Energy Measurement Concepts

1. Energy Measurement Concepts SEPPA LEC 2 01 Aug 2016

2. Basic Energy Measurement Concepts • Energy commodities are measured in two types of unit: • Physical unit • Heat unit • Physical units are used to measure their physical entities such as mass (or weight) and volume, whereas heat units are used to measure power (watt) or work (joule, calorie, Btu) that can be derived from them.

3. Measurement Units • There are 4 basic types of units being used in energy measurements and assessments. • Stock energy units measure a quantity of energy in a resource or stock, such as the amount of oil in a reserve, kerosene in a tank, or wood energy in a tree at a given point in time, e.g., tons of oil equivalent (toe) or multiples of the joule (MJ, GJ).

4. Measurement Units • Flow or rate energy units measure quantities of energy produced or consumed per unit of time which are used for primary, delivered and utilized energy consumption, e.g., million barrels per day (MBD), MJ/day of cooking fuels. • Specific energy consumption relates a quantity of energy to a non-energy value. It is often referred to as an energy intensity, e.g., MJ per kg of cooked food, or MJ per unit of household income (MJ/$).

5. Measurement Units • Energy content or heating value measures the quantity of energy in a fuel per unit weight or volume such as MJ/kg and MJ/liter.

6. Gross and Net Heating Value (NHV) • There are two types for measuring heating values (HV) of fuels: gross and net. • Because of moisture content especially in biomass fuels, the both the values may differ. • Gross Heating Value (GHV) or sometimes called “higher heating value” is the total energy that would be released through combustion divided by the weight of the fuel. • Net Heating Value (NHV) or called as the “lower heating value” is the energy actually available from combustion after allowing for energy losses from free or combined evaoporation.

7. Heating Values

8. Heating Values

9. Moisture Content • Moisture content is given on ‘wet’ basis or ‘dry’ basis. Moisture content (%) dry basis (mcdb) = (water weight in fuel/Dry weight of fuel)x100 Moisture content (%) wet basis (mcwb) = (water weight in fuel/total weight of fuel)x100 To convert between wet (W%) and dry (D%) basis, W =D/(1+D/100) D= W/(1-W/100)

10. Energy Conversion • Resources and reserves • Have various subdivisions to indicate the certainty of the estimates or the availability of reserves under different technological and economic conditions. • Primary energy • Measures the potential energy content of the fuel at the time of initial harvest, production, or discovery prior to any type of conversion.

11. Energy Conversion • Secondary energy • Differs from primary energy by the amount of energy used and lost in supply side conversion systems such as oil refineries, power station, biomass gassifiers, and charcoal kilns. • Delivered energy • Or final energy records the energy delivered to or received by the final consumer, such as a household. • Utilized energy • Is sometimes called energy output, end-use delivered energy, available energy or useful energy. It refers to the amount of work or utilized heat to perform a specific task or service. Utilized energy may be as low as 5 to 8% of the delivered energy in case of open fire fuelwood stoves, and as high as 95 to 100% of delivered energy in the case of electric space heating.

12. Energy Conversion • Utilized energy is sometimes frequently used as the basis for comparing fuel prices (e.g. NR per MJ or $ per MJ of utilized heat for cooking) and for examining the economics and energy savings due to fuel and technology substitution (e.g., switching from open cooking fires to closed stoves).

13. Energy Efficiency • For comparing technologies, there are some distinctions between various measures of efficiency. • Combustion efficiency =Heat generated by combustion (MJ)/Delivered energy of fuel (MJ) • Heat transfer efficiency=Energy absorbed by end use task (MJ)/Heat generated by combustion (MJ) • Percentage of Heat Utilized (PHU) is the energy utilized and expressed as a percentage of that available at any stage in the energy conversion process. • For the consumer, it is the delivered to utilized energy efficiency which matters most, since this determines the energy cost for fhe task: delivered energy (MJ) x unit price (NR/MJ).

14. Cooking devices efficiency World bank, 1987

15. Energy Efficiency • Useful energy efficiency hi = UEi/Fieu = UEi/CVi . Fipu UEi =Fieu x hi = Fipu x CVi x hi Where Fieu - final energy consumption in energy units of fuel i Fipu - final energy consumption of fuel i in physical unit hi - useful (end-use) efficiency of fuel i CVi - calorific value of fuel I UEi - useful energy (In terms of energy service)

16. Energy Efficiency • Relative efficiency Reffi = hi / href where Reffi – relative efficiency of fuel I hi - useful energy efficiency (end-use) of fuel i

17. Specific Energy Consumption • The specific energy consumption (SEC) is a technical concept which measures the energy required to provide one unit of product or service in standardized technical conditions.

18. Power • It is energy production per unit time • It is also energy use per time • The unit is watt (J/s) E=P.t P=E/t

19. Energy carriers • If the substance is used as a source of energy such as coal, petroleum products, biomass, natural gas, then it is called energy carrier.

20. Load Factor (Capacity factor)

21. Load Duration Curve Time series are used in order to get an understanding how energy use or energy production varies over time

22. Load Duration curve in 12 hrs

23. NEA, 2015

24. Load Duration Curve in a year

25. Assignment #1 • Chapter 2 • 2.2, 2.4, and 2.5 • share in total final consumption of energy balance of Nepal 2005 • Load duration curve for highest load day in each month of the year 2071 of NEA load dispatch center