1. Energy Efficiency Terminology Dr. Mohammad A. Irfan Sept 19, 2016 Industrial Energy Assessment Lab Department of Mechanical Engineering, College of Engineering, Qassim University, Saudi Arabia REE 635 Energy Efficiency Lecture No. 3

2. Outline Energy Literacy Units of Energy Cost of Energy Use Energy Losses Energy Efficiency

3. Energy Literacy Energy literacy is an understanding of the essential aspects of energy, such as: energy sources and impacts, energy conversion, energy management, Energy accounting measuring energy use and energy efficiency.

4. An energy literate person will be able to: Determine how energy is sourced; Understand energy conversion and distribution; Make informed decisions based on an understanding of energy use and impacts; Determine how much energy is used over a determined time; Identify ways to use energy more efficiently; and Communicate about energy use and efficiency. Energy Literate Person

5. What is Energy? Energy is defined as the potential to do work or transfer heat. Kinetic energy is the energy of motion. For example, the energy a cyclist uses to pedal a bike is turned into kinetic energy. Potential energy is energy stored for later use. For example, water in a dam is potential energy used to generate electricity through a hydro plant.

6. Energy Laws: Law of conservation of energy: Energy cannot be created nor destroyed. For example, the electrical energy used to turn on a light globe doesn’t get used up, but is converted into both light and heat energy. Only the light is useful, therefore the heat released is ‘wasted’ energy given it is not being used.

7. Energy Laws: Entropy: The usefulness or quality of energy decreases as energy changes forms thus making it less useful. For example, most of the heat energy from an electric kettle is lost to the surrounding air and water and cannot be recaptured for any useful purpose.

8. Forms of Energy Electrical energy, the energy transmitted through electrical wires. Electromagnetic energy which includes micro-waves, frequency signals or infra-red heat. Thermal energy is the heat energy in the form of a solid, liquid or gas. Mechanical energy which is the energy of movement, and can either be stored or potential energy. Chemical energy, the energy released from stored energy in fossil fuels or biomass from both living and non-living organisms. Nuclear energy, the energy released from the nuclei of atoms or a nuclear reaction. Gravitational energy which includes unrestricted potential energy, like water in a dam or tidal energy.

9. Energy Sources

10. Non-renewable energy resources are finite; they will eventually be exhausted and not replenished within a human timescale. Non-renewable resources are formed over millions or billions of years, and include fossil fuels (gas, oil and coal), and nuclear fuels. Renewable energy sources are naturally replenished in a relatively short time, which makes them essentially inexhaustible. Renewable energy sources include the sun, wind, rain, ocean tides, geothermal and biomass, as well as the food we grow and eat.

11. What type of energy is available? The energy sources discussed in the previous section are generally not useful in their raw forms. Therefore, energy sources must be changed through conversion into a more useful form, for example wind is more useful when a sail is used to capture it to move a sail boat for transportation. A more complex example is when wind causes blades to move on a wind turbine to generate electricity for a range of end uses.

12. What type of energy is available? When primary energy sources are converted, the useable energy is reduced during the conversion process.

13. Understanding the cost of energy use The cost of energy use associated with the natural environment, our society (local and global communities) and our economy. Our society is dependent on energy and rising electricity and fuel prices are increasing costs across our economy. “the price of electricity is determined by a number of factors such as transmission and distribution network costs, the wholesale electricity price faced by retailers, and government policies.

14. Environmental Cost of Energy

15. Energy Conversion and Transmission Losses Demand Side Saving Supply Side Saving

16. Gas Turbine Power Plant

18. Energy Conversion Losses

19. A detailed example of transport energy includes the petrol or fuel used to power a car, which is a high quality energy source. In other words, it concentrates a large amount of energy into a relatively small mass. That energy is easily accessed by burning during combustion. In the process, around 70% of the energy is converted to other forms which are of no use in making the engine work.

20. Energy Conversion Losses

21. These forms include: Sound (mechanical energy); Friction (thermal energy); Air turbulence (mechanical energy); and Heat from the exhaust in the form of hot air (thermal energy). None of the above forms of energy help to make the car move forward

22. How do we measure Energy BTU: Amount of Heat required to raise the temperature of 1 lb of water through 1 F. 1 BTU = 1055 Joules

23. How do we measure Energy: Calorie Thermodynamics: Calorie: the energy needed to raise the temperature of 1 gram of water through 1 °C 1 Calorie = 4.2 Joules

24. How do we measure Energy: Calorie Physiology: A kilocalorie is the amount of heat required to raise the temperature of 1 kilogram of water one degree Celsius. 161 kCal

26. Nutrition: kilo Calorie

27. How do we measure Energy The scientific unit of work is a joule (J) (named after James Prescott Joule) which is work from a force of one newton acting over the distance of one meter. 1J = 1N x 1m A basic unit of energy is a joule (J), but more often energy is measured in much larger quantities such as kilojoules (1,000 joules), megajoules (1,000,000 joules) and gigajoules (1,000,000,000 joules).

