Minnesota recently legalized recreational cannabis – giving growers in the state the green light to apply for cultivation licenses and plan their grow facility design. In order for Minnesotan growers to be successful in the new market it’s important that they pursue innovative solutions to maximize their profits while minimizing their operational costs. That’s why we would like to demonstrate that sealed greenhouse technology offers a compelling alternative to traditional indoor growing methods. To show this, our data engineers have created a comprehensive report that shows the potential energy consumption and plant yield outputs of the SunChamber™ hybrid greenhouse versus an indoor grow facility in Minneapolis, Minnesota.
In this blog we will present the report and how we arrived at our calculations. The numbers given in this report are preliminary and are based on modeling results with assumptions as given in the following sections.
The equipment loads are based on Ceres SunChamber™ designs with the following features: LED artificial lighting (dimmable), recirculation & destratification fans and a fully integrated Heating Ventilation Air Conditioning and Dehumidification (HVACD) system. Energy consumption from supplemental lighting is based on a minimum target Daily Light Integral (DLI) of 35 mol/m²day. The canopy will therefore experience at least this amount of light and up to 55+ mol/m²day depending on the glazing, and time of the year. The DLI target for an indoor grow is kept the same as the minimum DLI for the greenhouse for a fair comparison (35 mol/m²day). This report does not take into account the differences in light spectrum between the sun and LED lights, which can increase terpene levels.
A Client’s specific equipment requirements can differ from our assumptions and can lead to a change in estimated energy consumption.
Assumptions used for this report
- Both greenhouses and indoor have a canopy to floor area ratio of 75%.
- Both facilities operate 340 days a year (to take into account harvest and cleaning procedures).
- LED lights used have an efficacy of 2.7 µmol/J.
- The Daily Light Integral (DLI) is a minimum of 35 mol/m²d (equal target indoor). The additional mol/m²d provided by the Sun is determined by the weather files of the particular location (in this case Minneapolis, MN). Knowing that one mol of photons can yield 0.4 grams of dry flower, we can deduce the increase of yield in a greenhouse compared to an indoor grow room.
- Sales price is US$ 3,600 per lb.
- Electricity cost and flower sales cost are based on current prices but are susceptible to change depending on location, time of the year, utilities, regulations, etc.
- The overall light transmission in the greenhouse is about 81% (conservative) including reductions from glazing, greenhouse framing, and equipment.
Cultivation area: energy and yields comparison vs. Indoor
We assume here a hypothetical efficient Indoor grow with the same type of lighting and HVACD efficiencies as we use for our greenhouses. The total energy usage (lighting, HVACD, plug loads) of the cultivation area of this facility is assumed to be 285 kWh/ft²-yr.
The SunChamberTM uses 162 kWh/ft²-yr. Assuming an electricity cost of 0.14* $/kWh, we can summarize the energy cost savings as shown in the table below.
Furthermore, in an indoor scenario, the Daily Light Integral (DLI) is restricted to artificial lighting capacities (11,900 mol/m² per year). In a greenhouse, not only can we reach the same DLI using less electricity but we can have more DLI when the Sun allows for it. Because if we count every day that the Sun provides more than 35 mol/m², the greenhouse receives an additional quantity of light. In Minnesota, the Sun will give 733 mol/m² every year that an indoor grow can’t achieve. This can translate into additional yields and additional sales as shown below, assuming a wholesale price of 3,600 $/lb of dry product.
*Assumptions on electricity cost and flower sales cost are based on current prices but are susceptible to change depending on your exact locations, time of the year, utilities, regulations etc.
**This is a conservative estimate. The true potential with an ideal crop (ideal genetic, nutrients delivery, environment, growing practices etc) can imply even higher yields. In optimal conditions each mol of photons can yield 0.4 grams of dry flower.
We hope that these energy consumption and yield estimates will serve as inspiration for Minnesotan growers interested in energy-efficient cannabis cultivation. Again, these numbers are preliminary, so we encourage you to reach out to Ceres and get more accurate profit estimates for your specific geographical location and growing needs. The more data you have, the more equipped you are for important business decisions like choosing a cultivation facility and applying for permits. At Ceres, we pride ourselves on our data-driven approach and we will be here for you at every stage of the design and engineering process, ensuring minimal roadblocks and maximum profitability.
Interested in learning more about The Ceres SunChamber™ or getting energy data for your cannabis project? Contact us today!