How much electricity does a freeze dryer use?

We are often asked "how much does it cost to run a freeze dryer ?"

On average, the average consumption ranges from 700-1200 watts per hour. Fundamentally, the variation is caused by the freeze dryer's type, size, and operating parameters. For example, a medium-sized freeze dryer might use 350-400 watts per hour during freezing, and about 800 watts per hour during drying. 

Energy utilization depends on freeze-drying cycle time. Foods with more moisture need longer cycles. Soups, raw fruits,  and meats containing a lot of water need longer sublimation times to preserve their structure and nutritional content. On the other hand, freeze drying cheese, greens, etc takes a shorter drying time because of low moisture and thus consumes less electricity. 

Phase-by-Phase Breakdown

Freezing Cycle

Only the compressor is running in the freezing cycle, and it draws 4-8 amps initially depending on the size of the home freeze dryer. Power utilization averages 350-400 watts during this period for a medium sized home freeze dryer.  This cycle lasts 4-12 hours, depending on the amount of food in the freeze dryer, until the drying cycle is triggered. So the it takes about 1-4 kWh.  Food may be pre-frozen to reduce the initial freezing time to save energy. It is required to run the compressor for 1 hour to freeze the chamber before customer put in the frozen food. In this scenario the electricity use would be 0.5 kWh. 

Main Drying Cycle

Drying adds operational complexity. The freeze dryer uses a vacuum pump, refrigeration, and intermittent resistive heaters under the food tray shelves. For a medium sized home freeze dryer, the max power draw when the heater is on is about 1100-1300w. When the heater is off, the power draw is about 500-700w. Energy usage averages 700-900 watts. The length of the drying cycle also depends on the amount of moisture in the food and how well the heat transfer from the shelf to the food.  A medium sized home freeze dryer usually extract 0.5 of moisture per hour from the food.  So for a batch of 8lb of food,  it takes about 16 hours to complete a main drying cycle and therefore about 12 kWh of electricity consumption.

Final Drying Cycle

Finally, the final drying cycle removes any remaining moisture in the food.  For most of the time, the heaters turn on and off to maintain the max shelf temperatures. The heater typically turns on less frequently in the final dry cycle comparing with the main drying cycle.  As a result, the average power usage becomes lower,  in the 700-800W range. This phase uses around 6 kWh of electricity for a factory-set 7 hours. 

Costs Analysis

Cost Per Load: Electricity Costs for Freeze Dryers

So how much does it cost to run a freeze dryer ? Let's do some simple math. As of now the national average electricity rate is 18 cents per kwh.  For a batch of 8lb of frozen food in a medium sized freeze dryer, it costs about 0.5 x 18 cents = $0.09 in the freeze cycle, 12x18 cents = $2.16 in the main drying cycle, and 6x18 cents = $1.08 in the final dry cycle, so a total of $0.09 + $2.16 +$1.08 = $3.33 for a 24 hour freeze drying process.  On average it costs about 14 cents per hour ($3.33 divided by 24hour) to operate a medium sized freeze dryer, based on the national electricity rate.  

Comparison with Other Appliances: Energy Usage

Freeze dryers utilize more energy each cycle than many home appliances. The average refrigerator utilizes 1-2 kWh daily, compared to 18.5 kWh for a 24 hour freeze-drying cycle. Freeze dryers use more power even in energy-efficient versions since they need to retain low pressures and temperatures for sublimation. The durability and preservation quality of freeze drying may help consumers cut food waste and preserve bulk food purchases, justifying the expense.

Energy-Saving Tips

Choosing an energy-efficient freeze dryer is important when considering how much electricity does a freeze dryer use and attempting to conserve energy. Besides, run a freeze dryer during off-peak electrical hours to save more. Pre-freezing food before drying reduces the energy-intensive initial freezing period. Additionally, correctly sizing your loads to match the dryer's capacity gives efficient energy use. Overloading may increase drying times and energy consumption.