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Is District Cooling really the answer?

Rehan Shahid contends that District Cooling probably poses more questions than answers

| | Aug 18, 2019 | 5:35 pm
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Putting aside the debate over the energy efficiency of District Cooling systems, we need to steer our attention towards the underground reticulation pipes and the construction of permanent structures, such as huge valve chambers, by District Cooling providers, who are not only adding to the pollution of the planet but also contributing to subsequent issues that future generations will likely have to address and deal with.

In contrast, with overhead or above-grade utilities, there is a choice of rerouting or even completely eliminating these systems, if an alternative technology is available in the future. One reasonably acceptable example would be satellite and mobile phones versus landlines.

The intensity of effort required to remove buried services from the ground is immense. We are talking hundreds of miles of pipes, which is a formidable task, not to mention an expensive one, as well, and, consequently, almost impossible for a small city to handle.

So, what do we do, then? Leave the underground piping networks in the ground for future generations to deal with? Continue with a fresh piece of land, till we run out of that, too?

Let’s assume that we leave them, as is. Doing so would mean the spectre of a huge cost in maintaining the networks, which is something that is inadequately considered while carrying out feasibility studies. Moreover, the cost of land used for this purpose – thousands and thousands of square miles of it – on top of which you are not allowed to build any structures, is not quite adequately considered, either.

Broadly speaking, it is important we take a step back and seriously evaluate the advantages and disadvantages of having more District Cooling plants everywhere.

We all understand that pulling a 300mm2 copper cable out of the ground is much easier than digging an 800mm diameter, or bigger, pipe out. But let’s not delude ourselves – when it comes to sewage, we may be stuck with the sewage infrastructure for a very long time to come. Although a micro model may also be adopted, where the sewage is dealt with at the source — that is, have mini treatment plants, at present, such an apparatus is neither encouraged nor economically feasible at a micro level.

So, does a District Cooling system provide what it promises – that is, an energy-efficient, economical and greener solution? Perhaps not. District Cooling systems waste water, use more energy than an onsite plant and demand that huge diversities are applied to the plants, in order to make more profit. The consumer has to pay for the connected load, which is 100% and not diversified.

District Cooling plants also often underperform for various reasons – a discussion better left for another time. Furthermore, the consumer is unfairly penalised for not having the right return water temperature, when it should also be the District Cooling provider’s responsibility to take care of this variable and, in addition, have sufficient capacity to cater to all the clients it has signed on.

Let us take a further look at the rather inaccurate representation of energy-efficient, “optimised” District Cooling plants. Let’s consider the Holy Month of Ramadan (during summer). Without any hesitation and having to go into much detail, it would not be incorrect to suggest that most residential blocks and commercial premises will be occupied at around 3pm. In that case, the diversity that the District Cooling plants consider is no longer relevant, as all the connected blocks would require simultaneous cooling. Hence, it’s highly probable that the District Cooling plant would underperform and not provide adequate chilled water to all consumers. As a result, consumers are left high and dry, without any reasonable clarification forthcoming. In essence, it may be said that the District Cooling providers have more consumers than what their plant is capable of handling, and they are forced to have to ‘catch up’, so to speak. This certainly cannot be regarded as an acceptable energy-efficient solution.

So, what may be considered as a possible direction? If there is an alternative to having an extensive network of buried assets, it should be considered, even if it costs a little more. In that context, serious consideration should be given to air-cooled systems.

There is a serious need to embrace available sources of renewable energy, such as solar and wind energy, at a micro level at a pace that is faster than the current speed of uptake. End users should be encouraged to install solar panels on every building, new or old. And grants may be offered as an incentive for this purpose. The energy thus obtained can then be used to supplement energy required to run appliances, air conditioning systems and the such, while the top-up may come from power utility companies.

In keeping with the theme, the Solid State Thermoelectric Air Conditioner, which uses the Peltier Effect, is definitely something to keep an eye on, considering that air conditioning systems are the biggest users of energy.

For District Cooling systems, feasibility studies should be carried out with utmost transparency and through taking a holistic approach. It is important to consider the pace of future trends and technologies, including the cost of maintenance, the stripping of roads, re-carpeting them and rerouting them, in some cases. It is equally important to take into account CO2 emissions due to the use of heavy machinery, associated equipment, materials and activities. And the most important factor of all – the world we will be leaving behind for future generations to inherit.

I am sure once all these are considered, the case in favour of District Cooling systems will come into question.

Let us not ignore, and in due course forget, that once we start moving in the direction of District Cooling, it becomes almost impossible to even consider any other technology, as a fortune is spent to nurture a white elephant. The business model demands exorbitant amounts of returns. The expansion in District cooling business is driven by the handsome profits the utility firms reap, whilst the consumers foot the bill for the upkeep and maintenance of such systems.

In that context, end-users should be provided with options and allowed to make informed decisions based on independent studies. We talk about not enough power being available, for various but mainly economic reasons, yet we waste this expensively acquired energy to light up and cool massive shopping centres and malls regardless of occupancy levels. Consumers ought to be educated and reminded that cooling an unoccupied dwelling is simply not acceptable. It is important to introduce weekly/monthly programmable thermostats, occupancy sensors and the such, so they can stop wasting energy as much as possible. It will not be long before we will have IoT (Internet of Things) sensors as allies in the bid to lower energy consumption. Until that happens, our fraternity needs to do its bit and spread the word.

We need to consider options that don’t further destroy the environment. We all know that the air conditioning industry is an ever-evolving one, so does it make sense to build towns and cities based on the assumption that District Cooling is the best way forward, when the ability of the system to meet the need for energy-efficient air conditioning is debatable?

FOR WHAT IT’S WORTH…

When the result of District Cooling is a high level of pollution, in my opinion, there is no argument. We should not be allowed to destroy something we do not own in the name of ‘development’ or whatever else we would like to call it.

District Cooling doesn’t make economic sense, nor is it environmentally friendly. Water is wasted, be it Treated Sewage Effluent (TSE), which is further treated, so it can be used in cooling towers, thus using even more energy in the process, or precious potable water.

In the Middle East, thermal desalination, a highly energy intensive process, is the dominant approach in making seawater potable.

Water is too precious to be wasted – a 1,000 tonnes of refrigeration (TR) water-cooled chilled water plant would use up to 170 cubic metres of water a day. Putting that into perspective, 170 cubic metres (170,000 litres) of potable water is enough to fulfil the two-litres-a-day requirement of 85,000. This alone should be enough to look at other alternatives.

The need of the hour is the production of more green energy to power our cooling systems. With the pace at which technological advances are taking place, we can be certain that we will soon find even more viable and eco-friendly ways of cooling our habitats and producing more green energy. What will then become of these District Cooling networks with their reticulation networks spread underground? Whose problem will it be to clean up?

 

Rehan Shahid is Director, P&T Architects and Engineers Ltd. He can be contacted at rehan@ptdubai.ae

CPI Industry accepts no liability for the views or opinions expressed in this column, or for the consequences of any actions taken on the basis of the information provided here


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