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Resource consumption

Resource consumption. Rates of growth. Linear, exponential, geometric Some resources are so abundant we don’t think about exhaustion Al, Ca, Cl, H, Fe, Mg, N, O, K, Si, Na, S We should be careful about alarms. In 1930, it was stated that our resources of copper will last 30 more years.

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Resource consumption

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  1. Resource consumption

  2. Rates of growth • Linear, exponential, geometric • Some resources are so abundant we don’t think about exhaustion • Al, Ca, Cl, H, Fe, Mg, N, O, K, Si, Na, S • We should be careful about alarms. • In 1930, it was stated that our resources of copper will last 30 more years. • In 2008 is was stated that our resources of copper will last 30 years.

  3. Annual world production (tons/yr)

  4. Use of materials by class (tons)

  5. Sources of Energy • Sun • wind • wave • hydro • solar thermal • photovoltaic • Moon • Tidal • Nuclear decay • Hydrocarbons

  6. Energy use by source (ExoJoules/yr)

  7. Global energy consumption by source

  8. Global energy consumption by use

  9. Types of Energy • Chemical • fossil fuels, batteries, refined materials • Radiation • RF, microwave, infrared, optical, X-ray, gamma... • Thermal • high grade and low grade heat • Electrical and Magnetic • static and oscillating fields • Mechanical • potential and kinetic energy • Nuclear • decay of unstable elements

  10. Conversion • Energy can be converted from one form to another. • The efficiency, , tells us how well we convert (and how much is lost)

  11. Losses • Energy conversion usually has low grade heat as a by-product, which is lost. • Exception is electrical to thermal, which has 100% efficiency • Refining of metals, for example, involves conversion of thermal or electrical energy to chemical energy. Theoretically that energy could be recovered by allowing the metal to oxidize again. But the effiency is too low to be useful.

  12. Conversion Efficiencies • There are limits to the conversion efficiencies. Consider thermal to mechanical. • Carnot taught us that • where Tin is the temperature entering the heat engine and Tout is the exit temp.

  13. Carnot Efficiency with 150 C output

  14. Approximate efficiency factors

  15. Water

  16. Water and materials • Growth of natural materials (some irrigated, some not) • Cooling cycles (with evaporative loss) • Dust suppression • Washing

  17. Water to produce energy

  18. Reserves • a mineral Reserve, R, is that part of a known deposit that can be extracted legally and economically at the time it is determined. • Reserves are an economic construct, which change depending on economics, technology and legislation • The Resource Base is the real total. This includes things we don’t know how to extract and estimates unknown deposits.

  19. Reserves vs. Resource Base Rich already exploited Increased prospecting Reserves Ore Grade Improved mining tech Resource Base Lean Geologic Certainty Certain Uncertain

  20. Reserve movement • Commodity price (increased prices, increases reserve) • Improved technology (increase reserve) • Production costs (increased costs, reduce reserve) • Legislation (can go either way) • Depletion (if production exceeds discovery, reduces reserve)

  21. Time to Exhaustion • Balance between supply and demand • Suppose the reserve is R, measured in total tons of material • Let P be the production rate measured in tons per year. • The the static index of exhaustion, tex,s will be • tex,s = R/P

  22. Dynamic Index • The static index of exhaustion assumes there is no growth. • Production rate can increase, for example. • If r is the rate of production increase per year, then the dynamic exhaustion is

  23. Copper: dynamic and static indices

  24. Market Efficiency • We are assuming an efficient market - the supply and demand are in balance • If demand increases, then technology/economics offset. • What happens if the market forces don’t work?

  25. Market Breakdowns • Supply chain concentration • depend on a few countries/regions... if there are problems... • Cartel Action • Stock piling • Substitutions • Recycling

  26. Real criticality issues • The criticality of a resource is actually more complicated. • The resource base is finite (although partly unknown). The reserves increase for a while and then decrease when prospecting is saturated. • The exploitation (production) begins to consume the reserve, reducing it. • At some point, the rate of production exceeds the rate of discovery. Then prices rise, and criticality is pending.

  27. Price Rate (tons/year) Production rate Rate of discovery Time

  28. Indicators of criticality • Rate of growth of discovery falls below rate of growth of production • Production rate starts to decline • Minimum economic ore grade falls • Prices start to rise

  29. Real curves are not smooth...

  30. Production and discovery

  31. Reserves

  32. Exercise • Consider the following data about a resource (next slide). • Examine the trends (graph price, production and reserves vs time). What conclusions can you reach? • Calculate the static index of exhaustion. What does the result suggest about the reserves?

  33. Resource data for exercise

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