ChEn 433 Energy Use

US Energy Use

US Energy Sectors

US Energy Sectors

Note the factors: 1/3 (roughly)

Sources

  • Petroleum: 1/3
  • Natural Gas: 1/3
  • Other: 1/3
    • Renewable
    • Coal
    • Nuclear

End Uses

  • Transportation: 1/3
  • Industrial: 1/3
  • Other: 1/3
    • Residential
    • Commercial

US Electric Generation

See also this Washington Post article

Amounts and splits

  • Why is it important to know energy amounts by type and by use sector?
  • Issues
    • Conservation
    • Energy technology changes
    • Economics, politics, etc.
  • The overall impact needs to be weighted by the impact to the “sector” times the importances of the sector.
    • There’s a name for this ➔ ?
    • Base rate fallacy

Base rate fallacy: NPR

Base rate fallacy: simple example

To bring the lake back to a healthy state would require approximately 29% of additional water resources to be directed back into the lake’s tributaries and the lake itself. —The water that couldn’t save, Deseret News

Base rate fallacy example

  • Suppose COVID tests have a 5% false positive rate
    • meaning, whenever you don’t have COVID the test says you do 5% of the time.
  • You get a positive result.
  • What are the chances you really have it?

Need more information

Base rate fallacy example

  • Suppose 1 in 80 people (1.25%) have COVID
  • COVID test:
    • 100% accurate if you have COVID,
    • but has a 5% false positive rate
  • You test positive
  • What is the probability you actually have COVID?
    • A. 95%
    • B. 80%
    • C. 20%
    • D. 5%
    • E. 1.25%

Base rate fallacy example

  • If there were no false positives and you tested positive, you’d have it 100%
  • Consider 80 people
    • 1 has COVID
    • 79 don’t
    • positive tests:
      • 1 that has COVID
      • 79 * 5% = 3.95 who don’t
    • chances of having COVID given the positive test = 1/(1+3.95) ≈ 1/5 = 20%
  • Only 1/80 have it, but the test says 5/80 do.
  • The question is, given a positive test what are the chances of having COVID?
    • The “base rate” is 5, not 80, and the answer is 1/5 not 1/80.

Base rate fallacy example: Bayes’ law

\[P(C|+)P(+) = P(+|C)P(C)\] \[P(C|+) = \frac{P(+|C)P(C)}{P(+)}\] \[P(C|+) = \frac{(1)(1/80)}{\underbrace{1/80}_{\mbox{+ test, have COVID}} + \underbrace{0.05(79/80)}_{\mbox{+ test, no COVID}}} = 20.2\%\]

Units

  • What were the units of energy on the first couple slides?
    • Quadrillion Btu (per year)
  • What’s a Quadrillion Btu?!

Units

The US generated 4494 Terawatt-hours of electricity in 2023.
Convert this to the following units:

  • Quadrillion BTUs in 2023
  • Gigawatts (GW)
  • Number of average size (world) coal power plants at 878 MW each; use a capacity factor of 0.8.
  • Number of wind turbines at 3 MW; use a capacity factor of 0.3.
  • Number of olympic size swimming pools vaporized per minute (heated from 25 C, then boiled).
  • Number of cubic miles of oil (oil equivalent, that is, needed to produce the electricity).
  • Number of Boeing 747 flights around the world

There is something wrong with second two bullets? Can you see what it is?

Capacity, Availability, Efficiency

  • Availability factor is the fraction of time a plant can produce power
  • Capacity factor is the power output in some time period divided by the maximum possible output.
    • Capacity factor is lower than availability
    • Since the plant might not always be running at full power.
  • For solar, availability is like the fraction of time the sun is shining.
    • capacity factor accounts for this and the fact that the sunlight isn’t always at it’s peak power (time of day/year, clouds, etc.)
  • Efficiency in power production is the electricity produced divided by the energy input.
    • Coal plant: electricity produced divided by the heat energy of the coal burned
    • Solar: electricity produced divided by the solar energy striking the panels
    • Hydro: electricity produced divided by the potential energy change of the water

Capacity factor

These are actual utilizations, not necessarily the maximum possible capacity factors after considering maintenance, etc., that is, availability

World energy use

Energy use by country

  • China and the US consume as much energy as the next 26 countries combined.

World energy consumption history

EI statistical review of world energy

World energy consumption history

EI statistical review of world energy

Observations?

  • Nearly linear trend over 60 years.
  • This trend is scary when we think about the limited nature of our primary energy sources.
    • How many wars are fought over resources?
    • Water, energy, food nexus
    • This plot, and associated climate change drives the push for renewable energy.
  • Compare this plot to economics/recession.

A sense of scale: Costs

Replacing the current world oil, gas, coal, and electricity production capacity could cost about $10 trillion (current [2010] dollars) or about one-fourth of annual GWP. In 2000, investment in energy supply systems was estimated to be 15-20% of total capital investment, or 3-4% GWP.

We need to bear in mind that these past investments have been worth many trillions of dollars, and no substantial change in the overall pattern of energy production or use will take place without comparable new investments. Investments on the order of $50 billion, such as those being made in nuclear power plants globally over the next decade, are substantial, but they pale compared with the total cost of the effort we face, which as we just saw runs into the tens of trillions of dollars. —Crane et al. “A Cubic Mile of Oil”

A sense of scale: 1 CMO of Wind Turbines

  • 2,478,571 average sized land-based wind turbines


3 CMO for typical wind farm area

A sense of scale: 1 CMO of Wind Turbines

  • Questions?
    • where to get the land?
    • does the wind blow well there?
    • how far away is the power destination?
    • compare the copper (etc.) to the annual production.
      • or amount of known resource.
    • how long do they last?
    • can the blades be recycled, landfilled?
    • affect on birds, noise, neighbors


3 CMO for typical wind farm area