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On Economic Growth, Energy Consumption and Technological Change Jussieu 24 Avril 2006 Dr Benjamin Warr Professor Robert Ayres.

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Présentation au sujet: "On Economic Growth, Energy Consumption and Technological Change Jussieu 24 Avril 2006 Dr Benjamin Warr Professor Robert Ayres."— Transcription de la présentation:

1 On Economic Growth, Energy Consumption and Technological Change Jussieu 24 Avril 2006 Dr Benjamin Warr Professor Robert Ayres

2 Introduction to INSEAD Two fully connected campuses in Asia (Singapore) and Europe (France), 143 faculty members from 31 countries, 880 MBA participants, 55 executive MBAs, over 7000 executives and 64 PhD candidates. On both campuses, faculty conduct leading edge research projects with the support of 17 Centres of Excellence.

3 Sommaire Critique de lapproche «neo-classique » de la croissance économique Considération de la rôle dénergie Estimation dune « proxy » mesure de Technologie Développement dune méthode pour estimer la croissance du Produit Intérieur Brut.

4 Problématique Lapproche neo-classique économique –Ignore lenvironnement et des ressources naturelles Comme facteur de production Comme bien collectif –Considère la technologie comme exogène, continue et perpétuelle. Mais le progrès technologique est plutôt non linéaire (learning by doing) avec des limites

5 Une fonction de production Décrit les relations entre le « output » (PIB) et les « inputs », (les facteurs de production) Cobb-Douglas ont développe la forme le plus utilisé, Y = A K L where + = 1 Y=PIB, A=technology multiplier, K=capital, L=labour, et les élasticités de production

6 Quelques problèmes Les ressources naturelles exclus…. Constant returns to scale (rendement constant) Le dérivative défini la productivité marginal de chaque facteur en tant que constant, égal au « factor cost » =0.3 capital, =0.7 labour. Static substitution Rendu dynamique avec multiplicateur technologie (A), lerreur dune modèle OLS. PAS de RETROACTION suites aux changements dans le quantité et qualité du bilan énergétique.



9 Observations Même avec inclusion des ressources naturelles (B) le PIB estimé est inférieur au valeur empirique si on utilise les « factor costs » pour définir les paramètres. Le progrès technologique (lerreur) est responsable pour plus que 80% de la croissance. Si on utilise pour prévision on est obligé de faire lhypothèse que la technologie va développer comme avant. La croissance économique est assuré malgré nos actions.

10 Industrial Metabolism (Ayres and Simonis 1994) New conceptualisation of societys relation to and pressures on the environment. The economy is physically embedded into the environment. The economy is an open-system with regards matter & energy. Matter and energy societal throughputs must => minimum requirements = technological progress. RESOURCE SCARCITY: Societies intervene with purpose to gain better access to supplies of natural resources (through technology and resource substitutions.i.e. energy) – a supply-side problem. ASSIMILATIVE CAPACITY: Societies must restrict waste flows to the environment (output side).

11 The Salter Cycle, an engine for growth.

12 Criteria for Environmental Accounting Environmental accounting must be: –Politically relevant – strength of the concept to provide information for policy decision and public discourse. –Feasibility often requires reduced complexity –Definition of scale and then system boundaries –Accurate source information –Methods to estimate stocks & flows

13 Energie comme facteur de production – quel mesure faut il? Pas tout lénergie utilisé est utile dans léconomie – conséquence du 2eme loi de Thermodynamique. Faut considérer la quantité plus qualité de lénergie utilisé Faut quantifier le progrès technologique et leffet sur la quantité et le façon quon utilise énergie.


15 Task efficiency: specify service & define the task The first objective of any technical study of energy use is to establish a standard of performance. What is the difference between a service and a task? –(service) keeping warm, (task) providing heat to a home –(service) structures in society, (task) making aluminium –(service) mobility, (task) moving a vehicle Services must consider non-technical trade-offs, tasks require only a physics perspective. This permits, a)Evaluation of the efficiency of present uses. b)Definition of goals towards which technical innovation can strive.

