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‘District Cooling doesn’t have to be different to be better’

From a new entrant in the arena to a viable option, District Cooling has come a long way in Qatar, with many players vying for a bigger share of the country’s mega-project pie, while remaining cost- and energy-efficient. B Surendar speaks to Robert Miller, Technical Specialist District Cooling, Design Department, Marafeq Qatar, on a wide range of issues emanating from this scenario.

| | Jul 10, 2016 | 11:11 am
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Robert Miller

Robert Miller

Is Marafeq positioning itself for providing utility management and infrastructure designing support for any of the 2022 FIFA World Cup-related facilities, including stadiums?

Marafeq Qatar has submitted proposals to the Supreme Committee for Delivery and Legacy for several stadiums. A very promising proposal is to supply the Lusail stadium from our District Cooling network. The Supreme Committee can take cooling for the years they need it, and after that, the capacity will be used by the greater network as the city develops.

There is lot of Natural Gas in Qatar. Are you pushing to get Natural Gas to do any tri-gen schemes?

The country’s priority is to export Natural Gas internationally, and to use gas locally in power plants and large energy-intensive industries, so Natural Gas will not be available anytime soon for use in District Cooling plants. However, Marafeq Qatar knows full well the benefits of cogeneration and tri-generation, and has lectured about this in District Cooling summits. We understand the relationships between power generation and heating and cooling, and will seize opportunities that make sense.

Broadly, what initiatives are you taking to reduce grid dependence? Could you please describe your Renewable Energy profile?

In real estate developments, opportunities are limited to use power other than from the grid. Unlike industrial developments, constructing power generation facilities next to the District Cooling plant would not be palatable to the developers, office workers, and residents, with respect to space, appearance, smoke stacks, noise, etc. Having said that, to minimise the impact on the electrical system grid, our District Cooling projects will use Thermal Energy Storage (TES) to shift demand from the peak period to off-peak periods. Although the primary benefit of TES is peak shaving, using TES benefits efficiency, because chillers can operate more often near full load, where the chillers are more efficient, and can operate more often in the evening (off-peak period) when temperatures may be lower and, thus, the entering condenser water temperature can be lower, and the chiller efficiency higher. Reducing demand at peak periods, therefore, reduces grid dependence by reducing the amount of energy needed during peak periods.

Generally speaking, the cost of chilled water services is still being seen as an obstacle in the pathway to greater acceptance of District Cooling in the region. Have you introduced any financial innovations that will enable a more end user-friendly tariff structure?

Although plant and network design gets most of the press, it is O&M that sustains the business through the years

Many studies have demonstrated the cost of District Cooling is comparable with self-generation, if the total lifecycle costs are included. The problem facing District Cooling is the appearance of pricing.

End-users incorrectly compare raw costs of self-generation (electricity) to the manufactured cost of chilled water, so from the start, they fail to see the capital cost of self-generation which is built into the rent. The end-user typically does not see the cost of maintenance – it is also built into the rent, but the building owner does. Mini-splits are checked and components are replaced repeatedly when they fail, which is always at some inconvenience to the end-user. Operation and maintenance costs for District Cooling are typically in the tariff, so the end-user sees them every month.

The Qatari government benefits from the large power reduction offered by District Cooling, which opens the door to sharing those savings with District Cooling customers, and thus diminish the perceived cost differential between District Cooling and self-generation.

Marafeq is open to, and interested in, creating tariffs that will be better received by District Cooling end-users. One element could be to transfer some cost from the District Cooling provider to either the developer or the government. For example, a portion of the network could be paid by the government, based on savings on electrical infrastructure. The rest, if any, could be paid by the developer and the costs passed on to the land cost through the sub-developer and, eventually, to the end-user via rental or purchase cost.

Another element is the tariff design itself. A large portion of the District Cooling cost is fixed costs related to plants and energy transfer stations. These fixed costs are similar to the bricks and mortar in the building, and could very well be combined with the building cost. The building construction costs commonly are financed over time, resulting in monthly mortgage payments. District Cooling costs are also financed, and results in a similar mortgage payment, so the two payments could be combined and recovered through the mechanisms currently used to recover the building mortgage.

A very promising proposal is to supply the Lusail stadium from our District Cooling network

If the fixed costs are recovered in the rent or, in the case of the network, paid for or subsidised by the government, then the costs remaining in the tariff would be consumables (water, electricity, etc.) and fixed costs for O&M and administration. With this structure, the ‘manufactured’ cost of District Cooling would become more similar to the raw cost of selfgeneration.

