I have been in the large-tonnage chiller and chilled water plant service and solutions industry for over 44 years, and throughout my career, I have always been a proponent of reducing the power and water cost of operating chillers and chilled water plants.

Back in the early 1990s, when I worked in Kuwait for Bechtel Construction, The Kuwait Oil Company (KOC) and Carrier Corporation, I was looking for a non-chemical water treatment solution that would allow the repurposing of water, elimination of toxic chemicals and the reduction of blowdown water at the KOC District Cooling plants, in Ahmadi. By the way, KOC had District Cooling long before any of the companies you know of in the region now, were even dreamed of.
We tried a few of the “technologies” being offered back then, but none were successful.

Dan Mizesko

It wasn’t until the turn of the century, around 2005, that I learnt of Pulse Power technology. And after numerous site visits and beta testing, I found it to be the answer to non-chemical water treatment; and to this day, I recommend the technology to anyone who is interested in removing hazardous chemicals and saving water and power. The point of mentioning this is that looking for technologies that save energy (power, water, fuel, steam) in our industry is sometimes a long journey.

For the past 20 years, I have been wondering why the industry does not try and harvest energy from chilled water and condenser water loops. I touched on this topic about 12 years ago, when I presented at an IDEA (International District Energy Association) conference on the topic, Chiller Plant Efficiency is the Key to District Cooling Economics’. In the presentation, I suggested that an in-pipe Hydro Generator can be installed on the plant’s cooling tower blowdown water lines to generate electricity. I honestly thought someone in the IDEA community would have incorporated the technology, and even would have taken it a step further and utilised the technology on the makeup water supply and throughout the chilled water loop.

Well, it’s been over 12 years now, and I have not heard of any District Cooling company, standalone plant or high-rise building utilising this technology. I feel the time is perfect to revisit the opportunity, as the UN just gave a grave warning regarding climate change, and we all need to try and “think outside the box” to reduce our energy consumption.

In-pipe hydro systems can operate across a wide range of head and flow conditions inside most common piping materials. Almost all buildings in large cities across the region are served by pressured piping systems to supply water where it is needed for drinking, and for domestic and industrial use. Water-cooled district cooling plants and central chilled water plants consume large amounts of water and are also served by pressurised piping systems to supply water to the cooling towers, whether potable or treated sewage effluent (TSE). All buildings have drain and sewage systems, which are usually gravity fed, while District Cooling plants and central plants all have blowdown water drains. Both the supply water and blowdown water can be incorporated with in- pipe hydro generators to harvest untapped energy.

In chilled water loops, there are typically pressure-reducing valves (PRVs) that maintain pre-set pressure ranges to protect equipment and maintain proper flows. Theoretically, any chilled water system that utilises pressure-reducing devices could replace them with in-pipe generators, maintaining the same control on water flow and pressure whilst producing usable electricity.

The in-line hydro generators currently available have a design that utilises a Francis turbine with connected shaft as both the pressure-reducing and energy-harvesting device. These hydro generators come in sizes from one inch to 60 inches internal to the pipe or external with a water bypass. So, in my opinion, chilled water plants and high-rise buildings with chilled water piping can harvest energy with hydro generators.

Let’s take for example a high-rise building of 30-plus storeys. The Dubai Marina and Downtown Dubai alone have hundreds of buildings like this. The chilled water being pumped up throughout the building will require large amounts of pressure to supply water to the higher floors, and the excess pressure in the lower section is usually wasted via PRVs and could be hydro generator harvested. The taller the building, the more potential energy generation. I envision hydro generators could be installed on the cooling tower make up water, blow down lines, the domestic main water inlets, chilled water return lines, etc.

I feel the wasted and untapped energy in the industry is massive and can be harvested. With all the District Cooling piping networks, high-rise buildings, cooling towers, incoming water supply to buildings and cooling tower blowdown, the region is awash in opportunity to utilise in-pipe water hydro power harvesting. With known pressures and flows in pipe, hydro power will provide predictable and reliable energy generation.

As I write this article, we at US Chiller Services are working with a company in the United States that designs and manufactures in-pipe hydropower with technology that generates clean electricity from excess pressure in drinking, irrigation and industrial water systems. As we have not seen this technology in the region, we have decided to work with the company to try and identify potential sites that can benefit from the technology. When installed at a facility, the end-user can benefit from the energy and can either use in their facility or send it back to the power grid.

Dan Mizesko is Managing Partner/ President, U.S. Chiller Services International. He may be contacted at dmizesko@uscsny.com