How to keep the district cool?

Siemens Refrigeration Compressor Package The environmentally compatible chiller

Answers for energy.

Targeting Zero Emission Through Siemens Compressor Chiller Packages Big cities present many obvious environmental problems, but the challenge of energy-efficient housing is actually easier to tackle in compact urban areas than in loosely structured, low-density communities.

The growth of cities will be a dominant demographic trend of coming decades. The current proportion of the world‘s population living in urban areas just passed the halfway mark. The United Nations expect to rise to almost 60 % by 2025, and to reach 70 % around 2050. As cities grow, personal living conditions in cities become more important. Energy supply, whether electricity, steam, hot water or chilled water, will, in the future, place major challenges on infrastructure.

Modern architectural design generates a rapidly growing cooling demand.

Global population

Constantly growing floor space

Billion inhabitants

6.5

8.0

There are many reasons, including

people‘s increasing expectations of more living space corresponding to the spacious public areas construction of new buildings with huge window areas to provide sunlight buildings containing more heat-generating equipment such as computers.

A survey among 522 stakeholders in 25 large urban agglomerations world­ wide indicates the willingness to invest in an improved environment. There‘s a strong interest in megacities to reduce greenhouse-gas emissions and other air pollutants – megacities already emit roughly 10 % of global CO2 emissions.

Commitment to investment for environment

= 100 %

25 % Rural

51 %

43 %

Urban

49 %

57 %

2005

2025

Source: UN

District Cooling A district cooling plant offers a perfect alternative to conventional Window A/C, since the cooling capacity is generated in an effective and efficient manner. A central district cooling plant generates cool water and distributes it through a network of piping system to individual customer buildings. District cooling has been implemented in a variety of structures, both private and government-owned utilities, universities and airports. The district cooling systems serve a wide variety of types of buildings, including commercial offices, residential, hotels, sport areas.

17 %

Disagree

Undecided

58 % Agree

Source: Siemens Megacity Report (2007)

The benefits of district cooling are Comfort and convenience for customers as there is no noisy equipment in the window or on the roof Improved energy efficiency Enhanced environmental protection System reliability Decreased building capital costs Improved architectural design flexibility

1

Siemens Refrigeration Compressor Package (SRCP) Optimized for 10,000 tons of refrigeration (RT)

SRCP 10, a chiller generating 10,000 tons of refrigeration, is equipped with two highly efficient compressors, inlet guide vanes using high efficient tubes in the optimized heat exchangers. The system is completed with all required chiller auxiliaries including the control and protection system. This new system technology provides an overall efficiency improvement of 7 %, compared to conventional chiller equipment. This is thanks to the implementation of turbocompressor equipment design typically used in petrochemical plants and the phenomenal size of the 10,000 RT chiller system itself.

This capacity, and the use of one electrical motor to drive the compressors without a gear, leads to minimum losses. The new 10,000-ton design requires approximately 40 % less space compared to 4 chillers of 2,500 RT. Space is money, especially when the district cooling plant is located in the middle of the city.

The operating costs of a district cooling plant are mainly driven by the electricity and water consumption of the plant itself. The increased efficiency generates profit. Additional savings result from attractively low service costs for a large 10,000 RT chiller compared to smaller equipment.

Both engineering and construction companies benefit from the spacesaving effect of the Siemens Compressor Refrigeration Packages and the reduced engineering complexity as compared to existing conventional design, thanks to fewer auxiliary components such as pumps and valves.

3-D schematic of the Siemens Refrigeration Compressor Package SRCP 10 for district cooling 2

Features of the solution

Capacity 10,000 tons of refrigeration with one unit Cooling liquid R134a Two compressors on one single shaft Each compressor has inlet guide vanes Lowest friction losses No gear required One electrical motor as driver Motor available for 50 Hz or 60 Hz Dimensions 11.2x7.7x5.0 m (LxWxH) Max. weight of single transport unit 45 tons Advantages of the solution

Excellent coefficient of performance (COP) Enhanced efficiency High reliability as the compressor design is based on oil and gas requirements Less space needed Less engineering/piping Overall attractive life cycle costs Implementation The cooling demand in cities is directly correlated to the impact of the sun, in other words the load profile of a district cooling plant varies drastically from day to night. To compensate the varying refrigeration demand, a combination of the Siemens refrigeration compressor package with smaller chiller equipment is feasible.

