Not long ago Milan wrote a great post about "Numbers to know in Neurotech", inspired by Cell Biology by the Numbers, Physiology by Numbers, and Latency Numbers Every Programmer Should Know.

I love artifacts like these. They give intuition for scale, the ability to do napkin math, and act as some vaccination against bullshit when sifting through PDFs/conversations. Here are some helpful numbers for working in energy!

Caveats:

• Will be North America centric This might be incomplete, mostly from what I’ve researched/worked with (high voltage, DAQ, signals, software, economics)

Shoutout to Charles Yang for the input and Raffi Hotter for surfacing this idea.

Molecular

Conversions

• Avogadro's number is 6.022 × 10^23 particles/mole
• Boltzmann constant (k) is 1.380 × 10^−23 J/K
• Standard temperature and pressure (STP) is 0°C (273.15 K)
• 1 MCF (thousand cubic feet) ≈ 1,000,000 BTU ≈ 293 kWh

Matter

• Speed of light is ~2.998 x 10^8 m s
• Charge of electron ~1.602 × 10^-19 coulombs
• Vacuum permittivity is ~8.850 × 10^-19 coulombs
• Conductivity of common conductors at 20°C (Source)
  • Silver - 6.30 × 10^7 S/m
  • Copper - 5.96 × 10^7 S/m
  • Aluminum - 3.82 × 10^7 S/m
  • Iron - 1.03 × 10^7 S/m
  • Graphite - 1.01 × 10^5 S/m
  • Water - 10.00 × 10^3 S/m
  • Conductivity of common insulators
  • Water - 2 × 10^-4 S/m
  • Glass - 10 × 10^-10 S/m
  • Oil - 10 × 10^-12 S/m
  • HDPE - 10^-14 S/m - Very good, common cable insulator

Electronics

Power

• Common analog IC logic voltage levels are usually 3.3 or 5V
• Typical diode forward voltage:
  • ~0.6-0.7 V (Si, p-n)
  • ~0.15-0.45 V (Schottky, n) - Lower because of barrier height
• Silicon has a band gap of ~1.1 eV

Capacitors

• For reliable digital logic levels, noise margins are <10% of the supply voltage
• Decoupling capacitors should be placed as close to IC power pins as possible to filter out noise, 0.1µF capacitors are typical for high-frequency noise
• For every 10°C increase in operating temperature, the reliability of electronic components can be halved (Arrhenius equation)

Inductors

• Operate below 80% of inductor’s rated saturation current to avoid non-linear, a mix of magnetic saturation and hysteresis

Signals

• Trace length should be < 1/6 of signal rise time
• Nyquist sampling theorem, sampling rate must be twice has high as highest frequency to recreate signal
• For CANBUS wires, 1 twist per inch with ~120 Ohm resistor at the ends for impedance matching
• Clock signal inside a personal computer has a high frequency of ~3GHz

Generation

General

• World electricity consumption is ~23,000 TWh (Source - 2019)
• U.S. power grid (as of 2021):
  • Over 11,070 power plants
  • early 160,000 miles of high-voltage power lines, and millions of miles of low-voltage power lines and distribution transformers
    • About 600,000 miles of transmission lines
  • Serves 155 million “customers”. 1 customer can include multiple people (source) Note that these aren’t people
• Current Sources
  • Natural Gas: 40.3%
  • Nuclear: 19.7%
  • Renewable: 19.8% (Wind 8.4%, Hydropower 7.3%, Solar 2.3%, Biomass 1.4%, Geothermal 0.4%)
  • Coal: 19.3%
  • Petroleum: 0.5%
  • Other: 0.4% (Source: U.S. Energy Information Administration)

Embodied energy

• Hydrogen is ~39 kWh/kg Hydrogen - ~39 kWh/kg (lower heating value) Gasoline - ~12.2 kWh/kg Lithium-ion battery - ~0.1-0.265 kWh/kg