BUILDING SECTOR ENERGY EFFICIENCY PROJECT

July 2015

HPLooi@jkr.gov.my

THE ECONOMICS OF SITE SOURCE ENERGY

ABSTRACT

The ‘Economics of Site Source Energy’ is an account of energy use at (consumer) end which considers

energy life cycle from source (and even extraction). Site Source accounts for final energy use from the

perspective of national energy balance. This brief provide an explanation of the concepts of Site Source

Energy. While this brief do not purport to be an academically exhaustive treatise on the subject, it

approach the subject matter in a concise manner with the following topical discussions:

(a) Glossary of terms and key concepts;

(b) Examples of Site Source calculations in energy use.

GLOSSARY AND KEY CONCEPTS

1. PRIMARY AND SECONDARY ENERGY

Not all energy are equal from the perspective of energy life cycle and GHG. United Nations Statistics

Division (www.unstats.un.org) in their publication “International Recommendation on Energy

Statistics (IRES); Chapter 3 – Standard International Energy Classification (SIEC) has this definition:

Figure 1 – UN Definition of Primary and Secondary Energy

“Primary energy is energy embodied in sources which involve human induced extraction or

capture, that may include separation from contiguous material, cleaning or grading, to make

the energy available for trade, use or transformation”

“Secondary energy is energy embodied in commodities that comes from human induced energy

transformation”

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2. ENERGY CONVERTORS AND THERMAL PUMPS

Energy convertors and thermal pumps are two concepts commonly misunderstood by the general public. Heat pumps are in some cases confused as energy convertors. In all cases, the law of conservation of energy (“energy can neither be created nor destroyed”) itself may suffer misinterpretation when both terms are confused.

Energy convertors converts energy from one form to

another form. The input form may be either primary

or secondary energy source e.g. coal, natural gas,

petroleum, electricity etc.; while the useful energy

output include (examples) kinetic, shaft or

mechanical energy, thermal (heat or cold) energy, or

secondary energy such as electricity.

Thermal pumps move thermal energy from one

source to another location. A good illustration is the

Peltier heat pump. In the reverse ‘Seeback effect’, a

voltage difference will cause a cold and hot difference

at both junctions. This effectively “pumps” heat from

one end to the other. In contrast an electric heater is

an energy convertor. More conventional heat pumps

are chillers in space cooling.

Concomitant to the energy convertor is the efficiency

of conversion defined as:

Efficiency of Conversion; Ƞ =𝑈𝑠𝑒𝑓𝑢𝑙 𝐸𝑛𝑒𝑟𝑔𝑦 𝑂𝑢𝑝𝑢𝑡

𝐸𝑛𝑒𝑟𝑔𝑦 𝐼𝑛𝑝𝑢𝑡

Ƞ is less than 100% or 1 and the differences can be

attributed to losses such as friction, inefficiencies in

fuel conversion, exhaust gas, system cooling etc.

In the case of thermal pumps, efficiency is defined by

the Coefficient of Performance (CoP).

(𝐶𝑜𝑃) =𝑇ℎ𝑒𝑟𝑚𝑎𝑙 𝐸𝑛𝑒𝑟𝑔𝑦 𝐷𝑒𝑙𝑖𝑣𝑒𝑟𝑒𝑑

𝐸𝑛𝑒𝑟𝑔𝑦 𝐼𝑛𝑝𝑢𝑡

CoP may be more than 1 and represent the thermal

energy (heat or cold) which can be pumped with the

input of 1 unit of energy.

Figure 2 – Energy Convertors and Heat Pumps

Typical energy convertors are listed in Table 1 below.

Energy

Conversion

Device Energy

Input

Useful Energy Output

Thermal

Pump Thermal

Energy

Source

Thermal

Energy

Delivered

Energy Input

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Electricity

(kgCO2e/kWh)

Natural Gas

(kgCO2e/kWh)

Heating Oil

(kgCO2e/ltr)

LPG

(kgCO2e/ltr)

UK 0.5892 0.22674 3.0714 6.5276

US/ Canada 0.65849 6.349222 11.6266 1.7244

Asia 0.78213 0.22674 3.0714 1.7244

Europer (EU) 0.43650 0.22674 3.0714 1.7244

Singapore 0.63575 0.22674 3.0714 1.7244

South Africa 1.10196 0.22674 3.0714 1.7244

Emission Factor for Common Fuel/ Energy Use

PR China 0.92105 Taiwan 0.77051 Hong Kong 0.96825 India 1.42260

Indonesia 0.95300 Japan 0.51416 DPR Korea 0.59018 Malaysia 0.73159

Pakistan 0.62163 Philippines 0.61308 Singapore 0.63575 Thailand 0.64370

Emission Factor for Grid Electricity Asia (2012)

Table 2 – Typical Emission Factor (Source Carbon Trust Calculator)

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SITE SOURCE ENERGY IN END USE

We conclude that electricity as a secondary form of energy has a site source factor of about 3.3 (i.e. 3 times

more primary energy is required to utilise 1 unit of electrical energy.

Figure 3 – Electricity Generation

Natural gas for boiling water Electric heating for boiling water

In the first case of natural gas to boil water 1 unit primary energy will allow 0.85 useful energy to boil water.

However in the second case of electric heating, for every 1 unit of primary energy only about 0.28 unit of

useful energy is available to boil water.

Figure 4 – Heating water with natural gas and electricity.

Space cooling is a major consumer of energy in the building sector. In the next series of panels the

various options in reducing energy demand for space cooling are explored.

Electric kettle

95% efficiency

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In a district cooling plant aggregated CoP of space cooling

for the whole district will be improved. Additionally the Ice

Storage system ensure optimal management of cooling

demand profile thereby maintaining aggregated CoP at

optimal level. Assume distribution losses at 10%.

1unit of primary energy allows for approx. 1.8 units cooling

energy.

Conventional space cooling every

building within a district has its own

space cooling plant. The CoP of each

individual plant ranges from CoP 2 to 6

(smaller plants have lower CoP).

Additionally individual plant may not be

able to deal with part loads inherent in

the operation of each building. This will

further degrade the apparent CoP of

individual plants. The aggregated CoP of

a district may be estimated at say 4.0.

I unit primary energy provides

approx. 1.2 units cooling energy.

Figure 4 – District Cooling Plant with Ice Storage

Where natural gas (a primary energy) is available, district cooling may be further improved.

Figure 4 – District Cooling Plant with Natural Gas as Primary Energy Source

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In this case study (natural gas as primary energy source), electricity generation is included. An

electric driven chiller is used to cater for peaking loads. Gas engine is used instead of gas turbine

(capital cost and operational cost is cheaper). The resultant CoPPE shows more than 2 fold

improvement in Site Source energy use compared to conventional cooling (Figure 4 above).

At left, Energy balance of gas engine (typical),

with 100% energy input

Figure 6 – DC Plant with Electricity Generation and Gas Engines

VERSION 1.00

FIRST PUBLISHED 30th July 2015

COPYRIGHT Public Domain The content of this paper may be freely used in the public domain provided proper citation to the author is included

AUTHOR: IR LOOI HIP PEU HPLooi@jkr.gov.my mektricon@gmail.com

BUILDING SECTOR ENERGY EFFICIENCY PROJECT