Energy Management: 2017/2018

Transcription

1 Energy Management: 2017/2018 Primary, Final & Useful Energies Sankey Diagrams 1 st and 2 nd law efficiencies Historical Energy Use Class # 2 Prof. Tânia Sousa taniasousa@tecnico.ulisboa.pt

2 Primary, Final, Useful Energy & Energy Services

3 Forms of Energy - Primary energy

4 Forms of Energy - Final energy

5 Forms of Energy Useful Energy Other Electrical Uses Light Mechanical power Heat Muscle work Heat/Cooling

6 Forms of Energy Primary energy embodied in resources as it is found in nature (coal, oil, natural gas in the ground) Final energy sold to final consumers such as households or firms (electricity, diesel, processed natural gas) Useful energy in the form that is used: light, heat, cooling and mechanical power (stationary or transport) Productive energy the fraction of useful energy that we actually use

7 Energy Services

8 From Primary Energy to Energy Services

9 From Primary Energy to Energy Services Energy Supply energy flows driven by resource availability and conversion technologies IAASA - Global Energy Assessment 2012

10 From Primary Energy to Energy Services Energy Demand Energy system is service driven IAASA - Global Energy Assessment 2012

11 From Primary Energy to Energy Services Quality and cost of energy services IAASA - Global Energy Assessment 2012

12 Sankey Diagrams & First Law Efficiency

13 Sankey Diagrams Sankey Diagrams: a flow diagram used to represent flows of mass (water, CO2, etc) or energy or money or... by arrows where the thickness of arrows are proportional to the amount Miguel Águas (2009)

14 Example? Sankey Diagram

15 Sankey Diagram Schematic representation of the energy flow (natural gas electricity light reading) Natural gas 50% E E final primary W Q out in Electricity 50% E E useful final Light 20% E productive E useful What is the aggregate efficiency?

16 Sankey Diagram Schematic representation of the energy flow (natural gas electricity light reading) Natural gas 50% E E final primary W Q out in Electricity 50% E E useful final Light 20% E productive E useful What is the aggregate efficiency? 5%

17 World Sankey Diagram in 2005 E final? Eprimary E E useful final? US 94 EJ Portugal 1.1 EJ 1st law efficiencies from primary to final energy and primary to useful are 66 % and 34% IAASA Global Energy Assessment 2012

18 Typical values of 1 st law efficiencies 1 st Law efficiencies from primary to final energy 1 st Law efficiencies from final to useful energy

19 World Sankey Diagram in 2005 IAASA Global Energy Assessment 2012

20 World Sankey Diagram in 2005 IAASA Global Energy Assessment 2012

21 World Sankey Diagram in 2005 IAASA Global Energy Assessment 2012

22 World Sankey Diagram in 2005 IAASA Global Energy Assessment 2012

23 World Sankey Diagram in 2005 IAASA Global Energy Assessment 2012

24 World Sankey Diagram in 2005 IAASA Global Energy Assessment 2012

25 World Sankey Diagram in 2005 IAASA Global Energy Assessment 2012

26 From useful energy to energy services Passive systems: where useful energy is delivered into and mostly lost as unwanted heat, in exchange for energy services such as thermal comfort, illumination and transport (Cullen et al., 2011).

27 From useful energy to energy services Human behaviour & quality

28 Energy & Material Services

29 From Primary Energy to Service Cullen & Allwood, 2010

30 Direct vs. Embodied Energy Cullen & Allwood, 2010

31 Direct vs. Embodied Energy Cullen & Allwood, 2010

32 Energy & Material Energy Services materials Cullen & Allwood, 2010

33 First & Second Law Efficiencies

34 Are first law efficiencies enough? What is the 1 st Law efficiency in a heat pump?

35 Are first law efficiencies enough? What is the 1 st Law efficiency in a heat pump? Qout Qout 1 1 W Q Q out Qin in 1 Q out Typical values of between 3 5 What is the Sankey diagram like?

36 Are first law efficiencies enough? What is the 1 st Law efficiency in a heat pump? Qout Qout 1 1 W Q Q out Qin in 1 Q out Typical values of between 3 5 What is the Sankey diagram like?

