Imagine an HVAC system that consumes 40-60 per cent less electricity than a normal air-conditioning system and requires zero water in the cooling system. Yes, in today’s time, it is possible!
Depending upon the amount of cooling required, a typical IT company building or a large industrial plant uses about 25,000 units of electricity and between 3-5 lakh litres of water each day — supplied through tankers or ground water for air-conditioning or process cooling.
This is equivalent to the water that was carried by a 50-wagon train to drought-hit Latur district in Maharashtra just a few weeks back. And all of this water is completely lost to the atmosphere through evaporation, which is the fundamental principle on which traditional commercial and industrial air-conditioning systems operate.
The wastage via evaporation of natural resources has led a Mumbai-based start-up Green India Building Systems and Services (GIBSS) to devise a solution that makes use of the ground as a heat sink in place of the atmosphere in the cooling process. The technology developed by GIBSS is not just saving their clients huge bills, but is also saving the environment.
The initial investment is higher, but the savings are large. GIBBS has reduced water consumption in 75 companies and educational institutions, including the Sanjiv Goenka Group, Tata Communications and Indian School of Business, and cut electricity use by 20 per cent and bills by 25 per cent.
How geothermal cooling technology works
A majority of commercial and industrial air-conditioning systems in India are water-based. This means that while a substantial amount of energy is being used to pump heat from inside the building, the medium of this heat transfer is water, which acts as a cooling agent and amounts to millions of litres.
An important component in heat exchange — the cooling tower — works as an interface that interacts with the atmosphere to reject heat by using the principle of evaporation. Cooling towers have large fans that continuously rotate to cool down the water that has all the heat from the building.
But, in this cooling process, most of this water is lost to the atmosphere through evaporation. It is similar to holding our wet hands under a blower or a fan. While the air cools our hands, all the water in our hands is lost to the atmosphere through evaporation.
A geothermal air-conditioning technique uses the cooler ground as the outside atmosphere. The ground, after a certain depth, is much cooler when compared to the atmosphere in most seasons of the year in a tropical country like India.
GIBSS utilises the characteristics of the ground to build underground equipment that can be connected to water-based air-conditioners. The AC rejects heat to the ground rather than to the atmosphere. So it has to reject heat to a 26-27 degree Celsius environment because of which the electricity bill is substantially reduced.
During peak summer season, the electricity bills come down by about 40-60 per cent. Additionally, no evaporation of water takes place throughout this process. The water is circulated within the same loop. The hot water exchanges heat with the ground, regains its original temperature, and is re-circulated within the system. This process can save millions of litres of water per day.
Advantages of Geothermal System
• 50-60 per cent reduction in operating costs
• Payback of 1 to 1.5 years
• 100 per cent water-efficient system
• Economic life of 50 years
• Maintenance free system, resulting in higher labour and purchase process productivity
• Space conservation — no additional space above ground
• Noise-free system
• Carbon credits