Demonstration and Commercial Implementation of Energy Efficient Drying for Walnuts

Infrared Walnut Dryer at Emerald Farms in Maxwell, CA.

Infrared Walnut Drying - Saves Energy while Reducing Product Loss Due to Over and Under Drying Nuts

Project Overview

Recipient: UC Davis-Sub of UC San Diego

Program: Natural Gas

Award Amount: $1,118,285

Co-funded Amount: $280,000

Agreement Number: PIR-13-010

Project Term: 6/30/2014 - 3/31/2018

Project Status: Active

Recipient Location:  Davis, CA

Site Location(s):  Maxwell, CA

The Issue

The walnut drying process, the most energy intensive step in nut processing, is a large consumer of natural gas and electricity. Even though the processors have attempted different approaches to reduce energy consumption for walnut drying, the average energy consumption is still high. Walnut drying requires an average of 12 therms of natural gas or 13 gallons of propane and 24 kWh of electricity per ton of dried nuts and inefficient operations may even use twice this much.

Project Innovation

This project demonstrates a novel infrared technology for walnut drying at pilot and commercial scales to achieve up to 25 percent energy (natural gas and electricity) savings and reduce walnut drying time. This new technology uses infrared as an efficient heat source to quickly remove the surface and shell moisture of walnuts, followed by the final drying using hot air. Nuts are required to meet strict USDA standards for moisture content. With traditional methods, walnuts are washed and then moved to large drying bins where hot air is circulated for 12 to 24 hours. The wettest nuts are dried to the safe storage moisture to prevent mold development, resulting in 6 to 8 hours of additional drying time. As a result, nuts with low moisture are over dried. In addition to energy savings, the new infrared technology will improve product quality, and decrease product loss due to over drying. This new technology could also be used for drying other types of nuts.

Project Benefits

As walnut drying is one of the most energy intensive processes, consuming natural gas for heating and electricity for blowers and motors. The IR drying technology demonstrated overall energy savings compared to current drying technology and the potential to produce a superior product. This technology has the potential of increasing the revenue in walnut production by reducing energy costs and producing a quality product by avoiding over-drying of nuts. These can have a major effect on the environmental and economic sustainability of the walnut industry.*

This technology reduces natural gas consumption and reduces GHG emissions, as the infrared emitters do not produce any NOx.

*https://piet.ucdavis.edu/wp-content/uploads/2013/09/Energy-analysis-of-walnut-production-in-California.pdf

Lower Costs: This technology demonstrated a reduction in energy consumption for walnut drying by up to 25 percent, compared to currently used practices, while also improving the quality of the final product.

Environmental Benefits: Reductions in natural gas use for drying will result in GHG and other emission reductions.




Project Overview

Recipient: UC Davis-Sub of UC San Diego

Program: Natural Gas

Award Amount: $1,118,285

Co-funded Amount: $280,000

Agreement Number: PIR-13-010

Project Term: 6/30/2014 - 3/31/2018

Project Status: Active

Recipient Location:  Davis, CA

Site Location(s):  Maxwell, CA

Project Team

CEC Project Manager: Rajesh Kapoor

Recipient Contact: Zhongli Pan

Subcontractor(s): Wizard Manufacturing, Inc


 

 

For questions or additional information, please email RandDProjectinfo@energy.ca.gov

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