37 Are first law efficiencies enough? What is the ideal 1 st Law efficiency in a heat pump? Qout Qout 1 1 W Q Q out Qin in 1 Q out

38 Are first law efficiencies enough? Qout Qout 1 1 W Q Q out Qin in 1 Q out

39 Are first law efficiencies enough? Heating of a house can be done by one of the following methods: 1. Electrical heating using the Joule effect 2. Central heating 3. Heating using a heat pump

40 Are first law efficiencies enough? Providing 1 kwh of heat at 30ºC to a building with an outside temperature of 4ºC Electrical Resistance Central Heating Heat Pump Final (kwh) 1 1/0.90 1/3 1/12 Useful (kwh) Ideal Heat Pump First Law 100% 90% 300% 1200% First law efficiencies do not provide information on how much you can improve your efficiency

41 Work vs. Heat Is a kwh of electricity as valuable as a kwh of heat at 30ºC?

42 Work vs. Heat Is a kwh of electricity as valuable as a kwh of heat at 30ºC? Ideal heat pump cycle kwh of heat at 30ºC 30ºC 1 kwh of electricity 4ºC

43 Work vs. Heat Is a kwh of electricity as valuable as a kwh of heat at 30ºC? Ideal heat pump cycle kwh of heat at 30ºC Ideal power cycle 1 kwh of heat at 30ºC 30ºC 1 kwh of electricity 30ºC kwh of electricity 4ºC 4ºC

44 Work vs. Heat Is a kwh of electricity as valuable as a kwh of heat at 30ºC? Ideal heat pump cycle kwh of heat at 30ºC Ideal power cycle 1 kwh of heat at 30ºC 30ºC 1 kwh of electricity 30ºC kwh of electricity 4ºC 4ºC Electricity is much more valuable than heat

45 Heat at high vs. low temperature 160ºC 30ºC Energy = 100 kwh Energy = 100 kwh Potential Work = 36 kwh Exergy = 36 kwh Potential Work = 8.6 kwh Exergy = 8.6 kwh environment 4ºC

46 Exergy Exergy takes into account the quality of the energy carrier - it is the maximum amount of work that can be extracted from a system as it approaches equilibrium with its environment

47 Second Law energy efficiencies

48 Second Law energy efficiencies

49 Second Law energy efficiencies

50 Exergetic Efficiency Energy efficiency? Heat lost T 0 Moran et al., 2014

51 Exergetic Efficiency Energy efficiency Heat lost T 0 Moran et al., 2014

52 Exergetic Efficiency Exergy efficiency? Heat lost T 0 Moran et al., 2014

53 Exergetic Efficiency Exergy efficiency Heat lost T 0 Moran et al., 2014

54 Exergetic Efficiency Exergy efficiency Heat lost T 0 Moran et al., 2014 Exergy analysis: (mis)match between energy used and end-use

55 Exergetic Efficiency How does exergy efficiency varies assuming? T s =2200K =100% Exergy analysis: (mis)match between energy used and end-use T u Moran et al., 2014

56 Exergetic Efficiency Exergy efficiency Exergy analysis: (mis)match between energy used and end-use T s =2200K =100% Moran et al., 2014

57 First vs. Second Law energy efficiencies IAASA - Global Energy Assessment 2012 Overall 2 nd law efficiency in converting primary to final is 76% and primary to useful energy is 10%

58 First vs. Second Law energy efficiencies Second law efficiencies provide information on how much you can improve your efficiency Rosen and Dincer, 1997

59 Historical Energy Use

60 Primary Energy Use Population (lines) Primary energy use (bars) industrialized countries (white squares and bars) developing countries (gray triangles and bars) Energy use data includes estimates of noncommercial energy use Grubler, A. Energy Transitions

61 Primary Energy Use Population (lines) Primary energy use (bars) industrialized countries (white squares and bars) developing countries (gray triangles and bars) Energy use data includes estimates of noncommercial energy use Grubler, A. Energy Transitions Primary energy use increased more than 20-fold in 200 years Heterogeneity in per capita primary energy use: In industrialized countries population increased linearly while primary energy use increased exponentially until recently In developing countries energy use increased proportionally to population until recently Primary Energy Mix?

62 Primary Energy Mix Grubler, A. Energy Transitions IAASA Global Energy Assessment 2012

63 Primary Energy Mix Grubler, A. Energy Transitions IAASA Global Energy Assessment 2012 Mostly biomass in 1850 Increasing diversification of energy vectors

64 Primary Energy Mix Grubler, A. Energy Transitions

65 Primary Energy Mix

66 Primary Energy Mix Energy Transition biomass to coal

67 Primary Energy Mix Energy Transition biomass to coal Energy Transition coal to oil

68 Primary Energy Mix Energy Transition: The switch from an economic system dependent on one or a series of energy sources and technologies to another (Fouquet & Pearson, 2012) Energy Transition biomass to coal Energy Transition coal to oil Stabilization

