soil for future aquaponics or a fish tank. We can predict the amount of hot water we need to produce and maintain in order to heat the entire square footage of the greenhouse soil and top canopy through a cold winter night. We learned repeatedly that insulation is our most powerful tool. By embracing wind energy we opened up possibilities we hadn’t previously considered. We learned that the hybrid wind/turbine system creates a reciprocal balm to the nighttime temperature issues we encountered in the greenhouse and can provide more power and heat than we originally projected. This project has been a huge level up in our knowledge of Solar/Wind Power capability, Renewable Energy, Electricity, Plumbing and Automotive engineering. This creates a distinct scenario where we are joining mechanical equipment with plumbing equipment. There are many adaptors that exist but are hard to access which we had to test through trial and error. We are creating a .pdf document containing all the parts and providers we used so that a second system can be bundled into a kit that has everything from the tubing to each adaptor needed to connect the entire system. We combined the storage tank from an evacuated solar tube collector with a solar panel collector which saved money and time. The panels are also much less fragile than the glass evacuated tubes and can be mounted any where there is solar gain. The Solar Hot water system we used was originally created for a standard home to boost the water tank heat. We bypassed the heat exchanging unit and plugged directly into the existing heating coils on our storage tank. We used adaptors to create a successful marriage between systems. The solar hot water system can be used in many agricultural applications such as daily water thawing on stock tanks, boosting barn temperature and heating an aquaponic system.
Comments
Sweet Radish
Thank you!!! I’m so glad it’s finished!! Our Raspberries are from handpicked nursery .com also on Amazon. It’s veteran owned. The variety we have is one of their “everbearing thornless” ❤️
Cindy Grainger
Nice to see the finished product! Looks so cool on the outside! I need the name of your rasberry supplier!
Sweet Radish
Thank you so much! 🥰🙏🏽❤️
Patricia L. Meek
Wow! Congratulations!! That's A LOT of work. What an accomplishment!
