Energy
Working towards Carbon-Neutral.
Emory Knoll Farms is working towards being a 100% carbon neutral company. How are we doing it?
Solar and Wind Energy
The Grid:
Our ancient, creaky solar photovoltaic array still cranks out 1,200 Watts of electricity on a sunny day. When we started the nursery, this was enough to spin our meter backwards on most days. But as we’ve grown, we’ve added people and therefore computers and servers, finished rooms with light fixtures, printers, and pumps. Our current draw on the grid has become far more than our original solar array puts back. To complete the renewable energy component of our electric consumption we now purchase 100% wind energy from CleanCurrents.
Solar Irrigation:
We’ve implemented two solar irrigation systems. The first uses a small solar powered well pump to pump water into a reservoir. The overflow from this goes into a fish-pond in one of our greenhouses, and from there into a pond, where it recharges the ground water. Gravity and an AC booster pump provide water pressure from the reservoir.
The second solar system is more sophisticated, and supplies most of our water needs. A powerful solar well pump feeds water continuously into 4,000 gallon of water tanks. A float switch automatically shuts the pump off when the tanks are full. Another solar array charges a bank of batteries. The batteries then provides energy to a pressure booster pump, which charges our pressure system. A network of buried pipes brings the water to our greenhouses and outdoor storage areas. All of this is in an area where there is no grid energy available, so reliability of the system is a must.
Heat
For the past three years, we’ve heated the nursery – 4 greenhouses and our offices with waste vegetable oil. The oil comes from local restaurants, and is diverted from the waste stream (Re-use!). It is stored and used in our 350,000 btu/hour boiler. There are two key concepts to the success of this system: Efficiency and Effectiveness.
Efficiency:
In order to get the heat from the boiler to the plants, it must be moved in some way. While’s it’s possible to put a separate heating unit in each greenhouse, that can be very expensive and unreliable. And there aren’t many choices in smaller heating units that can use a fuel like WVO. SO we use a centralized boiler and we move the heat to the greenhouses by circulating hot water through underground tubing to the greenhouses. It only takes a small (1/10 HP or so) circulator pump to move a lot of heat from one place to another. And the boiler itself is very efficient too.
Finally, we heat only the smallest space necessary to keep the plants in our propagation greenhouses growing through the winter i.e. not the entire space within the greenhouse. The plants sit directly on the heated benches or heated floor, and the roots are kept at a constant warm temperature. The air in the greenhouse may go below freezing in some places, but the plants are quite content in their warm zone. This minimizes the heat loss in the greenhouse and results in an area in which plants can grow year-round with a minimum amount of energy input.
Effectiveness:
To us, effectiveness means that the system provides the same features we believe are important for us. Our heating system needs to be reliable, economical, and serve the horticultural needs of our plants. The description above is only a partial story. The WVO boiler is a primary boiler. We also have a smaller, fuel-oil boiler located near our greenhouses that works in conjunction with the primary boiler as a backup / auxiliary heat source. If the primary boiler stops operating for any reason, the secondary boiler will come on and continue to heat. And in extremely cold weather the secondary boiler will operate along with the primary to provide enough heat to maintain our plants. The secondary boiler uses a different fuel source (in this case, petroleum fuel oil), in case the primary boiler has a fuel related problem.
