Publisher: Earthscan, UK Homepage: earthscan.co.uk/?tabid=101807

1. Energy and the New Reality, Volume 1:Energy Efficiency and the Demand for Energy ServicesChapter 6: Industrial Energy Use L. D. Danny Harveyharvey@geog.utoronto.ca This material is intended for use in lectures, presentations and as handouts to students, and is provided in Powerpoint format so as to allow customization for the individual needs of course instructors. Permission of the author and publisher is required for any other usage. Please see www.earthscan.co.uk for contact details. Publisher: Earthscan, UKHomepage: www.earthscan.co.uk/?tabid=101807

2. Major Industrial Sectors - Iron & Steel - Aluminum - Copper - Cement - Glass - Pulp & Paper - Plastics - Petroleum refining - Chemicals (including fertilizers – Chapter 7) - Food processing (Chapter 7) - General manufacturing

3. Figure 6.1 Industrial Energy use in 2005 as a percent of total energy use in various regions

4. Figure 6.2a Industrial energy use in OECD countries in 2005

5. Figure 6.2b Industrial energy use in non-OECD countries

6. Figure 6.3 Global primary energy use for production of the 12 commodities (other than the production of fuels) using the most energy

7. Definitions: • Primary metals: made from virgin ores (raw materials) • Secondary metals: recycled from scrap • Feedstock energy: The energy content of fossil fuels that become part of the material in a commodity. It is equal to the heating value of the final product. • Process energy: energy (in the form of heat or electricity) used to power a chemical transformation. It is equal to the total energy inputs to the production process minus the embodied energy of the final products • Embodied energy: the total amount of energy (process + feedstock) that went into making something

8. Overview of global production of major commodities of energy interest

9. Figure 6.4: Trends in production of major commodities (solid lines use the left scale, dashed lines the right scale)

10. Processing of Minerals • Most minerals of interest occur as oxide minerals in ores (rock bodies with various minerals mixed together, besides the ones of interest) • The steps in processing minerals are thus – separation of the minerals of interest from the other minerals in the ores - removal of oxygen (reduction) - purification

11. Reduction of oxide minerals, calcination of CaCO3 (during production of cement), and processing of silica and limestone to make glass all release CO2 • Iron: 2Fe2O3 +3C → 4Fe+3CO2 • Alumina (made first from bauxite): 2Al2O3 + 3C → 4Al+3CO2 • Cuprite (produced by roasting Cu-containing minerals): 2CuO+C→2Cu+CO2

12. Calcination of limestone to make cement: CaCO3→CaO+CO2 Production of glass: nSiO2 + mCaCO3 + xNa2CO3 + .... → Glass + CO2

13. In the case of iron, aluminum and copper, the C used for reduction comes from fossil fuel inputs, or from materials (such as C anodes) made from fossil fuels, and so is accounted for in the energy use data combined with the emission factors (kgC/kg fuel) for these energy inputs.Thus, fossil fuel energy inputs play two roles in producing Fe, Al, or Cu – as a source of C for the reduction reaction and as a source of heat (through combustion) to drive the reaction.

14. In the case of calcination of limestone or transformation of raw materials into glass, however, the C that is released as CO2 comes from the raw materials themselves and so is not accounted for in the energy use data. Thus, you will find that national CO2 emission data are given separately for coal, oil, natural gas, and production of cement. This latter category refers to the CO2 that is produced through the chemical reactions involved in the formation of cement, and is in addition to the CO2 released from burning the fossil fuels used at the cement plants.

15. Chemical emissions from the production of glass are only about 1% of those from cement (due to about 30 times less global production and a 3 times smaller emission factor), and tend to be ignored in compilations of national emissions.

16. Iron and Steel

17. Figure 6.5a: World production of primary + secondary raw steel

18. Figure 6.5b: Production of raw steel in 2007

19. Figure 6.5c End uses of steel in the US in 2003

20. Figure 6.6 Anthropogenic iron flows in 2000 (Tg Fe/yr) Source: Wang et al (2007, Environmental Science and Technology 41, 5120–5129)

21. Traditional Steps in Making Steel: • Beneficiation of iron ores (removal of impurities) • Agglomeration of fine particles • Reduction of iron ore to make crude iron • Refining of crude iron to make steel (removing impurities, adding trace elements) • Shaping of steel into final products

22. Reduction of iron ore • Commonly done in a blast furnace • C from coke (which is like charcoal, and made from coal by driving off volatile materials) is used as a reducing agent • Theoretical minimum energy requirement is 6.8 GJ/t • Practical lower limit is 10 GJ/t, best blast furnaces use about 12 GJ/y, world average is about 14.4 GJ/t • Coke provides some of the heat energy required (as well as serving as a reducing agent), with the balance supplied by coal

24. Refining of crude iron • 3 options are: Open-hearth furnace, Basic Oxygen Furnace (BOF), Electric air furnace (EAF) • BOF requires pure oxygen (separated from air) • EAF is used for scrap metal and in the new direct-reduction process • Energy by EAFs per tonne of steel fell in half between 1960-1900

25. Figure 6.7 Refining of reduced iron to produce steel

26. Figure 6.8 Energy used by EAFs per tonne of crude steel Source: de Beer et al (1998a, Annual Review of Energy and the Environment 23, 123–205)

27. Shaping of Steel, Traditional Method Produce steel in cubical blocks, small bars, or slabs using a continuous caster, then convert into final products using various hot mills (heating and cooling occurs between steps, with an energy loss each time)

28. Shaping of Steel, Alternative approaches:Cast the molten steel closer to the desired final shape, using thin-slab casting, thin-strip casting, or powder metallurgy Thin-strip casting has the potential to reduce energy use for shaping by 90-95% In thin-strip casting, the length of the production line has been reduced from 500-800 m to 60 m – about a factor of ten reduction!

