Promethean Power Systems is a US-based company having operations in India that offers an innovative milk refrigeration system by storing energy when available and discharging it when required, after a few hours.
In a developing country like India, reliable power is often not available during the day in rural areas. Almost everywhere, milk is produced and needs to be stored using refrigeration technologies available at milk processing units. But these milk processing units need continuous power to operate and hence they use diesel-based back-up generators, which turns out to be very expensive.
Rural areas face acute shortage of power during business hours as urban areas consume more power during that time and priority is given to them. But, during the nights power is generally available in the rural areas as the demand (everywhere) is lesser. If there is a system that can store the energy when it is available and discharge it when required, wouldn't it be helpful for milk processing units in various parts of rural India? That, is the solution offered by Promethean Power Systems.
There are two components to their solution - A power storage/backup unit and a milk chiller. The power storage unit removes the need for a diesel-based back-up generator and stores electricity as thermal energy during the night, when power is available. It is very similar to a battery, except that battery stores electrical energy as such, but this unit stores thermal energy.
They store the energy by using a specialized material that can change its phase (freezing and melting). A fluid exchanger (liquid) is sent through this unit to store energy (in the nights) or to extract energy from it (in the mornings/day). The fluid is then sent to a rapid chiller unit that cools the milk quickly.
As you can see, they use grid power to achieve cooling, but if this unit can be run using solar panels (when they become affordable enough), it will become a renewable energy system. What is more interesting is, the way they store energy without using batteries. Perhaps such innovative technologies can be used for inexpensive renewable energy storage?
