Re-imagining the Cold Chain
India currently grows about 360 million tons of horticulture produce but has cold storage facilities of less than 40 million tons. According to NITI Aayog’s December 2018 study, “The lack of an adequate and efficient cold chain infrastructure leads to massive post-harvest losses, estimated at $1.4 billion annually. Perishables account for the bulk of post-harvest losses.” While the country loses food, individual farmers suffer and remain poor because they are forced to sell their perishables at low prices during harvest times since the produce cannot be preserved.
New Leaf Dynamic Technologies Pvt. Ltd. (New Delhi) and the Sustainable Thermal Systems Laboratory (STSL) at Georgia Tech (Atlanta) have jointly developed an adsorption refrigeration system driven by locally sourced carbon-neutral biomass and farm waste to provide cooling, thus removing the dependency on an unreliable electricity grid. The system has fewer moving parts unlike conventional vapor compression systems that rely on failure-prone compressors and uses refrigerant-adsorbent working pairs with zero global warming potential. The team is accelerating the deployment of safe, easy to install, and simple-to-use, environmentally friendly refrigeration systems that extend the storage life of perishables at very low running cost for dispersal to villages.
Electromagnetic Chemical Transformation
Drywall production is a very energy intensive process that requires ~500 kWh/ton of product, corresponding to CO2 emissions on the order of 100 kg/ton. The state of the art in the industry involves mining gypsum particles and reducing their sizes by milling. The gypsum particles then undergo calcination, which converts the dihydrate form of calcium sulfate to hemihydrate. The calcination products are mixed with water to form a slurry so that it can be poured on a conveyor belt and molded to the desired geometry. The slurry is eventually dried to form the final product.
While only 20 wt. % of water is needed for the conversion of stucco to gypsum, significant excess water is needed to ensure sufficient fluidity of the slurry. This is due to the low quality of the stucco particles produced in high throughput calcination units, which disintegrate upon mixing with water, thereby reducing the fluidity and processability of the slurry.
Both the energy and water consumption can be reduced by the development of a rapid microwave calcination technique producing high quality stucco particles that do not disintegrate in water and meeting the high throughput demand of the wall board manufacturing process. Additionally, the optimization and the control of the size distribution of high-quality stucco particles can help to further reduce the excess water usage. There is a potential for up to 49% reduction in energy consumption in the overall process, leading to 1.7 × 107 GJ of annual energy savings industry wide.