ENERGY

Energy is the capacity/ability to do work.

The basic scientific unit of energy is the Joule (J), Instead we normally use the unit, Watt hour or 1kWh is equivalent to 36,000 Kilojoule (kJ) or 3.6 Megajoule (MJ).

There are various forms of energy; chemical energy as is contained in fuels such as coal, oil or gas, mechanical energy which is held by rotating objects such as the flywheel of a CHP (combined heat and power) unit, thermal energy (Heat) that is released by burning fuels and electrical energy which is produced by the CHP unit generator. 

Typical energy values encountered in buildings are;

Energy used by a 1 bar electric fire each hour = 1 kWh
Energy used to heat a house for one year, 40,000kWh
Energy contained in 1m³ of gas = 10.5 kWh
Energy contained in 1kg of coal = 9.02 kWh
Energy contained in 1 litre of oil = 10.4 kWh

 

POWER

Power is the rate at which energy is used or transferred. 

The unit of power is the Watt (W).

1 Watt = 1 Joule/second

Typical power values encountered in buildings are;

Light bulb = 100W
1 bar electric fire = 1 kW
Boiler for a low energy house = 4kW
Boiler for a detached house = 12 - 18 kW
Commercial boiler = 150kW
Domestic refrigerator = 150W
Typical split A/C unit = 0.8 to 3kW (electrical input) giving 2.4 to 9kW of cooling

 

THERMAL CAPACITY

Thermal capacity is a measure of the ability of a material to absorb heat. It is usually specified in terms of the specific heat capacity of the material. This is the amount of heat, measured in Joules, that one kilogram of the material must absorb to raise its temperature by 1°C. The units of specific heat capacity are J/kg/°C.

For example the specific heat capacity of water is 4200 J/kg/°C, of air is 993J/kg/°C and of stone is 3300J/kg/°C.

 

Energy plants that support air conditioning and refrigeration in very hot countries play a vital role in ensuring comfort, safety, and food preservation. In such climates, demand for cooling is very high, especially during peak summer months. Here's a breakdown of how energy plants are involved and what types are most relevant:

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Types of Energy Plants Used

A. Natural Gas Power Plants

• Most common in hot countries like Saudi Arabia, UAE, and parts of the U.S.

• Quick to ramp up to meet peak cooling loads.

• Cleaner than coal and reliable.

B. Solar Power Plants

• Ideal for hot, sunny climates.

• Used to reduce pressure on the grid during daytime (when AC use peaks).

• Often paired with battery storage or used to power solar cooling systems (like absorption chillers).

C. Waste-to-Energy Plants

• Used in urban areas to manage waste and generate power.

• Can supply energy for district cooling systems.

D. Geothermal (in specific regions)

• In volcanic or geothermally active areas (like parts of Indonesia or Kenya).

• Provides consistent energy that can support refrigeration and AC needs.

 

Energy Demand for Air Conditioning & Refrigeration

• AC and refrigeration can consume 50–70% of electricity in buildings during summer in very hot countries.

• Commercial refrigeration (like in supermarkets or cold storage) adds constant base load.

• Demand peaks in the afternoon, which strains the grid.

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Cooling Solutions Powered by Energy Plants

1. District Cooling Systems

• Centralized cooling systems powered by energy plants.

• Chilled water is distributed to buildings via pipelines.

• Common in cities like Dubai, Doha, and Abu Dhabi.

2. Solar-Assisted Air Conditioning

• Hybrid systems using solar thermal energy for absorption or adsorption chillers.

• Reduces grid dependency and carbon emissions.

3. Thermal Energy Storage (TES)

• Stores chilled water or ice during off-peak hours (night) to use during the day.

• Lowers peak demand and optimizes plant operation.

 

Country Examples: Energy Source and Cooling System Comparison

This concise comparison outlines how different countries utilize specific energy sources and cooling technologies tailored to their climate, infrastructure, and energy strategies:

1. Saudi Arabia
   Energy Sources: Natural Gas, Solar
   Cooling Systems: District Cooling, Thermal Energy Storage (TES)

2. United Arab Emirates (UAE)
   Energy Sources: Natural Gas, Solar
   Cooling Systems: District Cooling, Smart Grid Integration

3. India
   Energy Sources: Coal, Solar
   Cooling Systems: Solar Air Conditioners (ACs), Decentralized Cooling

4. USA (Southwest)
   Energy Sources: Natural Gas, Solar
   Cooling Systems: Grid-Tied Air Conditioning, Smart Thermostats

5. Egypt
   Energy Sources: Natural Gas, Solar
   Cooling Systems: Grid-Connected AC, Pilot Solar Cooling Projects

Each country's approach reflects its geographic and economic context, highlighting the global diversity in sustainable cooling solutions.