Don’t misunderstand; the District Cooling system cost doesn’t evaporate; it is only packaged in a rational way to be more palatable to the end-user.

What is the average cost of your District Cooling plant? Till a few years ago, it was QR 4,000-6,000/TR. And the cost of a chilled water network was QR 1,000-2,500/TR. Have you been able to optimise costs?

Prices need to be taken in the correct context. In 2007/2008, small District Cooling plants in the UAE (around 10,000 TR) cost almost 10,000 AED/TR. In the same period, a large plant (50,000 TR) cost around 7,300 AED/TR. Those prices were from a time when construction was enthusiastic and prices were high. Our experience today is the cost of a small plant is about QAR 8,600/TR and a large plant is about QAR 6,300. Under current economic conditions, the market could be softening and prices could remain attractive.

Could you please share your views and experiences with regard to sub-metering?

Studies have shown sub-metering results in less energy consumption, because customers can see firsthand that changing the thermostat can save money. Lusail City is promoted as a ‘smart’ city, and there is interest in promoting sub-metering. Marafeq is participating with sub-metering projects, but currently sub-metering is optional, so at this moment, not every building is going down this road.

The problem facing District Cooling is the appearance of pricing

Some people ask how you will get paid if the building is owned by multiple tenants. Well, how is the building cost recovered? Use the same mechanism. The District Cooling bill can be based on the building bulk meter and distributed to the tenants based on area or flow/energy (sub-meters) or any other metric that is acceptable to the tenants. The cooling cost of common areas would have to be prorated like any other common area cost. The entity responsible for paying the building mortgage would also be responsible for paying the District Cooling costs.

Yet another cause of concern is the reliability of cooling in some District Cooling schemes. What innovations have you wrought to ensure a fail-proof hydraulic balancing regime?

In 1998, IDEA surveyed 20 District Cooling schemes and found the median reliability was 99.98%, so if some District Cooling projects are concerned about reliability, they should look at the root causes.

When planning plant production, Marafeq Qatar assured the design was well-thought out, incorporated redundant elements in order to maintain chilled water availability, and with design lives of 25 years for electrical and mechanical equipment, and 50 to 60 years for civil works and pipelines.

Marafeq Qatar designed a distribution network with strategically placed loops and isolation valves. To assure high quality, Marafeq Qatar selected an all-welded pre-insulated steel piping system with integrated leak detection system – all certified in accordance with the EN 253 family of standards. The key to EN 253 is the pipe is fixed in place by transmitting strain energy from thermal contraction to the ground through the insulation. If the bond between the insulation and the pipe or casing fails, then the pipe slips, and strain energy is transferred to pipe bends or valve bodies. Marafeq Qatar also discouraged flanges, except in special cases. Extensive industry practice in Europe has demonstrated flanged valves installed in chambers are weak links in the distribution system, and the European trend is to use an allwelded system.

What is the update on the availability of adequate TSE for your projects?

For Lusail City, the TSE network is installed or under construction, and one source of water will be the development’s sewage, but that may not be available in the quantities we need by the time we need it. Ashghal has other TSE available, and we expect adequate quantities will be available for our plants.

Generally speaking, current District Cooling technology is quite outdated. We are seeing that a small VSD chiller in a hotel can outperform District Cooling without piping losses. Standalone water-cooled systems are using VSDs, and are using grey water. That way, they are getting even lower costs than District Cooling. Of course, there is no denying that District Cooling has better operators and specialised expertise 24×7. What more are you doing that is different to give a USP to clients? What innovations are you introducing?

District Cooling is tried and true and not outdated. Although your premise that individual water-cooled chillers can be more efficient than District Cooling is true, it misses some key points. First, are individual water-cooled chillers really the alternative to District Cooling? I remember looking at the model of the Bahrain World Trade Center, and asking what that huge structure was at the side of the towers. Air-cooled chillers, I was told. The model didn’t show them as chillers, but then again, one would like the model to be as attractive as possible. The point is, the designers chose air-cooled chillers rather than water-cooled chillers, and why was that? In the United States, water-cooled chillers are relatively common. Water is available and discharging to the sanitary sewer is allowed. In Qatar, Kahramaa issued an edict stating potable water was forbidden in District Cooling plants. So if the 560,000 TR customers in Lusail City were to use individual water-cooled chillers, how would Kahramaa feel about that? Would the buildings be allowed to use potable water for cooling (because they are not District Cooling), or would they, too, be forbidden? If potable water is forbidden, then the buildings would have to use in-house grey water or TSE. In Minnesota, the building codes forbid using grey water. It’s not an option. Are you saying using grey water is allowed in Qatar or only that it would be a good thing to look into?

