By Kasey Worst
As part of a senior project, Rachel Sparks and a team of other students at Purdue University, designed a hydroponics system that could fit inside of a shipping container.
Hydroponics is a method of growing plants where no soil is needed. Instead, nutrient-filled water is delivered to the plants. The delivery method varies by system.
The project sponsor was The Village of Hope, a charity with directors in both the United States and Haiti. It provides education and health care to children. The organization wanted a system to provide fresh fruit and vegetables to students at a school and community center in Haiti.
Sparks and her adviser, Bob Stwalley, first traveled with representatives from The Village of Hope to Ganthier, Haiti, to visit the school.
“We wanted to get the lay of the land, and see where everything was, and what we would have access to at the site,” Sparks said.
They discovered a place with limited supplies. The rocky and hilly terrain near the school made it difficult to produce large amounts of food. Running water was shut off in the summer at the center since the children were out of school.
The school was on the top of a hill. Sparks and Stwalley met with the school’s principal and main agronomy teacher.
“At the school everyone was really excited to start working on this project,” Sparks said. They were “very friendly and willing to help us – very excited to get something started that the kids at the school would get to see and be excited about as well.”
Cubes of soil help ensure that the roots of lettuce plants grow long enough to reach water in the hydroponics system. The plants were grown from seeds, and took about a week to become big enough to move to the hydroponics system.
The system is good for food production in places experiencing droughts such as California, Sparks said.
“The system is closed, and it keeps recycling that water through the same tubes over and over again,” she said. “So it’s not continuously having to pump more water into the system.
“Since it was our first time trying anything in the system we wanted to make sure that it worked,” Sparks said. “So we used lettuce. It’s a little more hardy than a tomato plant, and honestly it grows a lot faster. So though tomatoes are obviously higher in nutrition and have more calories in them, lettuce grows a lot quicker and there’s a lot less turnaround time.”
Holes were cut into PVC tubes for the plants. The plants’ roots hung into the tube through which water was constantly pumped. This water was filled with a fertilizer that keeps the growing plants flourishing. The set up meant that the water did not need to be changed or have extra fertilizer added until after the monthly harvest.
Energy costs depend on the amount and types of technology used in hydroponics systems. Indoor units that do not take advantage of natural sunlight use more energy than units inside greenhouses or outside.
Two types of light were used: fluorescent and blue LED lights. This was done to test the rate the seedlings grew under the different lights and to measure the energy each kind used.
The seedlings grew at about the same rate regardless of the light, however the LEDs used less energy, Sparks said.
Sparks’ team won second place in the environmental category of their capstone project competition at Purdue University.
The vertical system they tested was meant to reduce the space required to grow the plants, but they discovered that this method made it hard for the water pumps to send enough nutrients to the plants. Gravity would pull the nutrients to the bottom of the system before the nutrients reached the plants.
Sparks is working on a new horizontal design to fix the problem.
She was drawn to this project because she is interested in improving the access that people have to food, she said.
“I was really excited about the international, far-reaching implications something like this had. “It’s very versatile. You can adapt it to use in any kind of climate or area that you have to work with.”
Listen to an interview with Rachel Sparks on the Food Fix podcast.