3

The future of energy supply: Intelligent, efficient, sustainable and profitable Renewable energy and distributed generation are gaining ground. And we need to mitigate climate change. District cooling in combination with solar thermal power offers the opportunity to to do just that.

or two hours between the electrical power generated and the cooling demand.

How does it work? As a leading company in solar thermal power plants, Siemens is in the position to build such plants outside the city and to feed the power produced into the national grid, which supplies the district cooling plants. This is a perfect match as the impact of the sun provides the electricity to drive the district-cooling plants at the very time when cooling is required since the sun has heated the buildings.

There are alternative solutions to compensate for this, one being the possibility to install thermal storage in the district cooling plant, to extend its cooling capacity in the evening hours. The other is to install thermal heat storage at the solar thermal power plant in order to extend the operating hours of the turbogenerator set in the evening hours. This technology is an excellent way of using the power of the sun to remove heat.

Taking into account that the buildings are cool in the morning and still heated in the evening, there is a slight difference of one

Concentrated solar power stations cover the electricity demand of the district cooling plants.

Siemens supply

Solar thermal power plant

4

District cooling plant

Siemens experience

Appropriate for solar thermal power plants: excellent very good good not appropriate

Siemens turbines power solar plants all over the world Siemens has secured orders for 45 steam turbines for solar thermal power plants: More than 40 steam turbine generator sets in Spain, using parabolic trough technology Units for central tower technologies with air, water/direct steam and molten salt rating from 1.5 MW to 123 MW Units for ISCC applications in North Africa Steam turbine for Fresnel application in Spain

Use the power of the sun to remove heat by employing Siemens competence.

6 am

12 am

3 pm Time

6 pm

9 pm

12 pm

Efficient District Cooling 142,867 MWh, equivalent to 71,433 tons of CO2 emission from 30 thousand cars.

The use of solar thermal power eliminates CO2 emission, i.e. emission is zero.

33,000 cars 80,000

30,000 cars

40,000 0 cars 0

Ef D C fic i P l ent an t su S pp ol lie ar d Th DC er Pl ma an l t

0%

to 165,317 tons of CO2 emission from 70 thousand cars.

120,000

nv e D C nt io Pl na an l t

25 %

Window A/C 330,635 MWh, equivalent

70,000 cars *

Co

50 %

Power/Load

75 %

160,000

L w oca A/ l C

Cooling Power Demand

Over one year, the calculation for 5,000 apartments results in the following comparative figures.

100 %

Excellent coefficient of performance (COP) emission reduction

do

Solar Generation

Usually the electrical supply is provided by power stations and the emission has to be calculated as 0.5 kg CO2 per kWh. As a comparison, a typical car emits 2.4 tons CO2 per year.

in

For regular Window A/C mounted at the apartment, the electrical demand is 1.62 kWh per RThour, leading to 204,095

For a high-efficiency district-cooling plant equipped with thermal energy storage, electrical demand is 0.70 kWh per RThour, leading to 204,095 kiloRThour, which results in an electrical power demand of 142,867 MWh per year.

In other words, a switch from Window A/C to an efficient district cooling plant with Siemens Refrigeration Compressor Package (SRCP 10) is like reducing the related emissions from 70 thousand cars to 30 thousand cars. And, finally, using the electrical power generated by a Siemens solar thermal power station, eliminates the emissions completely.

W

Let us assume 5,000 apartments, each covering 120 square meters, in a tropical (hot, humid, dusty) area, with a cooling demand for 260 Wthermic chillers operating 4,600 hours annually.

kiloRThour, which results in an electrical power demand of 330,635 MWh per year.

Tons CO2

Let us take a theoretical example to illustrate the advantages of the Siemens Refrigeration Compressor Package in both economic and environmental terms.

* Emission equivalent to

5

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