1. Energy Analysis: Process Analysis
Gestão de Energia: 2016/17
Energy Analysis: Process Analysis
Prof. Tânia Sousa

2. Energy Content
2.75 MJ/kg
31 MJ/kg

3. Embodied Energy
Embodied Energy is …

4. Embodied Energy
Embodied Energy is the sum of all the energy required to produce any goods or services,

5. Energy Analysis Embodied energy in a car? Auto-industry assembly line
kW/capita
GJ/capita
Region
1990
2008
USA
10.2
10.0
320.5
314.0
EU-27
4.6
4.7
144.9
147.0
Middle East
2.2
4.0
69.9
125.2
China
1.0
2.1
31.8
67.0
Latin America
1.3
1.6
40.6
51.9
Africa
0.8
0.9
25.5
28.1
India
0.5
0.7
15.9
22.6
Others*
2.9
2.7
90.8
85.9
The World
2.4
76.6
Auto-industry assembly line
Electricity
Paint
Embodied energy in a car?

6. Energy Analysis
Definition: the process of determining the embodied energy of a product or service, i.e., the energy required directly and indirectly to produce it
The energy used indirectly might be more important that the energy used directly
Auto-industry assembly line
Electricity
Paint
Embodied energy in a car: 270 GJ

7. Energy Analysis
What is Energy Analysis useful for:

8. Energy Analysis What is Energy Analysis useful for:
Determine the energy needed to produce a product
Compare the energy needed to produce a product in different places
Compute energy savings due to changes in the production processes, e.g., by recycling waste glass produced inside a glass factory back to the furnace?

9. Energy Analysis
Difficulties associated with the Energy Analysis framework:

10. Energy Analysis
Difficulties associated with the Energy Analysis framework:
Choosing the system boundary
Merge several kinds of energy
Ex: the production of fueloil from crude oil has a much higher efficiency than the production of electricity from coal
Energy Credit for by-products
Ex: by-products from the iron & steel industry are used by the cement industry

11. Energy Analysis: Basic Operations
Unitary Production Operation
Conventions:
The use of block letters for Operations
The use of numbers for Inputs/Outputs
Operation A m2 m3 mR EA
Materials
lnput
Production
Energy
consumption
Residues m1

12. Energy Analysis: Specific Consumption of Operation & Inputs
Specific Consumption of Operation A: CEA
Specific Consumption of Material 1: CE1

13. Energy Analysis: Mass Factors
Residue formation factor
Mass proportion

14. Energy Analysis: Specific Consumption of Production
What is the energy specific consumption of m3?

15. Energy Analysis: Specific Consumption of Production
What is the energy specific consumption of m3?
Write it as

16. Energy Analysis: Specific Consumption of Production
What is the energy specific consumption of m3?
Write it as
Direct Energy Use
Indirect Energy Use

17. Energy Analysis: Specific Consumption of Production
What is the energy specific consumption of m3?
What is the specific consumption of residues?

18. Energy Analysis: Specific Consumption of Production
What is the energy specific consumption of m3?
The specific consumption of residues is null
No energy consumption is attributed to mR (which is also an output of operation A)

19. Energy Analysis: Specific Consumption of Production
What is the energy specific consumption of m3?
Why does a higher residue formation factor, SA, implies a higher specific consumption of the useful output, CE3?

20. Energy Analysis: Sequential Process
What is the energy specific consumption CE4? EC EA EB B A C 2 3 4 1

21. Energy Analysis: Sequential Process
What is the energy specific consumption CE4?
Write it as a function of: EC EA EB B A C 2 3 4 1

22. Energy Analysis: Sequential Process
What is the energy specific consumption CE4? EC EA EB B A C 2 3 4 1

23. Energy Analysis: Sequential Process
What is the energy specific consumption CE4 using this exterior boundary? EC EA EB B A C 2 3 4 1

24. Energy Analysis: Sequential Process
What is the energy specific consumption CE4 using this exterior boundary?
Homework: Prove that this expression is equal to EC EA EB B A C 2 3 4 1