28. How do we measure Power? Electrical energy used for power, which we call electricity, is measured in watts(one joule per second). 1 W = 1 J/ sec Although, electrical energy is frequently measured as a kilo watt-hour (kWh), being 1,000 watts consumed over one hour. Note W x sec = J (Energy)

29. Units of Power and Energy

30. Electric Power - Units To calculate the power in watts (W), the voltage (V) is multiplied by the current amps (A). Example: The laptop data plate in requires 19 volts (V) and 3.42 amps (A), calculated as: 19V x 3.42A = 65W

31. Power Units For a comparison, a blender which is rated at 240V at 5.42A, is calculated as: (power) 240V x 5.42A = 1,300W Till here

32. (Electric ) Energy Units Energy is calculated in watt-hours (Wh), by multiplying power (W) by time in hours (h). Example: The laptop discussed previously required 65W of electrical energy. If it is used over 3 hours, the energy required is calculated as: 65W x 3h = 195 Wh For comparison, a blender is rated at 1,300W. How much energy is used by the blender in 2 hours? 1,300 x 2 = 2,600 Wh

33. kWhr Example: The laptop requires 65W over 3 hours calculated as 195 Wh. To calculate the kWh, divide the total Wh by 1000: 195/1000 = 0.195 kWh For comparison, the blender required 1,300 W over 2 hours calculated 2,600 Wh or 2.6 kWh

34. Energy Units : Joules or kWh? A kilo-watt hour can be converted to joules given there are 1,000 watts in a kilo-watt over 1 hour. Recall W = J / sec So J = W x sec Example: 1kWh = 1000w x 3600s = 3,600,000 J To determine MJ = 3,600,000 (J) / 1,000,000 (M) = 3.6 MJ So 1 kWh = 3.6 MJ or 1 kWh = 3600 kJ

35. Calculating energy Energy is the actual usage of electrical energy over time, most often reflected on a utility statement from the electricity company.

37. Comparing energy consumption To compare energy, the same unit of measurement is required. On a utility bill for natural gas usage it is often measured in joules (J) or mega-joules (MJ), although electricity is measured in kilo-watt hours (kWh). These units must be converted into joules or mega-joules for comparison. Thermal energy is sometimes measured using British Thermal Units (Btu), MJ (mega joules) and/or kWh are most often used to measure heating and cooling systems. HW: Handout for Energy Conversion Problems

38. Energy Utilization Index (EUI)

40. EUI: CW:DIYS Example: Consider a building with 20,000 sq. m of floor space. It uses 4 million kWh and 14,000 GJ of natural gas in one year. Find the EUI for this building? Sol. First bring both to a common unit. Electric: 4 x 10^6 kWh x 3600 kJ/kWh = 14.4 x 10^9 kJ Gas: : 14,000 GJ x (10^6 kJ/GJ) = 14 x 10^9 kJ Total Energy consumed = (14.4 kJ + 14 kJ) x 10^9 = 28.4 x 10^9 kJ EUI = 28.4 x 10^9 kJ/ 20,000 sq. m = 1.42 x 10^6 kJ/ sq.m. EUI = 1420 MJ/ sq.m/yr

41. What is energy efficiency? Generally, energy efficiency is based on an equation where the amount of energy input is compared to the amount of energy output. In an effort to increase efficiency the aim is to either: 1. Do less - conservation 2. Do the same with less - use less energy while achieving the same level of output or 3. Do more with less - use the same amount of input while increasing the level of output 4. Do less with even less – eliminate all unnecessary work and determine the most efficient process to carry out the remainder of the work

42. CW: Example of Energy Efficiency Assume 72% losses in Generation and Transmission

43. EXTRA MATERIAL

44. Gas Turbine Lighter in Weight Less moving parts Inlet temperature 800 C Higher inlet temperature gives higher Carnot Efficiency Combustion of fuel gives more energy to drive the turbine blades Steam Turbine Heavier in weight for same kW output More moving parts Inlet temperature 500 C Lower inlet temperature gives lower Carnot Efficiency High pressure steam gives less energy comparatively

47. Thank you