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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. - PowerPoint PPT Presentation
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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.
In 2008 is was stated that our resources of copper will last 30 years.
Annual world production (tons/yr)
Use of materials by class (tons)
Sources of Energy
Sunwindwavehydrosolar thermalphotovoltaic
MoonTidal
Nuclear decay
Hydrocarbons
Energy use by source (ExoJoules/yr)
Global energy consumption by source
Global energy consumption by use
Types of Energy
Chemicalfossil fuels, batteries, refined materials
RadiationRF, microwave, infrared, optical, X-ray, gamma...
Thermalhigh grade and low grade heat
Electrical and Magneticstatic and oscillating fields
Mechanicalpotential and kinetic energy
Nucleardecay of unstable elements
Conversion
Energy can be converted from one form to another.
The efficiency, , tells us how well we convert (and how much is lost)
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.
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.
Carnot Efficiency with 150 C output
Approximate efficiency factors
Conversion path Efficiency kg CO2/MJ
Fossil fuel to thermal (enclosed) 100 0.07
Fossil fuel to thermal (vented) 65-75 0.1
Fossil Fuel to electric 33-39 0.2
Fossil fuel to mechanical (steam turbine)
28-42 0.17
Fossil fuel to mechanical (gas turbine)
46-50 0.15
Electric to thermal 100 0.2
Electric to mechanical (elec motors)
85-93 0.23
Electric to chemical (battery) 80-90 0.24
Electric to EM radiation (incand lamp)
15-20 1.17
Electric to EM radiation (LED) 80-85 0.23
Light to electric (PV) 10-20 0
Water
Water and materials
Growth of natural materials (some irrigated, some not)
Cooling cycles (with evaporative loss)
Dust suppression
Washing
Water to produce energy
Energy source Water used (l/MJ)
Grid electricity 24
Industrial electricity 11
Energy direct from coal 0.35
Energy direct from oil 0.3
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.
Reserves vs. Resource BaseO
re G
rade
Rich
Lean
Geologic CertaintyCertain Uncertain
alreadyexploited
Reserves
ResourceBase
Increasedprospecting
Improvedminingtech
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)
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
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
Copper: dynamic and static indices
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?
Market Breakdowns
Supply chain concentration
depend on a few countries/regions... if there are problems...
Cartel Action
Stock piling
Substitutions
Recycling
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.
Rate
(to
ns/
year)
Time
Rate of discoveryProduction rate
Price
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
Real curves are not smooth...
Production and discovery
Reserves
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?
Resource data for exercise
Year Price ($/kg)World production (M-
tons/year)Reserves (M-
tons)
1995 2.93 9.8 310
1996 2.25 10.7 310
1997 2.27 11.3 320
1998 1.65 12.2 340
1999 1.56 12.6 340
2000 1.81 13.2 340
2001 1.67 13.7 340
2002 1.59 13.4 440
2003 1.78 13.9 470
2004 2.86 14.6 470
2005 3.7 14.9 470
2006 6.81 15.3 480
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