16 Thermodynamics and « available work » Necessary to define a Minimum Task Energy to allow consideration of : Interchanging devices or systems (mass transport vs. Cars) Seeking technological innovations (aluminium for steel) The 1st Law (convervation of energy) is inadequate for considering minimimum task energy. The 2nd law (the entropy law) indicates that « in any process involving heat, there is an inexorable increase of entropy (disorder), meaning that not all the energy is available in useful form »

17 The 1st Law (conservation of energy) is inadequate for considering minimimum task energy. η = energy transfer (of desired kind) / energy input Maximum value may be greater than 1. No explicit consideration of the quality of the energy and its ability to do useful work. Cannot be generalised to complex systems with work and heat outputs.

18 The 2nd law (the entropy law) indicates that « in any process involving heat, there is an inexorable increase of entropy (disorder), meaning that not all the energy is available in useful form » For any device or system the 2nd Law Efficiency ε is the ratio of the minimum exergy that could perform the task (B min ), to the exergy actually consumed in doing the job (B actual ). Its maximum value is 1. Maximising ε minimises exergy demand and wastes generated for a given task.

19 Exergy and Exergy Balance Exergy is the useful part of the energy. There are 4 components: –Kinetic exergy of bulk motion –Potential gravitational or electro-magnetic field differentials –Physical exergy from temperature and pressure differentials –Chemical exergy arising from differences in chemical composition We can ignore the first two for many industrial and economic applications.

20 Exergy or « Available Work » So, not all energy can be made available in useful form (consequence of 2nd Law). Available work is an energy measure that is actually consumed in a process. Work is the highest quality (lowest entropy) form of energy. It is often called exergy. Exergy = The maximum amount of work that a subsystem can do on its surroundings as it approaches thermodynamic equilibrium reversibly. Exergy is proportional to the future entropy production, but has units of energy. Exergy is gained or lost in physical processes. Minimising exergy consumption is a measureable objective to optimise energy consuming tasks.




24 Example: Chemical exergy Production of pure iron (Fe 2 ) from iron oxide (Fe 2 O 3 ) This requires exergy from burning coke (pure carbon) Carbon dioxide (CO 2 ) is the waste product 2Fe 2 O 3 + 3C 4Fe + 3CO 2 Correct mass balance – all atoms in ome out. Conversion of mass causes inevitable joint product CO 2 0.75 moles of CO 2 per Kg of Fe.

25 Iron production 1 1.2Fe 2 O 3 + 3C 4Fe + 3CO 2 2.Making 4 moles of Fe requires generation of 3 moles of CO 2 3.And 1505.6 Kj which comes from this oxidation of carbon 4.But 3 moles of C contain only 1230.9 5.We need 0.76 C extra. WeightkJ/mole exergy Fe56376.4 Fe 2 O 3 16016.5 C12410.3 CO 2 4419.9 O2O2 324.4

26 Iron Production 2 2Fe 2 O 3 + 3C 4Fe + 3CO 2 Correct mass balance, incorrect exergy balance 2 Fe 2 O 3 + 3.76 C + 0.76 O 2 4 Fe + 3.76 CO 2 (33.0) (1542.7) (3.0) (1505.6) (74.8) On the input side oxygen has been added to fulfill the balance of the extra C required 1580 kJ in 1580 kJ out This is for an ideal reversible transformation. No entropy generated or exergy lost. Hence 0.94 moles of waste CO 2 are inevitable per mole Fe produced (corresponds to 0.74kg CO 2 per kg Fe) This is the thermodynamic minimum.

27 Iron Production: Reality The 410.3 kJ/mole from source C is never used 100% efficiently Blast furnace average have efficiencies of 33%. So, one mole of C one obtains only 135.4kJ As a result need 12.42 moles of C instead of 3.76. 2 Fe 2 O 3 + 12.42 C + 9.42 O 2 4 Fe + 12.42 CO 2 + heat (33.0) (5095.9) (37.7) (1505.6) (247.2) B lost = 3413.8 kJ 2/3 rd of waste produced is unecessary.

