Scarcity of clean water poses an enormous threat to food security around the world. Both in the developing world, including China and India, and even in the United States, farmers increasingly face the arduous challenge of obtaining sufficient clean water to grow crops. Faced with this daunting challenge, the team behind the GreenTop platform developed an innovative system that uses wind power to capture atmospheric water moisture, which in turn is used to grow fruits and vegetables hydroponically.
By creating an affordable, scalable technology that relies solely on renewable energy, the GreenTop platform enables farmers to boost food production, particularly in developing countries where the climate is arid, arable land scarce and access to clean water limited.
Winners of the Dow Sustainability Innovation Student Challenge Award (SISCA), the GreenTop team is comprised of PhD chemists and MBA students at Northwestern University, and is led by Ashish Basuray. While working in Nepal as a Peace Corps volunteer, Basuray witnessed a variety of homegrown sustainable innovations that evolved from new or low-cost technologies that were integrated into existing infrastructure.
“If a technology is going to work in developing nations, it should aim to be cheap, interchangeable, and maximize the locally abundant resources,” Basuray explains. “In my village, the water situation was not dire, but with Bangladesh just a stone’s throw away, I became immediately aware of water and food scarcity.”
Basuray noticed that with the advent of low-cost pumps and durable plastics, villagers no longer had to carry water up to rooftops where gravity was used to create water pressure. Now the water is automatically pumped to the roof where it is stored and heated by the sun in black plastic tanks and readily accessible. Inspired by this practical innovation, Basuray realized that by utilizing the vast amount of unused rooftops, where water was typically stored already, and the popularity and demand for household gardens, he could combine all three components to create a system that grows crops while conserving precious clean water.
The GreenTop platform uses a lightweight, residential wind turbine, roughly ten to fifteen feet tall and weighing around 500 lbs, which can be supported by most rooftops. The turbine produces approximately 1 kW of energy to power a cooling unit composed of a recycling ethylene-glycol pump, an inexpensive and commonly used technology, which allows moisture to condense from atmospheric humidity into a steady stream of water. Given average humidity levels of 40% in semi-arid climates, the pump can potentially generate two liters of water per hour with wind speeds of roughly seven miles per hour.
After collecting this “free” atmospheric water, the GreenTop platform then applies it to a vertical hydroponic system for crops. The collected water is stored in a reservoir, which slowly percolates through a sealed container full of local compost, where the water extracts nutrients, and filters pathogens and fine particulate matter through a nanoporous permeable membrane. The nutrient-rich water then flows through a honeycomb structure where it is delivered to crops. The compact and lightweight system can increase agricultural yield density, while reducing the weight from soil or the need for large amounts of land or other clean water sources.
Given that much of the design utilizes existing technologies, cheap and readily available components, and minimal resource input, the GreenTop platform looks to be a very sustainable, affordable and scalable solution. Basuray estimates that his team could produce the GreenTop device for approximately $800, with the cost expected to drop once produced on a larger scale. Provided with optimal growing conditions, the system could potentially pay for itself within three years.
“The GreenTop platform is a very clever systems approach to resource use, energy harvesting and rooftop gardening, which can fill an immediate niche in local economies,” explains Kimberly Gray, Professor of Civil and Environmental Engineering at Northwestern and chair of the SISCA judging panel. “The design can make the urban landscape much more productive by utilizing lot of rooftops in cities that do nothing more than increase the energy burden of cities and create heat islands. GreenTop can make a liability into an asset.”
According to Basuray, the GreenTop platform will largely be targeted towards developing countries with non-potable water, as well as urban environments that lack ample local food supply for lower socioeconomic areas. After refining the design and developing functioning prototypes, they intend to sell the system to international development organizations for the first several generations. Once GreenTop is able to scale up, they would then target users through government agencies or local commercial enterprises.
“Using low cost resources was a key motivation for this project, hence finding components and parts that are readily available in most parts of the world translates to greater scalability,” explains Basuray.
Currently, GreenTop is actively seeking investment capital to build a prototype and begin field-testing the device. Ideally they are looking for angel investors and government grants to help support the initial proof of concept stage. The greatest challenge facing the development of the GreenTop platform is lack of manpower. Now that the Dow SISCA recognition is past, Basuray is currently the sole contributor to the project, and is searching out for collaborators with passion and expertise.
Basuray plans to develop and test a GreenTop prototype within the next six months. Following successful testing he then will look to increasing funding to scale up production and connect with target markets. Provided his experience working in the Peace Corps, Basuray imagines Nepal to be an ideal location to pilot the program in collaboration with humanitarian agencies to monitor the outcomes. Further down the road, he aims to target five developing nations well suited to utilize the GreenTop platform, and begin working with international aid organizations (UN, USAID and private companies) to implement the infrastructure.
“Within a decade, GreenTop hopes to be a commonplace name in most developing nations,” according to Basuray, “hopefully working with local, governmental, and international agencies to mitigate food shortages and produce potable water for those without these essential resources.”
Climate change, growing populations, pollution, combined with poor infrastructure and management, pose major risks to the already the already limited 3% of the global water supply that is fresh water. The GreenTop system is sure to be a welcome addition to the marketplace to harness and maximize existing clean water and grow crops in a cost-effective, sustainable way.