The District Cooling system cost doesn’t evaporate; it is only packaged in a rational way to be more palatable to the end-user

The reasons to choose District Cooling over self-generation are numerous. You mentioned 24/7 O&M by dedicated professional staff, but look at any building in Lusail City, and imagine where you are going to put the cooling tower. There’s no room on the ground, so the towers have to go on top of the 12- to 30-storey building. Wouldn’t it be more valuable to put a pool and social area up there? We struggle when a crane is needed to remove a fan gear box so the bearing can be replaced. Now, do this from the top of a tower – or replace the tower in 15 years!

District Cooling doesn’t have to be different to be better. Need some more reasons?

• The capital expense for producing chilled water is transferred from the building developer to the end-user via the District Cooling provider’s tariff.
• District Cooling requires less capacity due to load diversity and reduced standby capacity. Individual buildings must design for the instantaneous peak (usually with a safety margin), and with standby production units for redundancy and reliability.
• Since production is centralised, utility networks for TSE water, electricity and sewer are less.
• Compared to air-cooled chillers, greater efficiency means lower peak and annual power consumption, which translates into lower investment in generation, transmission and distribution facilities.
• Lower power consumption means lower emissions of air pollutants for the full lifecycle.
• District Cooling production equipment is more likely to maintain its level of efficiency than is expected for individual buildings.
• Facility managers purchase a manufactured product (chilled water) rather than raw materials (chillers, structures, power, water, etc.) and produce their own product. Building owners can focus on their core business (real estate) rather than to venture into the utility business. Over the building lifecycle, facility management costs will be lower compared to self-generation.
• Noise levels are greatly reduced compared to site-located outdoor units or air-cooled condensers.

It takes up to four litres of water to produce 1 kW of energy, and it takes nine litres to produce 1 TR. So if we can give 0.25kW/TR as opposed to 1.25kW/TR, we save on power, so less kW needs to be produced, so less water. Would you agree?

I will take you at your word that power uses 4 litres/kWh. The metric would depend on the type and mix of generation assets. A simple cycle gas turbine would use essentially no water. A combined cycle would use water to reject heat from the steam, Rankine cycle, so it would use water. But your premise is interesting. The annual average power consumption for an air-cooled chiller is 1.60 kW/TR (for mini-splits it is 1.80 kW/TR). For District Cooling, the annual average power consumption is 0.90 or even 0.85 kW/TR. Using your values, water consumption for each would be:

• Air cooled: 1.60 x 4 = 6.4 l/hr per TR
• District Cooling: 0.90 x 9 = 8.10 l/hr per TR

So yes, District Cooling uses more water, which only serves to show not to draw conclusions from only one perspective.

Are you undertaking any initiatives related to Net Zero Energy Buildings?

As a utility provider, we do not actively participate in building design other than we carefully watch trends so we can better prepare for the future. District Cooling providers suffer a natural contradiction. On the one hand, as good neighbours and stewards of Qatar, we want energy to be fully used and not wasted. On the other hand, we make money selling energy (cold water).

In the context of COP 21, what is Marafeq’s stand on refrigerants? Have you identified a low-GWP alternative for high-ambient conditions that you would like to go ahead with in all your projects?

Marafeq Qatar is a consumer of refrigerants. We are not researchers or policy-makers; however, we certainly follow trends and developments, and we will always comply with national laws. There are new developments in refrigerants, and Marafeq Qatar embraces them as long as the vendors can demonstrate the equipment is reliable.

And what are you doing to proactively address refrigerant leakage issues, if any, in your projects. The global refrigerant leakage is an alarming 132 kilotonnes/annum, hence the question.

Chillers that use low-pressure refrigerants don’t leak refrigerant out; they leak air in. Chillers that use high-pressure refrigerants can leak out refrigerant, and open-drive chillers probably leak more than hermetically or semi-hermetically sealed compressors. The chiller is our key ingredient for making money. If refrigerant leaks out, chiller performance degrades, and we will take corrective action right away. Here again, I highlight that our plants are run 24/7 by dedicated professional staff. Our core business is energy, and not real estate or making widgets.


(The writer is the Editor of Climate Control Middle East.)


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