Spice to Meet You

Project undertaken in course year 2017-2018 with the Precourt Institute for Energy

This project has continued into 2021 and beyond, with followon projects in each of the subsequent years of this course. See "Update" below

Project Goal

Devise a faster and more effective chili-drying system to lower food waste, reduce economic loss, and maintain affordability and sustainable practices for Producer Companies (PCs) in Karnataka, India

Project Motivation

  • Approximately 1.3 billion tons of food produced worldwide, with $310 billion of losses in developing countries. Food loss could be reduced by drying produce at the primary level of farming

  • India accounts for 34% of the worldwide production of chilies


Approximately 1.3 billion tonnes of food waste accumulate per year; this has large impacts on energy consumption, food waste and economic losses for farmers. Food loss, however could be reduced by drying produce at the primary level of farming.

Team meeting with Producer Company on visit to Karnataka, India

High Priority Requirements

  • Reduce the number of chilies lost due to degradation and spoilage from 15% to 10%

  • Decrease the time it takes to dry the chilies from 30 days to 3 days

  • Effectively dry chilies and maintain chili quality by creating environment 45-60C

  • Hold capacity of 500kg of chilies

Ethical Considerations

  • Displacing laborers

  • Conflicting interests of PCs and farmers

  • Sustainable sourcing

  • Releasing spice

  • Ergonomics


Our system consists of an outdoor enclosure, similar to a greenhouse, that contains a system for adding heat, storing heat, and insulating the enclosure to minimize heat loss during the night. The system is designed to receive and store heat from the sun during the day, and then utilize that heat and minimizing heat loss in the evenings

System - Day

The system is composed of an an external structure, electric heat source, a solar panel to collect and deliver heat to a water storage system. The water is then used as a heat source in the evenings when the sun is down.

System - Night

An insulation layer is placed over the enclosure when the sun is down, to reduce heat loss

Temperature results

Use of solar dryer and insulation is effective at maintaining up to 10C higher temperatures, as compared to use of electric heater and no insulation (control)

Humidity results

Use of solar dryer and insulation results in lower humidity, as compared to use of electric heater and no insulation (control)

The chilies

Comparisons between spoilage from three different processes. Results show that use of solar dryer and insulation results in lower spoilage than the others, but improvement still required

Summary results

Summary of results. The Experimental setup results a significant improvement in energy used as compared to the control, while delivering roughly comparable drying.

Student team

Area of focus

The focus region for the project is in Karnataka, India

Members of the team visit India

Future Work

  • Develop larger scale prototype

  • Address spoilage

  • Subsystem optimization

  • Plan travel and build in Karnataka, India


Since this project was conducted in AY2018, much work has continued. One of the team members continued to work on the project with the Precourt Institute, and they have scaled up the system to 100kg at O'Donohue Farms at Stanford, 500 kg in India, and then 2000kg scale in India, as shown below. This project has also been the basis for follow-on projects in each of the subsequent class-years in ME170, with the following projects

AY2019: Red Dried Chili Peppers, Welcome to Chilis, Water n' Spice

AY2020: Spice Girls, Hot Box

AY2021: Team Jookali, Hot & Spicy

AY2022: Raisin' the Roof

100 kg scale at O'Donohue Farms

500 kg scale in Karnataka, India

2000 kg scale in Karnataka, India