69 Energy Eras and Transitions Energy Transformations before industrial civilization:

70 Energy Eras and Transitions Energy Transformations before industrial civilization: Solar radiation food & feed, light and heat Animate labor from humans and work animals (levers, inclined planes, pulleys) mechanical work & transport Kinetic energies of water & wind mechanical work & transport Biomass fuels (wood, charcoal, crop residues, dung) residential & industrial heat and light By Dennis Jarvis from Halifax, Canada - Tibet Something smells here!, CC BY-SA 2.0,

71 Energy Eras and Transitions Energy Transformations before industrial civilization: Dominant in the western world until the 2 nd half of the 19 th century Dominant for most of humankind until middlle of the 20 th century Annual per capita primary energy consumption 20 GJ

72 Energy Eras and Transitions Energy Transformations that came with industrial civilization: Fossil fuels heat & mechanical work & transport (steam engines, internal combustion engines and steam turbines)

73 Energy Transitions An aggregated transition to other energy source(s) includes numerous services and sectors

74 Energy Transitions 16 th century (tall narrow chimneys and suitable grates ) 17 th century (coal gets even cheaper) The switch from an economic system dependent on one or a series of energy sources and technologies to another (Fouquet & Pearson, 2012)

75 Energy Transitions 1709 (coke) 18 th century (efficiency improvments) The switch from an economic system dependent on one or a series of energy sources and technologies to another (Fouquet & Pearson, 2012)

76 Energy Transitions 1804 (1 st steam locomotive) The switch from an economic system dependent on one or a series of energy sources and technologies to another (Fouquet & Pearson, 2012)

77 Why do energy transitions occur? Main Drivers/Catalyst for adoption of a new energy carrier: Price of energy Better/Different Service Technological change and innovation Efficiency improvments

78 Why do energy transitions occur? Main Drivers/Catalyst for adoption of a new energy carrier: Price of energy Better/Different Service Technological change and innovation Efficiency improvments Environmental Impacts?

79 Decarbonization of Energy Systems Decreasing trend in CO 2 emitted per GJ from 1850 to : 108 GJ/capita/year 7600 kg CO 2 /capita/year

80 Decarbonization of Energy Systems Historically energy related biomass burning has not been carbon-neutral (maximum estimated value of 38%)

81 Decarbonization of Energy Systems Why a slight increasing trend in the last 10 years?

82 Why do energy transitions occur?

83 Final Energy from World final energy use by consumers. Solids (such as coal and biomass, brown), Liquids (such as oil, red) and fuels delivered via dedicated Grids (such as natural gas and electricity, green). Grubler, A. Energy Transitions

84 Final Energy from World final energy use by consumers. Solids (such as coal and biomass, brown), Liquids (such as oil, red) and fuels delivered via dedicated Grids (such as natural gas and electricity, green). With rising incomes, consumers pay increasing attention to convenience and cleanliness, favoring liquids and grid-delivered energy forms Grubler, A. Energy Transitions

85 Final Energy from World final energy use by consumers. Solids (such as coal and biomass, brown), Liquids (such as oil, red) and fuels delivered via dedicated Grids (such as natural gas and electricity, green). Grubler, A. Energy Transitions Developing countries OECD (squares)

86 Final Energy from World final energy use by consumers. Solids (such as coal and biomass, brown), Liquids (such as oil, red) and fuels delivered via dedicated Grids (such as natural gas and electricity, green). Grubler, A. Energy Transitions Heterogeneity in final energy quality

87 Final Energy per capita in 2010 Heterogeneity in Final Energy Use per capita: IAASA Global Energy Assessment 2012

88 What is Final Energy used for? UK IAASA Global Energy Assessment 2012

89 What is Final Energy used for? Regular expansion of energy services in 19 th dominated by heat and transport High volatility due to political and economic events Moderated growth after 1970 Decline in industrial energy services compensated by strong growth in transport Saturated at a level of 6 EJ or 100 GJ/capita What about energy services? IAASA Global Energy Assessment 2012

90 From Final Energy to Energy Services UK IAASA Global Energy Assessment 2012

91 From Final Energy to Energy Services UK Increasing efficiencies in converting final energy to energy services Ranges between a factor of 5 for transportation and 600 for lighting IAASA Global Energy Assessment 2012

92 From Final Energy to Energy Services UK Lower prices of energy services Ranges between a factor of 10 for heating and 70 for lighting IAASA Global Energy Assessment 2012

93 Energy services cannot be expressed in common units Transport 13 km/day/per capita Energy Services ton 20 km/day/per capita Industry 9 ton/year/per capita (steel + fertilizers + construction materials + plastics Buldings Heating/cooling to 20m 2 /per capita Useful energy minimizes distortions among different energy service categories, as it most closely measures the actual energy service provided.