29. Alternative Approaches for Reducing Iron Ore: • Blast Furnace with coke through reaction with CO while the ore is still solid (traditional approach) • Direct reduction of the ore using coal or natural gas to produce a H2-rich gas (or direct use of purchased H2) combined with a DC current • Smelting reduction of the ore in the liquid state, directly using coal

30. Figure 6.9a Primary energy use with best current blast-furnace/BOF route for making primary steel

31. Figure 6.9b Primary energy use with advanced blast-furnace/BOF making primary steel By comparison, the present world average primary energy requirement for primary steel is about 36 GJ/t

32. Figure 6.9c Primary energy use with best current direct reduction/EAF steel making

33. Figure 6.9d Primary energy use with advanced direct reduction/EAF steel making and advanced refining, casting, and shaping

34. Figure 6.9e Primary energy use with advanced smelting-reduction/BOF steel making and advanced refining, casting, and shaping This is a reduction by 63% (~two thirds) compared to the present average primary energy use for primary steel of 36 GJ/t. The savings is due in part to an assumed improvement in the efficiency in generating the electricity that is supplied to the steel plant from 40% to 60%.

35. Figure 6.10a Current mill using scrap steel to make secondary steel Source: de Beer et al (1998a, Annual Review of Energy and the Environment 23, 123–205)

36. Figure 6.10b Advanced mill using scrap steel to make secondary steel This is a reduction by 50% from the present world average of 7 GJ/t for secondary steel. The savings is due in part to an assumed improvement in the efficiency in generating the electricity that is supplied to the steel plant from 40% to 60%. de Beer et al (1998a, Annual Review of Energy and the Environment 23, 123–205) Source: de Beer et al (1998a, Annual Review of Energy and the Environment 23, 123–205)

37. Steel Summary: Primary Energy Requirements • Primary Steel: - 36 GJ/t world average today, assuming electricity supplied at 40% efficiency • Secondary Steel: - 7 GJ/t world average today – a reduction by about a factor of 5 compared to primary steel

38. Steel Summary (continued): • Current average with 32% secondary: 26.3 GJ/t • Future average with 90% secondary and current best practice as average: 6.9 GJ/t This is a reduction by a factor of 3.8 • Future average with 90% secondary, best projected energy intensities for primary and secondary steel: 5.9 GJ/t This is a reduction by a factor of 4.5 • All of the above plus 60% electricity supply efficiency instead of 40%: 4.5 GJ/t This is a reduction by a factor of 5.8 • Thus, the overall potential reduction in the average primary energy intensity of steel is a factor of 4.5 to 6

39. Aluminium

40. Figure 6.11a World production of primary aluminium

41. Figure 6.11b Production of primary aluminium in 2007

42. Figure 6.11c End uses of aluminium in the US in 2003

43. Production of Aluminium • Mining of bauxite (mostly Al(OH)3 and AlO(OH)) (most of the mining is through strip mining) • Refining of bauxite into alumina (Al2O3) -grinding, then digestion with caustic soda at high T and P • Smelting of alumina into aluminium, through electrolysis of alumina that has been dissolved into cryolite (Na3AlF6) at 900oC -both the cathode and anode are made of C -the net reaction is 2Al2O3+3C→4Al+3CO2

44. Figure 6.12 Aluminium Mass Flow in 2005 From this diagram it can be seen that a little over 4 t of dry bauxite are mined for every tonne of primary aluminium that is produced Source: IAI (www.world-aluminium.org)

45. Figure 6.13 Secondary energy used in making aluminium metal

46. Figure 6.14: World average electricity use for the production of aluminium

47. Figure 6.15 Efficiencies of individual processes in producing aluminium Source: Thekdi (2003, Aluminum 2003, The Minerals, Metals & Materials Society, 225–237)

48. Figure 6.16: World production of primary and secondary aluminium, and the secondary share of total production

49. Aluminium Summary: Primary Energy Requirements • Primary aluminium: - 193 GJ/t world average today, assuming electricity supplied at 40% efficiency • Secondary aluminium: - 17 GJ/t world average today – more than a factor of 10 smaller than for primary aluminium • Average of the above (with 18.7% recycled) is 160.3 GJ/t (more than 5 times that of steel)

50. Aluminium Summary (continued): • Future average with 90% secondary and current average energy use separately for primary and secondary Al: 34.5 GJ/t This is a reduction by a factor of 4.6 • Future average with 90% secondary, best projected energy intensities for primary and secondary steel: 23.3 GJ/t This is a reduction by a factor of 6.9 • All of the above plus 60% electricity supply efficiency instead of 40%: 19.1 GJ/t This is a reduction by a factor of 8.4 • Thus, the overall potential reduction in the average primary energy intensity of aluminium is a factor of 5 to 8