25. Exercise
Consider the production system of floor pavement that has only: a ceramic oven, choice of defective parts and storage. The specific consumption of the furnace is 200 kJ / kg, whereas the specific energy consumption of the choice operation is 5 kJ / kg and the specific energy consumption of storage operation is 20 kJ / kg. The floor raw material involved an energy consumption of 50 kJ / kg in the clay processing operations. The operation of cooking promotes the volatilization of certain components of raw pavement representing 5%. The operation of choice rejects 10% of the output of the furnace and breaks during storage are 1%. Determine the specific consumption of the floor pavement.

26. Exercise
Scheme CEA = 200 kJ/kg; CEB = 5 kJ/kg; CEC = 20 kJ/kg CE1 = 50 kJ/kg; SA = 1/0.95; SB = 1/0.9; SC = 1/0.99 EC EA EB
Choice
Oven
Storage 2 3 4 1

27. Energy Analyis: Convergent Process
What is the energy specific consumption CE5? A B C 5 4 2 3 1

28. Energy Analyis: Convergent Process
What is the energy specific consumption CE5? A B C 5 4 2 3 1

29. Exercise
A company manufacturing sunflower oil imports 60% of raw material and the remaining 40% is domestically produced. The sunflower imported is transported by sea 1000 km, while the national sunflower is transported by truck 200 km. The operation of oil refining has a specific consumption of 100 kJ/kg. The oil content of sunflower is 10%, meaning that the rejection mass on refining is 90% (in fact this material is used in the manufacture of cattle feed). The specific consumption of transport is kJ/kg.km by truck and kJ/kg.km by sea. Losses in sunflower transportation are 1% on truck and 0.1% on ship. Determine the specific consumption of refined oil.

30. Exercise Scheme CEA =10000.01 kJ/kg; CEB =2000.025 kJ/kg;
CEC =100 kJ/kg;
SA = 1/0.999; SB = 1/0.99; SC = 1/0.1;
CE1 = CE3 = 0;
A: Transport ship
B: Transport truck
C: Refining 5 4 2 3 1

31. Energy Analyis: Divergent Process
In a divergent process all products that are an output of the same operation have the same specific energy consumption
There are other options to give energy credit to by-products, e.g., economic. B C A 3 5 2 4 1

32. Energy Analyis: Divergent Process
What are the energy specific consumptions CE5 & CE3? B C A 3 5 2 4 1

33. Energy Analyis: Divergent Process
What are the energy specific consumptions CE5 & CE3? B C A 3 5 2 4 1

34. Exercise Compute CE11 and CE12 D E C G A 11 10 9 7 5 2 F 1 4 B 3 6 128

35. Exercise Compute CE11 and CE12 D E C G A 11 10 9 7 5 2 F 1 4 B 3 6 128

36. Energy Analysis: Treatment Operation
What is the energy specific consumption CE2?
Energy consumption in a treatment operation is assigned to the operation that generates the residues (A)

37. Energy Analysis: Treatment Operation
What is the energy specific consumption CE2?

38. Energy Analysis: Treatment Operation
What is the energy specific consumption CE2?
What is the energy specific consumption CE3?

39. Energy Analysis: Treatment Operation
What is the energy specific consumption CE2?
What is the energy specific consumption CE3?
The energy specific consumption of the output from the treatment operation is null

40. Energy Analysis: Recycling
What is the specific consumption of production CE2?
Operation A m 1 2 R E A
Materials
input
Production
Energy
consumption
Residues
Treatment
operation B 3
Recycled
residues B
in treatment
Recycling
operation C m4

41. Energy Analysis: Recycling
What is the specific consumption of production CE2?
Other recycling schemes:
Operation A m 1 2 R E A
Materials
input
Production
Energy
consumption
Residues
Treatment
operation B 3
Recycled
residues B
in treatment
Recycling
operation C m4