28 Types of Exergy Service Prime Movers ( electricity) Transport High Temperature Process Heat Mid and Low Temperature Process Heat Lighting Non-Fuel

29 Petroleum Exergy Flows

30 Coal, Petroleum, Gas: Exergy breakdown by use, US 1900-2000 Declining fraction to heat Increasing fraction to electricity Transport uses

31 Total Exergy Breakdown by Use, US 1900-2000 Heat Other Prime Movers Electricity Non-Fuel

32 Lighting Efficiency

33 Simplified process view: Aluminium


35 Efficiencies and GDP/Exergy Input

36 Technical efficiency, US 1900-2000

37 Useful Work/GDP Ratios, US 1900-2000 1st Oil Crisis - US Peak Oil Production

38 How does our model work ? Cobb-Douglas or LINEX A t the total factor productivity is REMOVED R t natural resource services replaced by Useful Work, where U = F * R F t technical efficiency of energy to work conversion

39 REXS economic output module

40 Labour supply feedback dynamics Parameters for USA 1900-2000 Structural Shift Time C=1959, Structural Shift Time D=1920 F Labour Fire Rate A=0.108,F Labour Fire Rate B=0.120 F Labour Hire Rate A=0.124F Labour Hire Rate B=0.135

41 Labour hire and fire parameters

42 Labour – validation by empirical fit

43 Capital accumulation feedback loop Parameters for USA 1900-2000 Investment Fraction A=0.081Investment Fraction B=0.074 Depreciation Rate A=0.059Depreciation Rate B=0.106 Structural Shift Time A=1970Structural Shift Time B=1930

44 Capital investment and depreciation

45 Capital – validation by empirical fit

46 Output – validation of full model, US 1900-2000

47 LINEX fits for GDP, Japan and US 1900-2000.


49 A commonly used reference mode

50 The REXS alternative Average rate of decline 1.2% per annum

51 The dematerialising dynamics

52 Primary exergy intensity (B/GDP) of output decay feedback mechanism. Parameters Rate of Decay = Fractional Decay Rate*Primary Exergy Intensity of Output Fractional Decay Rate=0.012 To the right: Processes aggregated in the REXS dynamics

53 Projections of future output Altering the future rates of the energy intensity of output The average decay rate of the exergy intensity of output (R/GDP) for the period 1900-1998 is 1.2% The simulations involved increasing or decreasing this parameter from 1998 onwards, while keeping the values of all other parameters fixed. The following illustrations provide a summary of the results.

54 Varying rates of dematerialisation The constant rate of exergy intensity decline was altered to vary between – 0.55 and –1.65 % p.a.

55 Effects on efficiency improvements The business as usual case: If technical efficiency does not increase in pace with de- materialisation The rate of growth slows.

56 GDP forecasts dematerialisation scenarios,US 2000-2050 The sensitivity of future projections of GDP were assessed, the red line indicates the business as usual for a fractional decay rate of energy intensity of output –1.2 % per annum and technical efficiency at 1% p.a.

57 Historical and forecast GDP for alternative rates of decline of the energy intensity of output, US 1900-2000

58 Forecast GDP growth rates for three alternative technology scenarios (US 2050). Alternative Technology Scenarios LowMidHigh Growth ratefGDPf f Minimum0.16%-2.97%0.43%-1.89%1.11%1.94% Average0.40%-1.29%0.72%0.38%1.18%2.20% Maximum0.62%0.92%0.89%1.75%1.23%2.63% Note the feedback between f growth and GDP growth

59 Historical and forecast technical efficiency of energy conversion, for 3 alternative rates of technical efficiency growth, US 1950-2000.

60 Historical and forecast GDP, for 3 alternative rates of technical efficiency growth, US 1950- 2050

61 Conclusions Travail utile comme facteur de production Application du 2° loi pour « proxy » de progrès technologique Fonction LINEX et représentation Systèmes Dynamique permettant –Estimation historique –« substitution dynamique » suite aux progrès –Feedback entre progrès technologique et le quantité et qualité des sources énergétique et lefficacité dutilisation

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